Oxidation of bromocresol green by different advanced oxidation processes: Fenton, Fenton-like, photo-Fenton, photo-Fenton-like and solar light. Comparative study

摘要

The aim of this study is to test some advanced oxidation techniques (AOTs) in the absence of light (Fenton and Fenton-like) and in its presence (photo-Fenton and photo-Fenton-like) to obtain total decolorization of an anionic dye in aqueous solution: the bromocresol Green (CI Reactive Green 15 and abbreviated as BCG). Experiments were conducted on a laboratory-scale set up with all these processes. Best operatory conditions were found to be of pH 3, hydrogen peroxide to iron (Ⅱ or Ⅲ) molar ratio of 30:1, artificial (254 nm) and solar light. Besides, several parameters were investigated like pH, oxygen, dose of H_2O_2, light effect, and reaction time. The obtained results showed that color removal followed the increasing order: Fe(Ⅲ)/H_2O_2 ＜ Fe(Ⅱ)/H_2O_2 ＜ Fe(Ⅱ)/H_2O_2/Solar ＜ Fe(Ⅱ)/H_2O_2/UV_(254nm) ＜ Fe(Ⅲ)/H_2O_2/UV_(254nm). This improvement could be related to a better production of radicals OH". In another hand, decolorization kinetic followed pseudo-first-order type in all cases and no synergic effect was observed when Cu~(2+) ion (10~(-4)M) was added to the solution of the dye.