Department of Geography and Environmental Science, University of Reading, Reading, UK.
Department of Plant Biology and Soil Science, University of Vigo, Vigo, Spain.
Environ Sci Pollut Res Int. 2018 Mar;25(8):7730-7739. doi: 10.1007/s11356-017-1047-2. Epub 2017 Dec 29.
Biochars have been proposed for remediation of metal-contaminated water due to their low cost, high surface area and high sorption capacity for metals. However, there is a lack of understanding over how feedstock material and pyrolysis conditions contribute to the metal sorption capacity of biochar. We produced biochars from 10 different organic materials by pyrolysing at 450 °C and a further 10 biochars from cedar wood by pyrolysing at 50 °C intervals (250-700 °C). Batch sorption experiments were conducted to derive the maximum Cu and Zn sorption capacity of each biochar. The results revealed an exponential relationship between Cu and Zn sorption capacity and the feedstock C/N ratio and a sigmoidal relationship between the pyrolysis temperature and the maximum Cu and Zn sorption capacity. FTIR analysis revealed that as temperature increased, the abundance of functional groups reduced. We conclude that the high sorption capacity of high temperature biochars is due to an electrostatic attraction between positively charged Cu and Zn ions and delocalised pi-electrons on the greater surface area of these biochars. These findings demonstrate a method for predicting the maximum sorption capacity of a biochar based on the feedstock C/N ratio and the pyrolysis temperature.
生物炭由于其低成本、高比表面积和对金属的高吸附能力，已被提议用于修复受金属污染的水。然而，人们对原料和热解条件如何影响生物炭的金属吸附能力缺乏了解。我们通过在 450°C 下热解 10 种不同的有机材料，以及在 50°C 的间隔（250-700°C）下热解雪松木材，制备了 10 种生物炭。通过批量吸附实验得出了每种生物炭的最大 Cu 和 Zn 吸附容量。结果表明，Cu 和 Zn 吸附容量与原料的 C/N 比呈指数关系，与热解温度呈钟形关系。FTIR 分析表明，随着温度的升高，官能团的丰度减少。我们得出结论，高温生物炭具有高吸附能力是由于带正电荷的 Cu 和 Zn 离子与这些生物炭较大表面积上的离域 pi 电子之间的静电吸引。这些发现表明了一种基于原料 C/N 比和热解温度预测生物炭最大吸附容量的方法。
