Remediation of PAHs contaminated soil using a sequence of soil washing with biosurfactant produced by Pseudomonas aeruginosa strain PF2 and electrokinetic oxidation of desorbed solution, effect of electrode modification with Fe3O4 nanoparticles

This work aimed to investigate the performance of biosurfactant, produced by a halotolerant bacterial strain, Pseudomonas aeruginosa PF2, for desorption of PAHs from soil, followed by electrokinetic oxidation of the desorbed solution using Magnetite Nanoparticles Modified Graphite (MNMG). Pyrene (PYR), anthracene (ANT) and phenanthrene (PHE) were used as contamination model. Produced and extracted biosurfactant was characterized as rhamnolipid with Critical Micelle Concentration (CMC) of 60 mg/L and emulsification index (E-24) value of 60.2% for n-hexadecane, 58.4% for n-heptane and 55.6% for n-Hexane, respectively. Results of LC-MS/MS analysis indicated the presence of seven major peaks at m/z of 677.5, 531.1, 649.3, 528.9, 475.1, 359 and 503.2, which corresponded to the deprotonated molecules of RhaFthaC(12)C(10), RhaC(12)C(10), RhaFthaC(10)C(10), RhaC(12:1)C(10), RhaC(8)C(10), Rha-C-12:2 and RhaC(10)C(10), respectively. The maximum desorption of PAHs was derived at pH value of 6, CMC of 3 and contact time of 24 h. Modification of graphite electrode enhanced the PAH degradation significantly. In electrokinetic oxidation of desorbed solution, the best results were observed at pH value of 5, contact time of 6 h, voltage of 3 V and electrolyte concentration of 25 mg/L, with the average removal efficiency of higher than 99% for all studied PAHs.