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Determination of Iron: Colorimetric o-Phenanthroline Method
... The results of quantitative analyses for total and soluble iron and manganese of the midsection fractions of active leaves of pineapple plants in the various treatments are presented in table 10. They provide no conclusive evidence of a direct relationship between the iron and manganese content of the plant tissues analyzed and yields of pineapples reported in table 1. ...
... The results suggest that the use of lime in pineapple growing is not a sound agricultural practice, insofar as the correction of soil iron-manganese imbalance, and its detrimental effects on the crop are concerned. 10. The results also underline the possibility that factors other than the availability of iron and manganese adversely affect pineapple production in the Island. ...
This paper reports the results obtained in studies carried out to establish the relationship between iron and manganese imbalance in the soil and remedial treatments on pineapple growth, development, and production. In addition to lime carbonate, organic matter in the form of filter press cake was also tested as a soil remedial treatment.
... Available iron was determined after extraction from the soil with Morgan's universal extracting solution, normal sodium acetate bufiered at pH 4.8, with acetic acid as used for extraction of phosphorus from soil. The Saywell and Cunningham o-phenanthroline method was used for iron determination (9). Available or exchangeable manganese was run according to Peech's procedure and was determined by the periodate method of Peech (6). ...
... The highest yields were directly related to the lowest soil pH and highest organic-matter and nitrogen content of the soil from the filter-press cake treatment. 9. Except for one case, no definite relationship was found between the iron and manganese content of the plant tissue analyzed and yield of pineapples. ...
This paper presents the results of further studies carried out to establish the relationship between iron and manganese imbalance in the soil and remedial treatments on pineapple growth, development, and production.
... To investigate the concentration of dissolved iron in the aqueous phase, a colorimetric method was used with oligophenanthroline [24][25][26]. Saywell [27] noted that ferrous ortho-phenanthroline complex ions exhibit a highly stable, vivid red colour, the intensity of which is directly proportional to the amount of iron. Ortho-phenanthroline reacted instantaneously with divalent Fe, forming a colored complex of [Fe(C 12 H 8 N 2 ) 3 ] + 2 . ...
This work employed a simple colorimetric method (UV-Vis spectroscopy) to measure the concentration of ferrous ions resulting from steel corrosion by using the ortho-phenanthroline method. ortho-Phenanthroline is a chelating agent that forms a stable ferrous complex with ferrous ions. Thus, this colorimetric method was used to measure the characteristics of corrosion and inhibition processes. Consequently, the properties of the expired pentoxifylline medication were assessed as an anti-corrosion agent for steel in a 0.2 M HCl solution. The concentration of dissolved iron was used to calculate the inhibition efficiency and corrosion rate. Additionally, studies on the synergistic impacts of pentoxifylline and potassium iodide (KI) have been conducted. After adding potassium iodide, the maximal pentoxifylline inhibitory efficiency of 88% rose to 94%. The free energy of adsorption was computed by fitting several adsorption isotherms. The limitations of this method include the use of the Beer-Lambert equation, which limits the measurement of ferrous ions in corrosive environments to a maximum of 21 parts per million.
... The iron concentration was quantified by measuring the absorbance at a wavelength of 510 nm using the 1,10-phenanthroline method (Saywell & Cunningham, 1937). The COD was determined by the potassium permanganate index (MnI) according to the protocol recommended by NF T90-050:1989 (Cardot & Gilles, 2013). ...
In this work, methyl orange degradation was investigated using iron-modified dolomite prepared by simple impregnation of iron followed by calcination at 500 °C for 4 h. The natural dolomite before and after modification was subjected to comprehensive characterization utilizing various techniques. XRD and FTIR analysis confirmed the preservation of the dolomite structure and functional groups. The chemical composition obtained by XRF and EDX showed a successful insertion of iron into the dolomite structure with an increase from 1.3 to 5.3 wt % of this metal. The study of the reaction parameters showed that decolorization performance significantly depended on the temperature, catalyst dosage, H2O2 concentration and initial dye concentration. In addition, kinetics reaction followed the first-order model with rate constants in the range 3.2·10–2 to 45·10–2 min⁻¹. The thermodynamic study revealed that the reaction was endothermic (ΔH° = 65.48 kJ/mol) and accompanied by a decrease in the disorder (ΔS° = -0.055 kJ/mol·K). The activation energy value (Ea = 63.98 kJ/mol) showed that the process was controlled by a surface reaction. The modelling using central composite design (CCD), with 40 experiments performed to complete the matrix of the experimental design established the optimum reaction conditions at C0 = 40 mg/L, 0.93 g/L of catalyst dosage and 7.26 mM of H2O2 concentration. The catalyst preserved high performance and stability after six successive cycles (90.23% decolorization efficiency) with a low iron leaching of less than 0.75 mg/L. The final effluent showed low ecotoxicity with a chemical oxygen demand (COD) lower than 8.23 mg O2/L.
... The dilution medium used is 5-10% hydrochloric acid solution. The concentration of Fe(II) was determined using the colorimetric O-phenanthroline method [41], and the concentration of Fe(III) was calculated by the following equation: C Fe(III) = C (total Fe) -C Fe(II) , where C (total Fe) was measured using ICP-AES. The analytical results for the concentrations are presented in Table 1. ...
Currently, removing arsenic (As) from ZnSO4 solution using lime presents several drawbacks, including high wet precipitate content, long reaction time, and the introduction of new impurities. In this study, we propose a novel ultrasonic (US) ozone one-pot method for effectively removing As from a high-arsenic ZnSO4 solution. In this method, as in ZnSO4 solution was removed by ultrasound enhanced ozone oxidation combined with zinc roasting dust (ZRD). No secondary pollution will occur with the addition of ZRD and ozone, as neither introduces new impurities. The experimental results show that under the conditions of initial As and Fe concentrations of 1640 mg/L and 2963 mg/L, US power of 480 W, frequency of 20 kHz, reaction temperature of 60 °C, reaction time of 1 h, ZRD dose of 12 g/L and gas flow rate of 900 mL/min, the removal rate of As can reach 99.4%. The introduction of US can further enhance the oxidation effect of ozone on As(III) and Fe²⁺ by increasing the solubility of ozone and promoting the production of •OH radicals. Additionally, US cavitation and mechanical action increase the probability of contact between various reactants in the solution, facilitating the occurrence of reactions. US also reduces the aggregation of arsenic-containing precipitates and the encapsulation of ZRD by arsenic containing precipitates, thereby decreasing the amount of arsenic-containing precipitates. In comparison to the traditional lime method, this approach results in a significant reduction in the amount of arsenic-containing precipitate by 54.5% and a 60% decrease in the total reaction time. The As removal mechanism of our method encompasses ZRD neutralization, US-enhanced ozone mass transfer and decomposition, oxidation of As(III) and Fe²⁺, and adsorption and coprecipitation. Consequently, the proposed method provides a cost-effective, fast, safe and environmentally friendly alternative for treating arsenic-contaminated ZnSO4 solutions.
... For the quantification of the dissolved iron (II) in the filtrate, the 1,10-phenanthroline modified complexometry method was used and the complex was then analyzed at the wavelength of λ = 510 nm [40]. ...
... Here C 0 is the initial dye concentration (mg/L), C t represents the dye concentration at different times (mg/L) and k 1 is the first-order reaction rate constant (min −1 ). The iron concentration in the reaction medium was determined by the ortho-phenanthroline colorimetric method using UV-1606 Shimadzu at 510 nm [24]. Fig. 1a represents the XRD patterns of the montmorillonite before (Ma) and after modification (Fe-Ma). ...
In this investigation, a low-cost catalyst was prepared using a natural Maghnia sodic bentonite submitted to a simple ion exchange process and calcination at 500 °C for 3 h. This material was used in the removal of methyl orange (MO) dye by heterogeneous Fenton oxidation. The chemical composition was quantified by XRF and EDX and showed a significant increase in the iron content indicating a successful insertion of the iron within the clay reaching 5.98 wt%. Furthermore, XRD and FTIR analysis showed that the clay preserved its crystalline structure with the presence of montmorillonite as the main phase with some loss of characteristic peaks related to hydroxyl groups due to the calcination. Moreover, the specific surface area increased from 56 to 86 m2/g after the ion exchange treatment. High catalytic activity was reached, achieving the complete decolorization of the dye solution after only 10 min at T = 65 °C, [H2O2] = 9.8 mM and mcatalyst = 1 g/L. The kinetic constant rates were calculated by adjusting the experimental data to the nonlinear first-order model. The positive value of enthalpy variation (∆H° = 23.70 kJ/mol) indicated the endothermic nature of the process. The reaction rate was also found to be controlled by diffusion with an activation energy smaller than 29 kJ/mol (Ea = 26.35 kJ/mol). The reusability of the catalyst was also examined showing high degradation efficiency (90%) even after 8 cycles. The catalyst showed low iron leaching during reaction experiments even in an acidic medium at 65 °C.
... The mixture was then transferred to sample bottles ready for machine analysis. After the analysis the mineral content was read in an atomic absorption spectrophotometer model PG-990 (PG Instruments Limited, UK) [16]. ...
