Composite membranes based on polyvinyl alcohol and lamellar solids for water decontamination

Abstract

The removal of pollutants from wastewater is of primary importance for the environment and human health. The materials that we propose for the first time for this application are composite membranes obtained using polyvinyl alcohol and lamellar solids as fillers. First, layered double hydroxides (LDHs) MgAlNO₃ and ZnAlNO₃ and sodium exchanged zirconium phosphate (ZrP-Na) were synthesized and characterized, and their water decontamination efficacy was studied. Then composite membranes were prepared by incorporating one or both inorganic components (MgAlNO₃ and ZrP-Na), with a total inorganic filler content of 40 and 60 wt%. The efficacy and selectivity of the composite membranes were investigated by batch experimental analysis. The polyvinyl alcohol/sodium exchanged α-zirconium phosphate/layered double hydroxide membranes were tested for the removal of Pb²⁺, Cr³⁺, Ni²⁺ and diclofenac sodium (DS) from aqueous solution. The best overall removal efficiencies of 99.6, 86.1, 56.7 and 44.0% for Pb²⁺, Cr³⁺, Ni²⁺ and DS, respectively, were observed for the PVA membranes containing 20 wt% ZrP-Na and 20 wt% MgAlNO₃. The use of composite membranes offers the possibility of combining the high exchange capacity of the inorganic materials presented in this work and the flexibility of the polymer in such a way as to be used in flow systems in the future.