Wastewater treatment is a growing challenge, especially with industrial pollutants becoming more complex and resistant to degradation. In a new review published in the Alexandria Engineering Journal, Ruinan Zhao explores an innovative solution: heteroelement-doped biocharBiochar is a carbon-rich material created from biomass decomposition in low-oxygen conditions. It has important applications in environmental remediation, soil improvement, agriculture, carbon sequestration, energy storage, and sustainable materials, promoting efficiency and reducing waste in various contexts while addressing climate change challenges. More as a catalyst for ozone-based water purification. The study examines how doping biochar with metals and non-metals improves its efficiency in breaking down pollutants like dyes, antibiotics, and industrial chemicals.

Biochar, a carbon-rich material derived from biomassBiomass is a complex biological organic or non-organic solid product derived from living or recently living organism and available naturally. Various types of wastes such as animal manure, waste paper, sludge and many industrial wastes are also treated as biomass because like natural biomass these More 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, is already known for its adsorption properties. However, pure biochar has limited catalytic potential. By introducing elements such as iron, nitrogen, or sulfur, researchers can enhance its reactivity and stability. The study categorizes two main doping methods: external doping, where elements are added after biochar production, and internal doping, where naturally occurring elements in biomass form active sites during pyrolysis.

Doped biochar plays a crucial role in catalytic ozonation, a process where ozone (O₃) reacts with organic pollutants. The addition of metals like iron (Fe) or manganese (Mn) increases electron transfer, producing reactive oxygen species (ROS) that accelerate pollutant degradation. Non-metal dopants such as nitrogen (N) improve biochar’s conductivity, enhancing its catalytic power. The study highlights successful applications, including Fe-N biochar for removing dye pollutants and Mn-biochar for breaking down antibiotics in wastewater.

While the technology is promising, challenges remain. External doping can be costly and may lead to environmental concerns, such as metal leachingLeaching is the process where nutrients are dissolved and carried away from the soil by water. This can lead to nutrient depletion and environmental pollution. Biochar can help reduce leaching by improving nutrient retention in the soil.   More. Internal doping, though cheaper and more sustainable, lacks precise control over dopant content. Future research should focus on balancing cost, efficiency, and environmental safety for large-scale wastewater treatment applications.

Zhao, R. (2025). A review on the catalytic ozonation of pollutants in wastewater by heteroelements-doped biochar: Internal and external doping strategies. Alexandria Engineering Journal, 119, 35–44. https://doi.org/10.1016/j.aej.2025.01.088