Biofouling resistance of reverse osmosis membrane modified with polydopamine

It has been reported that surface modification with polydopamine (PDA) increases the hydrophilicity and the negative charge density of membrane surfaces, which improves their antifouling potential against organic foulants. Thus, in this paper, we attempted to modify a reverse osmosis (RO) membrane with PDA to improve antibiofouling potential. The deposition of PDA was confirmed by several methods, including X-ray photoelectron and Fourier-transform infrared spectroscopy. However, increases in hydrophilicity and negative charge density were not clearly observed. Nevertheless, the improvement of antibiofouling properties was confirmed by cross-flow filtration of a bacterial (Pseudomonas putida) suspension. The high antiadhesion property of the PDA-modified membrane was confirmed by scanning electron microscope surface images after 1200 minute continuous filtration of the bacterial suspension. In addition, it was confirmed by using a shake flask test with Escherichia coli that the PDA-modified membrane had a bactericidal property. Using shake flask tests in the different pH solutions, it was concluded that the antibiofouling property of PDA-modified membranes could be attributed to the bactericidal property of protonated amine groups of PDA deposited on the membrane surface.