Effect of quaternary ammonium surfactant modification on oil removal capability of polystyrene resin

Quaternary ammonium modified resins for emulsified oily wastewater treatment were synthesized from polystyrene resin through ion exchange reaction between sulfonic acid groups and three quaternary ammonium surfactants. The base resin and modified resins were characterized by infrared spectra, zeta potential measurement and capillary rise test (the Washburn method) to evaluate the effect of modification with quaternary ammonium on the surface characteristics of the resin. The surface electrostatic and hydrophobic characteristics of the resin were significantly altered due to grafting hexadecyltrimethylammonium bromide (HTAB), hexadecylpyridinium bromide (HPB) and tetrabutylammonium bromide (TBAB) onto the resin surface. The grafted quaternary ammonium surfactants made the resin more effective for removing oil droplets by coalescence-filtration because of a less negative-charged and more hydrophobic resin surface. In addition, incorporation of a longer alkyl group on resin surface had a more positive effect on its oil removal capability. The resin modified by HTAB demonstrated a better oil removal capability than other modified resins.

Figure optionsDownload as PowerPoint slideResearch highlights▶ Various quaternary ammonium surfactants had different effects on the polystyrene resin surface characteristics. ▶ A capillary rise test was conducted to evaluate the wettability of modified resin. ▶ A less negative-charged and more hydrophobic resin surface benefits the oil removal process. ▶ Incorporation of a longer alkyl group on resin surface had a more positive effect on its oil removal capability.