Optimization of Operational Parameters for Application of Zirconium/Polyvinyl Alcohol Modified Flat-Sheet Polyvinylidene Fluoride Membrane As Better Adsorptive Material in Treatment of Organic Arsenic Containing Wastewater

Organic arsenic in waters has been a global concern due to its toxicity. In this study, a novel polyvinyl alcohol (PVA)/zirconium modified polyvinylidene fluoride (PVDF) membrane was applied to remove organic arsenic from water. The impregnation of zirconium ions within the modified membrane was attributed to the coordination reactions among the zirconium ions, ether and hydroxyl groups. The synthesized membrane worked better at the acidic conditions and achieved the optimal uptake for both monomethylarsonic (MMA) and dimethylarsinic (DMA) at pH 2.0. The adsorption isotherm study demonstrated that the adsorption of both organic arsenic species was controlled by the mono-layer adsorption process, and the maximum adsorption capacities of 73.04 and 29.78 mg/g for MMA and DMA can be achieved at pH 2.0. The presence of humic acid had a negligible impact on the uptake of organic arsenic, whereas varying impacts on the arsenic adsorption were observed due to the presence of coexisting anions such as fluoride, phosphate, carbonate and silicate. The filtration study was also carried out to evaluate the performance of the modified membrane on the removal of organic arsenic. Based on the XPS analyses, the exchange between chloride ions on the membrane surface and organic arsenic species should be responsible for the removal of both MMA and DMA.