Fenton-like oxidation of dyes using CoxFe3-xO4 catalyst / Mohammad Khairul Azam Selamat

The cobalt ferrite catalyst were synthesised through the substitution of cobalt into iron oxide matrix via co-precipitation and inverse co-precipitation methods. XRD analysis shown that both catalysts exhibited with cubic spinel phase. No impurity was detected in co-precipitated cobalt ferrite phase. Meanwhile, there is a presence of halide impurity being observed in the inversed co-precipitated catalyst. The FTIR spectrum of co-precipitated cobalt ferrite depicted with higher tetrahedral and octahedral bond substitution compared to inverse co-precipitation catalyst. The particle size of both catalysts were found to be approximately 1.44 ± 0.19 and 1.71 ± 0.28 (xm for co¬precipitation and inverse route, respectively. Interestingly, both catalyst were stable in suspension at neutral pH based on the zeta potential value of -32 mV. The inherent catalytic activity of these catalyst were evaluated based on the degradation of three types of difference dyes. The oxidative degradation of Acid Orange 7 (AO7), Methylene Blue (MB), Rhodamine B (RhB) were performed in the heterogeneous Fenton-like reaction. It was found that different dye behaved differently during the catalysis. AO7 has shown significant removal in both adsorption and catalysis processes; whilst the removal of MB and RhB were negligible. The co-precipitated catalyst shown higher performance in AO7 degradation (66%) compared to inverse co-precipitated catalyst (11%). Such findings suggested that the catalyst synthesised through co-precipitation method was favourable in contrast with the inverse co¬precipitation method.