Fenton-like oxidative degradation of Orange G dye and binary dye mixtures using Oxone® activated with cobalt-doped alumina catalysts

Two texturally and structurally different Co-doped aluminas were obtained by using the solgel method followed by calcination at temperatures of 1000 degrees C and 1100 degrees C. The obtained materials were tested as catalysts in anionic textile dye Orange G (OG) degradation using Oxone (R) as a precursor of sulfate anion radical s, the main reactive oxygen species. Effects of temperature and initial pH on degradation efficiency was investigated. The increase in temperature accelerated the reaction rate and the maximal degradation efficiency was obtained at 60 degrees C. Different kinetic models were applied and pseudo-first order rate was found to be the most appropriate. Both catalysts showed the optimal performance in the pH range around neutral. Coexisting cations (Ca 2+ , Mg 2+ , K + and Na + ) enhanced the OG degradation rate, as well as anions: Cl- and H 2 PO 4- , while NO 3- , SO 4 2- and HCO 3- inhibited the degradation. The catalysts were also proved effective in degradation of the other investigated dyes: Methylene blue, Basic blue 41, and Remazol brilliant blue R. Finally, simultaneous degradation of OG in binary dye mixtures was investigated showing that the synthesized catalysts can be also used in simultaneous processes of dye degradation. However, differences in structural and textural properties of the two catalysts affected their catalytic performance.