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Biosorption of a cationic dye using raw and functionalized Chenopodium quinoa pericarp biomass after saponin glycosides extraction
Abstract
ynthetic toxic dyes from liquid wastes can be harmful for living organisms and the environment, even at low concentrations. This research investigated the utilization of the Chenopodium quinoa pericarp bio-waste (QBW) after saponin glycosides extraction as biosorbent in the removal of methylene blue (MB) dye as a model contaminant from aqueous solution. QBW was successfully modified by chemical (sulfuric acid) and thermal (pyrolysis) treatments. The biosorbent was characterized by FTIR, TGA, BET, Zeta Potential, SEM/EDX, and contact angle analysis to get further insight into the adsorbent’s behavior and to propose a suitable biosorption mechanism. Batch experiments were explored to study the effect of various parameters on MB removal efficiency, including contact time, adsorbent quantity, initial concentration, and process temperature. The optimum conditions for QBW biosorption of MB were at neutral pH and contact time of 60 min. The maximum adsorption capacity of the biosorbent (QBW-II), which demonstrated the highest MB removal efficiency in the biosorption test was 193.802 ± 4.365 mg.g−1. The kinetic and isotherm study of MB dye biosorption revealed that the pseudo-second-order model and Langmuir isotherm were the best fit. Thermodynamic parameters for the biosorption showed that the process was spontaneous and exothermic. Our findings demonstrate that QBW has a high potential to be used as an environmentally friendly and promising bio-sorbent to effectively remove organic contaminants from aqueous systems.
... Such discharges are known to contain harmful substances such as dyes [6], heavy metals [7], and polycyclic aromatic hydrocarbons (PHAs) [8], which can be detrimental to marine ecosystems and human health. There are several effective techniques for removing organic materials from water, such as ozonation [9], adsorption [10], photocatalytic degradation [11], biosorption [12], chemical precipitation [13], and coagulation [14]. Nevertheless, membrane technology has emerged as a promising purifying and recycling water 2 of 22 solution. ...
In this study, we aim to evaluate how cyclodextrin molecules affect the hydrophilicity and selec-tivity of PVDF membrane. Herein, we prepared PVDF-PVP(1-x) β-CDx membranes, with x rang-ing from 0 to 1 wt%. The membranes were deeply characterized by means of X-ray diffraction (XRD), attenuated total reflectance infrared (ATR-IR), Raman spectroscopies, Thermal gravimet-ric analysis (TGA), Contact angle measurement (CA), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The study unequivocally demonstrates the effectiveness of the addition of β-CD molecules on membranes' structural, morphological, and dielectric properties. Adding 0.25wt% β-CD enhanced hydrophilicity, with CA decreasing from 72.6° to 56° and roughness decreasing from 81 to 29 nm. The PVDF-PVP(1-x) β-CDx membranes were then fully characterized using electrochemical impedance spectroscopy (EIS) to determine their dielectric properties, which clearly showed that the presence of β-CD induced polarization of the mem-brane. The separation of various dyes with different sizes and charges was utilized. These dyes included methylene blue (MB, positive, 0.504 nm), methyl red (MR, neutral, 0.487 nm), rose Bengal (RB, negative, 0.588 nm), and brilliant blue (BB, negative, 0.798 nm). Based on our re-search, we found that the membrane's selectivity is determined by both exclusion factors (such as size and dielectric properties) and inclusion inside the β-CD cage. We found that using alpha-CD instead of beta-CD led to the disappearance of dye inclusion. These findings strongly sug-gest that β-CD molecules can be a viable solution for dye removal from wastewater.
... Typically, these molecules include dyes, phenolic compounds, pharmaceuticals, or chemical intermediates that can resist degradation in the human organism and the environment. In this context, MB is employed as a representative dye in assessing visual pollution due to its exceptionally hazardous nature (Oulkhir et al., 2023). In addition to the positive effect of phosphoric acid pretreatment on biogas production, this study also evaluated the activation effect of the recovered phosphoric acid on the solid digestate. ...
This investigation aims to evaluate the co-valorization of olive mill wastewater with other organic residues involving acid pretreatment, co-digestion, pyrolysis, and microalgae cultivation. Phosphoric acid pretreatment (5%, 60°C for 1 h) was used to solubilize the organic matter in a mixture of coffee grounds, orange peel, olive mill wastewater, and cardboard. The acidic treatment led to the production of 328 Nml of biogas/gVS, while the untreated mixture provided 257 Nml of biogas/gVS. The solid digestates were subjected to pyrolysis (500°C for 1 h), providing a biochar yield of approximately 44% for both digestates. Adsorption tests using methylene blue revealed an adsorption capacity of the biochar generated from the digestate of the acid pre-treated mixture of 4 mg/g, which was higher than that of the biochar from the untreated mixture (3.5 mg/g). The liquid digestates were also used as growth media for microalgae. Compared to the reference media (BG11), the use of the digestates-based media resulted in a lower growth rate (0.04 d-1) and biomass (247 mg/L) but significantly higher lipid content (49%). The study shows, therefore, that the use of acid pretreatment had a positive effect on biogas production (solubilization of sugars), on the adsorption efficiency of the biochar (improvement of the porosity of the material), and on the production of lipids from the microalgae which can be destined to biodiesel.
... Thermogravimetric analysis (TGA/DTG) was also achieved by the Labsys Evo-gas option instrument. Samples were heated from 30 • to 700 • C under a nitrogen atmosphere (flow of 25 mL.min − 1 ) at a heating rate of 10 • C.min − 1 [21]. On the other hand, PG solubility in a medium of varying conductivity was determined using the protocol reported by Hammas et al. [22]. ...
Phosphogypsum (PG) is generated annually from phosphoric acid production. This by-product contains 50% of sulfate (SO42−), which can be recycled biologically. Biorecovery of elemental sulfur (S0) involves firstly converting SO42− into biogenic sulfide using sulfate-reducing bacteria under anaerobic conditions, then oxidizing the sulfide produced into S0 using sulfur-oxidizing bacteria. This study focused on selecting and evaluating natural microbial consortia from SO42− rich biotopes for their application in the initial first step of S0 biorecovery. The PG sample was first comprehensively characterized using ICP-MS/OES, XRD, FTIR, and TGA analyses. Subsequently, SO42− leaching optimization was performed through a design of experiments approach. The analysis revealed that CaSO4 was the major component of the PG (78%), and the optimal parameters for leaching of SO42− from PG were at a NaOH concentration of 7.4% and PG concentration of 158 g.L−1. Furthermore, the MYC-consortium isolated from a hydrothermal niche demonstrated the highest reduction capacity among the studied consortia. It also exhibited the highest performance under SO42− concentrations up to 3.5 g.L−1, salinity levels up to 30 g.L−1, and in the presence of 60 ppm of Zn(II), 3 ppm of Cd(II), and 6 ppm of Pb(II). Moreover, this consortium showed a high capacity for reducing SO42− in the bioreactor (90% after 6 weeks) when utilizing SO42− from the PG-leached solution, as attested by the chemical analyses of the precipitate formed in the bioreactor. This research offers a comprehensive insight into the potential of MYC-consortium to convert leached SO42− from PG into sulfide, which is the most critical step in the S0-biorecovery.
Adsorption isotherms are valuable tools for describing the interaction between adsorbate and adsorbent since they demonstrate the equilibrium relationship. The Langmuir and Freundlich models are the most commonly used isotherm models to describe these relationships; still, they cannot consistently deliver efficient results due to the assumptions of the model not predicting more complex situations as occurs in biosorption. Artificial neural networks (ANN) are a set of algorithms modelled loosely after the human brain and are designed to recognize patterns. The ANN tool can overcome problems isotherm models have in describing the interactions mentioned and help define the best conditions for a given adsorption process. This paper reports the application of ANNs for predicting the removal efficiency of textile dye Neolan Black WA (Acid Black 52) using orange peel and sugarcane bagasse as biosorbents. The Freundlich, Langmuir, pseudo‐first‐order, and pseudo‐second‐order models were applied and compared to the ANN model. The parameters evaluated were initial dye concentration (10–600 mg/L), final dye concentration (0–83.44 mg/L), biosorbent mass (1.5 g), pH (2), and contact time of dye (0.167–24 h). Two classes of ANNs, Elman and feed‐forward networks, were tested with a mean square error of 0.0212 and 0.7274 for the isotherm and kinetics, respectively. Compared to the conventional isotherm and kinetic models, the Elman network predicted the amount adsorbed by the biosorbents with higher precision, acquiring a determination coefficient of 0.9998 and a mean square error of 8.75 × 10 ⁻⁵ .
