Biofouling performance of RO membranes coated with Iron NPs on graphene oxide

Biofouling performance was evaluated for polyamide commercial RO membranes coated with iron nanoparticles (FeNPs) and graphene oxide (GO), under controlled conditions using a cross-flow system. Feed water obtained from the Sea of Cortez, Mexico, was pretreated, sterilized and inoculated with a high concentration (10(9) CFU mL(-1))of Bacillus halotolerans MCC1, isolated from the Sea of Cortez. The zeta potential was determined for FeNPs and GO-FeNPs. XRD, roughness, contact angle, permeance and flux were determined for the coated and uncoated membranes. To evaluate the anti-biofouling effect, total organic carbon, total cell count, optical density and percentage of live/dead cells were determined for the biofilm. The GO-FeNP coating showed less agglomeration tendency and surface roughness compared to pure FeNP, and contact angle (49.1 degrees +/- degrees 4.3) similar to the uncoated membrane (50.2 degrees +/- 4.3 degrees). Despite reducing the membrane permeance, the FeNP and GO-FeNP coatings presented larger fluxes after fouling (18% and 5.3% larger, respectively) than the fouled uncoated membrane. This was corroborated by both FeNP and GO-FeNP coated membranes presenting reduced biofilm layer thickness (89% and 65% thinner), total cell count (67% and 40% lower), optical density (40% and 48% lower) and total organic carbon (91% and 98% lower), than the uncoated membrane.