Preparation of n-doped biochar from palm oil mill sludge and urea for peroxydisulfate (PDS) activation: A kinetic study.

Transition metal-based homogeneous/heterogeneous catalysts have been identified as a viable option for persulfate activation. However, metal leaching is unavoidable, leading to significant secondary contamination. Alternatively, nitrogen-doped biochar is considered a promising persulfate activator because it is environmentally friendly and low-cost. In this study, biochar-doped with nitrogen source urea was synthesized in a single-pot pyrolysis and used to activate peroxydisulfate (PDS). The nitrogen content of synthesized POME biochar was altered by adding different ratios of urea to the precursors. The catalytic application of biochar was then considered, including the feasibility of catalytic removal of methylene blue dye. This study was conducted based on 3 ratios of urea-doped biochar: 25:75, 50:50 and 75:25. The optimum pH, dosage of urea-doped biochar and concentration of PDS were subsequently determined. Based on the experimental results, the optimum conditions were identified as pH3, 8mM PDS concentration and 0.1g 75:25 biochar: urea ratio. Based on the optimized conditions, a removal rate of 92.6±0.9% was attained. The kinetic model for this degradation was found to be well fitted to the pseudo first-order reaction. This research provides an effective method for enhancing the N functionality of sludge-based carbocatalysts, as well for sludge recovery and reuse. [ABSTRACT FROM AUTHOR]