Development of a dopamine-based surface modification technique to enhance protein fouling resistance in commercial ultrafiltration membranes

This study introduces a new method for modifying ultrafiltration membranes using dopamine polymerization to overcome issues such as prolonged polymerization times, potential pore narrowing, and insufficient formation of hydrophilic groups. The technique involves continuously supplying oxygen (O 2 ) gas from the porous backside of the membrane while simultaneously applying an aqueous dopamine solution to the active top surface. TGA and XPS analyses revealed that 10 kDa commercial polysulfone (PSF) membranes coated with O 2 backflow contained more dopamine than those modified using the classical method. Additionally, changes in contact angle and zeta potential values were more pronounced with the O 2 backflow method. Dopamine coating for 10 and 20 min improved the pure water permeance of the PSF membrane, whereas a 40-min coating decreased it. Notably, the reduction in permeance was 2.5 times less with the O 2 backflow method than with the classical method. The classical dopamine coating method did not enhance the PSF membrane's resistance to fouling during whey filtration; in fact, 20 and 40-min coatings caused more significant flux declines compared to the unmodified membrane. Conversely, 10 and 20 min of PDA coating under O 2 backflow improved fouling resistance, though this benefit disappeared with a 40-min coating. • PSf membrane was modified with dopamine coating using new oxygen backflow method. • New coating method shortened coating time, enhanced membrane flux after coating. • Traditional modification method didn't enhance membrane protein fouling resistance. • 10-min coating under oxygen backflow significantly enhanced fouling resistance. • New method requires no additional chemicals/steps compared to classical method.