Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China; Jiangsu Engineering Laboratory for Soil and Groundwater Remediation of Contaminated Sites, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China.
Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003, China.
Sci Total Environ. 2021 Jan 10;751:141491. doi: 10.1016/j.scitotenv.2020.141491. Epub 2020 Aug 4.
Dissolved black carbon (DBC) is becoming increasingly concerned by researchers due to its unique environmental behavior. However, understanding of the influence mechanism of biopolymer compositions of cellulose (CEL), hemicellulose (HEM) and lignin (LIG) on the formation and physiochemical characteristics of DBC from lignocellulose-based biochar is limited. This study therefore examined the formation of DBCs derived from the biopolymer compositions, corn straw (CS), corncob (CC), bamboo sawdust (BS) and pinewood sawdust (PS) under the heat treatment temperatures (HTTs) of 300-500 °C. Zeta potential and hydrodynamic diameters (D) of DBCs produced under 300 °C were further investigated. DBC formation may be closely associated with the HTT-dependent heterogeneities of biopolymer compositions, in which significant effects of CEL and HEM charring on physiochemical properties of DBCs were identified under the HTT of 300 and 400 °C, while the formation of DBCs was closely related to LIG and its proportions in biomass under high HTT (>500 °C). On the rise of the HTT, the carbonaceous structures of biopolymer compositions were reorganized and converted to graphitic structures in biochar accompanied by the large decomposition or carbonization of CEL and HEM, leading to the reduced carbon content, surface functional groups, aromaticity and molecular weight of DBCs, as well as the decrease of protein-like and relative increase of fulvic-like fluorescent substances in most DBCs. LIG in biomass may facilitate the migration of DBCs due to abundant surface negative charges and the formation of low D. This study offered new insights into our understanding of influencing mechanisms of biopolymer compositions on the characteristic of DBCs under different HTTs.
溶解态黑碳（DBC）因其独特的环境行为而引起了研究人员的越来越多的关注。然而，对于生物聚合物纤维素（CEL）、半纤维素（HEM）和木质素（LIG）的组成对木质纤维素基生物炭中 DBC 的形成和物理化学特性的影响机制的理解有限。因此，本研究考察了在 300-500°C 的热处理温度（HTT）下，生物聚合物组成物（玉米秸秆（CS）、玉米芯（CC）、竹屑（BS）和松木屑（PS））衍生的 DBC 的形成。还进一步研究了在 300°C 下产生的 DBC 的动电电势和水动力学直径（D）。DBC 的形成可能与 HTT 依赖的生物聚合物组成的异质性密切相关，其中在 300 和 400°C 的 HTT 下，CEL 和 HEM 热解对 DBC 物理化学性质的显著影响，而在高温 HTT（>500°C）下，DBC 的形成与木质素及其在生物质中的比例密切相关。随着 HTT 的升高，生物聚合物组成物的碳质结构在生物炭中被重新组织并转化为石墨结构，伴随着 CEL 和 HEM 的大量分解或碳化，导致 DBC 的碳含量、表面官能团、芳香度和分子量降低，以及大多数 DBC 中蛋白质样物质的相对减少和富里酸样荧光物质的相对增加。生物质中的木质素可能由于表面带大量负电荷和形成低 D，从而促进 DBC 的迁移。本研究为我们在不同 HTT 下理解生物聚合物组成对 DBC 特征的影响机制提供了新的见解。
