Oxidation effectiveness and kinetics of potassium permanganate on low-permeability phenanthrene-contaminated soil under fracturing conditions

For low-permeability contaminated sites, existing combined fracturing-oxidation remediation technologies rely on diffusive migration of the oxidant to remediate only a small area near the fracture, resulting in long site-wide remediation times. Therefore, this study proposed a new fracturing-enhanced oxidative remediation method aimed at achieving rapid remediation of low-permeability polycyclic aromatic hydrocarbon-contaminated sites. Specifically, this study investigated the effect of potassium permanganate (KMnO4) 4 ) oxidation on the remediation time, total oxidant demand, phenanthrene (PHE) removal, oxidation kinetics, and physicochemical properties of low-permeability PHE-contaminated soil under fracturing conditions through one-dimensional rigid-wall hydraulic conductivity tests and a series of laboratory experiments. The results indicate that according to systematic evaluation, the optimal Darcy velocity was >= 5.95 x 10-6-6 m/s, and the optimal KMnO4 4 concentrations for remediation of contaminated soils with low and medium-high PHE concentrations were 1 g/L and 2 g/L, respectively. The migration of KMnO4 4 within the soil matrix between two adjacent parallel fractures followed piecewise first-order reaction kinetics. Additionally, KMnO4 4 oxidation under fracturing conditions had less impact on the physicochemical properties of low-permeability PHE-contaminated soils while significantly reducing their ecotoxicity. Overall, this new remediation method shows promise for the rapid and efficient cleanup of low-permeability contaminated sites. Further research is warranted to evaluate the influence of other factors (e.g., permeability) on the oxidation effectiveness and kinetics of KMnO4 4 in low-permeability PHEcontaminated soils.