Removal of oil from oil-in-water emulsion using a packed bed of commercial resin

The present study reports the removal of oil from oil-in-water (o/w) emulsion using a commercial resin which is a co-polymer of styrene and di-vinyl benzene. The stability of the 0.05% (w/w) o/w emulsion was investigated for different surfactant concentrations (0.25–4%), mixing time (5–60 min) and stirring rate (500–2500 rpm). The emulsion stability was estimated by measuring the relative volume of emulsion after 24 h of the preparation of emulsion and the zeta potential. 1% of surfactant, 18 min of mixing time and 2000 rpm stirring were found to be the optimum conditions for the most stable emulsions. A series of experiments were performed to investigate the effect of such parameters as influent oil concentration (30–500 mg/dm3), bed height (30–100 mm) and flow rate (10–20 dm3/h) on the oil removal efficiency of the resin. More than 89% of emulsified oil was removed under optimal operating conditions: 10 dm3/h flow velocity, 75 mm bed height, and 500 mg/dm3 influent concentration of oil in the o/w emulsion. SEM and FTIR results indicate that the hydrogen bonding and hydrophilic interaction were the principal driving forces for the adhesion of oil onto the polymeric resin surfaces. The results indicated that the resin is very effective in removing oil from o/w emulsion.