The complete study is comprised with three important investigations on the plant based natural surfactant saponin (NS). The primary extraction of the NS was done from Acacia Concinna (native name shikakai or soap-pod) fruit-pericarp. After isolation and purification, characterization of the saponin (NS) was performed by employing HR-ESI-TOF–MS (ES +), 1H-NMR, 13C-NMR, FT-IR, HR-TEM, HR-SEM and UV–Vis spectroscopic methods. The CMC of the extracted saponin was determined by conductometric and UV–Vis Spectro-photometric methods, the CMC values of the NS were recorded to be 4.67 × 10–4 M and 5.7 × 10–4 M respectively, which indeed are much lower in value with respect to most of the commercially available surfactants. The thermodynamics of dye-surfactant interaction studies among selective cationic dye Rhodamine-B (RhB) with the isolated saponin were studied. Two other synthetic surfactants CPC (cationic) and SDS (anionic) were also used to have an inclusive comparative understanding of the dye-surfactant interaction. The presence of a replaceable ‘–H’ in the natural surfactant moiety is the reason behind its ability to interact with the selected cationic dye. The self-degradation of the NS in normal temperature and in aerobic and anaerobic condition was also kept in record. The NS is definitely a proven alternate for the synthetic surfactants that best suits with the sustainable goals of UNSDGs.
Adsorption is a widely used chemical engineering unit operation for the separation and purification of fluid streams. Typical uses of adsorption include the removal of targeted pollutants like antibiotics, dyes, heavy metals, and other small to large molecules from aqueous solutions or wastewater. To date several adsorbents that vary in terms of their physicochemical properties and costs have been tested for their efficacy to remove these pollutants from wastewater. Irrespective of the type of adsorbent, nature of the pollutant, or experimental conditions, the overall cost of adsorption depends directly on the adsorption contact time and the cost of the adsorbent materials. Thus, it is essential to minimize the amount of adsorbent and the contact time required. We carefully reviewed the attempts made by several researchers to minimize these two parameters using theoretical adsorption kinetics and isotherms. We also clearly explained the theoretical methods and the calculation procedures involved during the optimization of the adsorbent mass and the contact time. To complement the theoretical calculation procedures, we also made a detailed review on the theoretical adsorption isotherms that are commonly used to model experimental equilibrium data that can be used to optimize the adsorbent mass.
The transition of the mineral processing sectors, which depend mainly on various petroleum-origin chemicals, to the green industry based on the production of greener materials and the reduction of carbon footprints, is mandatory due to the growing concerns regarding the extensive environmental impact of the mining industry. In this context, biological ore beneficiation is spurring increasing interest from scientists and industrials. The latest scientific developments in bio-metallurgy have allowed it to exploit biotechnologies in the flotation process as a novel/cleaner approach for separating gangue materials from valuables minerals. Current fundamental research projects have focused on the progress of biotechnology and the employment of biopolymers, microorganisms, and their metabolites, as well as plant-derived biosurfactants in the emerging field of bioprocessing, particularly bioflotation. Almost all studies on flotation have focused on chemical and physical parameters, and the role of natural biosurfactants remains little explored. This review presents a thorough understanding of the bioflotation concept by assessing previous research on several elements of bioflotation, including the impacts of biotechnology and operating factors (pH, biomass, and biosurfactants concentration), probable mechanisms, and unexplored areas, but from various pragmatic viewpoints. Recent studies are summarized by categorizing microorganisms, plants, and biopolymers based on their bioflotation performances. Furthermore, the most recent research investigations on biological flotation of specific minerals (salt-type sulphide and oxide) are reviewed. Finally, critical challenges of bioflotation are discussed, and novel perspectives are provided to contribute to solving the difficulties faced in its implementation.
Graphical abstract
The handling of used cell phones in Indonesia is mostly carried out by informal actors, starting from second-hand market actors. However, the activities of the informal actors often endanger the environment and human health. To reduce the impact, some of the activities should be transferred to formal parties. This requires collaboration of both parties as a form of waste management, which previously has never been established. The objective of this study is to explore the driving factors of collaboration intention of informal actors in handling used cell phones with the formal ones. Data were collected using questionnaires distributed to second-hand market actors in five districts in the Special Region of Yogyakarta Province. In this study, three internal driving factors are considered, which are environmental attitude, management commitment, and financial benefits, as well as two external driving factors: government support and competitor pressure. The regression analysis in each region revealed that the most significant driving factors vary across different regions, such as government support in Gunungkidul, management commitment in Bantul, competitive pressure and government support in Kulonprogo, government support, management commitment, and financial benefit in Sleman, as well as environmental attitude and financial benefit in Yogyakarta City. From the structural equation modeling at the provincial level, it was found that financial benefit and government support were the most significant factors influencing the collaboration intentions of all informal actors. The results of this study can be used as a reference. Doi: 10.28991/CEJ-2022-08-10-016 Full Text: PDF
The pseudocereal grain, Quinoa (Chenopodium quinoa Willd.), has a great nutritional value due to its high contents of proteins, fiber, minerals, and vitamins. However, saponins naturally present outside the grains represent an obstacle to their consumption as human food. Before consumption, the grains are subjected to various treatments, which alter their nutritional value. In an attempt to eliminate the maximum of saponins using the wet process, while minimizing the washing conditions and preserving the nutritional quality, we explored the effects of several parameters, including volume of water, treatment time, soaking time, number of washing, and water temperature, followed by an optimization process using Box–Behnken Design, and finally, the impact of this process on the physicochemical and techno-functional properties of six quinoa genotypes seeds was evaluated. As a result, the variation of the treatment time, volume, and temperature of the water positively affected the saponins leaching. According to the quadratic model, the maximum percentages of eliminated saponins (96.53%−96.77%) were found at a temperature of 50°C, treatment times from 60 to 69 min, and water volumes from 6.99 to 7.50 mL per gram of seeds. The optimized method did not affect the proteins and microelements content (Zn, Mn, B, Mo), while a slight decrease of macro-elements (K, P, Ca, S, Mg) was noted in the level of some genotypes. On the other hand, a significant improvement of the techno-functional properties such as water and oil holding capacity was noted, with a sharp drop-in emulsifying activity in all genotypes without affecting the standard values of pH (6.4–6.8) and moisture content (10%−11%) of the seeds. Hence, the optimized method showed to be a more potential method for saponins removal than the currently used dry method.
The biomass of a yeast stain of Wickerhamomyces anomalus was evaluated as a natural biosorbent for the removal of Acid Red14 dye (AR14) in batch experiments. The outcome revealed a maximum biosorption capacity of 71.37 mg g⁻¹. Biosorption kinetic followed both the pseudo-second-order and intra-particle-diffusion model, while thermodynamic parameters showed a spontaneous and endothermic nature of the biosorption process. The Freundlich model was the best-fitting isotherms, suggesting a monolayer biosorption via chemisorption at homogeneous sites on the yeast surface. Next, the physicochemical characterization of W. anomalus biomass before and after biosorption using scanning electron microscopy coupled with X-ray spectroscopy, and the Fourier-transforms infrared spectroscopy indicated the involvement of various functional groups (amino, carboxyl, hydroxyl, and carbonyl groups) in AR14-biosorption. Also, the zeta potential of cells at a negative charge, and the acidic value of the zero-charge point confirmed the predominance of anionic groups in the cell wall. Hence, H-binding, π-π, and n-π interactions are likely to participate in the biosorption mechanism. Additionally, the influence of batch conditions on the decolorization capacity was statically screened and optimized using Plackett–Burman and Box–Behnken design, respectively. Results show that biomass dosage is the significant factor having a positive influence on the discoloration rate, while a negative correlation was found for dye concentration and high pH values. Maximum decolorization (77%) was achieved at pH level (3–4), with dye concentrations (50–75 mg L⁻¹) and yeast biomass 1.25 g L⁻¹. These results suggest that W. anomalus might be exploited as an effective, inexpensive, and environmentally friendly biosorbent.
