Arsenic is a toxic element and is found in natural waters throughout the globe. The purpose of present study is to demonstrate the As (V) uptake by orange peel from real ground water samples through adsorption. Different parameters such as pH, shaking speed, contact time, adsorbent dosage, concentration, volume and temperature etc, were optimized. The maximum uptake capacity was observed at pH-7. The sorption was found to be time dependent and the kinetics followed well by the Morrisweber, Pseudo second order and Elovich equations. The Freundlich, Langmuir, Dubinin Redushkevich and FloryHuggins isotherm were used to model the adsorption behavior of arsenic retention. Thermodynamic parameters calculated from these isotherms show that the adsorption was spontaneous and endothermic in nature. Orange peel was found to be effective (*85%) for arsenic removal from real water systems containing concomitant ions.

Expanded polystyrene (EPS) waste was chemically recycled to a novel functional polystyrene-hydrazone (PSH) surface by acetylation of polystyrene (PS) and then condensation with phenyl hydrazine. The synthesized surface was characterized by the FT-IR and elemental analysis. Synthesized novel functional PSH surface was successfully applied for the treatment of phenol-contaminated industrial wastewater by solid-phase extraction. Multivariant sorption optimization was achieved by factorial design approach. 99.93% of phenol was removed from aqueous solution. FT-IR study showed the involvement of nitrogen of hydrazone moiety of synthesized surface for the uptake of phenol through the hydrogen bonding.

The present study demonstrates the sorptive efficiency of okra leaves for the Cr(III) and Cr(VI) in aqueous system. The batch dynamic sorption method was carried out as the function of the pH of the solution, sorbent doze, initial bulk concentration, shaking speed and contact time. The experimental data were examined by Langmuir and Freundlich isotherms. Cr(III) at pH-4.0 and Cr(VI) pH-2.0 showed a maximum sorption capacities 221.17 mg/g and 81.94 mg/g respectively. Kinetically experimental data of both chromium species were well fitted to pseudo second order rate, Elovich, Morris-Weber and Richenberg equations. Positive values of enthalpy change and negative values of Gibbs free energy indicated the endothermic and spontaneous nature of sorption reaction respectively. The developed method was applied to real ground water samples (affected by industrial wastewater). Up to 92.15% of chromium metal was removed from the real water samples.

This study aims to explore the effi ciency of an agro waste material for the remediation of Pb(II) contaminated water. A factorial design approach is adopted to optimize removal effi ciency and to study the interaction between effective variables. A face-centered Draper-Lin composite design predicted 100% removal effi ciency at optimum variables; pH 8, initial concentration of Pb(II) ion 12mg/L , sorbent dose 200mg and agitation time 110 min. Regration coeffi cient (R 2 = 99.9%) of a plot of the predicted versus the observed values and p value (>0.05) confi rms the applicability of the predicted model. Langmuir and Dubinin-Radushkevich (D-R) isotherm models were applicable to sorption data with the Langmuir sorption capacity of 21.61±0.78 mg/g. The energy of sorption was found to be 13.62±0.32 kJ/mol expected for ion-exchange or chemisorption nature of sorption process. Characterization of Grewia seed suggested a possible contribution of carboxyl and hydroxyl groups in the process of biosorption. The present study shows that Grewia seeds can be used effectively for the remediation of Pb(II) contaminated water.

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