Separation of oil contaminants by surfactant-aided foam fractionation

The separation of oily contaminants out of aqueous/non-aqueous phases using foam fractionation with a surfactant was investigated. In the separation of the light oil (hexadecane), the eluted amount of oil and the o/w (oil/water) ratio increased with the weight percentage of SDS (sodium dodecyl sulfate); and the ratio actually remained the same above the CMC critical micelle concentration) point (0.23 wt% of SDS). Most of the oil was eluted even at 49:1 initial o/w ratio with the surfactant. For the heavy oil (carbon tetrachloride), the eluted o/w ratio and the oil recovery had maxima at 0.05 and 0.1 wt% of SDS solution, respectively, even though the overall recovery of 20-30% was much lower than that of 80-100 % in the light oil. It was speculated that emulsion formation might affect oil entrapment in the foams. Higher gas flow rates, in general, increased the oil recovery, but did not increase the o/w ratio in the effluents.