Polycyclic Aromatic Hydrocarbons Occurrences in Biomass Char and Its Mitigation Approaches: A Mini Review

Biochar is a porous fine-grained substance produced from the pyrolysis technology of biomass that can be commercially used as a soil conditioner to promote soil fertility. Biochar is characterized by high carbon content, stability, and porosity. However, organic pollutants residue of polycyclic aromatic hydrocarbons (PAHs) is also formed during the pyrolysis of biochar. The high concentration of PAHs adversely degrades the quality of biochar for soil amendment application. Meanwhile, highly toxic-PAHs concentration may pose a potential threat to both human health and the environment. The total PAHs yield is mainly influenced by the pyrolysis condition and feedstock resource. This review aims to discuss the conversion pyrolysis technology of biochar and factors that may influence the PAHs formation. The key research findings from this literature will lead to some strategies to minimize the PAHs compound in biochar by controlling the pyrolysis conditions through higher pyrolysis temperature, carrier gas flow, and prolonged pyrolysis time or by selecting suitable feedstock with lower lignin content.

Automated summary

Biochar is a porous substance made from biomass through pyrolysis technology, which can be used as a soil conditioner to improve soil fertility. However, the pyrolysis process also generates organic pollutants called polycyclic aromatic hydrocarbons (PAHs) in biochar. The high concentration of PAHs affects the quality of biochar for soil amendment and poses a potential threat to human health and the environment. The yield of PAHs is influenced by pyrolysis conditions and feedstock resources. This review aims to discuss the pyrolysis technology of biochar and factors influencing PAHs formation. Strategies to minimize PAHs in biochar include controlling pyrolysis conditions (such as increasing temperature, gas flow, and time) and selecting suitable feedstock with lower lignin content.