Cowpea leaves are lost annually due to infestation and spoilage when being transported to clients and the losses at the local markets are brought on by inadequate postharvest handling procedures and market glut, particularly during peak seasons. High moisture content from the cowpea leaves at harvest stage may contribute to increased spoilage hence lowering quantity and quality. The choice of appropriate harvesting stage and drying method can help to reduce this problem. The aim of this study was to determine the best harvesting stage and efficient drying method that would maintain high leaf nutrient composition. Cowpeas variety M66 was used for the research and the treatments included three harvesting stages (21, 35 and 49 days after sowing [DAS]), three drying methods (open sun, solar dryer and oven. Data was collected on iron, calcium, crude fibre, beta carotene, protein and moisture content. The data was subjected for variance using Statistical Analysis System 9.2 edition and significantly different means separated using least significant difference at 5%. The results indicated significant (p<0.05) differences in moisture, calcium, proteins, beta carotene and crude fibre content in both trials. Harvest stage and drying method did not significantly (p<0.05) influence the iron content. Oven and solar drying methods showed better nutrient and mineral retention in the three harvesting stages when compared to the open sun drying method.
... The H 2 O 2 concentration was measured by the spectrophotometric Eisenberg method, using titanium(IV) oxysulfate (TiOSO 4 ), which shows an absorption maximum wavelength (λ) at 406 nm (Eisenberg, 1943). The Fe 2+ concentration was measured by the spectrophotometric 1, 10-phenanthroline method at λ = 510 nm (Saywell and Cunningham, 1937). The decay of coumarin was monitored spectrophotometrically, at λ = 277 nm (Medel et al., 2020;Montanaro et al., 2017). ...
Conventional peroxi-coagulation process is based on the combined occurrence of electrocoagulation and oxidation in a single unit, since H2O2 and Fe2+ are electrogenerated on site from cathodic and anodic reactions, respectively. The present work aims to evaluate the effect of pH and applied current on the generation of hydroxyl radicals (●OH) from Fenton’s reaction during peroxi-coagulation treatment. The electrochemical cell consisted of a gas-diffusion cathode with graphite cloth, and an iron plate anode. By using a fluorescence probe (coumarin) and kinetic modeling, it has been possible to estimate the ●OH concentration at different current values and to determine the effect of pH on their production. A system with six ordinary differential equations was established and solved to predict the concentrations of the main species of Fenton’s reaction. In addition, the interference of possible by-products and side coumarin hydroxylation reactions in the determination of ●OH was considered. The simulation results reveal that current increase from 10 to 50 mA positively influences the ●OH generation, further decreasing when operating at 70 mA. This is attributed to: (i) the negative effect of an excessive H2O2 generation, and (ii) the increase in pH during the electrolysis. This latter phenomenon is detrimental because of the partial precipitation of Fe2+ catalyst. A sensitivity analysis was performed to determine the most influential kinetic constants of the model on ●OH and 7-hydroxycoumarin concentrations. This work demonstrates the importance of considering possible side reactions, which may occur when coumarin is used as a probe compound to quantify the ●OH.
... Dissolved Fe(II) and total dissolved Fe were determined photometrically with an acetate buffered phenanthroline solution at 510 nm (Saywell & Cunningham, 1971). For total dissolved Fe, the samples were pre-reduced with hydroxylammonium chloride. ...
Mitigation measures are needed to prevent large loads of phosphate originating in agriculture from reaching surface waters. Iron‐coated sand (ICS) is a residual product from drinking water production. It has a high phosphate adsorption capacity and can be placed around tile drains, taking no extra space, which increases the farmers’ acceptance. The main concern regarding the use of ICS filters below groundwater level is that limited oxygen supply and high organic matter concentrations may lead to the reduction and dissolution of iron (hydr)oxides present and the release of previously adsorbed phosphate. This study aimed to investigate phosphate adsorption on ICS at the onset of iron reduction. First, we investigated whether simultaneous metal reduction and phosphate adsorption were relevant at two field sites in the Netherlands that use ICS filters around tile drains. Second, the onset of microbially mediated reduction of ICS in drainage water was mimicked in complementary laboratory microcosm experiments by varying the intensity of reduction through controlling the oxygen availability and the concentration of degradable organic matter. After 3 yr, ICS filters in the field removed phosphorus under low redox conditions. Over 45 d, the microbial reduction of manganese and iron oxides did not lead to phosphate release, confirming field observations. Electron microscopy and X‐ray absorption spectroscopy did not evince systematic structural or compositional changes; only under strongly reducing conditions did iron sulfides form in small percentages in the outer layer of the iron coating. Our results suggest that detrimental effects only become relevant after long periods of operation.
... The bottles were mechanically agitated for sixty (60) minutes and phase allowed to separate out. 0.4 mL from the aqueous raffinates was taken with a micropipette and analysed for Cadmium, Nickel and Lead with an Atomic Absorbance Spectrophotometer, while 0.6 mL from the raffinates was taken and analysed for Iron using a UV Spectrophotometer at 520 nm with 0.1 mL of 0.01% 1,10-phenanthroline after addition of 0.1 mL each of 10% CH 3 COONa and 10% NH 2 OH solutions [32]. ...
The role of some common acids CH 3 COOH, HCl, HNO 3 , H 3 PO 4 and H 2 SO 4 in the multi-metal distribution/extraction of Cadmium, Nickel, Lead and Iron from aqueous media buffered to either pH 4.75 or 7.5 using the ligand 4´4-(1E,1E´)-1,1´-(ethane-1,2-diylbis(azan-1-yl-1ylidene))bis(5-methyl-2-phenyl-2,3-dihydro-1H-pyrazol-3-ol) H 2 BuEtP alone and in the presence of 1-(3-hydroxy-5-methyl-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl) butan-1-one (HBuP) was studied using solvent-solvent extraction method. An equilibration time of 60 minutes was used. The extraction raffinates were analysed for Cadmium, Nickel and Lead with an Atomic Absorption Spectrophotometer (AAS) while Iron was colorimetrically determined with 1,10-phenanthroline and absorbances compared with standards and extraction parameters; distribution ratios, percentage % E and number of batches n needed to achieve 99.9% extraction of the four metals calculated. The distribution ratios of the metals were statistically analysed for differences between the two buffers, organic extractants and the acids. All the acids showed good potentials in the selective separation of Iron from Cadmium, Nickel and Lead. The conditions for the use of the different acids for the selective separations of Cadmium/Iron from Nickel/Lead, Nickel/Iron from Cadmium/Lead and Lead/Iron from Cadmium/Nickel were established with calculated number of batches needed to obtain 99.9% extractions of the metals. Only 0.01 M-0.05 M H 3 PO 4 showed good potentials in the mult-imetal extraction of the four metals from an aqueous medium containing the four metals and buffered to pH 7.5 using the mixed ligands H 2 BuEtP/HBuP organic phase and 99.9% extraction of the four metals calculated to be achievable after 9 batches of extractions with fresh organic phase. The synergic effect of the second ligand HBuP was observed in only a few cases.
... Leaching tests were performed following the procedure suggested by Saywell and Cunningham (1937). 0.1 g of each adsorbent sample was introduced in a 20 mL test tube containing 15 mL deionized water, agitated for 24 h at room temperature and then filtered through Whatman No. 1 filter paper. ...
The efficient reduction of accumulated waste biomass and red mud by converting them into a value-added magnetic adsorbent is both difficult and tempting in terms of sustainability. This study focused on investigating the reaction mechanism of co-pyrolysis of different biomasses, including pine wood, cellulose, and lignin, with red mud at 500, 650, and 800 °C, and the comprehensive characterizations of the produced bio-magnetic particles. The performance of biomass and red mud based magnetic adsorbents is also evaluated, and their primary adsorption mechanisms for organic pollutants are revealed by using different organic model compounds. The samples produced at 800 °C showed the best performance. For example, the sample prepared using red mud and pine wood at 800 °C showed the highest adsorption capacity of ibuprofen, which was 21.01 mg/g at ∼pH 4.5, indicating strong π stacking interactions as the dominant adsorption mechanism. When compared to lignin-rich biomass, adsorbents composed of cellulose-rich biomass showed greater adsorption efficacy. The findings show that co-pyrolysis of biomass with red mud can reduce waste while also producing a flexible adsorbent that is magnetically separable and effective at absorbing different organic contaminants from water.
... The slight differences between the two methods go back to the nature of the two methods. For example, the presence of disturbances such as organic matter, polyphosphates, or the presence of metals such as copper in the colorimetric method can make the results far from reality (Mohite 2011;Saywell and Cunningham 1937). ...
One of the problems of calcareous soils is the lack of absorbable iron for plants grown in these areas. Research by various researchers has shown that some rhizosphere-dwelling microorganisms have the ability to solubilize resources containing low-soluble iron and conversion it to soluble and absorbable for the plants. Different mechanisms such as proton secretion, production of organic acids, and production of siderophore can be effective in solubilizing low-soluble iron. Accordingly, in this study, the potential of twenty rhizobacteria for solubilizing low-soluble iron sources (eg, iron phosphate, hematite, and goethite) has been evaluated. The experiment was performed under in-vitro condition in a completely randomized design with three replications. According to the results, three isolates, namely, ZP15, ZC10, and ZP13 were characterized as promising isolates. In the presence of iron phosphate, the concentration of solubilized iron by isolates ZP15, ZP13, and ZC10 was 5.19, 4.35, and 4.27 mg/l, respectively. These values for the isolates ZC10 and ZP13 in the presence of hematite was recorded 6.49 and 5.35 mg/l, respectively, and in the presence of goethite was 7.02 and 6.70 mg/l, respectively. The amount of siderophore production for the three isolates ZP15, ZC10, and ZP13 was 16.47, 17.1, and 31.55 mM, respectively. The high-performance liquid chromatography analysis revealed that the most important acids produced by these isolates were 2-ketogluconic acid (303.8 mg/ml) for ZP15, oxalic acid (246.9 mg/ml) for ZC10, and gluconic acid (100.2 mg/ml) for ZP13, respectively. The molecular and biochemical identification of these three isolates ZP15, ZC10, and ZP13 showed that they belong to the genera Stenotrophomonas, Pantoea, and Agromyces, respectively.
