Affinitive Poly(vinylidene difluoride) Membranes for Enhancing Au(III) Separation with Extremely High Selectivity

Abstract

Thiourea-poly(vinylidene difluoride) (Th-PVDF) resin was synthesized and then cast into affinitive microporous membranes for Au(III) adsorption. The addition degree of thiourea to the resin was promoted from 22.6 % to 36.3 % when using NaOH as the catalyst. Higher addition degrees resulted in enhanced resin adsorption capacity. It also led to increased membrane hydrophilicity, higher membrane loading capacity, and membrane utilization efficiency. The membrane exhibited an extremely high selectivity toward Au(III) over other metal ions, and was easily regenerated for reuse without performance deterioration within four adsorptionregeneration cycles. X-Ray photoelectron spectroscopy (XRS) analysis and scanning electron microscopy (SEM) observation revealed that Au(III) was partially bonded to the membrane as gold chloride and partially reduced to Au(0) as gold particles.