Study on the Application of “Spear” and “Shield” Switchable Surfactants in Washing Oily Sludge

A novel CO2/N2 responsive surfactant EDOA was explored through electrostatic interaction, and characterized by FTIR and 1HNMR. The process of surface activity deactivation and reassembly of EDOA emulsion after alternating introduction of CO2/N2 was verified by the change of pH value and conductivity. More importantly, it has excellent ability to reduce oil–water interfacial tension, which can effectively wash oily sludge. After solid–liquid separation, the stable oil in water emulsion in the upper layer can effectively separate oil–water only by introducing CO2. Therefore, the surfactant is expected to be further applied in the field of solid waste production in oil fields.