Effect of precipitating agent on the catalytic activity of Fe3-xCoxO4 catalyst / Nur Syaherra Paisan

This research work focuses on the investigation on effect of precipitating agent on the catalytic activity of Fe3-xCoxO4. The catalyst is synthesized by co-precipitation method where using two (2) different precipitating agents i.e. sodium hydroxide (NaOH) act as a strong base and ammonium hydroxide (NH4OH) act as a weak base. Precipitation agent plays a key role in precipitating the resultant catalyst, which in turn will lead to different in physico-chemical properties of Fe3-xCoxO4 catalyst. The oxidative degradation of the AO7 is performed using heterogeneous Fenton-like reaction in order to evaluate the catalytic activity of synthesized catalyst. The physical properties of resultant Fe3-xCoxO4 catalyst were characterized using N2 sorption and XRD respectively. The results of catalytic and adsorption test shown catalytic test have higher yield of degradation in AO7 dye due to the presence of active •OH radicals from the decomposition of H2O2. Nanoparticles of Fe3-xCoxO4 lead to a dense structure when the molarity of the bases increased. The pore size at 1M, 3M and 5M of Fe3-xCoxO4 (NH4OH) were 6.41 nm, 3.08 nm and 3.06 nm respectively whereas for Fe3-xCoxO4 (NaOH) were 8.22 nm, 8.15 nm, 8.49 nm respectively as formed with 1M, 3M and 5M. XRD characterization was carried out to determine the phase purity of Fe3-xCoxO4 catalysts. The orientation of the particles in the catalyst has a strong effect on the intensities where sometimes the particles are needles or plateles that are somewhat aligned. A low shape peak indicates the particles were randomly oriented and the missing of cobalt ferrite phase in XRD patterns at NaOH due to an even dispersion of Co2+ species and clusters finely dispersed on the cobalt ferrite. However, as for 1M of NH4OH there was only iron oxide was formed without any other impurities due to the tendency of NH4OH to produce agglomeration was very high. Thus, the Co2+ substitution was not presence in the iron oxide itself. As a conclusion, it is shown that strong base was better in synthesizing the catalyst compared to the weak base in order to obtain a better degradation of dye and a better substitution of Co2+ ion to enhance the catalytic activity.