Arsenate removal by reactive mixed matrix PVDF hollow fiber membranes with UIO-66 metal organic frameworks

High arsenic concentration in drinking water is a great threat to human health. In this study, reactive mixed matrix polyvinylidene fluoride (PVDF) hollow fiber membrane (HFM) was fabricated by embedding UiO-66 particles, a water stable metal organic frameworks (MOFs), for the removal of arsenate from aqueous solutions. Adsorption and membrane filtration were combined for arsenate treatment and the results showed that arsenate could be removed efficiently by this strategy. Adsorption of arsenate onto UiO-66 particles was first investigated using batch experiments for the determination of adsorption isotherm, pH edge, and adsorption kinetics. The maximum arsenic adsorption by UiO-66 was found to reach 267 mg/g at pH 4.7, which was ranked among the top of all arsenic sorbents reported in the literature. UiO-66 particles were then mixed in the dope of PVDF to produce the mixed matrix HFM for arsenate removal from water. The removal efficiency was studied for 6 types of HFMs with an increasing amount of UiO-66 particles. The pristine PVDF HFM without UiO-66 particles could not remove arsenate from water as expected; the pores of ultrafiltration membranes are too large to reject arsenate. With UiO-66 particles embedded into the membrane matrix, the adsorption capacity of membrane was increased significantly, resulting in arsenate removal primarily by sorption during the membrane filtration. The UiO-66 particles-embedded HFM was characterized by morphology, hydrophilicity, arsenate rejection, and ATR-FTIR. This study demonstrated that the reactive ultrafiltration membrane had a great premise to treat drinking water with arsenic.