Influence of precipitating agent on catalytic activity of Fe3-xCoxO4 catalyst

Abstract

Cobalt ferrite catalysts (Fe3-xCoxO4) were synthesized by substituting cobalt into the structure of iron oxide via oxidation-coprecipitation method. Two types of precipitating agent (strong and weak base) were utilised at different molarity (1M, 3M and 5M) during the synthesis. NaOH and NH4OH were used as strong base and weak base, respectively. The resultant catalysts were further tested for its catalytic activity in the oxidative degradation of acid orange 7 (AO7). It was found that 43% of dye removal was obtained for the catalyst synthesized using 1M NaOH solution. Meanwhile on 20% of dye removal was observed for weak base at the similar concentration. Such differences could be corresponded to the differences in structural formation of resultant Fe3-xCoxO4 catalyts. The pore volume of catalyst synthesized by strong base comprised of 18% higher compared to the weak base; which may lead to better accessibility of pollutants directly to the active sites during the catalysis. In addition, the formation of synthesized catalyst from the strong base exhibited with crystalline phase; whilst amorphous for the weak base. Hence, it can be concluded that the used of strong base precipitating agent provides modest influence during the catalyst’s formation which directly affecting the overall catalytic performance of the Fe3-xCoxO4 catalyst during the Fenton-like reaction