生物炭理化性质对其反应活性的影响

Effect of physical and chemical properties of biochar on its reactivity

生物炭作为一种富炭材料,由于其具有固碳、增强土壤肥力、促进植物生长等特性,在固碳减排及土壤改良方面的应用价值受到广泛关注.同时,生物炭具有较大的比表面积和较高的孔隙率,常被作为吸附剂用于污染物的去除.研究发现生物炭在吸附有机污染物的过程中可降解有机污染物,因此生物炭的反应活性成为近年来研究的热点.生物炭的反应活性主要由其制备过程中生成的环境持久性自由基(EPFRs)和自身的氧化还原能力贡献.生物炭的EPFRs活性与官能团种类、过渡金属含量和EPFRs种类有关,其中官能团和过渡金属通过影响EPFRs的生成及稳定从而影响EPFRs的浓度和种类,进而影响EPFRs活性,而EPFRs种类直接影响EPFRs活性.生物炭的氧化还原活性与官能团、芳香性和导电性有关,其中官能团影响氧化还原活性基团(RAMs)的生成,芳香性和导电性影响基质电导(ECBC)结构的生成及导电活性,从而影响氧化还原活性.本文总结了生物炭的反应活性机理和影响因素,旨在为生物炭处理有机物污染物等方面的应用提供理论支撑和技术参考.

Biochar, as a kind of carbonaceous material has been widely concerned due to its promising application potential in carbon emission reduction and soil amendment. On the other hand, biochar also has been intensively employed as the adsorbent, owing to its big surface area and porosity. Interestingly, it was found that biochar could degrade organic pollutants during the adsorption process. Therefore, more and more attentions have been placed on the reactivity of biochar recently. The reactivity of biochar was mainly decided by the environmental persistent free radicals(EPFRs) and redox ability, which were produced during the preparation process. Firstly, the reactivity of EPFRs was related with the type of functional groups and EPFRs, the content of transition metal. Functional groups and transition metal affected the concentration and the types of EPFRs by affecting the formation and stability of EPFRs, which in turn affected the reactivity of EPFRs. However, the types of EPFRs affected its activity directly. Secondly, the redox reactivity of biochar was related to the functional groups, aromaticity and conductivity. Among them, the functional groups affected the formation of redox active groups(RAMs), and the aromaticity and conductivity affected the formation and conductivity of matrix conductance(ECBC) structures, thereby affecting the redox activity. This review summarized the reaction activity mechanism and influencing factors of the biochar, and then to provide theoretical support and technical reference for the biochar application in the organic pollutants treatment.