Oil recovery from oily sludge using amidinium bicarbonate-based CO2-responsive microemulsion

In the petroleum and petrochemical industries, oil sludge is a common contaminant that causes environmental pollution and resource wastage. Currently, recovering crude oil from oily sludge presents a significant challenge during processing. In this study, an amidinium bicarbonate-based CO 2 -responsive microemulsion was developed to effectively treat sludge and recover crude oil. The microemulsion system demonstrates a strong capability for oil solubilization. After the microemulsion treatment, the residual oil contents in the sludge can be reduced to as low as 2.93% (ME-1, n-butanol as cosurfactant) and 1.44% (ME-2, n-hexanol as cosurfactant). Complete oil/water phase separation can be achieved by introducing N 2 at 65°C.