Iron nanoparticle coating and plasma-activated water cleaning as a biofouling removal method for reverse osmosis membranes suitable for desalination

Abstract

Desalination provides crucial freshwater, but biofouling on reverse osmosis (RO) membranes is a major challenge due to hard-to-remove biofilms. Conventional treatments are often ineffective, prompting a shift to coatings with nanoparticles like copper, silver, and iron to combat fouling. This study demonstrates a unique combination of coating RO membranes with iron nanoparticles (FeNPs) and treatment with plasma-activated water (PAW) for the removal of biofilm formation. Pure and unbound FeNPs showed no significant inhibition of Escherichia coli biofilms. However, the attachment of FeNPs to RO membranes led to a decrease in biofilm growth on the membrane, and an additional PAW treatment was shown to significantly inhibit mature biofilms. SEM imaging revealed a higher density and uniform distribution of FeNPs on the RO membranes after PAW treatment. Zeta potential measurements showed positively charged FeNPs in PAW, enhancing their attraction with the negative membrane surfaces. The coated membrane using PAW solution with FeNPs exhibited no degradation in terms of pure water flux, saline water flux, and salt rejection compared to the immersion process in DI with FeNPs.