In
this study, a series of glucose-derived carbon catalysts were
developed and applied for the activation of sulfite for the oxidation
of As(III). The process of sulfite activation with the carbon catalysts
is based on the production of oxysulfur free radicals such as SO3•–, SO5•–, and SO4•–. The factors responsible
for the sulfite activation performance of carbon catalysts are conductivity
and ketonic functional groups. A complex is formed between the sulfite
and carbon catalysts, and the electron transfer that takes place within
the complex leads to the generation of semiquinone and oxysulfur radicals,
and finally, the oxysulfur radicals are converted into SO4•– by means of O2, which results
in the As(III) oxidation. The efficiency of the sulfite/carbon system
is enhanced under normoxia conditions due to the reversible transformation
cycle occurring among CO/C–O•/C–OH
triads. The present study is of great environmental significance as
sulfite is a source of SO4•– generated,
and the activation is achieved by a metal-free carbon material, which
makes the process viable and environmentally friendly.