Novel low-fouling copper-charged nanofiltration and reverse osmosis membranes

Glycidal Methacrylate (GMA) has been found to be a useful epoxy in the attachment of chelating agents onto the surface for polymer membranes. Flat sheet membranes were cast from a dope solution of cellulose acetate (CA), N-methyl-2-pyrrolidone (NMP), and GMA in a 21/77/2 wt% ratio. Half of the membranes were subjected to a treatment to attach the chelating agent, iminodiacetate (IDA), to the surface and then treated in a bath of copper ion solution. Copper ions have been shown to disinfect water against microbial biofilms through interfering with enzymes involved in cellular respiration and bind DNA at specific sites (Hausman). Both the untreated membranes and the treated membranes were put into separate 50/50 deionized water/glycerol baths for a day prior to characterization testing. The treated membranes were examined using scanning electron microscopy (SEM) energy dispersive spectroscopy (EDS) analysis to detect the dispersion of copper on the surface. The results of the analysis showed the copper was evenly dispersed and successfully attached to the surface. All the membranes were characterized by their pure water permeability (PWP) and by Bovine serum albumin (BSA) and Lipase rejections. The treated membrane showed a lower PWP but higher permeation values for of both proteins. This resulted from increased resistance from the IDA and copper on the surface during PWP testing, and reduced fouling from both proteins. The addition of IDA and copper to the surface increases the hydrophilic nature of the membrane, which leads to reduced fouling (Hausman 2). Additionally, the rejection of BSA and Lipase was the same for both the treated and non-treated membranes. This is favorable because it shows pore size of the membrane is unaffected by the IDA and copper treatment. Therefore, the modified membranes have a potential to be used as low-biofouling membranes in the future.