Synthesis of hydrated ferric oxide on cation exchange resin for phosphate and hardness removal in water

In this study, a potential adsorbent was synthesized from iron salt and cation exchange resin (FeOOH@CR) and applied for phosphate adsorption in batch experiments. The characteristics of FeOOH@CR materials before and after phosphate adsorption were determined by FTIR, XRD, and SEM. The factors affecting the adsorption process such as reaction time, solution pH, material dosage, concentration, temperature, and competing ions were tested. Kinetic, thermodynamic and isothermal models of the adsorption process were applied to study the nature of the adsorption process. The properties of phosphate adsorption, effect of competitive ions and material reusability were also examined. Results showed that the adsorption time reached equilibrium after 48 h and the suitable adsorption condition was found at solution pH of 6.5, material dosage of 5 g/L. In addition, the durability of the material after 5 times of regeneration was investigated with the remained adsorption ability of about 55% as compared to the original one.

Equilibrium and Kinetic Study of Removal Copper(II) from Aqueous Solution Using Chicken Eggshells: Low Cost Sorbent

The research aims to investigate feasibility eggshells as potential adsorbent to remove copper(II) ions from aqueous solution. Eggshells powder was characterized using X-ray diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy. Effect of copper(II) initial concentration, adsorbent dosage, and contact time have conducted. The optimum adsorption condition obtained when 0.7 g eggshells applied to 50 mg/L copper(II) solution for 50 minutes. The maximum percentage of copper(II) removal was exceeded more than 85%. Langmuir and Freundlich isotherm model were applied to describe the equilibrium adsorption. Copper(II) kinetics sorption process was fitted to pseudo-second order model with a rate constant equal to 0.516 g/mg.min. The results clearly exhibit that eggshells powder can be effectively used to remove copper(II) ions from aqueous solutions.

Fabrication of high surface area acid-treated activated carbon from pomegranate husk for 2,4-dichlorophenol adsorption

In the present study, zinc chloride followed by acid treating was employed for fabrication activated carbon with a high surface area from pomegranate husk (APHAC) for 2,4-dichlorophenol (2,4-DCP) adsorption. The APHAC was a well-developed pore and exhibiting specific surface areas of 1576 m2/g. Based on the XRD analysis, the diffraction peaks between 15 ° and 35 ° corresponded to amorphous carbon, and the pHpzc values of APHAC was 6.15 ± 0.15. According to batch experiments, the optimum adsorption condition of 2,4-DCP was pH of 3, contact time 60 min, and APHAC dose of 1.75. The absorption capacity of 2,4-DCP at the APHAC dose of 0.5 promptly decreased from 259.5 ± 12.9 mg/g at the initial concentration of 150 mg/L to 74.5 ± 3.7 mg/g dose of 2 g/L. With increasing temperature from 10°C to 50°C, the adsorption efficiency declined from 99.8 ± 0.5% to 75.6 ± 1.89%. The isotherm and kinetic of 2,4-DCP by APHAC revealed that Freundlich and Elovich satisfactorily fitted with experimental data.

A comparative study of the adsorption of azo dyes in mixed adsorbents composed of Aspergillus niger and Citrus sinensis chemically modified: Influence of pH

The economic growth of the textile sector in Brazil has contributed to the generation of new jobs, qualification of the workforce and better living conditions for the population. However, due to the high activity of the sector, large volumes of toxic effluents have been generated which, if improperly disposed of, cause serious environmental damage. Therefore, alternatives in the treatment of effluents are interesting to increase the availability of this resource. A technique that has stood out, for being efficient, easy to operate and economical, is adsorption, a passive capture process where pollutants are deposited on the surface of materials. Thus, the work aimed to carry out a comparative study of the influence of pH in the removal of the dyes Remazol Black (RB), Remazol Red (RR) and Remazol Yellow (RGY) using different mixed adsorbents constituted by the fungus Aspergillus niger grown in orange peel in two different culture media. Six types of adsorbents (three for each culture medium) were produced and were treated with acid, base and without treatment. These were subjected to adsorption tests at different pHs (2, 7 and 9), using a solution (25 mg.L-1) volume of 100 mL, 0.5 g of biomass, rotation 150 rpm, 30 oC. The results showed that the adsorbents produced were able to adsorb the dyes RB, RGY, RR at different pHs. The best adsorption condition was obtained at pH 2 and the adsorbents were treated with acid, showing a promising alternative for the treatment of textile effluents.

Preparation and optimization of the composition of novel nZVI/(Fe-Mn) binary oxide/bentonite adsorbent for removal of reactive yellow 145 dye (RY-145) from aqueous solution

In this study, a new composite of nZVI/ (Fe - Mn) binary oxide/bentonite (IFMB) was synthesized and used as an adsorbent for the removal of reactive yellow 145 dye (RY- 145) from aqueous solution. Optimization of composition of IFMB composite for removal of RY - 145 dye was conducted with the help of surface response method (SRM). Three independent variables affecting to the RY-145 adsorption efficiency were selected for optimization study: Fe/Mn ratio (mol/mol), Bentonite content (wt. %) and nZVI content (wt. %). The study reveals that optimal compositions of IFMB composite for RY-145 removal was Fe/Mn = 1,75; Bentonite 9,46 wt. % and nZVI 16,97 wt. %. In the adsorption condition: adsorbent dose of 1g.L-1, initial dye concentration of 200 mg.L-1, contact time of 120 min at 120 rpm and at 25 oC, the adsorption capacity for RY-145 dye on IMFB composite is 197 mg.g-1. The value of RY-145 adsorption efficiency calculated by the model at the optimal point has been compared with the experimental value and the error is very small (0,36%). This proves that the RSM model has good repeatability.