The aim of this work is to study the removal of Basic Blue 3 (BB3) and Methylene blue (MB) from aqueous solutions using raw and chemically treated cedar sawdust as eco friendly and sustainable bioadsorbents. The raw and treated cedar sawdust (CS) samples were activated with NaOH (0.1 N) and HCl (0.1 N) solutions. The surface characteristics of the bioadsorbents were analyzed by diverse physico-chemical methods such as scanning electron microscopy with energy-dispersive X-ray analysis, Fourier transform infrared spectroscopy, point of zero charge (pHpzc), X-ray diffraction. The monitoring of the optimal experimental conditions of the different parameters such as dye
concentration, contact time, adsorbent dose and solution pH were performed in a batch system. Experimental results show that the adsorption process is rapid and reaches equilibrium after 1 h of contact time. The adsorption capacities of the CS bioadsorbent depend on the pH of the solution and adsorbent dose. Consequently, the adsorption of BB3 and MB is favored at basic pH with the maximum adsorption percentage removal of 98% for BB3 and 99.8% for MB. Adsorption kinetics and equilibrium isotherm parameters were fit using two classic adsorption models (Langmuir and Freundlich). The adsorption kinetics of dyes onto CS followed could be described well with the pseudo-second-order model, whereas the equilibrium data fitted well to the Langmuir isotherm model with a correlating constant (R2) higher than 0.98. The maximum adsorption capacities (Qmax) onto of raw-CS, HCl-CS and NaOH-CS were estimated to be 47.62, 71.94 and 76.92 mg g 1 for MB and 33.67, 72.46 and 85.3 mg g–1 for BB3 respectively, showing that the NaOH-CS adsorbent is about 1.6–2.6 time more efficient that the natural-CS. As a result, chemically treated cedar sawdust has great potential as an inexpensive and readily available alternative bioadsorbent for the removal of cationic dyes from industrial wastewaters
The combination of nanotechnology and green chemistry, based on the valorization of natural resources for environmental applications becomes a top priority for scientific researchers in the last decades. Biomass with fascinating features including abundance, environmentally safe nature and low cost can be easily manipulated as an infinite source for green and advanced sorbent materials design. In this study, date palm fibers as one of the most plenty resources in Morocco was exploited to extract pure cellulosic fibers, which were combined with TiO2 nanoparticles in the form of highly porous blocks using a natural linker to be used as green photocatalyst for both cationic and anionic dyes photodegradation. Structural, morphological, thermal and textural properties of the resulting composites were determinate using X-ray diffraction (XRD), Fourier transform infrared spectrometry (FTIR), Scanning electron microscopy coupled to Energy dispersive X-ray spectroscopy (SEM & EDX), Thermogravimetric analysis (TGA) and nitrogen adsorption-desorption. The effect of environmental parameters including initial dye concentration, contact time and initial pH solution on the composite sorption performances were consistently investigated. Under optimized conditions, the resulting blocks exhibited impressive adsorption capacity, greater photocatalytic efficiency for both methylene blue (MB) and congo red (CR) dyes and excellent regeneration after several cycles with easier separation.
Doum is a type of palm tree having leaves with a lower surface (looking like palm leaves) and trunk with relatively reduced height (< 1 m). It is naturally growing in a wide range of conditions and tolerating extreme temperatures (36–38 °C). In this work, doum leaves fibers and doum trunk fibers were identified as potential sources to produce cellulose derivatives, namely cellulose microfibers (CMFs) and cellulose nanocrystals (CNCs). CMFs were obtained from the identified sources via chemical treatments and then subjected to sulfuric acid hydrolysis to produce CNCs. The studied materials were characterized at different stages of treatment. It was found that CMFs, extracted from both sources, exhibited a uniform size with a microfiber diameter ranged from 3 to 10 µm and crystallinity between 80 and 76%. The as-produced CNCs showed the same characteristics with an average diameter of 5.3 nm, an average length of about 450 nm and a crystallinity of 90%. This study can draw the attention of researchers towards doum tree as a new source of cellulosic materials. Owing to their excellent characteristics, the produced CMFs and CNCs could be used as additives or reinforcing agents for polymer composite development and beyond.
Agricultural production in the Rehamna region, Morocco is limited with various challenges including drought and salinity. Introduction of climate resilient and rustic crops such as quinoa was an optimal solution to increase farmer’s income and improve food security. This study summarizes results obtained from a research project aiming to develop quinoa value chain in Morocco. The study tackled several aspects including agronomic traits (yield and growth), transformation, quality (nutritional and antinutritional traits) and economic analysis and, finally, a strength–weaknesses–opportunities–threats analysis, lessons learned and development perspectives were presented. From an agronomic point of view, introduced new quinoa cultivars showed higher performance than locally cultivated seeds and, furthermore, the use of irrigation and organic amendment has tremendously improved seed yield by double and three times, respectively, compared to rainfed conditions. Nutritional analysis revealed that protein and phosphorus content remained stable after seed pearling while most of the micronutrients content decreased after seed pearling. However, saponins content was reduced by 68% using mechanical pearling compared to 57% using both traditional abrasion and washing. The economic analysis showed that production cost of quinoa seeds could be further decreased using mechanized intensive tools along with irrigation and organic amendment supply. This study revealed several lessons learned from the field experience and proposed several development actions for each value chain component that can be implemented within a national quinoa program.
The United Nations’ Sustainable Development Goals have sparked growing interest in biosurfactants from many surfactant-loaded industries including those utilizing froth flotation for mineral separation. However, the interaction of biosurfactants with mineral surfaces is currently poorly understood. We bridge this gap by studying adsorption of a yeast-derived bola acidic sophorolipid (ASL) biosurfactant on djurleite (Cu1.94S). The methods used include Hallimond flotation, contact angle, adsorption isotherm, zeta potential, leaching measurements, and X-ray photoelectron spectroscopy (XPS). To facilitate the interpretation of the adsorption results, we characterize the activity of ASL at the air-water interface and measure its critical micelle concentration (CMC) at different pH using static surface tension. We find ASL to be a multifunctional surfactant with an unusual, pH-sensitive interfacial behavior. At the air-water interface, ASL is most active at pH 8, while its CMC goes through minimum as low as 40 μM at pH 7. The surfactant adsorption at the djurleite-water interface makes the sulfide surface hydrophilic at acidic pH and hydrophobic at neutral and basic pH. In addition, ASL has strong affinity to copper sulfide and demonstrates metal leaching properties. Finally, ASL demonstrates detergency properties. We offer a mechanistic interpretation of these findings. Our results provide a basis for the application of acidic glycolipids in froth flotation and have implications for their application in ion separation using hydrometallurgical routes, as well as for the chemical stability of metal sulfides in environmental systems.
Adsorption is one of the oldest and extensively studied techniques for water and wastewater treatment. As a surface phenomenon, adsorption efficiency relies heavily on the surface chemistry of the natural and modified material. The mode of surface modification and the nature of the precursor have significant impacts on surface functionalities. Chemical method of surface treatment is a technique that alters the structure and the surface properties of the precursor to enhance adsorption process. The present work intends to deliver precise knowledge on the choice and impacts of chemical modification on some known adsorbing materials.
In the current study, the mechanistic understanding of the adsorption isotherm and thermodynamic aspects of cationic methylene blue (MB) dye adsorption onto cellulosic olive stones biomass from wastewater were investigated. The batch adsorption of MB onto the olive stones (black and green olive stones) was tested at a variety of pH, dye concentrations, temperatures, and biomass particle sizes. The adsorption thermodynamics such as Gibbs free energy, enthalpy, and entropy changes were also calculated. Moreover, the desorption studies of MB from the spent olive stones were studied to explore the re-usability of the biomasses. The results revealed that under the optimum pH of 10, the maximum MB uptake was achieved i.e. 80.2% for the green olive stones and 70.9% for the black olive stones. The green olive stones were found to be more efficient in remediating higher MB concentrations from water than the black olive stones. The highest MB removal of the green olive stones was achieved at 600 ppm of MB, while the highest MB removal of the black olive stones was observed at 50 ppm of MB. Furthermore, for almost all the concentrations studied (50-1000 ppm), the MB adsorption was the highest at the temperature of 45 °C (P value < 0.05). It was shown by the Fourier transform infrared that the electrostatic interaction and hydrogen bonding were proposed as dominant adsorption mechanisms at basic and acidic pH, respectively. While the hydrophobic-hydrophobic interaction was a dominant mechanism at neutral pH. The thermodynamic studies revealed that the adsorption process was endothermic, spontaneous, and favorable. Moreover, the real wastewater experiment and the desorption studies showed that the green and black olive stones were a cost-effective and promising adsorbents for MB remediation from wastewater on account of their high adsorption and desorption removal capacities.