... The absorbance was measured at l ¼ 510 nm by UV visible spectrophotometer (Thermo-scientific evolution 2001). The full method was described by Saywell & Cunningham (1937). This method was used to determine the iron concentration during the treatment and the iron content in the beads. ...
Iron alginate beads (Fe-Alg) were prepared, characterized and implemented for the degradation of amoxicillin (AMX) by the heterogeneous electro-Fenton process using a graphite cathode recovered from used batteries. Scanning electron microscopy (SEM) showed that (Fe-Alg) beads have a spherical shape and the results of energy dispersive spectrometric (EDS) revealed the presence of iron in (Fe-Alg). Optimization of the operating parameters showed that a complete degradation of AMX was achieved within 90 min of heterogeneous electro-Fenton treatment by operating under these conditions: initial AMX concentration: 0.0136 mM, I = 600 mA, [Na2SO4] = 50 mM, pH = 3, T = 25 °C, ω = 360 rpm. The corresponding chemical oxygen demand (COD) abatement was 50%. Increasing the contact time increased the COD abatement to 85.71%, after 150 min of heterogeneous electro-Fenton treatment. The results of the kinetic study by using nonlinear methods demonstrated that the reaction of AMX degradation obeyed to a pseudo-second-order kinetic. Iron content of 4.63% w/w was determined by the acid digestion method. After 5 cycles of use, the Alg-Fe catalyst depletion was only 8%. Biodegradability was remarkably improved after electro-Fenton pretreatment, since it increased from 0.07 initially to 0.36. The heterogeneous electro-Fenton process had efficiently eliminated AMX and it increased the biodegradability of the treated solution. HIGHLIGHTS
The heterogeneous electro-Fenton process was used for the degradation of amoxicillin (AMX).;
The Fe-Alg catalyst has proved its efficiency and stability.;
The kinetic model of the AMX degradation obeyed to a pseudo-second-order.;
The COD abatement and removal yield of AMX were 50% and 100% respectively.;
The heterogeneous electro-Fenton pretreatment improved the biodegradability of the AMX from 0.07 initially to 0.36.;
... The phases were allowed to separate out; 0.1 mL for Cadmium, Lead and Nickel and 0.4 mL for Iron was taken from each aqueous raffinate; analysed by comparing absorbances with standards of each metal; Equations 1 and 2 were used to calculate Distribution Ratios (D) and Percentage Extraction (%E), tabulated in tables and plotted in Figures. Cadmium, Lead and Nickel was analysed with an Atomic Absorption Spectrophotometer while Iron was analysed colorimetrically with a UV Spectrophotometer at 520 nm with 0.1 mL of 0.01% 1,10-phenanthroline after addition of 0.1 mL each of 10% CH 3 COONa and 10% NH 2 OH solutions (Saywell and Cunningham, 1937). ...
Heavy metals toxicity has led to the continuous study of new and efficient methods for their removal from the environment. Solvent extraction method was used to study the potentials of the auxiliary complexing agents Ethylenediaminetetraacetic acid (EDTA), Oxalate (C 2 O 4 2-), Thiocyanate (SCN-) and Tartrate (C 4 H 4 O 6 2-) ions in the simultaneous extraction of Cadmium, Iron, Nickel and Lead from aqueous solutions buffered to either pH 4.75 or 7.5 using the organic extractant 4,4´-(1E,1E´)-1,1´-(ethane-1,2-diylbis(azan-1-yl-1ylidene))bis(5-methyl-2-phenyl-2,3-dihydro-1H-pyrazol-3-ol) (H 2 BuEtP) alone or in the presence 4-butanoyl-2-4-dihydro-5-methyl-2-phenyl-3H-pyrazol-3-one (HBuP). 0.001 to 0.1 M of the auxiliary complexing agents and equilibration time of 60 min was used. Distribution ratios and percentage extraction was calculated using raffinates and metal standard absorbances. EDTA, Oxalate and Thiocyanate ions and pH 4.75 was found not suitable for the multi-metal extraction of the four metals attributed to the formation of very stable complexes with these auxiliary complexing agents' ions masking the extraction of the metals, although statistically, there were no significant differences in most cases between the extractions of the metals in the two buffers. Using the ligand H 2 BuEtP alone with a buffer of pH 7.5 and 0.001 M Tartrate, 7 batches of extraction are theoretically required to achieve 99.9% simultaneous extraction of the four metals as the best result while with the mixed ligands H 2 BuEtP/HBuP organic extractant system, 7 batches are required for 0.001 to 0.005 M Tartrate, 5 batches for 0.05 M Tartrate and 4 batches for 0.01 M Tartrate as the best results. Statistically, there was no significant difference between the two organic phases with the exception being Thiocyanate for Nickel with buffer of pH 7.5 that showed slight synergic effect of HBuP.
... Exchangeable Ca and exchangeable Mg were determined by Ethylene Diamine Tetraacetic Acid (EDTA) titrations [26]. Concentrations of SO 4 2-, available B, DTPA-Fe, DTPA-Cu and Clwere determined by Barium sulfate turbidimetry [27], Colorimetric o-Phenanthroline method [28], sequential extraction method of 0.1M HCl reagent [29], azomethine-H method [30] and Silver chloride turbidimetry [31], respectively. ...
Soil quality is the basis for the development of sustainable agriculture and may be used for evaluating the sustainability of soil management practices. Soil quality status and integrated soil quality index (SQI) in sampled 97 farmlands distributed in 7 barley agro-ecological areas of China were analyzed by using 13 soil chemical parameters. The results showed six principal components totally explained 72% variability for the 13 parameters and identified 9 parameters (includes pH, NH 4 ⁺ -N, NO 3 ⁻ -N, available P, available K, exchangeable Mg, DTPA-Fe, DTPA-Cu and Cl ⁻ ) with high factor loading values as the minimum data set (MDS) for assessing soil quality. Average soil quality of all farmlands is moderate (SQI = 0.62). The SQI of barley farmlands in 7 agro-ecological areas showed the following order: Inner Mongolia Plateau (0.75 ± 0.02) > Yunnan-Kweichow Plateau (0.72 ± 0.06) > Qinghai-Tibet Plateau (0.63 ± 0.08) > Yangtze Plain (0.62 ± 0.10) > Huanghuai Region (0.58 ± 0.09) > Northeast China Plain (0.56 ± 0.07) > Xinjiang Province (0.54 ± 0.07). Total 29 out of 97 farmlands in 7 areas have low SQI level (< 0.55). Hence, these farmlands require urgent attention for soil quality improvement through modification of the soil parameters in the MDS.
... A cuvette with 1.0 cm light path was used. The iron determination followed the o-phenanthroline method (Saywell andGunningham 1937, Fortune andMellon 1937 ...
of production of FeCPs (reactivity loss), and (ii) Fe0- based filters will experience porosity loss with increasing service life (permeability loss). In other words, reactivity loss and permeability loss are inherent characteristics of Fe0-based filters which should be addressed in the design stage. Moreover, designed systems should be tested for months or years, given the incertitude on the kinetics of iron corrosion. The objective of the present work was to design a science-based household filter and to test it for one year in the coastal city of Douala (Cameroon). The work started with a systematic review of available designs and a presentation of two main potentially durable designs. The one with a Fe0/sand filter sandwiched between two biological sand filters (BSFs) was tested with polluted well water from Logpom (Douala, Cameroon) using 300 g of a commercial SW (grade 000; d = 50 m) as Fe0 source. Previous works using Fe0 SW in water filters revealed that grade 00 (d = 25 m) was depleted after some 6 months. The used well water was slightly turbid, polluted with pathogens (total coliforms = 1950 UFC mL−1), and contaminated with nitrate ([NO3−] = 24.0 mg L−1). The following parameters were monitored twice per month for one year in the influent and effluent water of the filter unit: (i) nitrate concentration, (ii) coliform level, (iii) pH value, and (iv) turbidity. The iron concentration and the hydraulic conductivity (permeability) were also determined. Prior to pilot testing, the impact of chloride ions (Cl-) on the efficiency of Fe0 filters was characterized in laboratory column experiments, using the methylene blue discoloration method. Results of laboratory column experiments revealed that the chloride concentrations expected in well waters in Douala would not negatively impact the efficiency of Fe0 filters. The tested design could produce safe drinking water for at least one year. Coliforms (> 99% decrease), nitrate (> 99%) and turbidity (> 96%) were nearly quantitatively removed over the whole testing period and well below the recommended limits of the World Health Organization (WHO). The effluent pH increased continuously from 6.6 to 8.4. The effluent iron concentration was constantly lower than 0.2 mg L−1. These values are within the WHO drinking water quality standards. The initial flow velocity of 20 L h-1 decreased to ~8.33 L h–1 after one year, corresponding to a permeability loss of nearly 41.5 %. At the end, the filter was still producing 200 L of drinking water These results confirmed the suitability of commercial Fe0 SW as efficient material to construct durable water filters for households. It appears that the success of the design relied on the low ratio of Fe0 SW (10 vol %) dispersed in the matrix of sand (90 vol %). The tested design can be immediately be applied practically, provide that appropriate construction materials are found. Future research should include (i) testing lower Fe0 SW ratios (same grade), (ii) testing other grades of Fe0 SW in parallel experiments (1 year or more); (iii) testing the same systems for the removal of arsenic and uranium which are the most widespread natural pollutants. Fe0 SW based water filters can be considered as one of the best tools for the achievement of Goal 6 of the United Nations sustainable development goals (SDGs), despite the threat of COVID-19.