Synthesis and application of magnetized nanoparticles to remove lead from drinking water: Taguchi design of experiment

Contamination in drinking water from heavy metals like Pb2+ has severe effects on health. In this study, potato peel (PP) was used as the substrate and magnetic iron nanoparticles (MI) were deposited on PP using a co-precipitated method. Fourier transformation infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analysis confirmed the deposition of MI on PP. The L16 (4^4) method of Taguchi design of experiment (DOE) was used for the optimization of adsorption condition, i.e., at 6 pH, 10 min of contact time, and a dose of 15 g/L can give more than 90% removal efficiency of Pb2+ using PP-MI. Contour maps, Taguchi response analysis, and analysis of variance (ANOVA) suggested that pH has a dominant contribution in the removal of Pb2+. The adsorption process was favorable, spontaneous, and exothermic in nature and was followed by pseudo second order kinetics. A comparison of the sorption capacity of PP-MI for Pb2+ with literature values suggested that PP-MI has good potential for the removal of Pb2+. This article has been made Open Access thanks to the generous support of a global network of libraries as part of the Knowledge Unlatched Select initiative.

Optimization of Cd(II) adsorption condition by glycine-modified silica-based adsorbent using central composite design

Silica gel (SG) is one of common adsorbent on solid phase extraction for preconcentration. Due to the low selectivity and effectiveness of adsorption to metal ions, SG should be modified. The SG was modified with d-glycine (Si-Gly) using 3-aminopropyltrimethoxysilane and glutaraldehyde as a crosslinker. Capability of Si-Gly as adsorbent for cadmium ions (Cd) was investigated using batch adsorption. The result was proved by infrared spectra. The optimum condition of Cd adsorption by the Si-Gly was obtained at pH 5, with 0.3 g of adsorbent and 11 minutes of contact time. The percentage of Cd adsorption at the optimum condition by the Si-Gly (99.34%) which is greater than the SG (89.03%). The maximum adsorption capacity of the Si-Gly is 9.77 mg/g, obtained at 400 mg/L. The Cd(II) adsorption on the SG and the Si-Gly follow the Langmuir isotherm equation.

Waste Brick Dust as Potential Sorbent of Lead and Cesium from Contaminated Water

Adsorption properties of waste brick dust (WBD) were studied by the removing of PbII and CsI from an aqueous system. For adsorption experiments, 0.1 M and 0.5 M aqueous solutions of Cs+ and Pb2+ and two WBD (Libochovice—LB, and Tyn nad Vltavou—TN) in the fraction below 125 µm were used. The structural and surface properties of WBD were characterized by X-ray diffraction (XRD) in combination with solid-state nuclear magnetic resonance (NMR), supplemented by scanning electron microscopy (SEM), specific surface area (SBET), total pore volume and zero point of charge (pHZPC). LB was a more amorphous material showing a better adsorption condition than that of TN. The adsorption process indicated better results for Pb2+, due to the inner-sphere surface complexation in all Pb2+ systems, supported by the formation of insoluble Pb(OH)2 precipitation on the sorbent surface. A weak adsorption of Cs+ on WBD corresponded to the non-Langmuir adsorption run followed by the outer-sphere surface complexation. The leachability of Pb2+ from saturated WBDs varied from 0.001% to 0.3%, while in the case of Cs+, 4% to 12% of the initial amount was leached. Both LB and TN met the standards for PbII adsorption, yet completely failed for any CsI removal from water systems.

Preparation of modified pomelo peel's pulp adsorbent and its adsorption to uranyl ions

Using pomelo peel's pulp (PPP) as raw material, a new chemically modified PPP was prepared by the process of fermentation, cooking, freeze-drying, and so on. The adsorbent has been characterized by EDS, IR, BET and SEM. The factors of different adsorption conditions such as pH value, adsorption temperature, mass of adsorbent, adsorption time and initial concentration of UO 2 2+ were investigated. The adsorption mechanism was explored by adsorption thermodynamics and kinetics experiments. The results indicate that the pH value is 6.0, the dosage of adsorbent is 500 mg l –1 , the temperature is 50°C and the adsorption time is 90 min, which is the best adsorption condition. When the initial concentration of UO 2 2+ is 35 mg l –1 , the adsorbed amount of uranyl ions by the modified PPP adsorbent can reach 42.733 mg g −1 , 26.8% higher than the adsorption amount of unmodified adsorbent (31.276 mg g −1 ), which is obviously enhanced. The kinetic and thermodynamic experiments show that the adsorption process is in good agreement with the pseudo second-order kinetics model, that it is an endothermic reaction, and the reaction is spontaneous. The adsorption process is entropy-dominated. The Freundlich adsorption isotherm can describe the adsorption process more accurately.