Enhanced decomposition of dyes by hemin-ACF with significant improvement in pH tolerance and stability

Highlights: • ACF-supported hemin allowed enhanced decomposition of dyes compared with bare hemin. • Hemin-ACF exhibited excellent pH tolerance over a wide pH range from acidic to alkaline. • The introduction of ACF accelerated the generation of reactive species by electron transfer from ACF to hemin. -- Abstract: In this study, we evaluated a novel heterogeneous catalytic system (hemin-ACF/H2O2) based on activated carbon fiber supported hemin for the rapid removal of dyes. Contrast experiments, effects of pH and temperature, and sustained catalytic stability of hemin-ACF for the catalytic decomposition of azo dye RR195 used as a model pollutant were investigated. Surprisingly, the introduction of ACF significantly enhanced the decomposition of dyes by hemin with an obvious improvement in pH tolerance and stability. Inhibition and probe studies combined with electron paramagnetic resonance (EPR) were conducted to ascertain the role of several radicals (·OH, O2·−/HO2·, 1O2 and FeIV=O) on dye degradation. ACF are rich in free electrons, and the π-conjugated macrocyclic structure of hemin may present convenient channels for the transfer of free electrons from the ACF, promoting the generation of hydroxyl radicals and high-valence iron species. These results are promising because they offer new insight for the application of hemin as a catalyzer upon treatment of organic pollutants and contribute to identification of the interaction between support material and catalyzer from a new perspective