Acid pretreated biomass Lemna minor (BM-H 3 PO 4) was used as support for CuO nanoparticles loading, to investigate the dye biosorption capacity and the photocatalytic performance under artificial visible light. The surface morphology, crystal structure, elemental composition, and the bandgap of modified biomass have been determined using FE-SEM, XRD, EDX, XPS, FTIR, and UV-DR analysis. The results showed that NH 2 and P-O functional groups of (BM-H 3 PO 4) can attract the copper ions (Cu 2+), which can facilitate the loading of CuO nanoparticles hence, smaller nanoparticles with an average diameter of 21 nm was obtained. It was also found that when the CuO was incorporated in BM-H 3 PO 4 in a proper mass ratio of 0.4, the biosorption efficiency was enhanced to 3 times compared with BM-H 3 PO 4 and reached a maximum of 91%, at a dye concentration of 20 mg/ L, solution pH equal to 5, and an ambient temperature of 25°C. Furthermore, CuO-modified BM-H 3 PO 4 exhibits a better photocatalytic activity than pure CuO in the presence of H 2 O 2 and visible light irradiation, where the dye was completely removed and mineralized after 240 min, evidenced by COD measurement. The photocatalytic regeneration also shows that the biosorption efficiency was maintained at 91% over 3 cycles, indicating the significant self-regenerative capacity of the biosorbent.
Pennisetum purpureum is one of the most invasive perennial grasses of the Poaceae family, which are abundant in southeast Asia including Brunei Darussalam. The pyrolysis process at a slow heating rate proved to be highly promising for biochar production. The production and characterization of different Pennisetum purpureum biochars have been investigated at the pyrolysis temperatures of 400 °C, 500 °C and 600 °C with a heating and nitrogen flow rate of 5 °C/min and 0.5 L/min, respectively. The observed higher heating values were 22.18 MJ/kg, 23.02 MJ/kg, 23.75 MJ/kg, and the alkaline pH were 9.10, 9.86, 10.17 for the biochar at 400 °C, 500 °C, 600 °C temperatures, respectively. The water holding capacity was one hundred percent for all biochars and continued to increase for higher pyrolysis temperature. SEM images show that the porosity of the biochars has been enhanced with increased temperatures due to the rearrangement of crystallinity and aromaticity. On the other hand, the yields of biochar have been decreased from 35.13% to 23.02% for the increase of pyrolysis temperature from 400 °C to 600 °C. Energy dispersive X-ray analysis shows that the O/C atomic ratios were 0.15, 0.08 and 0.06 for the biochar of 400, 500 and 600 °C which validates the improvement in heating values. FT-IR analysis revealed that the available functional groups in the biochars were CO , C=C, and C-H. Thermogravimetric analysis (TGA) under pyrolysis condition showed residue of 46.56%, 51.13% and 55.67% from the biochar at 400, 500, and 600 °C, respectively. The derivative thermogravimetry (DTG) graph indicates that the degradation rate is higher for 400 °C biochar than the 600 °C biochar.
Coconut (Cocos nucifera) shell was chemically treated with sulfuric acid (H2SO4) to produce acid- factionalized biosorbent for methylene blue (MB) dye removal from aqueous environment. Various analytical techniques were utilized to investigate the surface area, surface morphology, crystallinity, elemental composition, and functional group of the sulfuric acid-treated coconut shell (SATCS). The adsorption parameters such as adsorbent dosage (0.02–0.20 g), solution pH (3–10), contact time (0–360 min), and initial MB dye concentration (25–200 mg/L) were studied. The adsorption results were illustrated by pseudo-second order kinetic and Freundlich isotherm models. It was found that SATCS has a maximum adsorption capacity (qmax) of 50.6 mg/g at 303 K. The adsorption mechanism of MB dye on the SATCS surface can be assigned to the various types of interactions such as electrostatic attractions, H-bonding interaction, and π-π interaction. This work shows SATCS as promising acid- factionalized biosorbent for removal MB dye.
In this study, NaOH treated pine (NTP) and magnetite-pine composite (NTP-NC) were prepared and applied for Cr(VI) adsorption at varying temperatures and the impact of the inorganic-organic nanocomposite combination on the kinetics, diffusion, equilibrium and Cr(VI) uptake mechanism was determined. FE-SEM-EDX analysis of NTP-NC showed that the composite was homogeneous containing Fe, O and C and the iron oxide was well dispersed over the composite. XPS analysis of NTP-NC revealed a shift in the 1s O to higher binding energy suggesting the incorporation of Fe3O4 on oxygenated groups of lignin. Kinetic modelling showed pseudo-second and pseudo nth order model best fitted the experimental data for both adsorbents. Intraparticle diffusion modelling revealed that initial adsorption behaviour was classified as strong initial adsorption for NTP and approaching complete initial adsorption for NTP-NC. Intraparticle diffusion coefficient, Di, where in the range of 10⁻⁵ to 10⁻¹³ cm²/s indicating that intraparticle diffusion occurred in a chemisorption controlled process. This was confirmed by the good fit of the chemisorption-diffusion model with the experimental data. Film diffusion was found to be active in the mechanism of Cr(VI) uptake by NTP but pore diffusion was active for NTP-NC. Activation energies, Ea, entropies, ΔS# and enthalpies, ΔH# of activation for the kinetic and diffusion processes where calculated from the various rate constants. Pseudo-first order Ea and ΔH# had the highest values for NTP while pseudo-second order had the highest values for NTP-NC for adsorption kinetics while intraparticle diffusion and chemisorption-diffusion gave the highest Ea and ΔH# for NTP and NTP-NC for the diffusion processes.
One-pot chemical activation and pyrolysis process was developed for biochar
production from red macroalgae residue of Gelidium sesquipedale. The macroalgae
residue was activated by various catalysts (KOH, NaOH, H3PO4, and CH4ON2) with
the two concentrations (2.5 and 5 wt %) using a pulverization system followed by slow
pyrolysis at 500°C. The activated biochars showed a porous morphology with an
increase of water-holding capacity compared to the unactivated one. The properties of
activated biochar observed by further characterization (i.e. FTIR, SEM, TGA) revealed
their feasibility to be used as an adsorbent. The results of adsorption experiment
confirmed that adsorption was not only dependant on the surface area but also on the
surface charge, and functional groups. The sorption performance of activated biochars
(AcBC), in terms of the adsorption of methylene blue, were comparable to the
commercial activated charcoal (Norit®). NaOH (2.5 wt%)-activated biochar had the
most optimizing removal efficiency of 87% versus 97% for commercial activated
charcoal.
To evaluate the possibilities for biofuel and bioenergy production Acacia Holosericea, which is an invasive plant available in Brunei Darussalam, was investigated. Proximate analysis of Acacia Holosericea shows that the moisture content, volatile matters, fixed carbon, and ash contents were 9.56%, 65.12%, 21.21%, and 3.91%, respectively. Ultimate analysis shows carbon, hydrogen, and nitrogen as 44.03%, 5.67%, and 0.25%, respectively. The thermogravimetric analysis (TGA) results have shown that maximum weight loss occurred for this biomass at 357 • C for pyrolysis and 287 • C for combustion conditions. Low moisture content (<10%), high hydrogen content, and higher heating value (about 18.13 MJ/kg) makes this species a potential biomass. The production of bio-char, bio-oil, and biogas from Acacia Holosericea was found 34.45%, 32.56%, 33.09% for 500 • C with a heating rate 5 • C/min and 25.81%, 37.61%, 36.58% with a heating rate 10 • C/min, respectively, in this research. From Fourier transform infrared (FTIR) spectroscopy it was shown that a strong C-H, CO , and C=C bond exists in the bio-char of the sample.
In this paper, the synthesis and characterization of porous carbon (PC) and porous carbon loaded ZnO nanoparticles (PC@ZnO) were investigated. The removal efficiency of Methylene Blue (MB) under ultrasound waves (UAA) and without ultrasound waves (SA) was studied considering the adsorbents dose, contact time, solution pH, temperature and initial dye concentration. Ultrasound irradiation have a positive effect on the removal efficiency of MB whereas ZnO nanoparticles incorporate in the surface of PC improve the regeneration efficiency of PC. PC@ZnO NPs shows high performance of MB removal using UAA, which was used for simultaneous removal of Crystal Violet (CV) and Congo Red (CR). The ultrasonic adsorption of CV/CR on PC@ZnO was found to be dependent on different parameters such as contact time, solution pH and initial dye concentration. The experimental results were found to follow the pseudo‐second‐order and Langmuir models. The adsorbed amount was found to be 64 mg g⁻¹ (for CR) and 109 mg g⁻¹ (for CV). Further, the effects of various parameters such as contact time, pH, initial dye concentration, and CV:CR ratio, were studied using central composite design coupled with response surface methodology. The data showed that the PC@ZnO has strong selective adsorption of CV dye in comparison to CR, and optimum conditions were found to be natural pH, 11.19 mg, (55:45%) of CV:CR ratio, 25 min and 30 mg L⁻¹ at adsorption temperature T=25 °C ± 1. In these conditions, both dyes (CV and CR) are easily regenerated using HCl (0.1 M).
