Coating via Adsorption

FIGURE 3.6 A schematic representation of the adsorption of nonionic surfactants onto membranes (a) Triton X-100 and (b) Pluronic F108. (Reprinted from Journal of Membrane Science, 209, Maartens, A., et al., 81-92, Copyright (2002), with permission from Elsevier.) 

The hydrophilicity of the MF PP membranes may be increased by increasing the amount of surfactant Tween-20 adsorbed onto the surface or in the pores of the membrane (Xie et al. 2007). The PP membrane modified with a monolayer of the adsorbed surfactant showed higher flux and stronger antifouling ability than the unmodified membrane after operating in an MBR for about 12 days. 

Charge reversal on a low-pressure RO PA membrane surface, due to the electrostatic self-assembly of PEI, was found to increase the fouling resistance of the modified membrane to the cationic foulant DTAB, owing to the enhanced electrostatic repulsion and the increased surface hydrophilicity (Zhou et al. 2009). It was shown that the improved fouling resistance and the increased surface hydrophilicity compensated for the reduction in the membrane permeability due to the adsorption deposition of the PEI layer on the membrane surface. 

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