The influence of pH on catalytic degradation of tartrazine in presence of Oxone® activated by cobalt-supported carbon-smectite catalyst

In this work cobalt-supported carbon-smectite catalyst was synthesized and tested as peroxymonosulfate (in form of Oxone®) activator in the degradation of food dye tartrazine. The incipient wetness impregnation method was used to introduce cobalt species into chitosan-smectite biocomposite. The impregnated sample was carbonized in a tube furnace at 500 ºC in a nitrogen atmosphere. The obtained catalyst was characterized by FTIR spectroscopy and N2 physisorption. The FTIR spectra indicated the presence of bands characteristic for carbonaceous structures. It was observed that the presence of cobalt has a significant impact on the textural properties of the resulting cobalt-supported carbon-smectite catalyst. Catalytic tests were performed in 50.0 mg dm-3 tartrazine solution using 10 mg of catalyst in the presence of 0.130 mmol Oxone®. As the first step in catalytic degradation of tartrazine solution, decolorization was monitored using UV-Vis spectrophotometry at λmax= 426 nm. The catalytic process was fast at 30 ºC and besides decolorization included further degradation of products of tartrazine oxidation. After 60 minutes of reaction, the degree of decolorization reached 97%. The influence of the initial pH of reaction solution on catalytic efficiency was tested.