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 (similar to 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. (c) 2019 Society of Chemical Industry