Preparation, characteristics, and performance of the microemulsion system in the removal of oil from beach sand.

ABSTRACT

Oil deposited on shoreline substrates has serious adverse effects on the coastal environment and can persist for a long time. In this study, a green and effective microemulsion (ME) derived from vegetable oil was developed as a washing fluid to remove stranded oil from beach sand. The pseudo-ternary phase diagrams of the castor oil/water (without or without NaCl)/Triton X-100/ethanol were constructed to determine ME regions, and they also demonstrated that the phase behaviors of ME systems were almost independent of salinity. ME-A and ME-B exhibited high oil removal performance, low surfactant residues, and economic benefits, which were determined to be the W/O microstructure. Under optimal operation conditions, the oil removal efficiencies for both ME systems were 84.3 % and 86.8 %, respectively. Moreover, the reusability evaluation showed that the ME system still had over 70 % oil removal rates, even though it was used six times, implying its sustainability and reliability.