Poly(vinyl chloride)-based advanced polymer inclusion membranes with Aliquat 336 and inorganic filler for efficient Cr(VI) removal

Abstract

Poly(vinyl chloride) (PVC) hybrid polymer inclusion membranes (PIMs) with an ion carrier (Aliquat 336) and containing an inorganic filler (Cloisite (CNa) or mica) are successfully elaborated. The filler nature and its content in the PIM composition are optimized in terms of the PIM stability and reuse. It is found that the filler presence in the PVC matrix provokes a more irregular surface and an internal structure with apparent microvoids. Tensile tests reveal two different mechanical behaviors according to the filler type – a drop in Young’s modulus (up to ∼ 51 MPa) observed for membranes containing mica, thus resulting in more flexible membranes; on the contrary, membranes with decreased flexibility are obtained in the CNa presence. The higher Cr(VI) permeability of mica-based PIMs (∼9 µmol/(m2·s)) is attributed to their porous structure and high flexibility. During 5 cycles of Cr(VI) permeation measurements, membrane based on mica and Aliquat 336 preserves its stability, while the transport performance of both unfilled membrane and PIM with CNa is deteriorated. It is also noted that the carrier percolation threshold strongly affects the membrane stability – the lower is the percolation threshold, the higher is the membrane reusability, which is explained by the high stability of mica-based PIMs. This result testifies to the possibility of using hybrid PIMs loaded with mica and containing Aliquat 336 for metal ions separation.