Polymer Partitioning Approach for Petroleum Hydrocarbon Reduction in a Clay Soil

Abstract

Soil contamination by crude oil is a major environmental and health hazard. Extraction of the total petroleum hydrocarbons (TPH) sorbed to the clay soil (kaolin) was carried out using synthetic sorbent (Desmopan®) and 2-propanol as a mobilizing agent. The crude oil-loaded polymer beads were bioregenerated in a solid–liquid two-phase partitioning bioreactor (TPPB). A central composite design under response surface methodology was employed for the experimental design and analysis of the results. The independent variables were extraction phase to soil ratio, mobilizing agent to soil ratio, and initial concentration of crude oil in polluted soil. The influences of three independent variables on the TPH reduction efficiency were determined using a statistically significant quadratic model (R 2 = 0.9673). Remediation was more efficient when the mobilizing agent to the soil ratio was equal to 3.00 ml g−1, compared to the higher (4.00 ml g−1) and lower (2.00 ml g−1) levels. The results exhibited that the interaction between the extraction phase ratio and the initial concentration of crude oil in kaolin had significantly influenced the TPH removal. The bioregeneration studies showed a significant reduction (72.07 ± 0.63 %) of low-molecular-weight (two- to three-ring) polycyclic aromatic hydrocarbons and n-alkanes (97.75 ± 0.26 %) present in the crude oil-loaded solid polymers within a 10-day experiment. These findings show that solid polymer extraction followed by bioregeneration of sorbents in a TPPB is applicable to treat crude oil-contaminated kaolin.