(109g) Factors Controlling Complex Solvent Extraction of Petroleum Hydrocarbons Contaminated Soil

Sui Hong, Li Xingang^*, Du Yongliang

School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China;

National Engineering Research Centre for Distillation Technology, Tianjin 300072, China;

 Abstract:

Petroleum refining unavoidably generates considerable volumes of oily sludge during oil transportation, production and processing activities. Total petroleum hydrocarbons (TPH) are the most harmful components in oily sludge, because of their potential hazard to human health and the environment. Solvent extraction is a promising technology for the treatment of high oil contaminated soil, in which petroleum hydrocarbons are removed from soil using an individual solvent or mixture of solvents. Based on the results of single factor experiments (5 factors were investigated), the effects of water content, extraction time, temperature, ratio of soil to solvent and extraction times on the efficiency were evaluated using orthogonal experiments. Our results showed that the ratio of liquid to solid is the most important factor influencing greatly the oil extraction efficiency. Although less important, the other two factors, that is extraction temperature and time, have all increased the efficiency of extraction treatment. The calculated extreme difference of three factors (solid to solvent ratio, temperature and time) are 4.29, 1.07 and 1.07 respectively. Based on a treatment of 20 g of contaminated soil with a TPH concentration of 140 mg g^-1, optimal conditions (A₂B₂C₃) were found to be at 30 °C, 20 min extracting time and 160ml solvent. Under this optimal condition, efficiency of oil removal was reached 96.77 %. Considering practical process increasing temperature will greatly increase the operational costs, room temperature was chosen finally, so the reasonable optimal condition was 8:1ratio of solvent to liquid, 20 min extracting time at 20 °C.

 Key Words: Solvent extraction, petroleum hydrocarbons, contaminated soil, orthogonal experiments