Effects of Membrane Surface Modification on Calcium Carbonate Fouling and Membrane Efficiency for Desalination

Figure 1: Experimental approach. Graft PEG to membrane surface to help reduce fouling of hydrophobic solutes [3]. Desalination can be used as a means to replenish freshwater supplies of communities with growing population needs. Reverse osmosis (RO) is a pressure-driven process that requires a semi-permeable membrane to selectively remove salts and other particulate matter from brackish water or seawater. Common RO membranes are thin-film composites (TFCs), which are composed of a thin polyamide layer supported by a porous polysulfone layer. Although membrane desalination is an efficient method, a persistent problem is that the membrane is highly susceptible to fouling—accumulation of particles onto the membrane surface over time that can clog or otherwise compromise the efficiency or performance of the membrane [1]. The main cause of fouling appears to be a hydrophobic interaction between the membrane surface and the solutes in the water [2]. In our approach, we grafted polyethylene glycol (PEG), a hydrophilic monomer, to help disrupt hydrophobic interactions with calcium carbonate (CaCO3), a common hydrophobic fouling agent (Figure 1). After membrane characterization, we analyzed the interaction between CaCO3 and the membrane surface.