The present work describes the production of novel highly hydrated cellulose microfibrils (CMFs) with unique morphology from coffee pulp waste using specific chemical treatments. The as-produced CMFs were successfully characterized and then used as an adsorbent for removal of methylene blue (MB) from concentrated aqueous solutions. Surprisingly, it was found that the novel CMFs display high water-uptake ability, with a maximum swelling ratio of 265%, and that they form an entangled hydrated network gel in water. The morphological observation and nitrogen adsorption measurement demonstrated that the extracted CMFs exhibit an average fibril diameter of 11.5 µm and mesoporous structure with an average pore size of 6.37 nm. These special features make the as-produced CMFs excellent candidates to be used as adsorbents for removal of MB from concentrated solutions. The performed adsorption studies determined that the adsorption equilibrium was reached within 90 min. The adsorption kinetics data were well fitted to the pseudo-second-order kinetic model, and the adsorption isotherms were well described by the Freundlich isotherm model. In addition, the maximum adsorption capacity was 182.5 mg/g, much higher than that determined for other previously reported cellulose-based adsorbents. Through this study, we have demonstrated a possible strategy to give an added value to the coffee pulp waste, a by-product of the coffee processing industry, which is rich in cellulose, inexpensive and renewable source. Indeed, the extracted CMFs are very attractive for developing a sustainable and economically viable bio-sourced material for future growth of cellulose use in advanced applications.
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Macadamia activated carbon (MAC) was impregnated with different concentrations of sulphuric or phosphoric or nitric acid ranging from 20 to 60% v/v and heated in a muffle furnace to improve the structural characteristics of the adsorbents for enhanced Cr(VI) removal. The %S content ranging between 2.27 and 3.23% in H 2 SO 4 treated MAC corroborated the incorporation of sulphonate groups during modification. Fourier transform infrared spectroscopy displayed presence of CN, NO, sulphur and phosphorus peaks at 1213, 1531, 1204, and 1214 cm ⁻¹ , respectively, proving efficacious attachment of the functional groups because of acid treatments. The surface area of pristine MAC increased from 545 to 824 m ² /g following acid treatment. The optimum performance for the adsorption of Cr(VI) was 98% at pH 1 and 93% at pH 4 after 120 min of contact time. Compared to pristine carbons (22.3 mg/g), there was an improvement in adsorption capacity to 40.99 mg/g when 20% (v/v) HNO 3 activating agent was used, but the adsorption capacity dropped to 9.66 mg/g when 20% (v/v) H 2 SO 4 was used. Materials modified with HNO 3 and H 3 PO 4 exhibited superior performances to H 2 SO 4 modified adsorbents indicating the importance of evaluating various concentrations and type of acid as these had positive and negative effects on Cr(VI) removal. The removal mechanism was better explained by both the Langmuir monolayer and Freundlich multilayer isotherms.
The raw and activated biomass of a green microalga, Chlamydomonas variabilis, were investigated as adsorbents for the
removal of methylene blue (MB) dye from aqueous solutions. Chlamydomonas variabilis was isolated and cultivated to obtain
a sufficient algal biomass. The collected biomass was first oven-dried and then activated by H2SO4. The results obtained
showed that the optimum adsorption of MB occurred over 30 min of contact time at pH 7 and an biosorbent dose of 1.5
and 1.0 g·L−1 of dried biomass and activated biosorbent, respectively. Point of zero charge (pHpzc) was recorded at pH 6.8
and 6.9 for dried and activated biomass, respectively. The activated biomass was a more effective biosorbent than was the
dried biomass: At a MB concentration of 82.4 mg·L−1, the minimum removal was greater than 98% using 1 g·L−1 activated
biomass with a maximum adsorption capacity (qmax) of 115 mg·g−1, whereas at a MB concentration of 56.4 mg·L−1, the
maximum removal did not exceed 80.8% using 1.5 g·L−1 raw biomass with a qmax of 18.3 mg·g−1. Furthermore, the Freundlich
and Langmuir isotherm models of adsorption showed a better model fit when using activated biomass than when using raw
biomass, with the former yielding R2 values greater than 0.9. The kinetic data suggest that the adsorption of MB follows the
pseudo-second-order equation better than the pseudo-first-order one. This study demonstrates that the activated biomass of
Chlamydomonas variabilis can be used as an effective biosorbent for the treatment of dye-containing wastewater streams.
The brewing by-product brewer’s yeast biomass (BYB) was evaluated as a bioadsorbent for removal of basic dyes and lead from aqueous solutions. The functional groups including the hydroxyl group and cyano group are the major sources of adsorption by BYB. The adsorption of dyes on BYB was negatively correlated with temperature, whereas with lead, it was positively correlated with temperature. The adsorption kinetic of methylene blue (MB), malachite green (MG), and lead on BYB were identified as pseudo-second order, whereas safranin O (SO) was identified as pseudo-first order. A low dosage of BYB effectively adsorbed four adsorbates and reached equilibrium in 3–5 min. The maximum monolayer adsorption capacities of BYB for MB, MG, SO, and lead were 212.05, 212.05, 76.77, and 106.88 mg/g, respectively.
The adsorptive removal of environmental pollutants is an effective method for the treatment of contaminated water. Thus, the preparation of adsorbents from low-cost, readily available, and renewable resources has garnered immense attention in recent years. In this study, a facile one-step method for the preparation of a high-capacity adsorbent is demonstrated by refluxing pine cones in concentrated sulfuric acid. With sulfuric acid reflux, the pine cones undergone carbonization as well as functionalization with sulfonic acid groups. The adsorbent demonstrated high adsorption capacity for two emerging organic pollutants, methylene blue (MB) and tetracycline (TC). Different variables such as pH, temperature, contact time, and initial concentration of the pollutants were analyzed and showed that the adsorption capacity for MB increased in a basic pH and vice versa for TC. Also, the elevated temperature favored the adsorption for both MB and TC. The maximum adsorption capacity was found to be 1666.66, and 357.14 mg g À1 for MB and TC, respectively. In comparison to the pristine pine cone, the sulfuric acid treated pine cone demonstrated an extraordinary improvement in the adsorption capacity. The adsorption of MB and TC was performed from the tap water matrix and similar adsorption capacities were found. A packed glass column was also prepared to demonstrate the adsorption of MB from tap water under flow conditions.
We researched industrial wood ash in order to assess its posed threats and possible applications. The ash is type S; due to the content of SiO2, CaO, Al2 O3, K2 O, Fe2 O3, Na2 O, MgO, SO3, and TiO2 it is alkaline (pH = 12.9) with small bulk density (<1.4 g/mL); and it is characterized by high fragmentation and irregularly shaped grains (research SEM/EDS). It has a high cationic-exchange capacity (56 mmol/100 g) and a negatively-charged surface (pH>pHPZC), which suggests the possibility of sorption cations. Research of the structure of phases present in the ash (FT-IR method) and physical or chemical changes with their accompanied thermal effects in the temperature range 25-900° (TG/DTG method) indicate no degradation of aluminum-silicon skeletons. Metals occur inside and in the surface layer of the grain (FAAS, SEM/EDS analyses). Research of fractionation of Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn (classic Tessier’s method) indicated high mobility among others (Co 28.44%, Cr 20.49%, and Pb 16.51%), which poses a risk of environmental pollution. The obtained results indicate 2 directions of ash application: (i) limited environmental due to heavy metal and (ii) processing in geopolymer.
Biochar is a low cost and renewable adsorbent which can be used to remove dye from wastewater. Cattle manure-derived low temperature biochar (CMB) was studied to remove methylene blue (MB) from aqueous solution in this paper. The effect of factors including initial concentration of MB, dosage, contact time, and pH on the adsorption properties of MB onto biochar were studied. Characterization of the CMB and MB adsorbed on CMB was performed using techniques including BET, FTIR and SEM. The adsorption isotherm, kinetics, thermodynamics and mechanism were also studied. The results showed the equilibrium data were well fitted to the Langmuir isotherm model, and the saturation adsorption capacity of CMB200 was 241.99 mg g⁻¹. Pseudo-second order kinetics was the most suitable model for describing the adsorption of MB onto biochar. The adsorption thermodynamics of MB on biochar showed that the adsorption was a spontaneous and endothermic process. Through zeta potential measurement, Boehm titration, cation exchange, deashing and esterification experiments, the importance of ash to adsorption was verified, as well as the adsorption mechanism. The adsorption mechanism of MB on CMB200 involved cation exchange, electrostatic interaction, hydrogen bonding, physical effects and others. This work shows that CMB200 holds promise to act as an effective adsorbent to remove MB in wastewater.
