Coating via Filtration

The UF PES membranes containing negatively charged sulfonic acid groups on the surface were obtained on filtration of an aqueous solution of poly(sodium 4-styrenesulfonate) (PSS) for about 100 min using a dead-end filtration cell (Reddy et al. 2003). It was shown that thin porous membranes are modified only on the top surface because the PSS macromolecules are not able to enter the pores. However, for membranes with wider pores, PSS permeation results in the formation of charged 

In general, the adsorbed coatings are relatively simple to apply and the process can be performed in commercial membrane elements. In addition, the type of coating can be tailored to the specific application of interest. However, despite the flexibility of the coating and the adsorption methods to change the hydrophilicity, smoothness, and charge of the membrane surface, their main drawback is the limited stability of the modified layer over time because of the possible desorption of the coated/ adsorbed polymers from the membrane surface into the bulk of the feed solutions. 

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