Abstract:
Removal of stabilized oil in wastewater emulsions was investigated by means of induced air flotation technique. Several operating parameters including (a) nonionic surfactant (poly(oxyethylene)(20)-sorbitane monooleate, tween 80), cationic surfactant (hexadecyltrimethyl ammonium bromide, CTAB), anionic surfactant (sodium dodecyl sulphate, SDS) and mixed surfactant between CTAB and tween 80 at ratio (2:8), (5:5), and (8:2) used for longer-life of air bubble, (b) concentrations and types of electrolyte, (c) pH, (d). air flow rate, (e) air bubble size and (f) flotation time were investigated to achieve the performance of induced air flotation for cutting oil removal. Zeta-potential, turbidity and UV-absorbance measurements were also performed in order to interpret the obtained results. An optimum condition for soluble cutting oil removal depended on types of surfactant and a quantity of electrolyte, such as 1 CMC tween 80 and 160 mg/l Al[subscript 2](SO[subscript 4])[subscript 3], 0.25 CMC CTAB and 480 mg/l Al[subscript 2](SO[subscript 4])[subscript 3], 0.25 CMC SDS and 280 mg/l Al[subscript 2](SO[subscript 4])[subscript 3],1 CMC CTAB : tween 80 (2:8) and 160 mg/l Al[subscript 2](SO[subscript 4])[subscript 3], 1 CMC CTAB : tween 80 (5:5) and 160 mg/l Al[subscript 2](SO[subscript 4])[subscript 3], 1 CMC CTAB : tween 80 (8:2). The results showed that an appropriate pH was at 7 except in case of using SDS was at pH 4. The higher oil removal was obtained when employing 8 ml/sec in air flow rate, 615-688 microm. in air bubble size and 20 mins in flotation time. It also found that aluminium cation had effectively induced the destabilization of stabilized oil. More than 99% of stabilized soluble cutting oil emulsions could be removed from the wastewater