A novel ion-imprinted membrane induced by amphiphilic block copolymer for selective separation of Pt(IV) from aqueous solutions

A novel ion-imprinted blend membrane was fabricated to separate selectively platinum(IV) from aqueous media. An amphiphilic copolymer poly(methyl methacrylate)-b-poly(4-vinylpyridine) (PMMA- b -P4VP) was firstly synthesized via the reversible addition fragmentation chain transfer polymerization , and characterized by 1 H NMR, FT-IR and GPC. Subsequently, poly(vinylidene fluoride) (PVDF) blend membranes were prepared using PMMA- b -P4VP as a blending additive. Effects of the following factors on performance of blend membranes were systematically examined: P4VP content of PMMA- b -P4VP, solvent type, and PMMA- b -P4VP/PVDF ratio. Further, platinum(IV) ion-imprinted membrane (Pt(IV)-IIM) was fabricated by blending polymer-Pt(IV) complexes with PVDF. SEM, FTIR-ATR, contact angle, water flux and adsorption capacity were employed to characterize all membranes. Results indicated that the membrane, which was prepared using the copolymer with high P4VP content (polymerization time 10 h) as a functional polymer , N,N-dimethylacetamide as a solvent and PMMA- b -P4VP/PVDF ratio of 30 wt%, exhibited an intriguing morphology and much higher performance. Pt(IV)-IIM showed higher adsorption and selectivity for Pt(IV) (selectivity coefficients of 27.66 ± 1.38 and 77.16 ± 3.86 for Pt(IV)/Cu(II) and Pt(IV)/Ni(II), respectively) compared with a non-imprinted membrane. During membrane filtration, Pt(IV)-IIM was effective and selective for separation of Pt(IV) in the presence of Cu(II) and Ni(II) ions. Also, Pt(IV)-IIM was chemical stable, and had a good regeneration performance.