One-step selective separation and catalytic transformation of an organic pollutant from pollutant mixture via a thermo-responsive semi-IPN/PVDF@Pd bilayer composite membrane

• A bilayer membrane is used for catalytic transformation of organic pollutants. • Organic pollutant mixture is selectively separated by a cross-flow model. • Selective separation and transformation is realized in a cross-flow process. • Interference of undesired pollutants and products for transformation is avoided. • Product is in situ discharged in the operating process. It is a great challenge to selectively translating a pollutant into a valuable product from multi-component organic pollutants for waste treatment. Herein, we design and then fabricate a novel thermo-responsive bilayer composite membrane realizing the selective separation, catalytic transformation and in situ product separation from two-component pollutants in a one-step. This bilayer membrane systematically characterized by FTIR, XPS, SEM and AFM and the other techniques, comprises a top semi- interpenetrating polymer network(semi-IPN) coating layer and a bottom poly(vinylidene fluoride) @Pd catalytic layer. In a continuous cross-flow filtration process, the pollutant BSA is directly separated by the membrane, while the pollutant p -nitrophenol controllably penetrates through the top semi-IPN layer and then reacts in the catalytic layer; subsequently, the product p -aminophenol is in situ separated and collected. The reactant is purified before reaction, further, any unexpected reactions on membrane surface are avoided by isolating reactants from the catalysts via the top layer, preventing the interference of the unexpected pollutants and products for the catalytic transformation. The transformation efficiency can be strengthened by adjusting temperature and an maximum conversion of 99.74% can be obtained for a p -nitrophenol solution of 10 mg/L at a flux of 27.0 L•m −2 •h −1 •bar −1 and a temperature of 30℃.