Study of the hydrophilic-enhanced ultrafiltration membrane

To reduce hydrophobic interactions between natural organic matter (NOM) and the membrane surface, and thereby fouling due to NOM, hydrophilic poly(ethylene glycol) (PEG) monomer chains were attached to a commercially available membrane via in situ graft polymerization. Modification of the membrane was carried out using an oxidizing agent as initiator, PEG monomer, and a chain transfer agent (CTA) as terminating agent. Graft polymerization was carried out by two different methods, bulk (i.e. immersing the membranes in the reactant solutions) and drop (i.e. adding reactants dropwise to the membrane surface). Two different feed solutions were used to characterize the modification. Dextran solution was used to compare the efficiency of each modification method. Synthetic seawater was then used to determine the influence of graft polymerization on flux decline, organic carbon rejection and cake accumulation during filtration. The drop method of modification was found to be the optimal procedure resulting in higher flux and rejection along with improved fouling resistance. Graft polymerization led to an increase in permeability when filtering synthetic seawater containing NOM. FTIR spectra demonstrated the occurrence of modification by showing carbonyl attachment and OH stretching. AFM images indicated lower cake accumulation patterns after modification. (C) 2008 American Institute of Chemical Engineers Environ Prog.