Surface modification of polyamide membranes using the layer-by-layer technique: Characterization and antifouling potential

In this paper, modification of NF90 and BW30 polyamide membranes via layer-by-layer deposition of polycationic and polyanionic polyelectrolytes of different molecular weights is reported. Three anionic polyelectrolytes: sodium salt of poly(sodium 4-styrene sulfonate), poly(4-styrene sulfonic acid-co-maleic acid) sodium salt, poly(acrylic acid) sodium salt, and two cationic polyelectrolytes: poly(diallyldimethylammonium chloride) and poly(ethylenimine) were used for membrane modification. The effects of deposition time, the number of polyelectrolyte layers, chemical nature and molecular weight of the polyelectrolytes on the degree of membrane modification were evaluated. The surface morphology of the prepared composite membranes were studied using atomic force microscopy. An enhanced resistance to membrane biofouling of the modified membrane samples was shown during seawater treatment in the non-continuous regime. A possible mechanism of the bactericidal action of the modified membranes is discussed.