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Coconut bagasse, an agricultural solid waste was used as biosorbent for the removal of cadmium after modification with thiourea. The adsorption of Cd2+ was studied at pH 5.5. Langmuir, Freundlich, and Temkin isotherms were used to model the adsorption equilibrium data, and it was found that the system followed the Langmuir and Temkin isotherms. The...
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... aqueous NaOH and liquid ammonia treatments alter the crystalline structure of cellulose, resulting in the formation of different allomorphs of cellulose. Kroon- Batenburg and Kroon 1997 showed that two different packing structures of cellulose chain (type I and type II) can be formed, as shown in Fig. ...
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... it is possible that the conversion of cellulose type I to type II is more efficient in the presence of NH 4 OH/thiourea solution, due to the formation of a cellulose-ammonia complex. In addition, the increase in adsorption capacity on coconut bagasse submitted to alkaline treatment can be attributed to the formation of cellulose type II (Fig. 1b), in light of the fact that such a structure has more active groups available to interact with the Cd 2+ . ...
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... F and 1/n are the Freundlich constants related to adsorption capacity and intensity of adsorption, respectively. The estimated parameters of these models were evaluated by regression analysis, and the results are shown in Table 4. Figure 10 shows the Freundlich isotherms obtained for the Cd +2 adsorption on CST adsorbent. The K F and 1/n values were found to be 16.12 and 0.24, respectively. ...
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Coconut bagasse, an agricultural solid waste was used as biosorbent for the removal of cadmium after modification with thiourea. The adsorption of Cd2+ was studied at pH 5.5. Langmuir, Freundlich, and Temkin isotherms were used to model the adsorption equilibrium data, and it was found that the system followed the Langmuir and Temkin isotherms. The...
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... Neto et al. treated coconut bagasse with a thiourea/ammonia solution to increase the adsorption capacity for the removal of cadmium, and the adsorption capacity was found to be 35.97 mg/g [94]. In another study, N/S doped magnetic carbon aerogel was fabricated using sugarcane bagasse-based cellulose and was successfully applied for the removal of bisphenol from aqueous solution. ...
Increases in agricultural waste, population, and industrialization are leading to serious environmental problems, in particular drinking water contamination. Continuous efforts have been made to remediate water pollution through different approaches, either by decreasing the interring of pollutants or treatment of already contaminated water. The development of an efficient, cheaper, and renewable adsorbent is the focus of the current research. Agricultural wastes are cheap materials for this purpose and have attracted much attention of researchers. These agricultural wastes are either field residues such as stems, stalks, and leaves, or process residues such as husks, roots, and bagasse, as they have the same chemical composition (cellulose, hemicelluloses, and lignocelluloses). These wastes are processed using different methods to yield an efficient adsorbent. Chemical modification is used to prepare novel efficient adsorbents using agricultural wastes, rather than incineration of these materials. This review summarizes the research outcomes in terms of chemical modification and application of agricultural wastes used for the eradication of organic and inorganic pollutants from water.
... Rapid achievement of equilibrium is attained [44]. To check the best performance, 0.1 M hydrochloric acid, 0.1 M sodium hydroxide, methanol, ethanol, iso-propanol, iso-butanol, acetone, urea [45], thio-urea [46], citric acid [47,48], tartaric acid [49], and ethylene diamine tetra acetic acid (EDTA) [50] were used. Tartaric acid gave the maximum biosorption capacity, so it was selected for further studies, as shown in Figure 1. 5 g of HA and CC was selected and added in aqueous solutions of 25 mL of abovementioned solvents and kept in glass beakers for 4 hours approximately. ...
