In Situ Cross-linked Poly(vinylidene Fluoride)/Polyamidoamine Porous Membrane for Selective Recovery of Low-Concentration Pt(IV) with Enhanced Antifouling Properties

Membrane separation is an efficient and energy-saving technology for resource recovery, yet it faces challenges such as low separation efficiency, poor selectivity, and membrane fouling when complex acid leachates containing low-concentration platinum. To address these issues, this study reports a novel antifouling porous membrane based on a poly(vinylidene fluoride)/polyamidoamine matrix for the highly selective recovery of platinum. The membrane was fabricated by in situ cross-linking of <i>N</i>-allylthiourea to form a functional layer, followed by monoethanolamine/NaOH treatment to create a hydrophilic surface, resulting in the final PPAT membrane. The membrane exhibited an outstanding pure water flux of 636.54 LMH·bar^-1 and achieved a high Pt(IV) rejection rate of 96.11% at a trace concentration of 5 mg·L^-1. In a competitive filtration system, the PPAT membrane demonstrated superior selectivity for Pt(IV) over Cd(II), Cu(II), and Ni(II), with relative selectivity coefficients of 309.66, 114.08, and 106.4, respectively. Combined XPS and DFT calculations revealed that Pt(IV) capture was governed by electrostatic interactions, coordination, and hydrogen bonding. In addition, the XDLVO theory confirmed strong interfacial repulsion between the membrane surface and foulant, enabling the membrane to maintain a stable flux of 459.68 LMH·bar^-1 after three water-bovine serum albumin filtration cycles, highlighting its excellent long-term stability. This work provides a new strategy for designing multifunctional membranes and offers an alternative approach for highly efficient platinum recovery.