“…In addition, since sulfate free radicals have a higher redox potential than permanganate, higher removal efficiency could be achieved by persulfate with sequential injections of ferrous ion. Generally, the advantages of using persulfate oxidation include the following: (1) persulfate is more persistent than hydrogen peroxide in the subsurface; (2) no heat or precipitation was produced by persulfate; (3) persulfate is colorless; (4) persulfate is less harmful to in situ microorganisms; and (5) longer radius of influence can be achieved due to the high solubility of persulfate (40%) [20,50,51]. Thus, persulfate oxidation could serve as an option for the remediation of petroleum-hydrocarbon contaminated soil.…”