Zirconium/polyvinyl alcohol modified flat-sheet polyvinyldene fluoride membrane for decontamination of arsenic: Material design and optimization, study of mechanisms, and application prospects

• A Zirconium/PVA modified PVDF membrane is fabricated for arsenate removal.
• Modification enhances hydrophilicity and BSA rejection rate of membrane.
• The membrane has good performance for arsenate removal in batch and filtration modes.
• The maximum adsorption capacity is as high as 128 mg-As/g at the optimal pH 2.0.
• The uptake of arsenic is a ligand-exchange between arsenate and chloride.

Arsenic contamination in industrial wastewater and groundwater has become an important environmental issue. In this study, a novel zirconium/polyvinyl alcohol (PVA) modified polyvinyldene fluoride (PVDF) membrane was developed for arsenate removal from simulated contaminated water. A PVDF flat-sheet membrane was first fabricated; it was then soaked in a zirconium-PVA solution and dried, and finally reacted with a glutaraldehyde solution, by which the zirconium ions were impregnated onto the PVDF surface through the ether and hydroxyl groups according to the cross-linkage mechanism. The fabrication procedure was optimized by the Box-Behnken experimental design approach. The adsorption kinetics study showed that most of uptake occurred in 5 h and the equilibrium was established in 24 h. The acidic condition was beneficial for the arsenate removal and the optimal removal efficiency can be obtained at pH 2.0. The experimental data of the adsorption isotherm was better described by Langmuir equation than Freundlich equation. The maximum adsorption capacity of 128 mg-As/g was achieved at pH 2.0. In the filtration study, the modified membrane with an area of 12.56 cm2 could treat 15.6 L arsenate solution (equivalent to 75,150 bed volumes) with an influent concentration of 98.6 μμg/L to meet the maximum contaminate level of 10 μμg/L. Several instrumental studies revealed that the removal was mainly associated with ion exchange between chloride and arsenate ions.