CAS-Key Laboratory of Crust-Mantle Materials and the Environments, School of Earth and Space Sciences, University of Science and Technology of China, Hefei, 230026, PR China.
CAS-Key Laboratory of Crust-Mantle Materials and the Environments, School of Earth and Space Sciences, University of Science and Technology of China, Hefei, 230026, PR China; State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, The Chinese Academy of Sciences, Xi'an, Shaanxi, 710075, China.
Environ Pollut. 2022 Dec 15;315:120335. doi: 10.1016/j.envpol.2022.120335. Epub 2022 Oct 3.
Potentially toxic metals have become a viable threat to the ecosystem due to their carcinogenic nature. Biochar has gained substantial interest due to its redox-mediated processes and redox-active metals. Biochar has the capacity to directly adsorb the pollutants from contaminated environments through several mechanisms such as coprecipitation, complexation, ion exchange, and electrostatic interaction. Biochar's electron-mediating potential may be influenced by the cyclic transition of surface moieties and conjugated carbon structures. Thus, pyrolysis configuration, biomass material, retention time, oxygen flow, and heating time also affect biochar's redox properties. Generally, reactive oxygen species (ROS) exist as free radicals (FRs) in radical and non-radical forms, i.e., hydroxyl radical, superoxide, nitric oxide, hydrogen peroxide, and singlet oxygen. Heavy metals are involved in the production of FRs during redox-mediated reactions, which may contribute to ROS formation. This review aims to critically evaluate the redox-mediated characteristics of biochar produced from various biomass feedstocks under different pyrolysis conditions. In addition, we assessed the impact of biochar-assisted FRs redox-mediated processes on heavy metal immobilization and mobility. We also revealed new insights into the function of FRs in biochar and its potential uses for environment-friendly remediation and reducing the dependency on fossil-based materials, utilizing local residual biomass as a raw material in terms of sustainability.
由于潜在毒性金属的致癌特性，它们已成为生态系统的一个可行威胁。生物炭由于其氧化还原介导的过程和氧化还原活性金属而引起了广泛的关注。生物炭通过几种机制，如共沉淀、络合、离子交换和静电相互作用，具有直接从污染环境中吸附污染物的能力。生物炭的电子介导能力可能受到表面基团和共轭碳结构的循环转变的影响。因此，热解配置、生物质材料、保留时间、氧气流量和加热时间也会影响生物炭的氧化还原特性。一般来说，活性氧物质 (ROS) 以自由基 (FRs) 的形式存在于自由基和非自由基形式中，即羟基自由基、超氧自由基、一氧化氮、过氧化氢和单线态氧。重金属在氧化还原介导反应中参与 FRs 的产生，这可能导致 ROS 的形成。本综述旨在批判性地评估在不同热解条件下由各种生物质原料制备的生物炭的氧化还原介导特性。此外，我们评估了生物炭辅助 FRs 氧化还原介导过程对重金属固定和迁移性的影响。我们还揭示了 FRs 在生物炭中的功能的新见解及其在环境友好型修复和减少对基于化石材料的依赖方面的潜在用途，从可持续性的角度出发，利用当地的剩余生物质作为原材料。
