Researchers have developed a novel method to repurpose Polygonatum kingianum dregs—waste from traditional Chinese medicine—as biochar-based catalysts for water purification. Using nitrogen (N) and sulfur (S) co-doping, they enhanced the ability of cobalt-embedded biochar to activate peroxymonosulfate (PMS), a powerful oxidant for pollutant degradation.

The biochar was synthesized through pyrolysisPyrolysis is a thermochemical process that converts waste biomass into bio-char, bio-oil, and pyro-gas. It offers significant advantages in waste valorization, turning low-value materials into economically valuable resources. Its versatility allows for tailored products based on operational conditions, presenting itself as a cost-effective and efficient More of the herbal dregs with cobalt and N/S doping. Analysis revealed that N-S co-doping significantly improved catalytic activity. Specifically, the N-S doped biochar (Co@BC-N,S) enhanced PMS adsorption and activation, leading to efficient removal of carbamazepine (CBZ), a persistent pharmaceutical pollutant. Within 20 minutes, Co@BC-N,S achieved complete CBZ degradation—up to 19.6 times more effective than non-doped biochar.

The improved performance is attributed to the synergistic interaction between cobalt sulfide nanoparticles and the modified carbon matrix, facilitating multiple oxidation pathways. The catalyst displayed excellent stability and reusability across five cycles, and it retained high efficiency under varying water conditions, including real-world water samples.

This approach offers a sustainable solution by turning waste into functional materials for environmental cleanup. While promising, further research is needed to scale production and assess long-term environmental impacts. These findings mark a step forward in integrating waste management with water treatment technology.