Overcoming bacterial fouling: Self-cleaning CNTs-PEI/Cu-ZnIn2S4 membranes for sustained water disinfection

A bactericidal membrane (CNTs-PEI/CZIS) was designed by anchoring Cu-ZnIn 2 S 4 on CNTs-PEI. • In N coordination contributes to the structural stabilization between the CZIS and CNTs-PEI. • CNTs-PEI/CZIS has ultra hydrophilicity/oleophobicity with O/W separation efficiency of ~100%. • CNTs-PEI/CZIS has bactericidal rate of ~100% both at 10 6  CFU mL −1 (artificial) and actual water. • CNTs-PEI/CZIS has excellent self-cleaning and stable long-term antibacterial activity. Membrane technology for water disinfection (MTWD) offers high effluent quality with a small footprint, but its practical application is still limited by bacterial fouling-induced flux decline and insufficient long-term disinfection capability. Herein, we designed a self-cleaning CNTs-PEI/Cu-ZnIn 2 S 4 composite membrane by depositing an ultralow amount of copper-supported ZnIn 2 S 4 (CZIS) nanoflowers (only 2.5 mg per 50 mm-diameter membrane) onto polyethyleneimine-functionalized carbon nanotubes (CNTs-PEI). This membrane preserves the high permeability and hydrophilic-oleophobic characteristics (oil-water separation efficiency of 99.3 ± 0.6%, with a max flux of 6470 ± 500 L m −2  h −1  bar −1 ) is mainly ascribed to the CNTs-PEI construction, as well as the efficient photocatalytic sterilization activity (with an efficiency ~100% under bacterial concentration of 10 6  CFU mL −1 ) and its self-cleaning capability (overall, >6000 L m −2  h −1  bar −1 ) is demonstrated to CZIS nanomaterial. In practical test, the antibacterial efficiency in natural water reaches ~100% even over 20 cycles. The integrated properties of CNTs-PEI/Cu-ZnIn 2 S 4 composite membrane are related to the design of interfacial coupling between CZIS and CNTs-PEI through In N coordination and the combination of visible-light photocatalytic activity. This work provides a promising strategy on constructing a novel composite membrane for overcoming biofouling by bacterial disinfection. A visible-light-driven carbon nanotubes (CNTs)-based composite membrane enables efficient water disinfection and purification. By anchoring Cu-ZnIn 2 S 4 nanoflowers onto hydrophilic-oleophobic PEI-functionalized CNTs, the membrane achieves ~100% bactericidal efficiency and excellent antifouling/self-cleaning performance. Its functionality in bacterial inactivation highlights its potential in sustainable and advanced water treatment technologies. Download: Download high-res image (211KB) Download: Download full-size image