College of Land Science and Technology, China Agricultural University, Key Laboratory of Arable Land Conservation in North China, Ministry of Agriculture and Rural Affairs, Beijing 100193, PR China.
Energy Research Institute, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250014, PR China.
Sci Total Environ. 2024 Oct 10;946:174097. doi: 10.1016/j.scitotenv.2024.174097. Epub 2024 Jun 20.
Abundant biochar colloids (BCs) produced from a wide range of feedstocks, resulting from forest fires, agricultural production, and environmental restoration, exhibit varying aggregation behaviors influenced by feedstock type and natural organic matter. However, the impact of natural organic matter on the colloidal stability of BCs derived from different feedstocks remains poorly understood. In this study, six selected biochars were derived from various feedstocks as follows: sewage sludge (SS), rice husk (RH), oil seed rape straw pellets (OSR), wheat straw pellets (WS), miscanthus straw pellets (MS) and softwood pellets (SW). The colloidal stability of BCs, with the exogenous addition of organic matter, was further determined. The order of critical coagulation concentrations (CCCs) of BCs with the presence of humic acid (HA) was as follows: RH (989.48 mM) < MS (1084.69 mM) < SS (1149.76 mM) < WS (1338.99 mM) < OSR (2402.98 mM) < SW (3151.32 mM). This order was significantly positively correlated with the specific surface area and negatively correlated with the ash content of the bulk biochar. Compared to HA, bovine serum albumin (BSA) more effectively inhibited the aggregation behavior of BCs due to steric hindrance. The initial aggregation rate constant (k) of BCs at 3000 mM NaCl was as follows: MS (0.238 nm/s) > OSR (0.142 nm/s) > WS (0.128 nm/s) > SS (0.126 nm/s) > RH (0.118 nm/s) > SW (0.112 nm/s). The stabilizing effects of BSA on biochar colloids were independent of the physicochemical properties of bulk biochar. In the presence of BSA, a thin layer of protein corona significantly enhanced the stability of biochar colloids, particularly the BCs derived from MS. Our results underscore the importance of considering feedstock resources and natural organic matter type when assessing the aggregation and potential risks of BCs in aquatic systems.
大量生物炭胶体（BC）由广泛的原料产生，包括森林火灾、农业生产和环境修复，由于原料类型和天然有机物的不同，表现出不同的聚集行为。然而，天然有机物对不同原料来源的生物炭胶体稳定性的影响仍知之甚少。在这项研究中，我们从不同的原料中提取了六种生物炭，包括污水污泥（SS）、稻壳（RH）、油菜秸秆颗粒（OSR）、麦秆颗粒（WS）、芒草秸秆颗粒（MS）和软木颗粒（SW）。进一步测定了添加外源有机物后生物炭胶体的稳定性。含有腐殖酸（HA）的生物炭胶体的临界聚沉浓度（CCC）顺序如下：RH（989.48 mM）<MS（1084.69 mM）<SS（1149.76 mM）<WS（1338.99 mM）<OSR（2402.98 mM）<SW（3151.32 mM）。这个顺序与比表面积显著正相关，与大块生物炭的灰分含量显著负相关。与 HA 相比，牛血清白蛋白（BSA）由于空间位阻的影响，更有效地抑制了生物炭胶体的聚集行为。在 3000 mM NaCl 下，BCs 的初始聚集速率常数（k）如下：MS（0.238 nm/s）>OSR（0.142 nm/s）>WS（0.128 nm/s）>SS（0.126 nm/s）>RH（0.118 nm/s）>SW（0.112 nm/s）。BSA 对生物炭胶体的稳定作用与大块生物炭的物理化学性质无关。在 BSA 存在的情况下，一层薄薄的蛋白质冠显著提高了生物炭胶体的稳定性，特别是 MS 来源的生物炭胶体。我们的研究结果强调了在评估水生系统中生物炭的聚集和潜在风险时，考虑原料资源和天然有机物类型的重要性。
