Researchers at Vietnam National University have successfully engineered a specialized form of activated biochar designed to mitigate indoor air pollution. By utilizing rice husk ashAsh is the non-combustible inorganic residue that remains after organic matter, like wood or biomass, is completely burned. It consists mainly of minerals and is different from biochar, which is produced through incomplete combustion.   Ash Ash is the residue that remains after the complete More, a ubiquitous agricultural byproduct in Vietnam, the team developed an adsorbent material specifically targeted at capturing formaldehyde molecules. This innovation, led by scientists Bang Tam Thi Dao and Chi-Nhan Ha-Thuc from the Faculty of Materials Science and Technology, was recently detailed in the journal “Carbon Research.” The study highlights a significant advancement in valorizing local waste streams into high-value environmental remediation tools.

The primary challenge addressed by this research is the pervasive presence of formaldehyde in modern indoor environments. This hazardous volatile organic compound (VOC) is commonly emitted by household items such as furniture, flooring, and various consumer goods, posing long-term respiratory and health risks. Traditional air purification methods often rely on high-energy, high-temperature processes that are both expensive and environmentally taxing. Furthermore, standard adsorbents frequently lack the chemical specificity required to efficiently capture low concentrations of formaldehyde, necessitating a more targeted and sustainable approach to indoor air quality management.

To solve this, the Vietnam National University team modified rice husk ash 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 with polyethyleneimine (PEI), a polymer rich in amine functional groups. These groups act as chemical “hooks” that effectively trap formaldehyde molecules through specific chemical interactions. To maintain environmental sustainability, the researchers employed a low-energy ultrasonic treatment instead of conventional high-temperature activation methods. This process significantly reduces the energy required for production and minimizes the carbon footprint of the manufacturing cycle. Structural analysis confirmed that the resulting material possesses a complex porous labyrinth that maximizes pollutant entrapment.

The outcomes of this study indicate that PEI modification doubles the formaldehyde adsorption efficiency compared to conventional biochar. Laboratory stability tests, including kinetic and isotherm studies, confirmed the material’s reliable and predictable performance under scientific models. By transforming agricultural waste into a sophisticated filtration medium, the project demonstrates a viable “circular chemistry” model that is both scalable and economically competitive. These findings suggest that the modified biochar could be integrated into commercial air purification systems, providing an effective defense against rising urban indoor pollution levels.