A nano-biosorbent for the removal of methylene blue (MB) was prepared by encapsulating iron oxide nanoparticles (NPs) and Agrobacterium fabrum strain SLAJ731, in calcium alginate. The prepared biosorbent was optimized for the maximum adsorption capacity at pH 11, 160 rpm, and 25 °C. Adsorption kinetics was examined using pseudo-first-order, pseudo-second-order, and intra-particle diffusion (IPD) models. The kinetic data agreed to pseudo-second-order model indicating chemisorption of MB, which was also explained by FTIR analysis. The adsorption rate constant (k2) decreased and initial adsorption rate (h, mg g⁻¹ min⁻¹) increased, with an increase in initial dye concentration. The dye adsorption process included both IPD and surface adsorption, where IPD was found to be a rate-limiting step after 60 min of adsorption. The adsorption capacity was found to be 91 mg g⁻¹ at 200 mg L⁻¹ dye concentration. Adsorption data fitted well to Freundlich isotherm; however, it did not fit to Langmuir isotherm, indicating adsorbent surfaces were not completely saturated (monolayer formed) up to the concentration of 200 mg L⁻¹ of MB. Thermodynamic studies proposed that the adsorption process was spontaneous and exothermic in nature. Biosorbent showed no significant decrease in adsorption capacity even after four consecutive cycles. The present study demonstrated dead biomass along with NPs as a potential biosorbent for the treatment of toxic industrial effluents.
The biowaste refinery concept has received significant attention in recent years as a sustainable alternative the petroleum refinery, exploiting the biowaste for producing high value bioproducts. However, waste-based biorefineries mainly apply homogeneous waste streams from agriculture and food processing as feedstock. This paper presents the state of the art of mixed-biowaste biorefinery concepts. We identified 20 studies that use the organic fraction of municipal solid waste (OFMSW) as feedstock, producing enzymes, bioplastics, biopesticides and other high value products. Valorisation efficiency (output product per kg OFMSW) and potential revenue by valorising the OFMSW into different products (Euro/ton OFMSW) was analysed for the identified studies. It was found that enzymes have the highest potential revenue followed by biopesticides and bioplastics. Developing biorefineries applying OFMSW as feedstock presents a promising opportunity for moving up the waste hierarch through coupling the waste and production sector in a future circular bioeconomy.
The performance of spinning basket membrane (SBM) module was tested for the separation of polyvinyl alcohol (PVA) from wastewater. The SBM performance was examined using 50 kDa polyethersulfone ultrafiltration membrane under different parametric conditions. Also, the effects of rotational speed and transmembrane pressure on permeate flux and PVA rejection were investigated. The rotational speed played a significant role in decreasing membrane fouling by reducing the particle deposition on the membrane surface due to enhanced turbulence and shear force. Also, the in-built hydrodynamic cleaning facility of the SBM module allowed easy cleaning of the membrane. The steady-state value of percentage rejection of PVA was above 90% when the steady-state permeate flux value was above 54% of its initial value. The results suggested that spinning basket membrane module was efficient as well as economical for the separation of PVA from aqueous solution.
Adsorption is a widely used unit process in various fields, such as chemical, environmental and pharmaceutical, etc. The intraparticle diffusion adsorption kinetics model is one of the most widely used adsorption kinetics models. However, the application and solving method of this model have yet to be discussed. This model has two forms (qt = kt1/2 and qt = kt1/2 + constant, where qt is the adsorption capacity at time t, k and constant are the model parameters), which have not been unified yet. Moreover, the interpretation of this kinetics model lacks a theoretical basis (if the line passes through the origin point (0, 0), the adsorption is dominated by the intraparticle diffusion; if not, it is a multiple adsorption process). In this study, we analyzed the proper equations of the intraparticle diffusion model and their applications, discussed the interpretation of the mass transfer steps revealed by this model, and provided the solving methods. The result indicated that the piecewise function qt = k1t1/2 (0 ≤ t ≤ t1); qt - qt = t1 = k2(t – t1)1/2 (t1 < t ≤ t2) is the proper form of this model. The adsorbate diffusion in the pores inside the adsorbent is the mass transfer step revealed by this model. The statistical parameters should be used to evaluate the fitting results instead of judging whether the model lines pass through the origin point (0, 0). We provide the solving methods to use the Origin and Microsoft EXCEL software to solve the model. Our study established the method for application of the intraparticle diffusion model.
The present work aims to isolate protein from shrimp waste for the formulation of wood adhesive. The obtained proteins were successfully characterized in terms of their morphology, physical and chemical properties. Then, the effect of protein (P) formulated with corn-starch–mimosa-tannin (CSMT) at different ratios of CMST/P (w/w) on mechanical properties such as internal bond (IB) modulus of elasticity (MOE), modulus of rupture (MOR) and surface of soundness (SS) as well as on physical performance such as thickness swelling (TS) and water absorption (WA) was investigated. Results show that the mechanical and physical properties were enhanced, particularly for particleboards glued with CSMT/P (99.2/0.8; w/ w) wood adhesive. Comparing to neat CSMT the IB, MOE, MOR and SS of particleboards bonded with CSMT/P (99.2/0.8; w/w) were increased by 18.18%, 19.56%, 34.61% and 17.03%, respectively. Additionally, a significant decrease in TS and WA was observed (~ 43.33% and 19.76% after 2 h, and 21.05% and 14.57% after 24 h of wetting in water, respectively), was observed.
Cactus fruit waste seeds (CWS) are a by-product of the cactus fruit processing industry. Until now, CWS are not recoverable in any sector. The valorization of these residues may reduce their volume in the environment and transform them into valuable products. In this work, CWS have been identified for the first time as a sustainable lignocellulosic source. Cellulose microfibers (CMFs) and nanocrystals (CNCs) were successfully produced via alkali and bleaching treatments followed by sulfuric acid hydrolysis. It was found that the extracted CMFs showed an average diameter of 11 μm, crystallinity of 72%, and a yield of 25%. The as-produced CNCs exhibited a needle-like shape with a diameter of 13 nm ± 3 and length of 419 nm ± 48, giving rise to an aspect ratio of 30.7, with a zeta potential value of – 30 mV and a charge content of sulfate groups of 287.8 mmol·kg−1. Herein, the obtained cellulosic derivatives with excellent properties from this underutilized waste can draw the attention of researchers towards CWS as a new type of biomass with virtually no hemicellulose, which could be of great interest to isolate and study the effects of how lignin interacts with cellulose.
Nitrate is ubiquitous pollutant due to its high water solubility, usually contributing to eutrophication, and posing a threat to aquatic ecosystem and human health. Adsorption approach has been widely used for nitrate removal because of the simplicity, easy operation, and low cost. Adsorbent plays a key role in the adsorptive removal of nitrate. The adsorption performance and adsorption mechanism are determined by the structural feature of adsorbent that is dependent on the preparation method. In this review, various types of adsorbents for nitrate removal were systematically summarized, their preparation, characterization, and adsorption performance were evaluated; the factors influencing the nitrate adsorption performance were discussed; the adsorption isotherm models, kinetic models and thermodynamic parameters were examined; and the possible adsorption mechanisms responsible for nitrate adsorption were categorized; the possible correlation of adsorbent structure to adsorption performance and adsorption mechanism were explained; the potential applications of adsorbents were discussed; finally, the strategies for improving adsorption capacity and selectivity towards nitrate, the challenges and future perspectives for developing novel adsorbent were also proposed. This review will deepen the understanding of nitrate removal by adsorption process and help the development of high-performance adsorbents for selective nitrate removal from water and wastewater.
Surfactin, a biosurfactant, has the potential to replace synthetic surfactants in froth flotation. This research investigates the surface interactions between surfactin and coal which determine whether surfactin has collecting or depressant characteristics on coal using electrokinetic, FTIR, and micro-flotation experiments. At concentrations of 5 mg/L, surfactin removes species on the surface of coal, especially in the alkaline pH range. At surfactin concentration of 15 mg/L adsorption of surfactin onto coal surfaces are indicated and likely to be due to hydrophobic physisorption between aliphatic groups of surfactin and the hydrophobic carbonaceous surface functional groups of coal. Hydrophobicity of coal was observed to be enhanced at pH 3,6 and 10 except the intermediate pH of 8. Micro-flotation tests showed that hydrophobicity of coal was most significantly enhanced by surfactin presence at pH 3 and 15 mg/L from 42.9% to 74%, and least impacted when surfactin concentration was 5 mg/L at a pH of 10. The collecting or depressant characteristics of surfactin on coal as a function of pH and surfactin concentration have been demonstrated for the potential use of this novel biosurfactant as a Green Chemistry substitute for synthetic surfactants.
