De-oiling characteristics and mechanism of oil-bearing sludge cleaned by CGAs

Abstract

There hasn't been much study on using Colloidal Gas Aphrons (CGAs) to clean oily sludge. In addition, the efficacy and mechanism of CGAs-enhanced surfactant cleaning of oily sludge are not yet clear. Therefore, in this study, CGAs prepared from the compound surfactant solution were used to clean oily sludge in an oil field in Xinjiang. The performance of CGAs in terms of oil removal and particle size was both examined when building the surfactant compounding system. The removal abilities of CGAs from different crude oil components and an analysis of the chemical cleaning process of CGAs were studied. The results demonstrated that the interfacial tension was as low as 3.535 mN/m and the oil removal rate of CGAs was as high as 92.9% when the ideal ratio of sophorolipid (SL) to sodium dodecyl benzene sulfonate (SDBS) was 6: 4. The average particle size of CGAs was 90.57 µm at this ideal ratio. The Zeta potential and turbidity of the supernatant after CGAs cleaning was lower than those of chemical cleaning. Infrared analysis, two-dimensional fluorescence analysis, and thermogravimetric methods were used to characterize the oily sludge after CGAs cleaned. According to the analysis's findings, CGAs' enormous specific surface area allows them to adsorb more petroleum pollutants and improved the ability of those pollutants to migrate between the water phase and other phases of the atmosphere. Also, CGAs are particularly successful in adhering to petroleum-based pollutants in oil sludge for the removal of light constituents like n-alkanes and aromatic hydrocarbons due to the synergistic effects of hydrophobic and electrostatic effects on the functional surface of CGAs. This work provides useful information on the mechanism of the enhanced removal of crude oil from oily sludge by CGAs and provides a new idea for oily sludge cleaning.