Turning pomelo peel into a honeycomb hero: Biochar's role in battling toxic chromium
image: Honeycomb-structured biochar from waste pomelo peel for synergistic adsorptive and photocatalytic removal of Cr(VI)
Credit: Wei Wang, Pengfei Wei, Chenjun Wang, Pengfei Liang, Feifei Tao, Song Yang, Weidong Dou & Baowei Hu
In a groundbreaking study, scientists have transformed waste pomelo peel into a honeycomb-structured biochar that not only adsorbs but also photocatalytically breaks down the highly toxic hexavalent chromium (Cr(VI)). This discovery could revolutionize wastewater treatment processes, offering a cost-effective, environmentally friendly solution to a pressing pollution problem.
Biochar, known for its high surface area and abundant pores, has been a promising candidate in pollutant removal. This research takes it a step further by creating activated biochar (APC) with interconnected porous frameworks, resulting in an exponentially higher specific surface area of 997.46 m²/g compared to pristine biochar (PPC) at 8.78 m²/g. The distinctive 3D honeycomb structure of APB significantly enhances its ability to capture Cr(VI) ions and convert them into less toxic Cr(III) ions.
The APB demonstrates superior adsorption and photocatalytic removal capabilities for Cr(VI), with an adsorption capacity reaching a maximum of 307.3 mg/g, compared to PPC's 194.2 mg/g. This process follows pseudo-second-order kinetics and is a spontaneous endothermic reaction primarily controlled by intraparticle diffusion. The APB's photocatalytic activity is further enhanced by its strong light absorption, low band gap, and rapid charge carrier transfer, leading to high photocatalytic activity.
This study introduces a novel approach to construct honeycomb-like APB for the synergistic adsorptive and photocatalytic removal of Cr(VI). The hierarchical porous frameworks and persistent free radicals (PFRs) are particularly beneficial for enhancing Cr(VI) removal, showing potential practical application in wastewater treatment.
===
Journal reference: Wang, W., Wei, P., Wang, C. et al. Honeycomb-structured biochar from waste pomelo peel for synergistic adsorptive and photocatalytic removal of Cr(VI). Carbon Res. 4, 10 (2025).
https://doi.org/10.1007/s44246-024-00174-5
===
About Carbon Research
The journal Carbon Research is an international multidisciplinary platform for communicating advances in fundamental and applied research on natural and engineered carbonaceous materials that are associated with ecological and environmental functions, energy generation, and global change. It is a fully Open Access (OA) journal and the Article Publishing Charges (APC) are waived until Dec 31, 2025. It is dedicated to serving as an innovative, efficient and professional platform for researchers in the field of carbon functions around the world to deliver findings from this rapidly expanding field of science. The journal is currently indexed by Scopus and Ei Compendex, and as of June 2025, the dynamic CiteScore value is 15.4.