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Mechanisms of Pb and/or Zn adsorption by different biochars: Biochar characteristics, stability, and binding energies.
Science of the Total Environment ( IF 8.2 ) Pub Date : 2020-01-23 , DOI: 10.1016/j.scitotenv.2020.136894 Man Zhao 1 , Yuan Dai 2 , Miaoyue Zhang 1 , Can Feng 2 , Baojia Qin 2 , Weihua Zhang 1 , Nan Zhao 1 , Yaying Li 1 , Zhuobiao Ni 1 , Zhihong Xu 3 , Daniel C W Tsang 4 , Rongliang Qiu 1
Science of the Total Environment ( IF 8.2 ) Pub Date : 2020-01-23 , DOI: 10.1016/j.scitotenv.2020.136894 Man Zhao 1 , Yuan Dai 2 , Miaoyue Zhang 1 , Can Feng 2 , Baojia Qin 2 , Weihua Zhang 1 , Nan Zhao 1 , Yaying Li 1 , Zhuobiao Ni 1 , Zhihong Xu 3 , Daniel C W Tsang 4 , Rongliang Qiu 1
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Biochar has been widely studied as an amendment for use in remediation of water and soil contaminated with heavy metals such as Pb2+ and Zn2+, but the effects of biochar characteristics, including stability, on the competitive adsorption of Pb2+ and Zn2+ by biochars from various sources are incompletely understood. In this work, biochars from three different feedstocks, including rice straw (RS), chicken manure (CM), and sewage sludge (SS), were prepared at two pyrolysis temperatures, 550 and 350 °C, and tested to investigate the influence of their stabilities and other characteristics on their adsorption of Pb2+ and Zn2+ in both single- and binary-metal systems. RS biochar had the highest carbon and hydrogen contents, greatest number of functional groups (e.g., OH and C=C/C=O), highest pH, most negative surface charge, and highest physical stability, and thus the highest adsorption capacity for Pb2+ and Zn2+. Pyrolysis at the higher temperature resulted in a slight decrease in aromatic functional groups on biochar surfaces but higher adsorption capacities for Pb2+ and Zn2+ due to the decreased biochar particle size and increased specific surface area. FTIR, XRD, and XPS analyses indicated that Pb2+ and Zn2+ were absorbed on the biochars primarily via chemical complexation with aromatic functional groups. Quantum chemistry calculations confirmed that these functional groups (e.g., -OH and-COOH) tended to bind more strongly with Pb2+ than with Zn2+ due to the former's lower binding energies, which also accounted for the notable decrease in adsorption of Zn2+ in the presence of Pb2+. In addition, compared to carboxyl groups, hydroxyl groups had smaller binding energies and stronger metal complexation. These findings provide a theoretical basis for improved understanding of potential applications of biochars in environmental remediation.
中文翻译：
不同生物炭吸附Pb和/或Zn的机理：生物炭特性，稳定性和结合能。
生物炭已被广泛研究作为修正物，用于修复被Pb2 +和Zn2 +等重金属污染的水和土壤，但是生物炭特性（包括稳定性）对来自各种来源的生物炭竞争性吸附Pb2 +和Zn2 +的影响是不完全了解。在这项工作中，分别在550和350°C的两种热解温度下制备了来自三种不同原料的生物炭，包括稻草（RS），鸡粪（CM）和污水污泥（SS），并进行了测试。它们在单金属和二元金属系统中对Pb2 +和Zn2 +吸附的稳定性和其他特性。RS生物炭的碳和氢含量最高，官能团数量最多（例如OH和C = C / C = O），pH最高，表面负电荷最多，物理稳定性最高，因此对Pb2 +和Zn2 +的吸附能力最高。高温下的热解导致生物炭表面的芳族官能团略有减少，但由于生物炭粒径的减小和比表面积的增加，对Pb2 +和Zn2 +的吸附能力更高。FTIR，XRD和XPS分析表明，Pb2 +和Zn2 +主要通过与芳香族官能团的化学络合被吸收到生物炭上。量子化学计算证实，由于前者的结合能较低，这些官能团（例如，-OH和-COOH）与Pb2 +的结合力比与Zn2 +的结合力更强，这也解释了在Pb2 +存在下， Pb2 +。此外，与羧基相比，羟基具有较小的结合能和较强的金属络合。这些发现为更好地理解生物炭在环境修复中的潜在应用提供了理论基础。
更新日期：2020-01-24
中文翻译：
不同生物炭吸附Pb和/或Zn的机理：生物炭特性，稳定性和结合能。
生物炭已被广泛研究作为修正物，用于修复被Pb2 +和Zn2 +等重金属污染的水和土壤，但是生物炭特性（包括稳定性）对来自各种来源的生物炭竞争性吸附Pb2 +和Zn2 +的影响是不完全了解。在这项工作中，分别在550和350°C的两种热解温度下制备了来自三种不同原料的生物炭，包括稻草（RS），鸡粪（CM）和污水污泥（SS），并进行了测试。它们在单金属和二元金属系统中对Pb2 +和Zn2 +吸附的稳定性和其他特性。RS生物炭的碳和氢含量最高，官能团数量最多（例如OH和C = C / C = O），pH最高，表面负电荷最多，物理稳定性最高，因此对Pb2 +和Zn2 +的吸附能力最高。高温下的热解导致生物炭表面的芳族官能团略有减少，但由于生物炭粒径的减小和比表面积的增加，对Pb2 +和Zn2 +的吸附能力更高。FTIR，XRD和XPS分析表明，Pb2 +和Zn2 +主要通过与芳香族官能团的化学络合被吸收到生物炭上。量子化学计算证实，由于前者的结合能较低，这些官能团（例如，-OH和-COOH）与Pb2 +的结合力比与Zn2 +的结合力更强，这也解释了在Pb2 +存在下， Pb2 +。此外，与羧基相比，羟基具有较小的结合能和较强的金属络合。这些发现为更好地理解生物炭在环境修复中的潜在应用提供了理论基础。
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