Degradation of textile dyes by Oxone® activated by cobalt supported chitosan-derived carbon-smectite catalyst

Chemical degradation by activated Oxone® is one of the most attractive advanced oxidation processes (AOPs) for the treatment of various pollutants including toxic azo dyes. However, the development of an effective heterogeneous catalyst for activating Oxone® is still challenging. In this work a novel cobalt supported carbon-smectite catalyst (Co/cC-S) was prepared through a two-step synthesis. First, the incipient wetness impregnation method was used for the cobalt species to be introduced into chitosan-smectite biocomposite. The impregnated sample was then carbonized in a tube furnace at 400 °C in a nitrogen atmosphere for 1h. The obtained catalyst was characterized using FTIR spectroscopy and low temperature N2 physisorption. The Co/cC-S catalyst was tested as peroxymonosulfate (in the form of Oxone®) activator in the degradation of two textile dyes, Acid orange 10 (AO10) and Basic Blue 41 (BB41), from their single component and two component aqueous solution. As the first step in catalytic degradation of dyes, decolorization was monitored using UV-Vis spectrophotometry (λmax=478 nm and 605 nm, for AO10 and BB41, respectively). The results showed that Oxone® alone is ineffective in the degradation of both dyes. The combination of Co/cC-S and Oxone® significantly improved their degradation. The investigated catalytic process at 30 °C in the single component dye solution was very fast for AO10 and somewhat slower for BB41. The AO10 decolorization from the two-component solution was as fast as from the single component solution. On the other hand, the degradation efficiency for BB41 substantially decreased when two dyes co-existed. This result suggests that Co/cC-S activated Oxone® exhibited a relatively high priority for attacking AO10. Co/cC-S showed to be a promising peroxymonosulfate activator in the catalytic treatment of wastewaters containing textile azo dyes