Adsorptive removal of arsenic from aqueous solution by a PVDF/zirconia blend flat sheet membrane

The groundwater contaminated with arsenic is often associated with unwanted natural organic matters and microorganisms. It is therefore important to develop multi-functional technologies for the treatment of groundwater. In this study, a PVDF/zirconia blend flat sheet membrane was prepared so that it could adsorb arsenate and remove other contaminants such as microorganisms. The crystal structure, hydrophobicity, porosity, water flux and arsenic adsorption capacity of the membrane were investigated. The PVDF was α-form and the zirconia was amorphous in the membrane. The addition of zirconia increased the hydrophilicity and porosity of the membrane, which led to a significant enhancement in the water flux of membrane. The batch adsorption experiments demonstrated that the membrane effectively removed arsenate in a wide optimal pH ranging from 3 to 8. The adsorption equilibrium could be established in 25 h, and the maximum adsorption capacity was 21.5 mg/g, comparable to most of the available adsorbents. Co-anions such as fluoride did not obviously affect the adsorption. In addition, the membrane was efficient for removal of arsenate and bacteria (Escherichia coli) under continuous filtration. The membrane saturated by arsenate could be easily regenerated using an alkaline solution and subsequently be reused. Finally, a potential interaction mechanism between the membrane and arsenate was proposed based on the results obtained from FTIR and XPS studies.