Furfural release from lignocellulosic biomass biochars: Environmental and health implications

Furfural is a versatile chemical with many applications across different industrial sectors. However, uncontrolled release of furfural, a volatile organic compound (VOC) primarily derived from thermal processing of lignocellulosic biomass, can pose significant environmental and health risks due to its toxic and potentially carcinogenic properties. Thermal treatment of biomass generates biochar, a carbonaceous by-product with the potential for agricultural, environmental, and biorenewable energy applications. This study investigated furfural release from biochar generated from standard biomass blends composed of lignin, cellulose, and hemicellulose. Furfural release from biochar were influenced by feedstock composition and process temperature, with hemicellulose identified as the primary source. Biochars derived from hemicellulose-rich biomass exhibited the highest furfural release potential, particularly at lower process temperatures (200–275 °C), while release decreased significantly with higher temperature processes (350 °C). Biochar derived primarily from cellulose demonstrated moderate furfural release, primarily at 225–275 °C, whereas biochar from lignin-rich blends had minimal release. A new metric, carbon relative molar mass (CRMM), to model furfural release was introduced. It was found that CRMM is a better predictor of furfural release than the process temperature. Biochars derived from higher CRMM (>27 g·mol−1) were more conducive to furfural release.