Catalytic Activity of Fe₃O₄ Transition Oxides from Wire Plating Sludge Waste for Application on Efficiency of Coal Combustion

The catalyst in the combustion process is a material additive. Catalyst is added to the fuel such as a subbitumin-type of coal which is having a caloric value of 4596.45 cal/g at a concentration of ± 0.1% w/w will increase energy of coal. The combustion catalyst are an alkali metal, an alkaline earth, and a transition metal as well as its oxide forms. In addition to having catalytic properties, metal oxide is also shown to have magnetite properties that will increase the catalytic activity such as Fe3O4. In this study, the Fe3O4 combustion catalyst was prepared from wire plating sludge (sludge) wastes having a high metal content and FeSO4 dispersed into a vegetable oil, water, and surfactant mixture to form a catalyst suspension. The catalytic activity of the transition oxide is compared with the sludge catalytic activity and mixing the ratio of 1: 1. The result of catalytic activity test using differential thermal analyzer obtained coal combustion efficiency up to 91.00% due to the addition of sludge catalyst suspension at combustion process or an increase of 34.30% combustion efficiency compared without catalyst. In contrast, the addition of Fe3O4 catalyst only resulted in a combustion efficiency of 55.63%. The value of this combustion efficiency is lower 6.96% compared without catalyst. This is concluded that the catalytic activity of the Fe3O4 transition oxide tends to decrease the combustion efficiency of coal.