Fouling-resistant membranes polymer modification

Reddy, A.V.R., Mohan, D.J., Bhattacharya, A., Shah, V.J. and Ghosh, P.K. 2003. Surface modification of ultrafiltration membranes by preadsorption of a negatively charged polymer 1. Permeation of water soluble polymers and inorganic salt solutions and fouling resistance properties. 214 211-221. 

Modification of the membranes affects the properties. Cross-linking improves mechanical properties and chemical resistivity. Fixed-charge membranes are formed by incorporating polyelectrolytes into polymer solution and cross-linking after the membrane is precipitated (6), or by substituting ionic species onto the polymer chain (eg, sulfonation). Polymer grafting alters surface properties (7). Enzymes are added to react with permeable species (8—11) and reduce fouling (12,13). 

Changes in cross-flow velocity or transmembrane pressure cannot always alleviate fouling. Membranes made from hydrophilic polymers like cellulose acetate are generally less prone to fouling than the hydrophobic polymers. However, cellulose acetate is limited in its tolerance to high or low pH, organic solvents and elevated temperature. In some cases, surface modification of the more chemically-resistant polymers has rendered them less susceptible to fouling. 

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