(625d) Novel Copper-Charged Anti-Microbial Membranes for Desalination

The need to control membrane fouling by microorganisms, also known as biofouling, is crucial in water separations applications. The purpose of this project was to investigate the charging of membrane surfaces with copper (Cu⁺²) to control biofouling by developing anti-microbial membranes. The use of anti-microbial membranes would reduce the cost associated with chemical pretreatment and cleaning as well as chemical storage. To this end, glycidyl methacrylate (GMA), an epoxy, was used to attach a chelating agent, iminodiacetic acid (IDA) to facilitate the charging of copper to the membrane surface. Both cellulose acetate (CA) and CA-GMA membranes were cast using the phase-inversion method. The CA-GMA membranes were then charged with copper ions to make them resistant to microbial growth. The pore size distribution analysis of CA and copper charged membranes were conducted using various molecular weights of polyethylene glycol (PEG). CA and copper charged membranes were characterized chemically using Fourier Transform Infrared (FTIR), and with respect to copper dispersion on the membrane surface using scanning electron microscope (SEM), hydrophilicity changes using contact angle. The permeation experiments were conducted with DI water and then subjected to protein rejection measurements. The permeation of the copper-charged membranes was initially lower than the cellulose acetate membrane during the filtration of DI water. The membranes were then subjected to bovine serum albumin (BSA) and lipase filtration. The copper charged membrane showed higher permeation values for of both proteins as compared to CA membranes.  This resulted from increased resistance from the IDA and copper on the surface during DI water filtration, and later, from reduced fouling from both proteins.  The rejection of BSA and lipase was the same for both the copper charged and CA membranes. Therefore, the modified membranes have a potential to be used as low-biofouling membranes in the future.