Effective degradation of phenol via catalytic wet peroxide oxidation over N, S, and Fe-tridoped activated carbon

Abstract

The N, S, and Fe-tridoped carbon catalysts (NSFe-Cs), Fe/ACNS1 and Fe/ACNS2, were synthesized by wet impregnation with different concentration of ammonium ferrous sulfate solution. The prepared catalysts have a similar textural structure. The N species, S species, FeII and FeIII were simultaneously introduced onto the surface of catalysts. Comparison with the only Fe doped catalyst, NSFe-Cs showed greater stability and higher phenol removal in catalytic wet peroxide oxidation at different reaction condition. The main intermediates including p-hydroxybenzoic acid, formic acid, and maleic acid were determined in the treated wastewater. The high catalytic activity for NSFe-C was related to the ability of H2O2 decomposition. NSFe-Cs have more amount of FeII partially due to the formation of FeS2, which promoted the decomposition of H2O2 on Fe/ACNS1 and Fe/ACNS2 surface. The generation of ·OH and ·HO2/·O2− radicals in the bulk solution was crucial to phenol degradation, and the decomposition of H2O2 complied with the pseudo-first-order kinetics. The highly linear relationship between decomposition kinetic constant for H2O2 and the amount of surface groups suggested, including FeII species, pyridinic N/Fe-bonded N, pyrrolic N as well as graphitic N were responsible to the high activity of NSFe-Cs.