Robust reactive oxygen species production in interfacial reaction between organic acids and biochar: The combined effect of electron acceptance and electron conduction

Interfacial electron transport and reactive oxygen species (ROS) generation in the redox action between biochar (BC) and low-molecular-weight organic acids (LMWOAs) have been overlooked during the utilization of BC in soil amelioration/remediation. Herein, BC and N-doped BC (NBC) with various physicochemical properties were prepared at pyrolysis temperatures of 350, 550 and 750 degrees C (namely BC/NBC350, 550 and 750) and their in-teractions with LMWOAs were systematically investigated. Results of ROS quenching and electrochemical cell experiments revealed that BC/NBC could strongly interact with LMWOAs, especially ascorbic acid (AA), and acted as an electron shuttle to mediate one electron transfer from AA to oxygen to generate O-2(center dot-), followed by the robust generation of H2O2 and center dot OH. Interestingly, the generation rates of center dot OH and H2O2 in the NBC-AA system were significantly higher than that in the BC-AA system, of which the NBC550-AA system exhibited the best performance, enabling its superior ability in bisphenol A degradation. Different from conventional wisdom, the electron shuttle capacity depended on a combined aromatization degree and electron-accepting capacity of BC/ NBC. These findings complement the interfacial electron transfer mechanism during the natural BC-LMWOAs interaction and provide new inspiration for the development of green and efficient organic pollutant removal technologies.

Automated summary

The interfacial electron transport and reactive oxygen species (ROS) generation in the redox action between biochar and low-molecular-weight organic acids have been overlooked. This study revealed that biochar could strongly interact with organic acids and act as an electron shuttle, leading to the generation of ROS. The findings provide new insights for the development of green and efficient organic pollutant removal technologies.