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Solar‐powered BDD‐electrolysis remediation of soil washing fluid spiked with diesel

BACKGROUND: The remediation of a soil spiked with diesel using Unitol L90 and sodium dodecyl sulfate (SDS) in a soil washing process was evaluated. The washing process was followed by an anodic oxidation based on boron doped‐diamond electrolysis (BDD‐electrolysis) to treat the washing liquid, using a solar photovoltaic (PV)‐battery system as a direct electrical power source. RESULTS: The results demonstrate that high concentrations of Unitol L 90 and SDS are required for the surfactant‐aided soil‐washing (SASW) to efficiently extract diesel from the soil. However, Unitol L 90 strongly interacts with the soil due to the adsorption process. The main characteristics of the effluents produced during this soil remediation was low conductivity. Therefore, the addition of 0.05 mol L–¹ sodium sulfate (Na₂SO₄) as an electrolyte, at current density of 30 mA cm⁻², was investigated. BDD‐electrolysis demonstrated that total organic carbon (TOC) and total petroleum hydrocarbon (TPH) were removed more effectively using SDS. The key of the treatment is associated to the electrogeneration of S₂O₈²⁻ due to the contribution of the surfactant composition and the addition of 0.05 mol L–¹ Na₂SO₄. Additionally, an average solar irradiation intensity and integration of PV cells produced more than 10 A current and continuous electricity (∼27 V), which was constantly supplied to the electrolytic reactor at all times through a direct current generator. CONCLUSIONS: Finally, based on the achieved results, BDD‐electrolysis is an efficient technology approach to remove hydrocarbons from the effluent produced during the soil washing process. © 2019 Society of Chemical Industry