... A cuvette with 1.0 cm light path was used. The iron determination followed the o-phenanthroline method (Saywell andGunningham 1937, Fortune andMellon 1937). The spectrophotometer was calibrated for iron concentrations ≤10.0 mg L −1 . ...
In rural and peri-urban regions of the developing world, many tube wells used as drinking water sources are microbially and chemically polluted. Consequently, hundreds of millions of people lack access to “safe” drinking water worldwide. People drinking tube well water may suffer from preventable water-borne diseases including diarrhea, skin lesions, and cancer. To address this problem, the United Nations have launched the Sustainable Development Goals (UN SDGs) which are regarded as a global urgent call for action by all countries, in a global partnership. The UN SDGs for safe drinking water (Goal 6) aims to achieve universal water supply by 2030. This goal can only be achieved if affordable and efficient water treatment technologies are made available for households and small communities for simultaneous removal of chemicals and pathogens. Ideally, such systems should be constructed using locally available materials and labor. Filtration on metallic iron (Fe0) based beds has been identified as such an appropriate technology and steel wool (SW) a universally available material. Moreover, Fe0-based filters have been designed and disseminated in some parts of the world but have not yet reached global applicability.
A critical review on the abundant literature on using Fe0-based filters for safe drinking water provision revealed that existing devices were not designed on the knowledge basis of the science of aqueous iron corrosion (corrosion science). Iron corrosion induces generation of solid iron corrosion products (FeCPs) which are well-documented contaminant scavengers. FeCPs consisting of Fe-oxide hydroxides are formed in the vicinity of the Fe0 surface and act as a diffusion barrier for dissolved species. Iron corrosion is additionally a volumetric expansive process because the volume of each oxide or hydroxide is at least twice larger than that of iron metal (Fe0). These two main characteristics imply that (i) the efficiency of each Fe0-based filter depends on the kinetics of production of FeCPs (reactivity loss), and (ii) Fe0- based filters will experience porosity loss with increasing service life (permeability loss). In other words, reactivity loss and permeability loss are inherent characteristics of Fe0-based filters which should be addressed in the design stage. Moreover, designed systems should be tested for months or years, given the incertitude on the kinetics of iron corrosion.
The objective of the present work was to design a science-based household filter and to test it for one year in the coastal city of Douala (Cameroon). The work started with a systematic review of available designs and a presentation of two main potentially durable designs. The one with a Fe0/sand filter sandwiched between two biological sand filters (BSFs) was tested with polluted well water from Logpom (Douala, Cameroon) using 300 g of a commercial SW (grade 000; d = 50 m) as Fe0 source. Previous works using Fe0 SW in water filters revealed
that grade 00 (d = 25 m) was depleted after some 6 months. The used well water was slightly turbid, polluted with pathogens (total coliforms = 1950 UFC mL−1), and contaminated with nitrate ([NO3−] = 24.0 mg L−1). The following parameters were monitored twice per month for one year in the influent and effluent water of the filter unit: (i) nitrate concentration, (ii) coliform level, (iii) pH value, and (iv) turbidity. The iron concentration and the hydraulic conductivity (permeability) were also determined. Prior to pilot testing, the impact of chloride ions (Cl-) on the efficiency of Fe0 filters was characterized in laboratory column experiments, using the methylene blue discoloration method.
Results of laboratory column experiments revealed that the chloride concentrations expected in well waters in Douala would not negatively impact the efficiency of Fe0 filters. The tested design could produce safe drinking water for at least one year. Coliforms (> 99% decrease), nitrate (> 99%) and turbidity (> 96%) were nearly quantitatively removed over the whole testing period and well below the recommended limits of the World Health Organization (WHO). The effluent pH increased continuously from 6.6 to 8.4. The effluent iron concentration was constantly lower than 0.2 mg L−1. These values are within the WHO drinking water quality standards. The initial flow velocity of 20 L h-1 decreased to ~8.33 L h–1 after one year, corresponding to a permeability loss of nearly 41.5 %. At the end, the filter was still producing 200 L of drinking water
These results confirmed the suitability of commercial Fe0 SW as efficient material to construct durable water filters for households. It appears that the success of the design relied on the low ratio of Fe0 SW (10 vol %) dispersed in the matrix of sand (90 vol %). The tested design can be immediately be applied practically, provide that appropriate construction materials are found. Future research should include (i) testing lower Fe0 SW ratios (same grade), (ii) testing other grades of Fe0 SW in parallel experiments (1 year or more); (iii) testing the same systems for the removal of arsenic and uranium which are the most widespread natural pollutants. Fe0 SW based water filters can be considered as one of the best tools for the achievement of Goal 6 of the United Nations sustainable development goals (SDGs), despite the threat of COVID-19.
... Finally, PF127DApG SPIOs uptake by fungi was analyzed by phenanthroline method, by measuring the iron content in the biofilms (Figure 3.4-13). 247 Higher absorption of particles was observed after 24 h of incubation, suggesting that more particles attached to mature fungi than to germlings. However, when high amounts of SPIOs (18 ppm/well) were used, there was no difference between samples, indicating saturation. ...
This thesis aimed to evaluate the possibility to use nanoparticles as antifungal drug carriers as well as their potential application in screening and diagnostics of invasive aspergillosis. The interaction of nanogels, superparamagnetic iron oxide nanoparticles (SPIOs) and gold nanoparticles (GNP) with fungal-specific polysaccharides, cells and biofilms was investigated. Firstly, it was evaluated how the charge of nanogels influence their interaction with fungal cells. Linear poly(glycidol)s (pG) and poly(2-methyl-2-oxazoline) (pMOx) polymers were synthesized and further functionalized with thiol groups for preparation of redox responsive nanogels. Results showed that negatively charged nanogels were internalized by the fungi to a much greater extent than positively charged ones. Furthermore, it was investigated how amphiphilicity of polymers used for preparation of nanogels influences nanogel-fungi interaction. It was concluded that nanogels prepared from polymers with degree of functionalization of 10% had the strongest interaction, regardless the length of the alkyl chain. Moreover, amphotericin B-loaded nanogels had a higher antifungal effect and lower toxicity towards mammalian cells than the free drug. In addition, inverse nanoprecipitation of thiol functionalized pGs was shown to be successful for preparation of nanogels with narrow size distribution. It was also demonstrated that crosslinking of the polymeric coating in hydrogel-like network with thiol functionalized pGs improved the SPIOs imaging performance. Finally, it was investigated whether GNPs could be used as model particles for the assessment of targeting to fungi. Fc dectin-1 was conjugated covalently to GNPs decorated with pGs, and binding affinity towards β-glucans was tested by surface plasmon resonance. In summary, this thesis demonstrated evidence for the potential of pG nanogels and pG coated nanoparticles for antifungal therapy and diagnostics of fungal infections caused by A. fumigatus.
... Clcontent in the raffinate phase was measured by an Ion Chromatography ICS-90. Fe 3+ content in the aqueous solution was determined by the o-phenanthroline colorimetric method using Congo red test paper as an acid-base indicator [26]. The contents of Fe 3+ and Cl − in the organic phase were obtained by subtracting the corresponding content in aqueous phase from the total initial content of Fe 3+ and Cl − , respectively. ...
Fe³⁺ is an impurity of the raw phosphoric acid from wet-process route and the waste phosphoric acid from the etching process of electronic industry. The effects of temperature, the Cl⁻ content and TBP dosage on the extraction performance of synthesized extractants to Fe³⁺ in raw phosphoric acid from HCl wet-process route were investigated systematically. The results show that the extractant containing 12.5vol% TBP and 87.5vol% kerosene effectively extracted Fe³⁺ at 293.15K from raw phosphoric acid containing 15.8wt% Cl⁻. The extraction efficiency of 100% was realized by counter-current three-stage extraction. The extract phase was characterized by FT-IR and UV-vis. The results show that Fe³⁺ was extracted by TBP with the form of HFeCl4. The interaction between TBP and HFeCl4 was simulated by DFT (density functional theory). The lowest energy structure, electrostatic potential distribution, energy change, bond level analysis, electron transfer, frontline molecular orbital and other information of the possible complex were simulated systematically. The results of the characterization of the extraction phase and DFT simulation were used to clarify the extraction mechanism and the structure of the complex. The simulation results show that the lone-pair electrons of the P=O double bond in TBP has a strong complexation interaction with the empty orbital of HFeCl4 and a strong bond Fe-O{TBP} is formed in the extraction process. The bond length of formed Fe-O{TBP} is 2.05A, the LBO bond level of Fe-O{TBP} is 0.076 (0.075), the Mayer bond level of Fe-O{TBP} is about 0.16, the ρb values of Fe-O{TBP} bond critical points range from 0.271 to 0.252 e⁻/bohr³. A minimum electrostatic potential of -50.59 kcal/mol is existed in TBP at the vicinity of O atom in P=O double bond. Two maximum electrostatic potential of 69.43 kcal/mol and 69.92 kcal/mol are distributed symmetrically on the opposite sides of the Fe vicinity of HFeCl4. Each HFeCl4 molecule combines two TBP molecules on the opposite sides, and the binding sites are near the O atom of the P=O double bond of TBP and near the Fe atom of HFeCl4. The absolute value of the binding energy is greater than 165kJ/mol. The complexation reaction of TBP and HFeCl4 occurs through the surface electrostatic potential attraction and molecular orbital complementation forms. The results are helpful to understand the extraction mechanism of TBP to extract Fe³⁺ from phosphoric acid.
