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土壤中污染物和养分的运输和归宿中起着重要作用。这项研究旨在调查主要土壤成分，高岭土（Kao），针铁矿（Goe）和腐殖酸（HA）胶体对源自牛粪（DM），污水污泥（SS）的生物炭胶体的聚集动力学的影响，和小麦秸秆（WS）。WS生物炭胶体的临界凝结浓度（CCC）（624 mM）比SS（200 mM）和DM（75 mM）高，因为​​其最丰富的羟基和羧基基团，显示出最高的稳定性。通过增加系统的静电排斥力，Kao显着提高了DM和SS生物炭胶体的稳定性，CCC分别提高了171％和52.5％。然而，WS生物炭胶体中的羟基和羧基官能团可以与Kao络合，从而产生静电屏蔽，因此在Kao存在下WS生物炭胶体变得更加聚集。Goe可以通过静电吸引与生物炭胶体快速结合，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上而增强了所有生物炭胶体的静电排斥力，从而导致生物炭胶体的位阻和稳定性增加，CCC从75增大到624 mM到827-1012 mM。我们的发现表明，土壤高岭土，针铁矿和腐植酸胶体对生物炭胶体的稳定性和聚集具有显着影响，