Two novel adsorbents Holarrhena antidysenterica (HA) and Citrullus colocynthis (CC) were collected from native Pakistan and treated with tartaric acid. The adsorbents were characterized by Fourier-transform infrared spectroscopy (FT-IR) and scanning electron microscopy, and their adsorptive behavior was studied against model cationic dye crystal violet (CV). Role of biosorbent dose, time of contact, temperature studies, agitation rates, and solution pH was investigated. Optimum conditions obtained for the removal of CV dye for H. antidysenterica-tartaric acid modified (HA-TA) were as follows: 0.8 g adsorbent dose, 35 minutes contact time, 5.0 pH, 40°C temperature, and 150 rpm agitation rates as compared to H. antidysenterica that gave 1.4 g adsorbent dose, 40 minutes time of contact, 6.0 pH, 50°C temperature, and 150 rpm agitation speed. C. colocynthis-tartaric acid modified (CC-TA) removed CV dye at 0.6 g adsorbent dose, 30 minutes contact interval, 4.0 pH, 40°C temperature, and 125 rpm agitation speed in contrast to C. colocynthis which gave 0.8 g adsorbent dose, 40 minutes time of contact, 6.0 pH, 50°C temperature, and 125 rpm agitation speed, respectively. Isothermal studies for both raw and modified biosorbents were compliant with the Langmuir model indicating monolayer, chemisorption. The maximum Langmuir capacities were up to 128.20 mg/g, 136.98 mg/g, 144.92 mg/g, and 166.66 mg/g for HA, CC, HA-TA, and CC-TA. Pseudo-second-order kinetic model well fitted the dye removal data. The rate-determining steps involved both surface and intraparticle diffusion mechanisms. Adsorption of dye molecules on active surfaces was governed by electrostatic attractions and chelating abilities. Thermodynamics research revealed the spontaneous and exothermic nature of the reaction. The adsorbents serve promising candidates for the effective removal of hazardous dyes from aqueous solutions.
... In this adsorption study with CGSL soils, the N was in the range of 0.21 to 0.39 likely due to using of high concentrations up to 1440 mg.L-1. Among other characteristics of soil and contaminant solution, high concentrations of metallic ions in solution tend to decrease the availability of adsorption sites in the surface of the adsorbent, distancing it from a linear behavior (SOUSA NETO et al., 2012). ...
A adsorção de metais pesados por liners de aterros sanitários representa mais uma medida de proteção às águas subterrâneas e superficiais contra a contaminação por metais, amenizando os riscos à saúde pública. O objetivo deste trabalho foi identificar, a partir de correlações, a influência de propriedades físico-químicas de solos utilizados em liners de aterros sanitários com parâmetros de adsorção do níquel. Os solos de estudo, areia argilosa e argila bentonítica, foram submetidos a ensaios de equilíbrio em lote individualmente e em misturas, com solução contaminante de níquel de 45 a 1440 mg.L-1. Os parâmetros de adsorção do níquel foram obtidos pelos modelos de isotermas de Langmuir e Freundlich, apresentando melhor ajuste pelos critérios de R² e REQM no de Freundlich. Constatou-se melhor adsorção ao níquel à medida em que a argila bentonítica foi adicionada às misturas, sendo a capacidade de troca catiônica (CTC) a propriedade que mais influenciou na retenção do metal.
... In this context, coconut (Cocos nucifera) shell, a waste lignocellulosic material, contains various polar functional groups such as carboxylic and phenolic acid groups that show affinity for metal complexation. 17 In this study, three adsorption models often reported in the literature were tested to provide the best description of Ca(II) adsorption, namely Langmuir, Freundlinch, and Temkin. It should be noted that for Langmuir, Freundlich, and Temkin models, the set of isotherm parameters was calculated not only by linearization but also in nonlinear forms. ...
... A zeta potential value on its own without a quoted pH is a virtually meaningless number. Therefore a zeta potential versus pH curve will often be positive at low pH and lower or negative at high pH 17 . The plot of zeta potential versus pH is shown in Figure (1) with a point of zero zeta potential at a pH around 2.0 and 4.5 to CHA and RCH adsorbents, respectively. ...
Biosorption potential of oxidised coconut coir (OCC) for removal of Cd(II) was evaluated by multi-column arrangement by connecting three columns in series. Effect of flow rate at 5, 10 and 15 mL/min was studied at 30 mg/L initial Cd(II) concentration. The dynamic capacity of the system was found to be 321, 206 and 83 mg/L for 5, 10 and 15 mL/min flow rates, respectively, by applying the bed depth service time model. Biosorbent usage rates for single-column and multi-column systems were compared. Better utilisation of biosorbent was observed when the columns are connected in series at similar operating parameters. A simple acid-base regeneration procedure was found to be effective in desorbing/regenerating the cadmium bound biosorbent. Adsorption efficiency was found to decrease from 76.3% for the first cycle to 72.2% and 70.6% in the second and third cycles, respectively. Regeneration efficiencies were more than 94% up to 3 cycles. The study highlights the effectiveness of the multi-column system in biosorption against the conventional single-column system.
