Nitrogen and phosphorus co-doped carbocatalyst for efficient organic pollutant removal through persulfate-based advanced oxidation processes

Carbocatalysts doped with heteroatoms such as nitrogen or sulphur have been reported to be useful in persulfate-based advanced oxidation processes for organic pollutant removal. How-ever, there is limited research on the effect of doping with phosphorus atoms on degradation per-formance. In this work, a new nitrogen and phosphorus-doped carbocatalyst (N, P-HC) was designed using hydrothermal carbonization followed by pyrolysis at 700 degrees C, with olive pomace as a carbon source, to degrade organic pollutants in the presence of peroxydisulfate (PDS). Exper-imental results showed that N, P-HC, with its large specific surface area (871.73 m2.g ⠁1), high content of N-pyridinic and N-pyrrolic groups, and the presence of P-O-C and O-P-C bonds, exhib- ited high degradation performance (98% degradation of Rhodamine B (RhB) in 40 min, with an apparent rate constant (kapp) of 0.055 min-1 and an excellent turnover frequency (TOF) of 0.275 min-1). Quenching study and EPR analysis revealed that singlet oxygen generation (1O2) and direct electron transfer were the main reaction pathways for the non-radical pathway in the degradation of RhB. The improved catalytic efficiency in the N, P-HC/PDS/RhB system can be attributed to the synergistic effect between N and P atoms in the graphitic structure of the carbo- catalyst, its high surface area, and the presence of oxygenated functional groups on the surface of the N, P-HC. The used N, P-HC carbocatalyst can also be efficiently recovered by heat treatment at 500 degrees C. Overall, this study presents a simple and environmentally friendly method for synthesizing a high-performance N, P co-doped olive pomace-based carbocatalyst for water decontamination through PS-AOPs processes. (c) 2023 The Author(s). Published by Elsevier B.V. on behalf of King Saud University. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).