In this study, the synergistic effect of silica nanoparticle and biosurfactants on oil storage tank clean up was investigated. Rhamnolipid, saponin and silica nanoparticles were used to recover oil from refinery oily sludge in laboratory experiments. From our results, the optimum HLB value for the extraction process was about 10.5 for the mixture of 62.5% of rhamnolipid and 37.5% of saponin. Our results also showed that the simultaneous use of the biosurfactants and nanoparticles results in a synergistic effect that significantly enhances the process efficiency. Maximum yield of oil residual was obtained about 4% at the optimum condition (HLB value of 10.5 for mixture of the biosurfactants and 3 g/l of silica nanoparticles). The results of present study showed that this method has the potential for industrial applications and may be used in oil recovery from oily sludge.
