(545aq) Application of Biosurfactant Surfactin for Efficient Oil Separation from Waste Crude Oil Via Two-Step Process

Waste crude oil, a W/O type of crude oil emulsion which is inevitable produced during petroleum production, transportation and refining processes, needed efficient oil separation before discharge due to environmental risk and economic reasons, while it was still a challenge. This study developed a two-step process using surfactin as novel demulsifier for efficient oil separation. Firstly, surfactin was added to adsorb onto oil-water interface to co-stabilize emulsion droplet, and then the addition of acid caused surfactin precipitate and should be resulted in a sufficient oil separation. Such process is mainly based on the pH-switch emulsification-demulsification activity of surfactin as a result of dissolution or precipitation nature of surfactin under alkaline or acid condition. As found, surfactin at 200 mg/L can readily co-stabilize emulsion droplet with the native emulsifiers in emulsion, and then acid addition at 1% of 1M H₂SO₄ can achieve a quite well oil separation (over 95 %) during 10 min at 50 ^oC. The validity of this process was further confirmed on the waste crude oil, over 95 % of oil was separated within 30 min at 70 ^oC. This process have of great feasibility in industrial application for oil separation from crude oil emulsion.