Fe/S doped granular activated carbon as a highly active heterogeneous persulfate catalyst toward the degradation of Orange G and diethyl phthalate

Fe/S doped granular activated carbon (Fe/SGAC) was synthesized with ferric nitrate, Na 2 S 2 O 3 and (NH 4 ) 2 S 2 O 8 via an impregnation–precipitation, reduction–oxidation combining with aqueous-phase synthesis method treatment. Surface density of functional groups, surface area changes as well as the chemical state inside Fe/SGAC catalyst were studied by Boehm titration, N 2 adsorption and X-ray photoelectron spectroscopy (XPS). The reactivity of the catalysts was tested by degrading Orange G (OG) and diethyl phthalate (DEP). The Fe/SGAC catalysts could significantly enhance the removal rate of OG as compared to persulfate alone and PS/GAC. And the catalytic capacity was also enhanced by S doping. But the degradation of DEP under the similar condition was inhibited by adsorption process because of the different hydrophobicities of OG and DEP molecule. Fe 2 O 3 /FeOOH (Fe 3+ ) (represents ferrihydrite) together with FeO/Fe 3 O 4 (Fe 2+ ) and Fe 2 O 3 -satellite, which provide the new active site for persulfate catalyst was found to be the major components of iron element in Fe/SGAC catalyst; the existence of FeS 2 (S − ) for sulfur element verified the assumption that the doped S element promoted the electron transfer between the persulfate species and iron oxide at the interface. COD removal experiment further confirmed that mostly contaminant removal was owed to the Fe/SGAC catalytic persulfate oxidation process.