Self-cleaning, antibacterial mixed matrix membranes enabled by photocatalyst Ti-MOFs for efficient dye removal

Membrane separation technologies have been extensively implemented in wastewater polluted by dyes because of their eco-friendliness, superior separation efficacy, and energy-saving capacity. Despite impressive advances of membrane technologies, membrane fouling severely impairs the separation performance and lifespan, remaining a challenging task to be addressed. In this study, the MIL-125(Ti)/PVDF mixed matrix membrane with a superb self-cleaning merit was constructed through a wet phase inversion method. Interestingly, MIL-125(Ti) was commonly utilized for photocatalytic degradation of organic matters under UV light, but the hybrid membranes containing MIL-125(Ti) were able to effectively degrade the foulant RhB under natural light. This was due to the sensitization of MIL-125(Ti) caused by the physical adsorption of RhB dye molecules on MIL-125(Ti) during the rejection process, where they could promote electron transfer to produce hole (hthorn) and superoxide free radicals (center dot O-2(-)). The optimal hybrid membranes exhibit ultrahigh water permeance (64.3 L m(-2) h(-1) bar(-1)) and remarkably high dye retention (RhB, 99.7%). Furthermore, due to superb photocatalytic degradation of the foulants, the flux of the treated membranes can almost be recovered to the initial state even after three cycles. More importantly, the mixed matrix membranes exhibit an ultra-high bacteriostatic rate of nearly 100%. The unique self-cleaning and antibacterial features render the MIL-125(Ti) modified membranes highly promising in the treatment of textile wastewater.