Modifying ceramic membranes with in situ grown iron oxide nanoparticles and their use for oily water treatment

Abstract

A facile technique for impregnating commercial ceramic membranes with in situ grown iron oxide nanoparticles (NPs) and their use for synthetic produced water treatment is presented. Unlike most literature, our technique led to NPs forming on the surface as well as within the pores of the membrane. The antifouling properties of the membrane were evaluated in terms of surface characteristics, hydrophilicity, fouling characteristics, organic rejection, and regeneration capacity. The contact angle and the rate of water penetration were used to determine optimum precursor concentration for which membrane hydrophilicity is improved without major pore blockage due to NP agglomeration and deposition. At such concentration, in situ generation of the NPs, mostly with sizes less than 4 nm, did not affect membrane morphology, porosity or the intrinsic hydraulic resistance. Membrane organic rejection and fouling behavior showed considerable enhancement in humic acid, a model natural organic matter also existing in produced water, retention at different transmembrane pressures. Organic rejection along with the permeate flux suggest fouling transition from concentration polarization and pore plugging to gel/cake layer formation occurs at higher critical gel concentration for the modified membranes. The steady permeate flux for modified and unmodified membranes are comparable, especially at higher humic acid concentration, and flux recovery and fouling ratios reveal enhanced antifouling properties. A new dimensionless number, membrane performance number, is introduced to couple the performance of the membrane in terms of permeate flux and contaminant rejection.