Pore-variable, layered-combination, and recyclable polypropylene matrix filtration membrane containing Cotton-FeMoO4-ZIF-L(Co) (C-F-Z) composites for highly efficient removal of organic pollutants from wastewater

The filter membrane is prone to clogging and contamination due to the accumulation of particles, colloids, and organic substances, resulting in a decreased filtration efficiency and a limited flux. Constructing filtration membrane with adsorption and catalytic activity functions can address this issue. Herein, a novel pore-variable and layered-combination polypropylene (PP) matrix hybrid membrane containing Cotton-FeMoO4-ZIF-L(Co) (C-F-Z) composites is developed. The C-F-Z composites loaded on PP non-woven wipe are prepared by in-situ growth of ZIF-L(Co) nanosheets on Cotton-FeMoO4 (C-F) composites, which can highly-efficient remove organic contaminants from industrial wastewater. Importantly, the flux and filtration efficiency of the membrane can be tuned by mediating its pore size and layer combination. The multi-valence Fe, Mo and Co ions in the C-F-Z composites can significantly enhance the fouling resistance of the membrane which exhibits excellent filtering efficiencies of 98 % for Congo red (CR), 100 % for methylene blue (MB), and 96.6 % for tetracycline hydrochloride (TC), and can be repeatedly used for an astonishing 15 cycles for CR. Although the membrane's filtration efficiency decreases to some degree after multi-filtration, the membrane can revive after peroxymonosulfate (PMS) activation with high filtration efficiency up to 98 % and can be utilized no less than 10 cycles. This is primarily because PMS activator donates the electrons, leading to a continuous redox cycle regeneration process of Fe2+/Fe3+, Co2+/Co3+, and Mo4+/Mo6+ ion pairs. Additionally, this redox cycling promotes the PMS activation to produce SO4∙−, HO∙, O2∙−, and 1O2 species which can decompose organic compounds. This study provides a promising strategy to prolong the membrane lifetime and simultaneously to improve its filtration efficiency by mitigating the contamination of organic pollutants.