China-UK Low Carbon College, Shanghai Jiao Tong University, Shanghai 201306, China.
School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
Sci Total Environ. 2021 Jun 1;771:145414. doi: 10.1016/j.scitotenv.2021.145414. Epub 2021 Jan 26.
The stability of biochar colloids plays an important role in the transport and fate of contaminants and nutrients in soil. This study aimed to investigate the effects of main soil components, kaolin (Kao), goethite (Goe), and humic acid (HA) colloids on the aggregation kinetics of biochar colloids derived from dairy manure (DM), sewage sludge (SS), and wheat straw (WS). The WS biochar colloid had the highest critical coagulation concentration (CCC) (624 mM) than that of SS (200 mM) and DM (75 mM) due to its richest hydroxyl and carboxyl groups, showing the highest stability. Kao markedly improved the stability of DM and SS biochar colloids with 171% and 52.5% increase of CCC, respectively, by increasing the electrostatic repulsion of the system. However, the WS biochar colloid became more aggregated in the presence of Kao since the hydroxyl and carboxyl functional groups in WS biochar colloid could complex with Kao, generating electrostatic shielding. Goe could rapidly combine with biochar colloids via electrostatic attraction, resulting in the aggregation of SS and WS, while the aggregation rate of DM/Goe mixed colloids was inhibited. The HA increased the electrostatic repulsion of all biochar colloids through adsorbed on the surface of biochar colloids, resulting in the increased steric hindrance and stability of biochar colloids, with the CCC increased from 75 to 624 mM to 827-1012 mM. Our findings reveal that soil kaolin, goethite, and humic acid colloids have remarkable effects on the stability and aggregation of biochar colloid, which will advance understanding of the potential environmental fate and behaviors of biochar colloids.
生物炭胶体的稳定性在污染物和养分在土壤中的迁移和归宿中起着重要作用。本研究旨在探讨主要土壤成分高岭土（Kao）、针铁矿（Goe）和腐殖酸（HA）胶体对来源于奶牛粪便（DM）、污水污泥（SS）和小麦秸秆（WS）的生物炭胶体聚集动力学的影响。WS 生物炭胶体的临界聚沉浓度（CCC）最高（624 mM），高于 SS（200 mM）和 DM（75 mM），这是由于其富含羟基和羧基，表现出最高的稳定性。Kao 通过增加体系的静电排斥，显著提高了 DM 和 SS 生物炭胶体的稳定性，CCC 分别增加了 171%和 52.5%。然而，由于 WS 生物炭胶体中的羟基和羧基官能团可以与 Kao 络合，产生静电屏蔽，因此在存在 Kao 的情况下，WS 生物炭胶体变得更容易聚集。Goe 可以通过静电吸引迅速与生物炭胶体结合，导致 SS 和 WS 的聚集，而 DM/Goe 混合胶体的聚集速率受到抑制。HA 通过吸附在生物炭胶体表面增加了所有生物炭胶体的静电排斥，导致生物炭胶体的空间位阻和稳定性增加，CCC 从 75 增加到 624 mM 到 827-1012 mM。我们的研究结果表明，土壤高岭土、针铁矿和腐殖酸胶体对生物炭胶体的稳定性和聚集有显著影响，这将有助于深入了解生物炭胶体的潜在环境归宿和行为。