... The iron content was measured using the phenanthroline colorimetric method [33]. For this, 0.05 g of PPI was dissolved in 50 mL of water, then 1.0 mL of the sample was mixed with 2.5 mL of 10% ascorbic acid solution and 5 mL of 0.1% o-phenanthroline solution. ...
In this study, the optimum synthetic process of the Pyracantha polysaccharide-iron (PPI) complex was studied via response surface methodology (RSM). Its antioxidant and anti-cancer activities were also investigated. It was demonstrated that the optimal conditions for the synthetic process of the complex were as follows: a pH of 8.9, a reaction temperature of 70 °C and a trisodium citrate:polysaccharide ratio of 1:2. PPI were analysis by UV, FTIR, SEM, CD, XRD, TGA and NMR. PPI was able to scavenge the metal ion, ABTS and free radicals of the superoxide anion, demonstrating its potential antioxidant activity. PPI was found to display cytotoxicity to Skov3 cells, as shown by its ability to induce apoptosis and alter gene expression in Skov3 cells. These findings show than PPI may represent a novel antioxidant and chemotherapeutic drug.
... The iron-binding abilities of single IBP and tandem repeat of IBP (4xIBP) were examined in two distinct pH environments, which is pH 5.5 and 7.0. The IBP-bound Fe in the supernatant was determined by orthophenanthroline, which results in a red solution when it binds with Fe 2+ [108]. ...
Background
Pretreatments are commonly used to facilitate the deconstruction of lignocellulosic biomass to its component sugars and aromatics. Previously, we showed that iron ions can be used as co-catalysts to reduce the severity of dilute acid pretreatment of biomass. Transgenic iron-accumulating Arabidopsis and rice plants exhibited higher iron content in grains, increased biomass yield, and importantly, enhanced sugar release from the biomass.
Results
In this study, we used intracellular ferritin (FerIN) alone and in combination with an improved version of cell wall-bound carbohydrate-binding module fused iron-binding peptide (IBPex) specifically targeting switchgrass, a bioenergy crop species. The FerIN switchgrass improved by 15% in height and 65% in yield, whereas the FerIN/IBPex transgenics showed enhancement up to 30% in height and 115% in yield. The FerIN and FerIN/IBPex switchgrass had 27% and 51% higher in planta iron accumulation than the empty vector (EV) control, respectively, under normal growth conditions. Improved pretreatability was observed in FerIN switchgrass (~ 14% more glucose release than the EV), and the FerIN/IBPex plants showed further enhancement in glucose release up to 24%.
Conclusions
We conclude that this iron-accumulating strategy can be transferred from model plants and applied to bioenergy crops, such as switchgrass. The intra- and extra-cellular iron incorporation approach improves biomass pretreatability and digestibility, providing upgraded feedstocks for the production of biofuels and bioproducts.
... CAR was calculated using a partially modified method which has been previously described (8). Briefly, deferoxamine solutions for the standard curve were adjusted to 198, 132, 88, 59, 39, and 26 µM in 0.25M NaOAc pH5.5 and the antibody sample was adjusted to 9 mg/mL (60 µM). 3 A total of 225 µL of sample or standard was added to 96 wells in a plate, followed by the addition of 25 µL of 50 mM Fe (II) to each well. ...
Monoclonal antibodies (mAb) developed to target specific cancers have achieved considerable success to date. To further enhance therapeutic efficacy, monoclonal antibodies may be conjugated with a cytotoxic drug or radioisotope. We present the development of a new method based on site-specific conjugation (SSC) for targeting HER2. The study design involves a comparison of the accumulation of Ga-67-labeled anti-HER2 antibodies with SSC (SSC-mAb) versus conventional chemical conjugation (Chem-mAb) in HER2-positive tumors. In vitro, the HER2-binding capacity of SSC-mAb and Chem-mAb was comparable. However, in vitro, the rate of tumor accumulation increased gradually with SSC-mAb not only in the tumors but also in the blood and other organs. The SSC may improve targeted antigen-specific cancer radioimmunotherapy and may, due to higher retention, reduce the amount of treatment required.
... Cuvettes with a 1.0 cm light path were used. The iron determination followed the 1,10 orthophenanthroline method 60 Presentation of experimental results. In order to characterize the magnitude of the tested systems for dye discoloration, the discoloration efficiency (E) was calculated (Eq. ...
The role of pyrite (FeS2) in the process of water treatment using metallic iron (Fe0) was investigated. FeS 2 was used as a pH-shifting agent while methylene blue (MB) was used as an indicator of reactivity. The effect of the final pH value on the extent of MB discoloration was characterized using 5 g L-1 of a Fe0 specimen. pH variation was achieved by adding 0 to 30 g L-1 of FeS2. Quiescent batch experiments with Fe 0 /FeS 2 /sand systems (sand loading: 25 g L-1) and 20 mL of MB were performed for 41 days. Final pH values varied from 3.3 to 7.0. Results demonstrated that MB discoloration is only quantitative when the final pH value was larger than 4.5 and that adsorption and co-precipitation are the fundamental mechanisms of decontamination in Fe0/H2O systems. Such mechanisms are consistent with the effects of the pH value on the decontamination process.
... Only iron (i.e., Fe 2+ and Fe 3+ ) can be assessed easily using assays relying on the reaction of a chromogene with iron II (phenanthroline, bathophenanthroline, ferrozine, and ferrene) (Saywell and Cunningham, 1937;Goodwin and Murphy, 1966;Hirayama and Nagasawa, 2017;Hopwood et al., 2017;Hach, 2020). Many of these assays are available as commercial kits and often allow the measurement of Fe 2+ and total Fe by adding a reducing agent (ascorbic acid or ammonium hydroxide) to convert Fe 3+ into Fe 2+ . ...
Viability and metabolic assays are commonly used as proxies to assess the overall metabolism of microorganisms. The variety of these assays combined with little information provided by some assay kits or online protocols often leads to mistakes or poor interpretation of the results. In addition, the use of some of these assays is restricted to simple systems (mostly pure cultures), and care must be taken in their application to environmental samples. In this review, the necessary data are compiled to understand the reactions or measurements performed in many of the assays commonly used in various aspects of microbiology. Also, their relationships to each other, as metabolism links many of these assays, resulting in correlations between measured values and parameters, are discussed. Finally, the limitations of these assays are discussed.
... The o-phenanthroline method, another colorimetric assay variant, can also be used and includes spectrophotometric analysis at 510 nm due to the formation of the ferrous o-phenanthroline complex [28]. As with ferrozine, the absorbance is inversely related to the iron chelating activity of peptides within the hydrolysates. ...
Iron, zinc, and calcium are essential micronutrients that play vital biological roles to maintain human health. Thus, their deficiencies are a public health concern worldwide. Mitigation of these deficiencies involves micronutrient fortification of staple foods, a strategy that can alter the physical and sensory properties of foods. Peptide-mineral complexes have been identified as promising alternatives for mineral-fortified functional foods or mineral supplements. This review outlines some of the methods used in the determination of the mineral chelating activities of food protein-derived peptides and the approaches for the preparation, purification and identification of mineral-binding peptides. The structure-activity relationship of mineral-binding peptides and the potential use of peptide-mineral complexes as functional food ingredients to mitigate micronutrient deficiency are discussed in relation to their chemical interactions, solubility, gastrointestinal digestion, absorption, and bioavailability. Finally, insights on the current challenges and future research directions in this area are provided.
... Cuvettes with a 1.0 cm light path were used. The iron determination followed the 1,10 orthophenanthroline method [66]. The spectrophotometer was calibrated for dye concentrations ≤ 15.0 mg L −1 and iron concentration ≤ 10.0 mg L −1 . ...
There is growing interest in using pyrite minerals (FeS 2) to enhance the efficiency of metallic iron (Fe 0) for water treatment (Fe 0 /H 2 O systems). This approach contradicts the thermodynamic predicting suppression of FeS 2 oxidation by Fe 0 addition. Available results are rooted on time series correlation between aqueous and solid phases based on data collected under various operational conditions. Herein, the methylene blue method (MB method) is used to clarify the controversy. The MB method exploits the differential adsorptive affinity of MB onto sand and sand coated with iron corrosion products to assess the extent of Fe 0 corrosion in Fe 0 /H 2 O systems. The effects of the addition of various amounts of FeS 2 to a Fe 0 /sand mixture (FeS 2 method) on MB discoloration were characterized in parallel quiescent batch experiments for up to 71 d (pH 0 = 6.8). A pristine and an aged FeS 2 specimens were used. Parallel experiments with methyl orange (MO) and reactive red 120 (RR120) enabled a better discussion of achieved results. Results clearly showed that FeS 2 induces a pH shift, and delays Fe precipitation and sand coating. Pristine FeS 2 induced a pH shift to values lower than 4.5, but no quantitative MB discoloration occurred after 45 d. Aged FeS 2 , could not significantly shift the pH value (final pH 6.4), but improved MB discoloration. The used systematic sequence of experiments demonstrated that adsorption and co-precipitation are the fundamental mechanisms of contaminant removal in Fe 0 /H 2 O systems. This research has clarified the reason why FeS 2 addition enhances the efficiency of Fe 0 environmental remediation.
... The water-holding capacity (WAC), oil holding capacity (OHC), and swelling capacity (SC) of native and modified starches were determined by the previously described method [14]. The iron-binding capacity (IBC) of starch was determined by the previously described method with some modifications [23]. Starch (0.2 g) was mixed with 0.1 M ferric chloride (FeCl 3 ) solution (10 ml), stirred at 25 ± 5 °C for 6 h and filtered through a Whatman filter paper No. 42. ...
