Mechanism and Characteristics of Oil Recovery from Oily Sludge by Sodium Lignosulfonate Treatment.

The separation of oil components from oily sludge is an important component of soil remediation and energy recovery. Therefore, establishing a green and efficient separation technology is of great significance. In this study, oily sludge was separated using sodium lignosulfonate (SL) treatment. The effects of temperature, SL concentration, rotate speed, time, and pH on the oil removal rate were studied. The optimal conditions were as follows: temperature, 30 °C; SL concentration, 2.0 g·L-1; rotate speed, 200 rpm; time, 60 min; and pH 11. The maximum oil removal rate was 83.21%. The physicochemical properties of oily sludge were analyzed. The soil was looser, and the contact angle (55°) of the soil surface was reduced. Alkanes, aldehydes, ketones, carbonic acids, benzene rings, and alicyclic ethers were removed. The result shows that the SL treatment removed a wider range of petroleum hydrocarbon and had a stronger oil removal capacity. It provides a new method for the green and efficient separation of oily sludge.