Formation of Fe3O4/C composite during pyrolysis of FeCl3-loaded pineapple (Ananas comosus) leaves

Pineapple leaves are an abundant and underutilized biomass resource released from cutting old plants with low productivity. The renewable waste was, therefore, used for the preparation of the Fe3O4/C composite via single-stage pyrolysis with FeCl3 addition. The results revealed that FeCl3-activation produced Fe3O4 crystals with an estimated content of 44 wt% in the resulting Fe3O4/C composite. In addition, the specific saturation magnetization of Fe3O4/C reached 4.62 emu/g, which supported its magnetic separatability. The material was accordingly explored as an oxidation catalyst for treating methyl orange (50 ppm) at pH 3.0. As a result, Fe3O4/C partly removed methyl orange with an adsorption capacity of 9.9±2.4 mg/g. When H2O2 (300 ppm) was added, 0.40 g/L of Fe3O4/C decolorized 93±2% methyl orange with an average rate of 72±3 mg.g−1.h−1. Furthermore, this decolorization obeyed pseudo-first-order kinetics with a rate constant of 0.030 min−1. Overall, the findings from this study strongly advocate for the use of low-cost Fe3O4/C as a highly effective catalyst for methyl orange removal from wastewater. Moreover, these results pave the way for further exploration of pineapple leaf-derived Fe3O4/C for a wide range of potential applications, contributing to sustainable waste management and green chemistry practices.