Arsenate removal from aqueous solutions using micellar-enhanced ultrafiltration

Adsorption of arsenic in aqueous solution onto iron impregnated bagasse fly ash

The present study examined the adsorption of As(III) and As(V) (arsenics) from aqueous solutions using FeCl3 impregnated bagasse fly ash (BFA-Fe). Batch adsorption studies were carried out to evaluate the effect of various parameters like initial pH (pH 0 ), adsorbent dose (m), contact time (t), initial concentration (C 0 ) and temperature (T) on the removal of As(III) and As(V) from aqueous solutions. The maximum removal of As(III) and As(V) was found ~ 95% and ~ 97% at lower concentration (< 20 μg/dm3) and ~ 86% and ~ 87% at higher concentration (500 μg/dm3), respectively, using 3 g/dm3 of BFA dosage at 303 K. The adsorption of arsenics on BFA-Fe was very rapid. Pseudo-second-order kinetic model well represented the adsorption kinetics of both As(III) and As(V). Error analyses functions for adsorption of As(III) and As(V) onto BFA-Fe. Based on these error analyses, R-P isotherm was found to be fitted. Thermodynamic parameters, i.e., ΔG°, ΔH°, and ΔS°, were also calculated. At 25.0 to 45.0 °C, the values of ΔG° lie in the range of -43.85, -45.34, -48.82, -51.31, -53.8, and -44.75, -48.3, -51.84, -55.39, -58.93, -55.57 for As (III), and As (V) respectively, indicating that adsorption is spontaneous and exothermic in nature. Regeneration study was carried out by different solvent and thermal methods. Our results revealed that BFA-Fe can be reused directly for making fire-briquettes to explore its energy value. From this study, As containment is most effective removal from aqueous solution and mimic to any contaminated water resources.

Solubilization and separation of o-toluidine and tricyclazole in sodium dodecyl sulfate micelles in micellar enhanced ultrafiltration

The solubilization laws of pollutants in micelles and their separation efficiency are very important in the successfully efficient application of micellar enhanced ultrafiltration (MEUF). The solubilization behavior of o-toluidine (OT) and tricyclazole (TC) into sodium dodecyl sulfate (SDS) micelles in MEUF was studied using nonlinear equation sets for concentration analysis, which resolved the issue on the overlap of absorption spectra of multicomponent compounds restricting the application of conventional ultraviolet (UV) spectroscopic method. The solubilization isotherms for both pollutants could be best explained by the Langmuir-Freudlich model (R²>0.99) followed by the modes of Langmuir and Freudlich, inferring the complexity of solubilization mechanism and solubilization advantage of monolayer over multilayer. The calculated thermodynamic parameters (ΔG⁰, ΔH⁰ and ΔS⁰) indicated that this process was endothermic and spontaneous. The solubilization of OT and TC well followed the pseudo second-order and pseudo first-order kinetics, respectively. The separation and recovery of SDS solubilizing these two pollutants were also investigated through lowering solution temperature to 2 °C followed by centrifugation. The best recovery rate of about 66% for SDS was achieved containing 10 and 5% of each initial amount of OT and TC, respectively, at near-neutral solution pH value. The recovery of SDS could decrease to some extent under alkaline and acidic conditions.

Cost-effective synthesis and characterization of CuO NPs as a nanosize adsorbent for As (III) remediation in synthetic arsenic-contaminated water

The lower concentration of arsenic in the groundwater is serious health concerns of the people who are continuously taking from their drinking water. In this study, synthetic arsenic-contaminated water was prepared in the laboratory with varying concentrations of arsenic (100 to 1000 μg/L) and treated by nanosize adsorbent (copper oxide nanoparticles (CuO NPs)). The colloidal and powder form of CuO NPs were synthesized in the laboratory by the hydrothermal technique on a large scale and their shape and size were confirmed by XRD, FTIR, FESEM, and HRTEM analysis. It was found 30 ± 2 nm as size and spherical shape. The equilibrium adsorption of As (III) occurred at 90 min of contact time, pH 7.5, and 4 g/L adsorbent dosage. The maximum percent removal of As (III) was reached to 97.8, 94.6, 91.5, and 88.4% at an initial arsenic concentration of 100, 200, 500, and 1000 μg/L, respectively. The adsorption of As (III) followed pseudo-second-order kinetic and Freundlich isotherm model. Moreover, the overall cost of the synthesized CuO NPs (including material, operational, manpower, and transport cost with other overhead charges) was Rs. 281.832 g^-1, which is lesser than the market price (Rs. 500.018 g^-1). Hence, the optimized adsorption design would help for the efficient removal of As (III) from aqueous medium.