State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing, 100083, PR China; School of Earth Sciences and Resources, China University of Geosciences, Beijing, 100083, PR China.
UK Biochar Research Centre, School of GeoSciences, University of Edinburgh, Edinburgh, EH9 3FF, UK.
Environ Pollut. 2019 Nov;254(Pt B):113123. doi: 10.1016/j.envpol.2019.113123. Epub 2019 Aug 28.
Biochar has potential to control the bioavailability and migration of potentially toxic heavy metals in soil by adsorption. Natural ageing in the environment may change the physicochemical properties and adsorption function of biochar over the long-term. The present study compared the effects of different simulated ageing treatments on Cd adsorption of high and low temperature biochar from straw of corn (Zea mays). Fresh and aged biochars were systematically characterized by elemental analysis, FTIR, XPS, Zeta, SEM-EDS, XRD and the composition of their mineral ash. The adsorption of Cd to fresh and aged biochars was then assessed under the influence of pH. Drawing the results together the effects of ageing on the extent and mode of Cd adsorption could be elucidated. The results showed that the adsorption capacity of fresh biochar produced at 650 °C was higher than of biochar made at 350 °C, and that mineral co-precipitation plays a dominant role in Cd sorption. Leaching removed organic and inorganic ash components from biochars, markedly diminishing the capacity of the high temperature biochar to adsorb Cd. The adsorption performance of the low temperature biochar was dependent on surface complexation. The adsorption capacity of low-temperature biochar was markedly enhanced by oxygen-containing functional groups formed through acidification and oxidation. The long-term benefits of biochar in the management of polluted soil require a rethink, considering the contrasting ageing behavior of different temperature biochar and their response to different ageing environments.
生物炭通过吸附作用具有控制土壤中潜在有毒重金属生物利用度和迁移性的潜力。在环境中自然老化可能会长期改变生物炭的物理化学性质和吸附功能。本研究比较了不同模拟老化处理对玉米秸秆高温和低温生物炭吸附 Cd 的影响。通过元素分析、FTIR、XPS、Zeta、SEM-EDS、XRD 和矿物灰分的组成，对新鲜和老化生物炭进行了系统的表征。然后在 pH 的影响下评估了 Cd 对新鲜和老化生物炭的吸附作用。综合这些结果，可以阐明老化对 Cd 吸附程度和模式的影响。结果表明，在 650°C 下生产的新鲜生物炭的吸附能力高于在 350°C 下生产的生物炭，并且矿物共沉淀在 Cd 吸附中起主导作用。浸出从生物炭中去除了有机和无机灰分成分，显著降低了高温生物炭吸附 Cd 的能力。低温生物炭的吸附性能取决于表面络合。通过酸化和氧化形成的含氧官能团显著增强了低温生物炭对 Cd 的吸附能力。考虑到不同温度生物炭的老化行为以及它们对不同老化环境的响应，需要重新思考生物炭在污染土壤管理中的长期效益。