The microwave-induced modifications in physical characteristics, functional properties, and antioxidant potential of Nelumbo nucifera rhizome starch were studied. The rhizome flour was subjected to microwave irradiation at different treatment times (1, 2, 3, 4 and 5 min) at the low-medium intensity (200 W). The starch was obtained from the native and microwave treated flour and analyzed for its physical characteristics, functional properties, and antioxidant potential. The microwave treatment showed a significant (p < 0.05) decrease in total starch yield and oil holding, swelling, and iron-binding capacity of the starch. Microwave treatment resulted in disruption of morphology and conversion of C-type crystalline structure to CA and CB-type structures of starch. The variations in antioxidant properties of starch were associated with the microwave-induced modification in the structure and physical characteristics of starch. A significant time-dependent increase in the content of reducing monosaccharides, Trolox equivalent total antioxidant activity, and free radical scavenging capacity was observed in microwave treated starch. The data may be a valuable contribution to the literature regarding microwave-induced modification in physical, functional and antioxidant properties of lotus rhizome starch.
... The detection limit of arsenic for this method is 0.003 mg/l. Total iron in groundwater samples was estimated spectrophotometrically utilizing the phenanthroline method having detection limit of 0.01 mg/l (Saywell and Cunningham, 1937). All the analyses were executed in triplicate and the obtained results were reproducible with �2% error. ...
The present study assessed the co-occurrence of fluoride and arsenic in groundwater of Dharmanagar region (Tripura, India). Co-occurrence of the two toxicants was observed in 59% of the analyzed groundwater samples (n = 71), out of which concentrations of both the toxicants exceeded the World Health Organization drinking water standards in 30% samples. Significant positive correlation (r = 0.6) was observed between groundwater fluoride (<0.005–4.8 mg/l) and arsenic (˂0.003–0.044 mg/l) contents. The range of cumulative estimated daily intakes (EDI) in the studied population was: 0.07–0.1 and 0.13–0.18 mg/kg-day for the Central Tendency Exposure (CTE) and the Reasonable Maximum Exposure (RME) scenarios, respectively. The EDI (fluoride) for the children of the study area was already found to reach the ‘Tolerable Upper Intake Level’ (UL) value (0.1 mg/kg-day), and the children are thus at high risk from developing dental fluorosis. Irrespective of the CTE or RME scenario, the hazard index of fluoride (HIFluoride = 1.2–3) and that of arsenic (HIArsenic = 1.5–5) were always found to be unsafe (HI > 1) in the studied population. The estimated Cumulative Noncancerous Lifetime Hazard Index for simultaneous fluoride and arsenic exposures was calculated to be prominently high (10 and 22 for the CTE and RME scenarios, respectively). The average urinary fluoride and arsenic contents of the studied population was observed to be correlated (r = 0.46 and 0.69) with the groundwater fluoride and arsenic concentrations, respectively. The observed content of urinary fluoride (mean = 3.1 ± 1.2 mg/l) of the studied population was determined to be 65–163% of their total fluoride intakes (1.9–7.2 mg/day). The obtained results are highly alarming and thus for reducing threats to human health, the government should immediately take necessary action for supplying safe drinking water for the residents.
Flooding and climate warming lead to the increase of low‐molecular‐weight organic acid (LMWOA) inputs to soil. However, it is unclear what the effects of flooding and climate warming on soil nitrogen fraction transformation under LMWOA input are. Fluvisol was collected in the riparian zone of the Three Gorges Reservoir to conduct an incubation experiment with the treatments of three LMWOAs at five contents, two hydrological environments and two temperatures. Compared with LMWOA input of 0 mg kg ⁻¹ , the soil nitrogen in ion exchangeable fraction (IEF‐N), strong oxidant extractable fraction (SOEF‐N) and non‐transformable nitrogen (NTF‐N) were increased by 35.77, 54.71 and 25.49 mg kg ⁻¹ , respectively, under LMWOA input of 40 mmol kg ⁻¹ . Soil nitrogen in the weak acid extractable fraction (WAEF‐N) was decreased by 117.41 mg kg ⁻¹ . Microbial biomass nitrogen (MBN) was increased by 25.29 mg kg ⁻¹ , and calcium carbonate (CaCO 3 ) was decreased by 8.03 g kg ⁻¹ . The contents of IEF‐N, NTF‐N and amorphous iron oxides were higher under the flooding environment than under the drying environment. In contrast, opposite results were observed for soil nitrogen in the strong alkali extractable fraction (SAEF‐N), SOEF‐N and MBN. IEF‐N and NTF‐N contents were higher at 20°C than at 30°C, and the contents of SOEF‐N and MBN were higher at 30°C than at 20°C. WAEF‐N was dissolved by LMWOA through CaCO 3 dissolution. The dissolved WAEF‐N was partly transformed into SOEF‐N and NTF‐N by microbial assimilation and humification. Flooding desorbed SAEF‐N through the crystalline transformation of iron oxides. Flooding inhibited the transformation of IEF‐N to SOEF‐N and promoted the formation of NTF‐N, while warming did the opposite. The results provide a perspective of the bound state between soil and nitrogen for understanding the soil nitrogen cycling and help to assess the impacts of climate warming and flooding on soil nitrogen loss from soil to the surrounding water.
Methylmercury (MeHg) produced in rice paddies is the main source of MeHg accumulation in rice, resulting in high risk of MeHg exposure to humans and wildlife. Net MeHg production is affected by Hg(II) reduction and MeHg demethylation, but it remains unclear to what extent these processes influence net MeHg production, as well as the role of the microbial guilds involved. We used isotopically labeled Hg species and specific microbial inhibitors in microcosm experiments to simultaneously investigate the rates of Hg(II) and MeHg transformations, as well as the key microbial guilds controlling these processes. Results showed that Hg(II) and MeHg reduction rate constants significantly decreased with addition of molybdate or BES, which inhibit sulfate-reduction and methanogenesis, respectively. This suggests that both sulfate-reduction and methanogenesis are important processes controlling Hg(II) and MeHg reduction in rice paddies. Meanwhile, up to 99% of MeHg demethylation was oxidative demethylation (OD) under the incubation conditions, suggesting that OD was the main MeHg degradative pathway in rice paddies. In addition, [202Hg(0)/Me202Hg] from the added 202Hg(NO3)2 was up to 13.9%, suggesting that Hg(II) reduction may constrain Hg(II) methylation in rice paddies at the abandoned Hg mining site. This study improves our understanding of Hg cycling pathways in rice paddies, and more specifically how reduction processes affect net MeHg production and related microbial metabolisms.
This is the first study aimed to investigate the anti-cholinesterase (anti-Alzheimer), anti-lipase, antioxidant and photoprotective effects of various organic extracts prepared from the aerial parts of Fagonia bruguieri DC species endemic to southern Algeria. The research was also aimed to determine the total phenolics and flavonoid contents and evaluate in vitro pharmacological activities of these extracts by means of spectrophoto-metric analysis. The in vitro antioxidant properties of F. bruguieri were examined by DPPH radical scaveng-ing, b-carotene bleaching, ferric reducing power, cupric reducing antioxidant capacity (CUPRAC), free galvinoxyl radical (GOR), and O-phenanthroline assays. The anti-Alzheimer action was characterized by inhibiting of the activity of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). The anti-lipase test was used to evaluate the inhibitory capacity against pancreatic lipase. In addition, the photoprotective effect was estimated by determining in vitro sun protection factor (SPF) of F. bruguieri extracts. The results showed that polar extracts exhibited excellent antioxidant activity in various systems, with the best performance of butanol extract. The butanol extract contains a significant amount of phenolics and flavonoids (444.49 ± 0.84 mg GAE/mg and 266.45 ± 0.44 mg QE/mg, respectively). The petroleum ether extract shows a potent AChE and BChE activity with IC 50 = 27.41 ± 1.03 mg/mL and 46.14 ± 0.78 mg/mL, respectively. Concerning the anti-lipase effect, dichloromethane extract showed a strong inhibition against the lipase enzyme. In addition, F. bruguieri exhibited high photoprotective activity for absorbing UV radiations with SPF index ranging from 11.25 ± 0.1 to 43.86 ± 0.12. These findings suggest that F. bruguieri extracts provide a valuable source of antioxidants that can be explored in multiple therapeutic remedies and can be used for the prevention of Alzheimer's disease and as anti-obesity agent. Extracts of F. bruguieri DC can also be used to treat skin conditions as cosmetic formulations and in the pharmaceutical industry.
The removal mechanisms of contaminants in Fe0/H2O are still poorly understood, and characterized by contradictory findings. Therefore, the present study aims to improve the understanding of the processes involved in phosphate removal in Fe0/H2O system. Herein, the methylene blue method (MB method) is used to trace the dynamics within the investigated systems. The MB method utilizes the differential adsorptive affinity of MB onto sand and sand coated with iron corrosion products to evaluate the degree of Fe0 corrosion in Fe0/H2O systems. The extent of MB discoloration and phosphate removal in various Fe0-based systems was characterized in parallel quiescent batch experiments for two weeks and two months. Parallel experiments with Orange II (O-II) as a model contaminant allowed an improved discussion of the results. The investigated systems were: (i) Fe0 alone, (ii) MnO2 alone, (iii) sand alone, (iv) Fe0 + sand, (v) Fe0 + MnO2, and (vi) Fe0 + sand + MnO2. Additional experiments were conducted to test the influence Fe0 type, Fe0 and sand mass loadings on dye discoloration and phosphate removal in Fe0/sand system. Each system was characterized by: (i) pH value, (ii) Fe concentration, (iii) dye discoloration (MB, O-II), and (iv) phosphate concentration. Results showed that the MB method was capable of tracing the extent of iron corrosion in the various investigated systems and clarified the role of in-situ generated iron corrosion products (FeCPs) in the removal of phosphate. The suitability of mixing sand aggregates with Fe0 for efficient phosphate removal is demonstrated through the MB method. Overall, the appropriateness of the MB method to characterize the dynamics of Fe0/H2O systems is validated.
