In situ modification of ultrafiltration membranes with eco-friendly pyrogallol/taurine to enhance antifouling performance

Fouling is a long-standing problem in water treatment membranes because it substantially deteriorates process efficiency. Here, we present a facile strategy for the in situ modification of polyethersulfone (PES) ultrafiltration (UF) membranes with eco-friendly antifouling materials (i.e., pyrogallol and taurine) to enhance their fouling resistance. When the PES dope solution was immersed into the nonsolvent containing pyrogallol and taurine, the phase separation and surface modification of the PES phase occurred simultaneously. Surface modification with taurine was mediated by pyrogallol, which reacted with taurine to form pyrogallol–taurine complexes. Amphiphilic pyrogallol–taurine complexes were effectively bound to the phase-transitioning PES, resulting in their uniform, dense, and robust deposition throughout the external and internal pore surfaces of the membrane without changing its pore structure. Consequently, the in situ-modified PES membrane exhibited remarkably higher surface hydrophilicity and a more negative charge than pristine PES. Importantly, the proposed in situ modification strategy significantly improved the protein anti-adhesive and antifouling properties of the pristine membrane and enhanced its permeance performance, which cannot be achieved by ex situ modification. Our study provides a facile antifouling strategy that can be applied to various membranes for water purification and desalination and extensively describes the underlying modification mechanism.