Highly dispersed β-FeOOH nanocatalysts anchored in confined membrane pores for simultaneously improving catalytic and separation performance

Heterogeneous advanced oxidation process performs a promising perspective in the field of refractory pollutant degradation. However, the agglomeration and difficulty-to-recycle characters of the heterogeneous catalysts greatly impede its further development. In this study, membrane-confined pores were employed as the immobilization support to anchor highly dispersed β-FeOOH via an in situ mineralization method, which not only exposed highly active sites for refractory pollutants degradation but also endowed the membrane with hydrophilic/underwater superoleophobic properties. Accordingly, the Polyvinylidene fluoride/β-FeOOH (PVDF/β-FeOOH) catalytic membrane demonstrated favorable separation capacity and attractive catalytic oxidation performance via activating peroxymonosulfate. Instantaneous degradation (contact time about 1 s) of recalcitrant pollutants (over 98%) and high oil rejections (96.4% to 99.1%) can be achieved simultaneously under low operating pressure. Both the confined pore structure-induced enhanced mass transfer and enrichment of radicals and pollutants lead to favorable catalytic degradation performance. The mechanism of the catalytic membrane was analyzed by radical quenching test and electron paramagnetic resonance analysis, proving that sulfate radicals were predominant reactive oxygen species during catalytic oxidation. Besides, the PVDF/β-FeOOH catalytic membrane also possessed attractive stability without tedious catalyst separation/recovery processes. This work provides a meaningful tactic to further enhance the catalytic oxidation performance of catalytic membrane in water treatment.