Enhanced Filtration Characteristics and Reduced Bacterial Attachment for Reverse Osmosis Membranes Modified by a Facile Method

Abstract

In this study, we report the facile surface modification of reverse osmosis (RO) membranes for improved filtration as well as bacterial resistance properties. Thin films of two silanes, 3-aminopropyltriethoxysilane (3-APS) and 6-aminohexylaminotriethoxysilane (6-AHAS), were dip-coated on commercial RO membranes, and their nitrogen atoms subsequently quaternized. Analyses of the modified membranes via scanning electron microscopy, Fourier transform infrared, and X-ray photoelectron spectroscopy confirmed the “peak and valley” morphology of the original membrane, silane deposition, and N quaternization, respectively. The original membrane showed a water contact angle of ∼90–100° that was significantly decreased after silane coating: 63° for 3-APS and ∼52° for 6-AHAS. Filtration experiments with a high-salinity feed revealed significant improvements in the permeate flux (∼25–40%) and salt rejection (∼10–15%) after the surface modification. Bacterial adhesion studies with two different species, Bacillus subtilis and Pseudomonas aeruginosa, showed significantly reduced cell attachment on the modified membranes. In addition, the coated and quaternized membranes significantly restricted the biological activity and colony formation of both strains with a bacteriostasis rate of ∼75%. The enhanced filtration and antifouling capabilities of the modified membranes were attributed to the presence of polar functionalities (R4N+).

Biomimetic redox-responsive smart coatings with resistance-release functions for reverse osmosis membranes

“…The water contact angle value of TFC-PA is 85.61, consistent with the reported literature. 51 The values of PDA/CA-coated membranes are 55.71, 53.51, 51.41 and 49.31, which are mainly due to the increased CA content in PDA/CA coatings. Compared with TFC-PA, the reduction of the water contact angle value is ascribed to the positive effect of PDA/CA coatings on membrane hydrophilicity.…”

Antifouling Performance of a Membrane Modified by Phase-Transited Bovine Serum Albumin

“…To achieve such a goal, various strategies ranging from pretreatment of feed water, optimization of operation parameters, and utilization of antifouling membranes have been developed . Considering the convenience of operation and removal of contaminants with various chemical properties, fabricating antifouling membranes is more feasible and reliable than the other strategies. − Due to the significant roles in antifouling against macromolecules and microbes, surface properties of membranes including hydrophilicity, − roughness, and charge have been tuned to prevent membrane fouling. ,,, For microbe-caused fouling, bactericidal chemicals were often grafted on membrane surfaces to kill cells . For example, Ag, quaternary ammonium, and antimicrobial peptides have been deposited on membrane surfaces to inactivate microbes and preserve the membrane permeate flux.…”