Mixed matrix membranes embedded with Janus mesoporous silica nanoparticles for highly efficient water treatment

A periodic mesoporous organosilica (PMO) Janus nanoparticle (PMO-SO 3 H&SiO 2 -NR) was gently synthesized and mixed with polyethersulfone (PES) to fabricate a series of mixed matrix membranes via the phase inversion method. The Janus structure of PMO-SO 3 H&SiO 2 -NR nanoparticle enabled the hydrophilic -SO 3 H and hydrophobic hexadecyl (-NR) to be separately distributed on the PMO cores and SiO 2 branches, and hence Janus PMO-SO 3 H&SiO 2 -NR nanoparticle was endowed with good hydrophilicity and excellent compatibility with PES membrane matrix. As a result, the mixed matrix membranes presented improved bulk porosity, surface mean pore size, hydrophilicity and permeability. Particularly, the pure water flux of the mixed matrix membrane with 5 wt% porous Janus PMO-SO 3 H&SiO 2 -NR nanoparticles (M5) was as high as 330 lm -2 h -1 that was 2.2 times that of the pristine PES ultrafiltration (UF) membrane (M0) while its rejection for bovine serum albumin (BSA) remained above 98.0%. Besides, after multi-cycles UF experiment with BSA as model contaminant, M5 retained a high flux recovery rate, permeation flux and rejection, suggesting its outstanding overall performance. Porous Janus PMO-SO 3 H&SiO 2 -NR nanoparticle is the first time to be used as an effective additive to prepare mixed matrix membrane, providing a new approach to achieve highly efficient water treatment of UF membranes.