One-pot preparation of magnetic biochar from dragon fruit branch for catalytic ozonation of sunset yellow

Dragon fruit branches are an abundant and underutilized waste released from the annual pruning of dragon fruit. In this study, dragon fruit branches were used for the first time as a raw material for producing magnetic biochar through one-pot pyrolysis. The results showed that zero-valent iron and magnetite particles were generated in the carbon matrix, providing a saturation magnetization of 5.92 emu/g. Due to FeCl3 activation, magnetic biochar possessed a total pore volume of 0.15 cm3 /g and a specific surface area of 203 m2 /g. Subsequently, magnetic biochar was explored as a catalyst for enhanced ozonation of sunset yellow. 95% of sunset yellow (50 ppm) was treated within 80 min at pH 7.0. From the calculation results using pseudo-first-order kinetics, the sunset yellow decolorization constant was improved by 79% by using the magnetic biochar catalyst compared to ozone alone. Overall, dragon fruit branchderived magnetic biochar is a promising material, especially as a green catalyst, because of its magnetic separability and potential catalytic activity for the treatment of sunset yellow by ozone.