Biosorption potential of oxidized coconut coir (OCC) for removal of Cd(II) from aqueous medium at batch and column level was studied. Lignin and cellulose groups of coir were modified to acidic groups. Optimum biosorption was observed at pH 6. Isotherm data revealed that Langmuir gives best fit for experimental results with maximum adsorption capacity of 12.35 mg/g compared to unmodified coconut coir (5.29 mg/g). The column experiments were conducted as a function of flow rate, bed height, and influent Cd(II) concentration. Biosorption has best performance at 10 mg/L inlet concentration, 5 ml/min flow rate and 7 cm bed height.
This study investigated the potential of mesoporous activated carbon derived from oil palm shell using phosphoric acid (H3PO4) impregnation followed by microwave-induced irradiation, for adsorption of cadmium from aqueous solution. This study investigated the effects of H3PO4 impregnation ratio (1:1, 1:2 and 1:3 w/w) and microwave irradiation time (5 and 8 min) on the characteristics of the synthesized activated carbon, encompassing the textural, morphological, proximate and chemical properties. Batch adsorption studies were conducted for the activated carbon to determine the effects of contact time, initial cadmium concentration (20–200 mg/L) and solution pH (2–10) on the cadmium ions uptake at 30 °C. The synthesis process resulted in the development of pores, with average diameter of 2.22 nm, on the surface of the oil palm shell, which contributed to the relatively large BET surface area and total pore volume of 854.42 m²/g and 0.74 cm³/g, respectively. Batch adsorption studies showed that the adsorption of cadmium increased with increasing concentration and was more favourable at acidic pH, achieving up to 99% removal. The adsorption of cadmium on the activated carbon was of chemisorption and governed by external mass transport. The maximum monolayer adsorption capacity of 227.27 mg/g showed the potential of the proposed synthesis method for deriving mesoporous oil palm shell-based activated carbon for removing cadmium from aqueous solutions. The saving in terms of the reduction of activation time and energy usage shall make the production of activated carbon from agricultural biomass to be more environmental friendly and sustainable for wastewater treatment.
Agricultural wastes which include shell of coconut dry fruits (CS) can be used to prepare filler in polymer composite for commercial use. The raw CS was converted into nanoparticle in 4 steps, namely, grinding, refining, sieving and high energy ball mill. The CSNs was extracted by n-hexane for oil removal process. The presence of the oil was studied by Transmission Electron Microscopy (TEM) and Energy Dispersive X-ray analysis (EDX) to identify the existence of the oil within the nanoparticle. The decomposition temperature of the nanoparticle was studied by thermal gravimetric analysis (TGA). The nanoparticle size obtained from TEM, X-ray Diffraction (XRD) analysis and particle size analyzer was found to be 10-30 nm, 21.61-44.46 nm and 50.75-91.28 nm (with nano size distribution intensity of 75.30%) respectively. The nanoparticle CS exhibits lower degree of crystallinity, or higher of amorphous area. The nanoparticle CS shape and surface was found to be smaller with angular, irregular and crushed shapes after been ball milling process.
In this study, the adsorption efficiency of cashew peduncle bagasse (CPB) is reported for the removal of single-(mono-) and multi-metal ions (Cd2+; Cu2+; Ni2+; Pb2+; and Zn2+) from synthetic and natural effluents using fixed-bed columns. The percentage of saturation realised in this study using a mono-elemental system was as follows: Pb2+ > Cd2+ > Zn2+ > Ni2+ > Cu2+. The metal ion recovery rate was determined by column elution; we demonstrated 100% metal ion recovery using 40 mL of HCl or HNO3 (0.1 mol L−1) as the eluent, with the exception of Pb2+. The adsorbent regeneration process decreased the removal efficiencies to 90% (Pb2+), 44% (Cu2+), 99% (Ni2+), 81% (Cd2+) and 74% (Zn2+) after the first cycle. The breakthrough curves and kinetic adsorption factors controlling the adsorption process were also studied. The Thomas model has produced the best fit with the experimental data.
