Application of a novel quaternized ammonium poly(vinyl alcohol)-based hybrid anion exchange membrane for the removal of Cr(VI) from wastewater

Two quaternized ammonium poly(vinyl alcohol) (QPVA)-based hybrid anion exchange membranes were successfully fabricated by using sol–gel method. The mass ratios of QPVA aqueous solution to polydimethyl allyl chloride (PDADMAC) aqueous solution were 4:1 and 2:1, then 10 wt% tetraethyl orthosilicate (TEOS) was added. The obtained membranes were separately designated as QPVA/0.25PDADMAC/0.1TEOSm and QPVA/0.5PDADMAC/0.1TEOSm. The properties for the adsorption removal of Cr(VI) and the effect on the Cr(VI) saturation adsorption amount and removal rate were investigated. Results indicated the adsorption was an exothermal reaction. Thus, low temperature was beneficial for the removal of Cr(VI). Optimal removal of Cr(VI) was achieved using the QPVA/0.5PDADMAC/0.1TEOSm membrane at a pH value of 2. Dynamic simulation was carried out simultaneously to determine if particle diffusion was the sole contributor for the adsorption rate, which was in accordance with the Langmuir isotherm adsorption model. Furthermore, the static adsorption amount (Q₀) was 61.77 mg/g, and the efficiency of recycling the hybrid membranes was higher than 90%. Scanning electron microscopy (SEM) characterization showed the surface and the cross-section tightened after the Cr(VI) adsorption, thereby demonstrating the potential application of these hybrid membranes for Cr(VI) removal.