Characterization and Assessment of Fouling Resistant Membrane Surfaces for Water and Wastewater Treatment

This project evaluated the abilities of two new nanostructured surface coatings, diamond-like carbon (DLC) and hydroxyapatite (HA) for mitigating the deposition and adsorption of proteins to ceramic membrane surfaces (i.e., membrane fouling) by altering the surface energetics. Membrane properties known to influence membrane fouling; surface roughness, pore geometry, and hydrophilicity/hydrophobicity were studied. Membrane performance was evaluated in terms of decline in permeate flux with time. Durapore® membranes designed to have low protein binding capabilities were used as baseline comparisons. Bovine serum albumin (BSA) was used as the model protein. BSA properties, charge and particle size, were also investigated and used to determine interaction energies including Lifshitz-van der Waals, electrostatic and acid-base interactions. Force-plots based on the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory were then generated. Compared to the unmodified alumina anodisk, HA surface coating reduced the amount of protein fouling (less flux decline). The DLC surface coating resulted in a higher rate of protein fouling relative to the unmodified anodisk membrane. Durapore® membranes exhibited the least protein fouling. The hydrophilic Durapore® and HA coated membranes exhibited an overall repulsive interaction with the model colloid BSA. The relatively hydrophobic DLC had an overall attractive interaction with BSA.