An attempt to enhance the adsorption capacity of biochar for organic pollutants - Characteristics of CaCl2 biochar under multiple design conditions

• Published in: The Science of the total environment 2023-01, Vol.854, p.158675, Article 158675
• Main Authors: Shao, Fulin, Xu, Jingtao, Kang, Xingsheng, Hu, Zhen, Shao, Yuanyuan, Lu, Chongxiao, Zhao, Congcong, Ren, Yangang, Zhang, Jian
• Format: Article
• Language: English
• Subjects: Activator; Adsorption; Alkali metal salt; Biochar; Organic pollutants
• ISSN: 0048-9697; 1879-1026; 1879-1026
• DOI: 10.1016/j.scitotenv.2022.158675

Activators affect the physical and chemical properties of carbon products. However, the effects of different activation mechanisms and pyrolysis conditions on the properties of carbon products still need to be explored. In this study, we obtained a new biochar by impregnation of reed powder with an alkali metal salt (CaCl2) under a specific pyrolysis procedure and pyrolysis conditions. Impregnation by CaCl2 can reduce the activation energy of the biomass while capturing and immobilizing oxygenated organic matter during pyrolysis. The new biochar has a high adsorption capacity of organic matters, for example Bisphenol A (BPA). The adsorption results showed that the modified biochar demonstrated a 364.5 % improvement in the adsorption capacity compared to the original biochar. The final performance enhancement was correlated with the confinement conditions of the environment and the procedure of pyrolysis. These procedures ultimately changed the pore distribution, functional group type, aromaticity, and degree of defects of the modified biochar. This study is important to screen synthetic pathways for identifying compounds with excellent adsorption effects. [Display omitted] •Calcium chloride plays a trapping role in biomass pyrolysis.•An effective method for increasing oxygen-containing functional groups of biochar.•The adsorption capacity was improved by 364.5 % compared to the original biochar.•Calcium chloride activation changed the defective structure of biochar.•The retention of BPA by micropore is reflected in molecular dynamics simulations.