Global Centre for Environmental Remediation, Faculty of Science, University of Newcastle, Callaghan, NSW 2308, Australia; Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE), Callaghan, NSW 2308, Australia.
Department of Land, Air and Water Resources, University of California, Davis, CA, USA.
Sci Total Environ. 2020 Nov 20;744:140714. doi: 10.1016/j.scitotenv.2020.140714. Epub 2020 Jul 12.
Biochar is a porous, amorphous, stable, and low-density carbon material derived from the carbonization of various biological residues. Biochars have multifunctional properties that make them promising adsorbents for the remediation of organic and inorganic contaminants from soil and water. High temperature treatment (HTT) and the properties of feedstocks are key factors influencing the properties of biochars. Feedstocks have distinctive physicochemical properties due to variations in elemental and structural composition, and they respond heterogeneously to specific pyrolysis conditions. The criteria for the selection of feedstocks and pyrolysis conditions for designing biochars for specific sorption properties are inadequately understood. We evaluated the influence of pyrolysis temperature on a wide range of feedstocks to investigate their effects on biochar properties. With increasing HTT, biochar pH, surface area, pore size, ash content, hydrophobicity and O/C vs. H/C (ratios that denote stability) increased, whereas, hydrophilicity, yield of biochar, O/C, and H/C decreased. Discriminant analysis of data from 533 published datasets revealed that biochar derived from hardwood (HBC) and softwood generally have greater surface area and carbon content, but lower content of oxygen and mineral constituents, than manure- (MBC) and grass-derived biochars (GBC). GBC and MBC have abundant oxygen-containing functional groups than SBC and HBC. The sequence of stability and aromaticity of feedstocks was MBC < GBC < SBC < HBC. Therefore, SBC and HBC are suitable for sorption of hydrophobic molecules. Biochars produced from low HTT are suitable for removal of ionic contaminants, whereas those produced at high HTT are suitable for removal of organic contaminants. The influences of biochar properties on sorption performance of heavy metals and organic contaminants are critically reviewed.
生物炭是一种多孔、无定形、稳定且低密度的碳材料，由各种生物残余物碳化而来。生物炭具有多种功能特性，使其成为修复土壤和水中有机和无机污染物的有前途的吸附剂。高温处理（HTT）和原料特性是影响生物炭特性的关键因素。由于元素和结构组成的差异，原料具有独特的物理化学性质，并且它们对特定热解条件表现出异质性响应。对于为特定吸附性能设计生物炭的原料选择和热解条件的标准，我们的理解还不够充分。我们评估了热解温度对广泛的原料的影响，以研究它们对生物炭特性的影响。随着 HTT 的增加，生物炭的 pH 值、表面积、孔径、灰分含量、疏水性和 O/C 与 H/C（表示稳定性的比值）增加，而亲水性、生物炭产率、O/C 和 H/C 降低。对 533 个已发表数据集的数据进行判别分析表明，与源自硬木（HBC）和软木的生物炭相比，源自粪便（MBC）和草衍生的生物炭（GBC）通常具有更大的表面积和碳含量，但较低的氧和矿物质含量。GBC 和 MBC 比 SBC 和 HBC 具有丰富的含氧官能团。原料的稳定性和芳香度顺序为 MBC<GBC<SBC<HBC。因此，SBC 和 HBC 适合于疏水分子的吸附。低 HTT 下生产的生物炭适合于去除离子污染物，而高 HTT 下生产的生物炭适合于去除有机污染物。本文还批判性地综述了生物炭性质对重金属和有机污染物吸附性能的影响。
