In a recent study published in the Proceedings of the 2024 10th International Conference on Advances in Energy Resources and Environment Engineering (ICAESEE 2024), Zhixuan Nie from Jilin University discusses the preparation and application of 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 using hydrothermal carbonization (HTC). The research emphasizes that China’s abundant 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 resource can be effectively utilized through biochar production. This process not only aids in waste treatment but also enhances biochar’s functionality for various applications.  

Biochar can be produced through methods like 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, microwave carbonization, and hydrothermal carbonization (HTC). Unlike pyrolysis and microwave carbonization, HTC does not require a drying pretreatment for biomass with high moisture content, simplifying the process and reducing costs.  The HTC process involves converting biomass into biochar in a closed system with water under mild conditions, typically between 100°C and 350°C. This process includes several reactions such as hydrolysis, dehydration, decarboxylation, condensation, polymerization, and aromatization.

The characteristics of raw materials significantly affect the yield and chemical composition of biochar. Different raw materials like agricultural waste, industrial organic waste, and algae produce biochar with varying properties. For example, corn husks yield biochar with a high surface area, and bamboo shoot shells can be used to create nitrogen-doped porous biochar. Algae-derived biochar is rich in nitrogen compounds, making it suitable for producing nitrogen-doped carbon materials.  

Reaction temperature is another critical factor. Reaction time also influences biochar properties. Longer reaction times can enhance the porosityPorosity of biochar is a key factor in its effectiveness as a soil amendment and its ability to retain water and nutrients. Biochar’s porosity is influenced by feedstock type and pyrolysis temperature, and it plays a crucial role in microbial activity and overall soil health. Biochar More and specific surface area of biochar. Similarly, reaction pressure affects the hydrothermal carbonization process by altering the polarity of water and facilitating organic matter reactions.   To improve the performance of biochar, activation methods are employed. Chemical and physical activation are the two main types. Organic acid activation and surface activation are common modification techniques.

Biochar has diverse applications, including fuel production, wastewater treatment, and energy storage. Its fuel properties are comparable to coal, and its high adsorption capacity makes it effective in removing pollutants from water. In energy storage, biochar is used in supercapacitors and lithium-ion batteries due to its unique physical and chemical properties.  

A limited understanding of the mechanisms behind modification methods, the need for improved regeneration and recycling processes, and enhancing the combustion performance of biochar from wet biomass. Additionally, scaling up production and reducing costs are essential for broader application.  

Hydrothermal carbonization is a versatile method for converting various biomass resources into biochar. The properties of biochar can be tailored through different preparation conditions and modification techniques, making it suitable for a wide range of applications.

Source: Nie, Z. (2025). The Research Progress on the Preparation and Application of Biochar Via Hydrothermal Carbonization. Proceedings of the 2024 10th International Conference on Advances in Energy Resources and Environment Engineering (ICAESEE 2024), 36, 94-102.