Hazardous organic pollutants have been attracting heightened interest in recent years due to their persisting properties, low biodegradability, and negative influence on aquatic life, wildlife, and humans even at low concentrations. Considering their dangerous effect on the environment, several treatments using different techniques were adopted to remove them from water and wastewater. Herein, electrochemical advanced oxidation processes (EAOPs), especially anodic oxidation (AO), electro-Fenton (EF), heterogeneous electro-Fenton (HEF), and photoelectro-Fenton (PEF), have been thoroughly reviewed and found to be promising compared to conventional methods. The state of the art of the previous treatment processes has been discussed in detail, where each technique has its own merits and challenges. These processes depend on their operating conditions mainly pH, current density, nature of electrodes used, and conductivity of the solution, etc. The efficiencies of EAOPs follows the order as PEF > EF > AO and can mineralize the recalcitrant organic pollutants completely.
In this study, we aimed to assess the possible reusability of native and surface-modified waste biomass of a novel ascomycetes fungi Trichoderma asperellum BPL MBT1 for the adsorption of triphenylmethane dyes. Spent biomass obtained from fermentation medium has been applied in the uptake of model cationic dyes viz., crystal violet and malachite green. Optimization of experimental parameters by batch mode studies revealed that dye adsorption is influenced by medium pH time, initial concentration of dyes, and adsorbent dosage. It was observed that pH 10 was optimum for cationic dye adsorption. Further, the adsorption process obeyed the bi-model (Langmuir–Freundlich model) isotherm and adhered to pseudo-second-order kinetics. The involvement of ion exchange as the dominant mechanism of dye adsorption was indicated by the mean free energy obtained from Dubinin–Radushkevich isotherm. Cellular morphology and the involved functional groups were studied by scanning electron microscopy and Fourier transform infrared spectroscopy that revealed the presence of carbon and oxygen containing groups on the surface. Maximum desorption efficiency was achieved using a 0.1 M solution of HCl and the stability of the biosorbent was confirmed through reusability analysis. Our results confirm the applicability of both native and surface-modified T. asperellum BPL MBT1 biomass as a potential biosorbent for the sustainable wastewater treatment and safe dye disposal.
Carbon nanostructures have a great potential in various applications. They are considered as promising sorbents of contaminants owing to their unique physical and chemical behaviors. In this work, a hybrid adsorbent was successfully prepared by oxidizing carbon nanotube (CNT) and grafted with polyethylene glycol (PEG). The performance of the hybrid material (CNT/PEG) as an adsorbent was investigated for the phenol removal in a batch system. The effects of contact time, initial solution pH, the initial concentration of phenol, and adsorbent dosage on the efficiency of phenol removal were investigated. The phenol adsorption by CNT/PEG was pH-dependent and under optimum conditions, high adsorption efficiency (≈100 %) was achieved at a contact time of 30 min. The magnitude of R2 acquired with the pseudo-second-order model is high (>0.99) which indicates the process follows this model. Both the Langmuir and Freundlich isotherm models show a good fit to the adsorption experimental data. However, Freundlich model shows a better fit to the experimental results than the Langmuir model (R2 > 0.98). The prepared hybrid material (CNT/PEG) demonstrated to be an efficient adsorbent for removal of phenol from water as well as for simultaneous removal of phenol with pollutants such as Cu, Hg, Cr, Fe, Co, Ni, Al and Pb from industrial wastewater.
In this work, a novel two-dimensional MXene decorated with Fe3O4 ([email protected]3O4) had been successfully synthesized via an in-situ growth method. The characteristic of nanomaterials was analyzed as well as the adsorption properties toward methylene blue (cationic dyes, MB) were investigated with various temperatures. The obtained complex [email protected]3O4 exhibited a typical 2D lamellar structure with superparamagnetic characteristic (20.3 emu·g⁻¹). Zeta potential measurement revealed a negative charged surface of [email protected]3O4 at neutral medium, which was favorable for cationic dye removal. Moreover, the removal process presented an excellent decolorization at high temperature with 91.93% (55 °C) compared with other lower temperatures. Adsorption isotherm indicated the removal process of MB fitted well with Freundlich isotherm model at high temperature (40 and 55 °C) whereas Langmuir isotherm for that at low temperature (25 °C). Thermodynamic study indicated an exothermic and chemisorption process for MB removal, further indicating that the increase of temperature could remarkably promote the removal capacity of [email protected]3O4. In addition, the removal mechanism at high or low temperature was investigated by XRD, FT-IR and XPS techniques. The abundant Ti–OH groups on [email protected]3O4 surface played a dominant role in enhancing the MB decolorization through hydrogen bonding (Ti–OH⋯N) and electrostatic attraction at high temperature system, while surface adsorption via electrostatic interaction contributed the MB removal process in the case of 25 °C.
In the present study, the removal of a cationic dye, methylene blue (MB) with brown (Nizamuddinia zanardinii), red (Gracilaria parvispora) and green (Ulva fasciata) macroalgae was studied. The effects of different parameters such as initial solution pH, initial dye concentration, biomass dosage and contact time were investigated on the biosorption of MB by algae. Biosorption isotherm was modeled using the Langmuir, Freundlich and Temkin models. The highest MB dye removal efficiency onto algae was observed in the range of 5–11. Increasing biosorbent dosage from 80 to 240 mg/L, significantly increased the removal efficiency of MB dye; however, increasing the biosorbent dosage above 240 mg/L up to 400 mg/L did not significantly increase the dye removal efficiency. The biosorption of MB dye onto macroalgae reached equilibrium after about 90 min. Based on the Langmuir model, the uptake of MB by brown, red and green algae was determined as 863.4, 83.08 and 1514 mg/g, respectively. The biosorption kinetic data were successfully described with pseudo-second-order model for three biosorbents. FT-IR spectrum analysis suggested amido or hydroxyl, C=C and C–H groups present on algae surface could take part in MB dye biosorption.
In the present study, Methylene Blue (MB) removal has been studied from its aqueous solution, using Ficcus Palmata Leaves (FPL) based plant material. The effect of different parameters such as contact time (10‐100) minutes, initial concentration (5‐25) mg/L, pH (4‐13), temperature (298‐318 K) and adsorbent dosage (0.15 ‐ 0.45 g/0.05 L) was investigated. The maximum removal efficiency was calculated to be 98% for sample having initial concentration 15 mg/L along with 0.45 g of adsorbent agitated for 80 minutes at 318 K and pH=7. The data were fitted to adsorption isotherm models (Langmuir and Freundlich) and kinetic models (pseudo‐first order, pseudo‐second order and intra‐particle diffusion). The data were found to be best fitted with Freundlich adsorption isotherm (R²= 0.99) and pseoudo‐second‐order (R²=0.991). Thermodynamic parameters (free energy change, enthalpy change and entropy change) were also estimated. The Gibb,s free energy values was found to be ‐1.808, ‐5.139 and ‐5.991 kJ/mol at 298, 308 and 318 K respectively. The decrease in free energy with increasing temperature has indicated spontaneity of adsorption process and positive enthalpy change (35.75 kJ/mol) showed that the adsorption process was endothermic. 0.1 M HCl was found to be most effective desorbing agent with percent desorption 53.51%.
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The organic and inorganic pollutants in water stream are due to the various industrial activities, consequent to the higher level environmental contamination. Considering the high toxicity and persistent property of wastewater pollutants, sequestration before discharge into water bodies becomes an important obligation. The conventional treatment methods are mostly associated with the drawbacks of energy intensive conditions and require high investment. Biochar produced through thermal decomposition of lignocellulosic biomass in the limited oxygen conditions offer as the sustainable potential adsorbent towards wastewater pollutants removal. The current review discusses on the utilization of various lignocellulosic biomass precursor for the production of biochar. The significant parameter influence and mechanistic aspects of the biochar production using pyrolysis were critically analyzed. The recent research on biochar modifications through different physical and chemical methods to enhance biochar adsorption property was reported. The new trend of the potential application of biochar in the adsorption of heavy metals, dyes and the underlying mechanisms are comprehensively reviewed. Further explorations are required in the directions of sustainable biochar development, continuous adsorption process, industry scale applications and spent biochar management.
