Fatty Acid Methyl Esters from Jatropha Curcas L. Seeds as a Green Solvent for Remediation of Soil Contaminated with Anthracene

The use of fatty acid methyl esters (FAME) as green solvents to remove hydrophobic pollutants from soil such as polycyclic aromatic hydrocarbons (PAH) is an emerging alternative for environmental remediation because they come from a renewable and abundant source unlike traditionally used solvents (i.e., dichloromethane, hexane, acetone, chloroform, dimethyl ether and alcohols). Previous reports on this kind of treatment are scarce, and their results showed a potential positive effect of FAME as a chemical agent to desorbed PAHs or crude oil from soil. However, the biodegradability effect of FAME over recalcitrant organic compounds was not evaluated. Furthermore, using renewable chemicals obtained from local natural resources in these treatments significantly diminishes the environmental impact of their operations, so the use of emerging feedstock like Jatropha curcas L. (JCL) to produce FAME offers opportunities for biorefinery products. In this research, it was possible to obtain FAME from JCL seeds through a sustainable process where high-value by-products such as protein seed cake and glycerol were also obtained. The J. curcas L. FAME (FJC) was evaluated as a green solvent to remove anthracene (ANT) from contaminated soil (CS) in batch experiments using a mass/volume ratio (CS/FJC) of 1:10 and 1:5 at 30 °C for 8 h. The desorption yield was determined by thermogravimetric analysis (TGA), UV–VIS spectroscopy and total organic carbon analysis. In addition, the biodegradability of ANT-FJC mixtures was evaluated through the ISO-10707:1994 method. The results revealed that the highest efficiency for cleaning contaminated soil with ANT was obtained at 1:2 ratio at which FJC removed 19.57% of ANT, whereas, at 1:1 ratio, the removal efficiency was 9.48%. Biodegradability of FJC-ANT in a1:1 mixture was 67%, improving in 10% the biodegradability of ANT after 28 days. Based on these results, the alternative of using FJC as a green solvent to remove recalcitrant organic compounds such as PAH is a promising option; however, further research is needed to evaluate its effect over additional PAH such as the priority pollutants recognized by the Environmental Protection Agency.