In Bengal Delta Plain (West Bengal and Bangladesh), shallow aquifer (<50 m) groundwa-
ter is often used in irrigation for paddy cultivation. The present study highlights the role
of anthropogenic activities on natural process and focuses on arsenic mobilization in the
shallow irrigation well water of rural Bengal. The major focus is to examine the role of
geochemistry, arsenic mobilization and their association with local microbial community
in irrigation well water. The results suggest that the groundwater of monitored wells is usu-
ally devoid of dissolved oxygen and consists of high concentration of dissolved redox ele-
ments like arsenic (AsT) (mean value 58.7 µgL−1) and iron (FeT) (mean value 2.6 mgL−1),
with low amount of oxyanions like sulphate (SO4
2−) and nitrate (NO3
−) (mean value 8.3
mgL−1 and 1.8 mgL−1, respectively). High concentration of alkaline earth metals like cal-
cium (Ca) (mean value 252.0 mgL−1) and magnesium (Mg) (mean value 96.9 mgL−1) with
high alkalinity (mean value 400.3 mgL−1) suggests that carbonate dissolution (calcite and
dolomite) is the key process in these monitored wells. The factor analysis reveals a positive
and strong correlation (r
2=0.716) between arsenic (As) and iron (Fe). Some of the wells
are contaminated with high concentration of chloride (up to 128.5 mgL−1), total coliforms
(no. of wells contaminated with coliforms=7) and faecal coliforms (no. of wells contam-
inated with faecal coliforms=5), which point towards the local anthropogenic infuence
(leakage of sewage). Some irrigation wells with non-permissible arsenic concentration also
harbour arsenic (As3+) and iron (Fe2+) hyper-tolerant bacteria. The microenvironment of
the irrigation wells consisting of suitable local reducing condition together advocates the
dominance of existing microbial community, particularly arsenic and iron hyper-tolerant
bacteria in them. In this study, an arsenic and iron hyper-tolerant bacterium has been iso-
lated from irrigation well water. Scanning electron microscopy and 16S rDNA sequencing
further established the identity of this bacterium as Enterobacter sp., which is a faculta-
tive anaerobe. The addition of fresh organic matter through local anthropogenic activities
could enhance the microbial activity in these monitored wells. The silver nitrate test reveals the biotransformation potential of this bacterium from arsenite (As3+) to arsenate (As5+).
Altogether, these results point towards the dependence of arsenic mobilization process on
multiple microbial and geochemical factors, where bacterium like Enterobacter sp. might
also play an important role. Such biogeochemical processes are not only responsible for
the unsafe nature of irrigation well water (for both domestic and irrigation purposes) in
rural Bengal, but also convert it into a major potential source for soil arsenic accumulation,
thereby contaminating the food chain.
Wastewater from industrial laundries is often difficult to treat because it usually presents high turbidity and chemical oxygen demand (COD). We studied several processes for the treatment of laundry wastewater which was provided by a hotel in the south of Gran Canaria, Spain. More specifically, we studied coagulation with iron (III) sulphate, Fenton, photo-Fenton and a biological treatment (using a biofilter, and a granular activated carbon, GAC, filtration). The coagulation and Fenton processes produced large amounts of sludge and could not meet the required standards for water reuse in Spain. The use of photo-Fenton and the BF resulted in complete turbidity removal and high COD removal. However, we found that the effluent from the BF did not meet the COD removal criteria for water reuse, and thus a GAC filtration post-treatment was employed to reduce COD to acceptable levels. The photo-Fenton process alone did meet the criteria for water reuse. The estimated cost to treat 1 m³ of wastewater was 6.72 € for photo-Fenton and 0.71 € for BF + GAC. The cost and life cycle assessment analyses that were also performed revealed that the acquisition of the necessary reagents is the main contribution to the overall economic and environmental costs for both options, and that the BF + GAC option is notably cheaper. Additionally, this option also causes much lower environmental impacts than photo-Fenton.
Life on earth evolved because of Sulfur as debated by many scholars. The anthropogenic sulfur released in the environment has started a visious cycle in the nature. Reckoned Sulfur is a yellow crystalline solid that occurs in nature as a pure element or as sulfide and sulfate minerals. It is a multivalent non-metal that is abundant, tasteless and odorless. The major derivative of sulfur is sulfuric acid (H 2 SO 4), one of the most important elements used as an industrial raw material, it is of central importance to the world's economies, its production and consumption is an indicator of a nation's industrial development. But when sulfur burns in air, it produces sulfur dioxide, the emissions of which cause adverse impacts to vegetation, including forests and agricultural crops. Hence a careful extraction of sulfur from the natural bodies is necessary. Acidithiobacillus ferrooxidans is a Gram-negative bacterium which is abundant in natural environments associated with pyritic ore bodies, coal deposits and their acidified drainages. It is an important member of microbial consortia used to recover copper via a process known as bioleaching or biomining. It is capable of anaerobic growth on elemental sulfur, using ferric iron as an electron acceptor. This ability of A.ferrooxidans to grow under anaerobic conditions is relevant to its application in biohydrometallurgy. For very low-grade metal sulfide ores that cannot be economically recovered using traditional metallurgical methods, the use of bioleaching is a environmental friendly alternative for the metallurgical industry. In this review, the sulfur production, its effects on the environment and the role Acidithiobacillus ferrooxidans in sulfur bioleaching is discussed. Furthermore, the closely related species of Acidithiobacillus ferrooxidans are also considered.
Control and mitigating crevice corrosion demand a thorough understanding of the prevailing chemistry conditions inside the crevice. To match and predict the dynamics in chemistry conditions occurring inside a crevice appropriately, good crevice models necessitate extensive experimental data. This paper presents the accurate determination of the ionic species in the minute volume of crevice solution and redox potential measurements in fabricated simulated crevices of different dimensions/geometry in different stainless steel alloys. Crevice geometries fabricated from carbon steel (CS) 106 B and stainless steel (SS) 316 materials were exposed to varying water chemistry conditions in a static autoclave at high temperatures. The change in pH, conductivity, ionic concentrations, electrochemical potential and effectof corrosion inhibitors inside the crevice were monitored after exposure in an alkaline medium with and without chloride. Bulk solution pH showed a reduction in alkalinity, conductivity and enhancement in anion concentrations. About 58 times increase in Cl⁻ was measured.
Coastal zones account for significant global marine methane emissions to the atmosphere. In coastal ecosystems, the tight balance between microbial methane production and oxidation in sediments prevents most methane from escaping to the water column. Anthropogenic activities, causing eutrophication and bottom water deoxygenation, could disrupt this balance in the microbial methane cycle and lead to increased methane release from coastal sediments. Here, we combined microbiological and biogeochemical analyses of sediments from three sites along a bottom water redox gradient (oxic-hypoxic-euxinic) in the eutrophic Stockholm Archipelago to investigate the impact of anthropogenically-induced redox shifts on microbial methane cycling. At both the hypoxic and euxinic site, sediments displayed a stronger depletion of terminal electron acceptors at depth and a shoaling of the sulfate-methane transition zone in comparison to the oxic site. Porewater methane and sulfide concentrations and potential methane production rates were also higher at the hypoxic and euxinic site. Analyses of metagenome-assembled genomes and 16S rRNA gene profiling indicated that methanogens became more abundant at the hypoxic and euxinic site, while anaerobic methane-oxidizing archaea (ANME), present in low coverage at the oxic site, increased at the hypoxic site but virtually disappeared at the euxinic site. A 98% complete genome of an ANME-2b Ca. Methanomarinus archaeon had genes encoding a complete reverse methanogenesis pathway, several multiheme cytochromes, and a sulfite reductase predicted to detoxify sulfite. Based on these results, we infer that sulfide exposure at the euxinic site led to toxicity in ANME, which, despite the abundance of substrates at this site, could no longer thrive. These mechanistic insights imply that the development of euxinia, driven by eutrophication, could disrupt the coastal methane biofilter, leading to increased benthic methane release and potential increased methane emissions from coastal zones to the atmosphere.
The effects of H2O2 on the flotation separation of chalcopyrite and pyrite in seawater were investigated. Pyrite was more significantly oxidized by 0.05 vol% H2O2 in seawater at pH 8, as compared to that of chalcopyrite. Under optimized condition, a recovery difference of greater than 70% was obtained for chalcopyrite and pyrite. The contact angle measurements showed that pyrite surface was more hydrophilic as compared to chalcopyrite in the presence of 0.05 vol% H2O2. In addition, the collector of butyl xanthate is more difficult to adsorb on the surface of H2O2-treated pyrite (adsorption dosage reduced from 0.18 to 0.06 mg g⁻¹), further decreasing its floatability. The heat released due to xanthate adsorption on chalcopyrite and pyrite decreased from 26.5 mJ to 25.9 mJ and from 23.1 mJ to 15.2 mJ, after H2O2 treatment, respectively, indicating less adsorption of xanthate due to the oxidation treatment, especially for pyrite. The XPS data indicated the dissolution of Fe from the oxidized chalcopyrite surface and the formation of various hydrophobic S species such as S2²⁻, Sn²⁻, S⁰ on chalcopyrite surface. In contrast, Fe(II) on pyrite surface was oxidized by H2O2 to form hydrophilic Fe2O3, Fe(OH)3, FeOOH and Fe2(SO4)3 species. Therefore, this study reveals that H2O2 can be used as a high-efficient depressant for pyrite when separating chalcopyrite and pyrite in low-alkali seawater flotation system.