The present study investigated the efficiency of the biosorbent developed from waste biomass of Sapindus mukorossi (reetha) pericarp for removal of methyl violet dye from wastewater. The saponin extracted waste biomass of reetha pericarp was developed as biosorbent by different techniques such as, chemical treatment (H2SO4 treated), physical modification (thermally treated) and combining them both. The developed biosorbent was characterized by BET, FTIR, FE-SEM and EDX analysis. The DTG analysis of reetha bio-waste reviled that hemicellulose (27%), cellulose (45%), and lignin (10%) were present in the saponin extracted reetha bio-waste (RBW). In the preliminary adsorption experiments, the thermally treated biosorbent (RBW-III) showed maximum MV removal efficiency among the developed biosorbents. The adsorption experiments were designed using central composite design (CCD) technique to optimize the process parameters such as pH, biosorbent dosage, initial MV concentration and agitation speed for thermally treated biosorbent (RBW-III). The adsorption kinetics, isotherms parameters were evaluated for thermally treated biosorbent (RBW-III). The RBW-III removed maximum 95% MV dye from 28 mg L⁻¹ initial MV concentration at pH of 4 using biosorbent dose of 0.1 g L⁻¹, with an agitation speed of 120 rpm and contact time of 150 min.
Cellulose-based substrates could represent potential funds for the sorption of pollutants. Herein, Methylene blue was selected for demonstrating the bio-sorption efficiency of Nerium Oleander, Pergularia Tomentosa and Populus Tremula seed fibers. Their cellulose contents were 45%, 43.8% and 60%. Their lignin amounts were 21%, 8.6% and 12%, respectively. Fourier Transform InfraRed suggested that the interaction of these bio-products with Methylene blue could occur between hydroxyl and ester groups of cellulose and lignin and the sulfur and nitrogen atoms of the dye. Scanning Electron Microscopy showed a swelling of the bio-matters after biosorption. From X-Ray Diffraction, the shifting for higher values of the peaks related to the amorphous phase indicated the establishment of new rearranged regions. Such change from the decomposition behavior event studied by Thermogravimetric Analysis/Differential Thermal Analysis revealed that Methylene blue was interacted with cellulose and lignin. The effect of adsorbent dosage, pH, time, dye concentration and temperature was investigated in batch experiments. Excellent sorption capacities followed the order: Nerium Oleander (280.2 mg g−1) > Populus Tremula (168 mg g−1) > Pergularia Tomentosa (145.3 mg g−1). Freundlich fitted best the equilibrium data suggesting cooperative interactions via physisorption and chemisorption phenomenon. Kinetic data complied with second-order suggesting a chemisorption mechanism.
A micro-mesoporous activated carbon (AC) was produced via an innovative approach combining microwave pyrolysis and chemical activation using NaOH/KOH mixture. The pyrolysis was examined over different chemical impregnation ratio, microwave power, microwave irradiation time and types of activating agents for the yield, chemical composition, and porous characteristic of the AC obtained. The AC was then tested for its feasibility as textile dye adsorbent. About 29 wt% yield of AC was obtained from the banana peel with low ash and moisture (<5 wt%), and showed a micro-mesoporous structure with high BET surface area (≤1038 m2/g) and pore volume (≤0.80 cm3/g), indicating that it can be utilized as adsorbent to remove dye. Up to 90% adsorption of malachite green dye was achieved by the AC. Our results indicate that the microwave-activation approach represents a promising attempt to produce good quality AC for dye adsorption.
The removal feasibility of malachite green (MG) on Magnetic Activated Carbon (Fe3O4-AC) from aqueous solution was investigated. The physicochemical/morphological properties of the prepared novel sorbents were identified using an analysis technique. The maximum adsorption capacity of the synthesized magnetic sorbent was found in the range of 217.68–311.40 mg/g at 298–318 K while it was determined between 103.64 and 106.54 mg/g for activated carbon (AC). All results showed that the synthesized adsorbent is an effective adsorbent for the removal of MG from aqueous solutions in addition to its advantageous properties such as considerable high surface area and porosity, natural source requirement, low cost and easy producible.
Native, iminodiacetic acid and triethylenetetraamine modified biomasses of Funalia trogii were used for removal of Congo Red dye (CRD) from aqueous medium. The native and modified fungal biomasses were characterized using ATR-FTIR, Zeta potential, contact angle studies and analytical methods. FTIR studies of the native and chemically modified adsorbent preparations show that amine, carboxyl and hydroxyl groups are involved in the adsorption of the model dye (i.e., Congo Red). The maximum adsorption of the CRD on the native, carboxyl and amine groups modified fungal biomasses was obtained at pH 5.0. The amount of adsorbed dye on the adsorbent samples increased as the initial concentration of CRD in the solution increased to 200mg/L. The adsorption capacities of native, carboxyl groups and amine modified fungal preparations were 90.4, 153.6 and 193.7mg/g dry adsorbents, respectively. The data was fitted well with the Langmuir isotherm model, and followed the pseudo-second-order equations. Thermodynamic parameters (ΔG⁰, ΔH⁰ and ΔS⁰) were also calculated. The results showed that triethylenetetraamine (TETA) modified biomass of F. trogii presented an excellent dye removal performance and can be used in various environmental applications such as various micro-pollutants removal from aqueous medium.
Despite of immense application potential of graphene in wastewater treatment, the colloidal stability, aggregation and recyclability remains a major challenge. To address this issue, we report biomaterial functionalized graphene-magnetite (Bio-GM) nanocomposite as a novel recyclable material for treatment of wastewater containing dyes and heavy metal. The integration of biomaterial including living cells of Shewanella oneidensis with graphene-magnetite nanocomposite was characterized through UV-vis, FTIR, FESEM and fluorescent microscopic studies. The contact angle measurement depicted the hydrophilic property (water contact-angle 27.93), while VSM result demonstrated super paramagnetic behavior of the nanocomposite with saturation magnetization value of 30.2 emu/g. The Bio-GM nanocomposite exhibited excellent adsorption capacity towards dyes and Cr6+ in both single and multicomponent system with removal capacity of 189.63 ± 7.11, and 222.2 ± 8.64 mg/g of dyes and Cr+6, respectively, suggesting selective binding capacity and high adsorption efficiency of Bio-GM nanocomposite. In the adsorption coupled redox reaction, the Cr+6 was reduced to Cr+3 through biocatalytic activity of Bio-GM nanocomposite. The nanocomposite could be easily regenerated and reused for multiple cycles of adsorption-desorption studies without release of graphene and magnetite, and thus eliminating the potential hazardous risk of nanomaterial to the environment. The proposed biomaterial functionalized graphene-magnetite nanocomposite thus offers a novel way for sustainable, affordable and efficient removal of coexisting toxic pollutants of dyes and heavy metal.
In this work, an environmentally benign superabsorbent hydrogel based on banana pseudo-stem has been synthesized by free radical graft co-polymerization of sodium acrylate (NaAc) and acrylamide (AM) on to modified banana pseudo-stem cellulose backbone using ammonium persulfate (APS) and N,N-methylene-bis-acrylamide (MBA) as initiator and crosslinker respectively.The optimum condition for initiator, monomers and crosslinker concentrations was found to be 0.0032molL-1, 0.013molL-1 and 0.00048molL-1 respectively. Structural confirmation of the hydrogel prepared is performed by FT-IR spectroscopy whereas the morphology and thermal properties assessments were performed by SEM and TGA analysis respectively. Swelling behavior in solutions with different pH (2, 4, 7, 9 and 12) and contact time (5-750min) indicated 323.54gg-1 in pH 7 solutions for 570min. The optimized hydrogel was used as adsorbent for methylene blue (MB) and methyl orange (MO) with a maximum adsorption of 333.3 and 124 mgg-1 respectively. Kinetics and Isotherm adsorption studies revealed pseudo second-order and Freundlich isotherm as befitting models.
The removal of sulfur from petroleum products is an important step in the refining process. Several techniques have been developed to address the limitations of hydrodesulfurization, including adsorptive desulfurization. One of the requirements of the adsorptive desulfurization process is the use of efficient and cost-effective materials. In this work, activated carbon (AC) derived from waste rubber tires was loaded with cobalt and copper nanoparticles. The prepared materials were evaluated for their efficiency in batch and fixed-bed systems for the simultaneous adsorptive desulfurization of thiophene (T), benzothiophene (BT), dibenzothiophene (DBT), 5-methyl-1-benzothiophene (MBT), 4-methyldibenzothiophene (MDBT), and 4,6-dimethyldibenzothiophene (DMDBT). AC loaded with cobalt and copper (CoCu/AC) showed enhanced simultaneous adsorptive desulfurization of the sulfur compounds in the order of DBT > MDBT > DMDBT > MBT > BT > T. The adsorption experimental data showed the closest match with the pseudo-second-order kinetic. The intraparticle diffusion indicates that other mechanisms may be included in the adsorption process along with the intraparticle diffusion. Simultaneous adsorptive desulfurization in fixed bed models indicated the following trend in breakthroughs: DBT > MDBT > DMDBT > MBT > BT > T. A mechanism proposed via the π-complexation and the direct S-M interaction could justify the trend in adsorption capacity.