Surface modification of thin-film-composite membranes with antibiotics for fouling reduction

Thin-film-composite (TFC) membranes are used in reverse osmosis (RO) and nanofiltration (NF) for producing fresh water. However, they are prone to fouling by biological and chemical contaminants, which significantly diminishes their efficiency. Therefore, feed pretreatments and membrane cleaning are required to maintain their proper functionality, which increase operational cost. Alternatively, the surface properties of TFC membranes can be modified to reduce fouling and increase membrane efficiency and lifetime. This project aimed to modify a commercial TFC membrane’s surface with polydopamine (PDA) mixed with an antibiotic tobramycin (TOB). Polymerization reactivity of dopamine was identified by UV-vis spectroscopy. The modified-TFC membranes were characterized by scanning electron microscopy, atomic force microscopy, and water contact angle analysis. The separation performance, antifouling and antibacterial properties of the membranes were also examined. The modified membranes showed antibacterial properties against E.coli and less flux reduction during filtration with bovine serum albumin (BSA) solution. The permeability and selectivity of the membrane after surface modification changed little. These results demonstrate that TOB can be directly deposited on TFC membranes using PDA as a matrix. Surface modification with TOB and PDA is an effective strategy to improve the organic fouling and biofouling resistance of TFC membranes.