Plasma-Induced Grafting of Membrane Surface

Yu et al. (2006) used air plasma-initiated grafting of polyvinylpyrrolidone (PVP) in attempts to reduce the PP membrane fouling in an SMBR. It was shown that after continuous operation for about 50 h, the flux recovery, reduction of flux, and relative flux ratio for the modified membranes were 53% higher, 17.9% lower, and 79% higher, respectively, than those for the unmodified membranes. The water contact angle on the PVP-immobilized membrane showed a minimum value of 72.3°, approximately 57° lower than that on the unmodified one. 

BSA due to an enhanced electrostatic repulsive force between the solutes and the modified-membrane surfaces (Zhan et al. 2004). In addition, a reduction of about 96% in biofilm formation by Listeria monocytogenes on the modified surfaces compared with the unmodified PA and PE polymers was observed after SiCl4 plasma treatment followed by PEG grafting (Dong et al. 2007). 

In general, it can be concluded that the attractive features of membrane modification via plasma treatment are the very short modification time and the possibility to adjust the surface membrane properties to satisfy a particular request without affecting the bulk of the polymer. However, it should be noted that there are some problems with the repeatability of this modification procedure and its scaling-up, especially for continued modification. 

Thereafter, many hydrophilic polymers, such as PVA, PAA, PEG-based hydrogels, and chitosan, have been coaled on different MF, UF, NF, and RO membranes using casting (Asatekin et al. 2006,2009 Du et al. 2009 Sagle et al. 2009), adsorption (Maartens et al. 2002 Ba et al. 2010), or filtration (Li et al. 2000 Reddy et al. 2003 Boributh et al. 2009) techniques. 

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