Department of Environmental Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, PR China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, PR China.
Department of Environmental Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, PR China.
J Hazard Mater. 2021 Aug 15;416:125785. doi: 10.1016/j.jhazmat.2021.125785. Epub 2021 Apr 3.
Two major obstacles that need to be addressed for environmental application of biochar include its environmental risk and remediation performance for target pollutants. In this study, kitchen waste was taken as an example to optimize the pyrolysis temperature for biochar production based on its heavy metal risk and Cd(II) remediation performance. The results showed that the pH and ash content of kitchen waste biochar (KWB) increased; however, the yield, H/C, and N/C decreased with increasing pyrolysis temperature. Total content of heavy metals in KWB got enriched after pyrolysis, while heavy metals' risk was reduced from moderate to low due to the transformation of directly toxic heavy metal fractions into potentially and/or non-toxic fractions. The equilibrium adsorption capacities of biochar for Cd(II) ranked as follows: 49.0 mg/g (600 °C), 46.5 mg/g (500 °C), 23.6 mg/g (400 °C), 18.2 mg/g (300 °C). KWB pyrolyzed at 500 °C was found to be the most suitable for green, efficient, and economic remediation of Cd(Ⅱ) contaminated water. SEM-EDS and XPS characterization results indicated that KWB removed Cd(II) via precipitation, complexation with carboxyl/hydroxyl, ion exchange with metal cations, and coordination with π-electrons. This study puts forward a new perspective for optimizing biochar production for environmental application.
生物炭在环境中的应用需要解决两个主要障碍，包括其环境风险和对目标污染物的修复性能。本研究以厨余垃圾为例，基于其重金属风险和 Cd(II)修复性能，优化了生物炭制备的热解温度。结果表明，厨余垃圾生物炭（KWB）的 pH 值和灰分含量增加；然而，产率、H/C 和 N/C 随着热解温度的升高而降低。热解后，KWB 中重金属的总量增加，而由于直接毒性重金属部分向潜在和/或非毒性部分转化，重金属的风险从中等降低到低。生物炭对 Cd(II)的平衡吸附容量依次为：49.0mg/g（600°C）、46.5mg/g（500°C）、23.6mg/g（400°C）、18.2mg/g（300°C）。发现 500°C 热解的 KWB 最适合绿色、高效、经济地修复 Cd(Ⅱ)污染水。SEM-EDS 和 XPS 表征结果表明，KWB 通过沉淀、与羧基/羟基络合、与金属阳离子的离子交换以及与π-电子的配位去除 Cd(II)。本研究为优化生物炭在环境中的应用提供了新的视角。