Roots of decapitated sunflower plants absorbed iron from the ferric chelate of ethylenediamine di( o -hydroxyphenylacetic acid), leaving most of the acid in the nutrient solution. The chelating capacity of the nutrient solution increased as iron was absorbed by the plants. Most of the absorbed iron was found in the plant exudate.
In this study, we performed a year-long in situ incubation experiment of a common ferrous sulfide (Fe-S) mineral, pyrite, at the oxidative deep seafloor in the hydrothermal vent field in the Izu-Bonin arc, Japan, and characterized its microbiological and biogeochemical properties to understand the microbial alteration processes of the pyrite, focusing on the Fe(II) oxidation. The microbial community analysis of the incubated pyrite showed that the domain Bacteria heavily dominated over Archaea compared with that of the ambient seawater, and Alphaproteobacteria and Gammaproteobacteria distinctively co-dominated at the class level. The mineralogical characterization by surface-sensitive Fe X-ray absorption near-edge structure (XANES) analysis revealed that specific Fe(III) hydroxides (schwertmannite and ferrihydrite) were locally formed at the pyrite surface as the pyrite alteration products. Based on the Fe(III) hydroxide species and proportion, we thermodynamically calculated the pH value at the pyrite surface to be pH 4.9-5.7, indicating that the acidic condition derived from pyrite alteration was locally formed at the surface against neutral ambient seawater. This acidic microenvironment at the pyrite surface might explain the distinct microbial communities found in our pyrite samples. Also, the acidity at the pyrite surface indicates that abiotic Fe(II) oxidation rate was much limited at the pyrite surface kinetically, 3.9 × 10 ³ −1.6 × 10 ⁵ -fold lower than that in the ambient seawater. Moreover, the nanoscale characterization of microbial biomolecules using carbon near-edge X-ray absorption fine structure (NEXAFS) analysis showed that the sessile cells attached to pyrite excreted the acidic polysaccharide-rich extracellular polymeric substances at the pyrite surface, which can lead to the promotion of biogenic Fe(II) oxidation and pyrite alteration.
Importance
Pyrite is one of the most common Fe-S minerals found in submarine hydrothermal environments. Previous studies demonstrated that the Fe-S mineral can be a suitable host for Fe(II)-oxidizing microbes in hydrothermal environments; however, the details of microbial Fe(II) oxidation processes with Fe-S mineral alteration are not well known. The spectroscopic and thermodynamic examination in the present study suggests that moderately acidic pH condition was locally formed at the pyrite surface during pyrite alteration at the seafloor due to proton releases with Fe(II) and sulfidic S oxidations. Following previous studies, the abiotic Fe(II) oxidation rate significantly decreases with a decrease in pH, but the biotic (microbial) Fe(II) oxidation rate is not sensitive to the pH decrease. Thus, our findings clearly suggest the pyrite surface is a unique microenvironment where abiotic Fe(II) oxidation is limited and biotic Fe(II) oxidation is more prominent than that in neutral ambient seawater.
Photo-oxidation of aqueous Fe(II) (Fe²⁺ and FeOH⁺) to Fe(III) (Fe³⁺) was likely involved in the formation of iron oxide deposits on early Mars and Earth. Previous studies have reported the photo-oxidation reaction rate (i.e., quantum yield, φ = the number of oxidized ferrous ions divided by the number of photons absorbed by ferrous ions) under acidic conditions (pH 0.4–3.0). However, the quantum yield has not been systematically investigated using chemical actinometry in the range of weakly acidic to neutral pH, where the photo-oxidation would have occurred on early Mars and Earth. We report quantum yields for the photo-oxidation of aqueous Fe(II) species over a pH range of 0.5–7.6 with Hg and Xe lamps (with and without optical filters) based on measured Fe(II) concentrations and photon fluxes. The quantum yield under continuous UV and visible light (> 200 nm, Xe lamp) varies with pH: φ = 0.103 (± 0.005) + 2.17 (± 0.27) × [H⁺]0.5 at pH = 3.0-7.0. Our quantum yield is a few times higher than those reported by the previous studies that used a Hg lamp, indicating the wavelength dependence of the quantum yield. At higher pH (7.1–7.6), with a UV cutoff at ≤ 300 nm (filtered Xe lamp), photo-oxidation of Fe(II) is attributed to oxidation of FeOH⁺, with a quantum yield of 0.08 ± 0.01. Based on these quantum yields, we estimated Fe(III) (hydro)oxide precipitation rates in the early Gale lakes on Mars, and in Archean oceans on Earth. Results suggest that photo-oxidation may account for the amounts of Fe(III) (hydro)oxides in Gale sediments, assuming aqueous Fe(II) was supplied to the lakes through upwelling groundwater. Photo-oxidation of Fe(II) in Archean oceans on Earth could have been several times more intense than previously thought.
Ferroptosis is a newly form of regulated cell death, which has attracted great attention for tumor therapy. Herein, we prepared nanoscale coordination polymer Fe-NQA particles to deliver iron and NQA (vitamin K3 derivative) into tumor cells, which synergistically promoted ferroptotic therapy for inhibiting tumor growth, preventing metastasis, and overcoming radioresistance. [Figure not available: see fulltext.]. © 2020, Tsinghua University Press and Springer-Verlag GmbH Germany, part of Springer Nature.
Pineapple experiments were carried on using imported Cuban slips and native slips with the object of investigating the apparent "degeneration" of slips. The suggestion that this apparent "degeneration" of slips might result from a nutritional derangement produced by an unfavorable balance of iron and manganese that was more severe in the plants developed from native slips, and resulted in a more marked chlorosis than in the plants developed from Cuban slips, led to studies of iron-manganese relationships in the pineapple plant under field conditions as the initial point of attack on this problem. Cuban as well as native slips were planted in untreated soil and in soil which received calcium carbonate as ordinarily applied by pineapple growers to control manganese in the soil. In addition, the plants which developed from each group of slips received either 2 or 4 iron sprays; the purpose was to find out which spray procedure was best.
The possibilities of ameliorating manganese-induced chlorosis with boron applications were studied under greenhouse conditions using soybean and corn as indicator plants. Five levels of boron with six manganese concentrations were used in the soybean experiment. Boron and manganese were used at five levels each in the corn experiment. Observations were made as to the development of toxicity symptoms. Boron, manganese, and iron were determined in the top leaves of the corn plants. Measurements of dry-matter production were made for both crops. Five parts per million of manganese was toxic to soybean plants and reduced yields, but toxicity was lessened by increasing the boron in the nutrient solution up to 0.5 p.p.m. Boron was toxic also at levels above 0.5 p.p.m. No definite manganese-toxicity symptoms developed in the corn plants. In general, high boron (2, 5 p.p.m.) reduced corn yields regardless of the manganese level. Chemical analyses of the corn leaves suggests the possibility that manganese accumulation may be modified to some extent by boron concentrations.
The term heavy metals is used to classify elements on the basis of their density (5 g/cm³) rather than physical and chemical properties. These metals have been known to mankind since ancient times and were used for various purposes. Their discovery gained momentum at the beginning of the nineteenth century, along with their uses, and spread in the environment. Since many heavy metals impart toxicity in one or other way they must be constantly monitored to prevent fatalities and ecological disasters. In different sections of this chapter we have discussed the mechanism of their toxicity and affordable analytical (spectrophotometric) methods for estimation of heavy metals, which includes arsenic, mercury, lead, cadmium, nickel, chromium, copper selenium, zinc and iron.
Copper smelting wastewater, one of the typical high arsenic-containing acidic wastewater in the metallurgical extraction process of arsenic-associated minerals, greatly threatens human health and ecological safety due to the possible leakage and diffusion from its secondary pollution. However, the state-of-the-art technologies suffer from the great challenge that the disposal of wastewater emits an enormous amount of arsenic-containing hazardous wastes with the poor long-term stability and the high arsenic leachability. Herein, a novel strategy is proposed to remove and stabilize arsenic from copper smelting wastewater in the form of environmental friendly scorodite using copper slag as a neutralizer and an in situ iron donator. The thermodynamic analysis and the bath experiments were investigated to explore the reaction behavior between wastewater and copper slag. The result shows that 97.86% of arsenic was successfully removed from wastewater with an initial arsenic concentration of 10230 g/L at by using copper slag at a Fe/As molar ratio of 2.0 and 80 °C for 12 h, resulting in a scorodite-SiO2-sulfate composite with an arsenic leached concentration of 3 mg/L in the leaching test. The main phases of Fe2SiO4 and Fe3O4 from copper slag dissolve in wastewater and release abundant Fe ions to synthesize scorodite and secondary minerals (silica gel and sulfate complexes). The initial precipitates from the second minerals are likely to serve as nucleation sites for the formation and growth of scorodite. We demonstrate an inherent arsenic disposal process for the copper smelting industries, and the process allows the removal and stabilization of arsenic from wastewater using solid waste. It might provide an efficient and low-cost solution for the disposal of arsenic-containing wastewater in the nonferrous smelting industry.