Mitigating biofouling on thin-film composite polyamide membranes using a controlled-release platform

Biofouling remains a major challenge for membrane processes. Several methods may curtail biofouling, including membrane surface modification with hydrophilic and antimicrobial polymers and nanomaterials. Although many of these modifications rely on compounds that leach from the membrane surface, the release of these compounds is not always characterized, understood, or controlled. Here, we adapt a technology used for drug delivery — controlled release — and apply it to the membrane biofouling problem. Capsules for controlled release can be designed using a number of polymers, and the loading and release rate of the capsules depends on a number of tunable variables. We have encapsulated two antimicrobial compounds, cinnamaldehyde and kanamycin, in biodegradable poly(lactic-co-glycolic acid), PLGA, particles. These capsules were then bound to the surface of thin-film composite polyamide membranes, targeting biofouling where it is most problematic. Cinnamaldehyde released from the capsules for ~2 days. Kanamycin, encapsulated in larger PLGA particles, showed continuous release over the 80 h period tested. Biofilm formation on modified membranes was assessed using model bacteria (Escherichia coli), and significant reductions in biofilm were observed on membranes modified with kanamycin capsules, indicating that sufficient kanamycin was released to curtail bacterial growth and biofilm development. This proof of concept study demonstrates that the controlled-release platform can be used to encapsulate a variety of compounds to slow membrane biofouling.