Pollutant degradation behaviors in a heterogeneous Fenton system through Fe/S-doped aerogel

To prepare a heterogeneous Fenton catalytic material with high pollutant degradation efficiency, Fe/alginate acid hydrogel was used as a template to obtain a Fe/S-doped aerogel (GFe2) and a Fe/O aerogel (GFe3). GFe2 and GFe3 exhibit different iron component crystal patterns; from our results, we deduced that S-doping improves the electron transportation in the Fenton reaction. GFe2 also exhibits a better spherical structure and a higher specific area than GFe3 due to the support of the FeS nanospheres. To further increase structural advantage, polyvinyl alcohol (PVA) was added to alginate hydrogel during in-situ pyrolysis, which further converts GFe2 into a more porous structure (PGFe). Experiments show that the organic removal efficiency of the samples are ordered as GFe3 < GFe2 < PGFe, which acts as additional evidence for the importance of S doping and the structural support that PVA offers which produces more active sites and faster electron transportation. PGFe shows a high reusability after 5 runs of repetitive use in tetracycline (TC) and perfluorooctanoic acid (PFOA) degradation. The removal rate of PFOA increased from 15.4% to 21.6% using PGFe; though not as significant as its effects on TC. The C₇, C₈, F₂₃, and O₂₄ atoms of PFOA are found easier to be attacked by hydroxyl radicals. Having used drinking and black odorous water to further evaluate the practical properties and industrial potentials of the aerogel, PGFe also shows a significant effect in degrading a variety of pollutants, both organic and heavy metal. This clearly demonstrates the promising potentials of Fe/S-doped carbon aerogel.