Fast and environmental-friendly degradation of tert-butyl mercaptan from contaminated soil using bimetallic-modified Fenton process

Abstract

In this work, the fast remediation of tert-butyl mercaptan from the polluted soil via a bimetallic Fenton treatment that included Fe2+/Fe3+/Fe0/Cu2+ in the presence of gasoline was studied. The analysis of variance and the Pareto analysis resulting from the central composite design (CCD) showed that the H2O2, CuSO4, Fe3O4 nanoparticles, nano zerovalent iron (nZVI), and gasoline initial concentrations as a secondary contaminant were influential factors on the removal efficiency of tert-butyl mercaptan (with an effectiveness of 2.09%, 13.38%, 1.92%, 2.01%, and 39.73% respectively). Moreover, the interaction of H2O2/nZVI, H2O2/nFe3O4, H2O2/CuSO4, nZVI/nFe3O4, and nZVI/CuSO4 had a positive effect on removal efficiency, while nFe3O4/CuSO4 had a negative one. Surprisingly, the mixing of nZVI and nFe3O4 before adding them to the reactor did not affect the removal efficiency. The optimum conditions suggested for the maximum removal efficiency of tert-butyl mercaptan were the minimum levels of the initial gasoline concentration (2.5 %w/w), a maximum level of CuSO4 (0.12 %w/w), and an optimum concentration of H2O2, nano-ZVI, and nano-Fe3O4 (8.92 %w/v, 0.1194 %w/w and 0.0898 %w/w, respectively) in the studied intervals. This condition led to a 99.27% efficiency removal of tert-butyl mercaptan removal in 20 minutes without pH and temperature adjustments.