XINXin,JIAORu-yuan,SUNHong-yan,et al.Impact of Humic Acid on Aggregation Kinetics of Silica Nanoparticles in Aquatic Environment[J].China Water & Wastewater,2025,41(11):91-98.
腐殖酸对水体纳米二氧化硅聚集动力学机制影响
- Title:
- Impact of Humic Acid on Aggregation Kinetics of Silica Nanoparticles in Aquatic Environment
- 摘要:
- 天然水体中存在多种纳米颗粒，由于粒径效应，其易与水中其他污染物相结合，从而对水质产生影响。腐殖酸是水体中常见的天然有机物，为了明确腐殖酸存在条件下纳米颗粒物在水环境中的迁移转化过程，分析了腐殖酸存在时不同pH和离子强度下纳米颗粒物的聚集特征，探讨了腐殖酸在纳米颗粒表面的吸附过程及对纳米颗粒物表面性质和聚集行为等产生的影响。结果表明，在单独腐殖酸与纳米颗粒物混合体系中，腐殖酸抑制了纳米颗粒的聚集，增加了溶液中纳米二氧化硅的稳定性；然而当阳离子存在时，酸性条件下促进了腐殖酸分子氢键的产生从而诱导颗粒物聚集，或在碱性条件下由于腐殖酸分子结构伸展为链状从而与阳离子结合发挥架桥作用，因此提高了纳米颗粒物的聚集速率；同时发现，阳离子与腐殖酸及纳米二氧化硅结合具有选择性，阳离子优先与纳米二氧化硅发生反应，而当纳米二氧化硅与腐殖酸进行预先混合时，由于纳米二氧化硅对腐殖酸的预吸附作用，提高了纳米颗粒物与有机物的协同去除效率。因此，在实际水体中，当有机物与纳米颗粒物具有足够的反应时间时，两者在阳离子存在条件下更容易发挥共团聚效应，可提高两者的协同去除效果。
- Abstract:
- Various nanoparticles are present in natural water bodies. Owing to the particle size effect, these nanoparticles tend to interact with other pollutants in water, consequently impacting water quality. Humic acid is a prevalent form of natural organic matter in aquatic environment. To elucidate the migration and transformation processes of nanoparticles in water systems under the influence of humic acid, this study investigated the aggregation behavior of nanoparticles under varying pH and ionic strengths in the presence of humic acid. Additionally, the adsorption mechanism of humic acid onto the nanoparticle surface was examined, along with its effects on the surface properties and aggregation dynamics of nanoparticles. In the mixed system of humic acid and nanoparticles, humic acid played a critical role in inhibiting nanoparticle aggregation, thereby enhancing the stability of nano-silica in solution. However, in the presence of cations, acidic conditions facilitated the formation of hydrogen bond within humic acid molecules, which subsequently induced the aggregation of particulates. Conversely, under alkaline conditions, the extension of the humic acid molecular structure into a linear chain enabled it to combine with cations, thereby exerting a bridging effect and enhancing the aggregation rate of nanoparticles. It was also observed that cations exhibited selectivity in their association with humic acid and nano-silica. Specifically, cations tended to preferentially interact with nano-silica. When nano-silica was pre-mixed with humic acid, the pre-adsorption effect of nano-silica on humic acid enhanced the synergistic removal efficiency of nanoparticles and organic matters. Therefore, in natural aquatic environment, when organic matters and nanoparticles are given sufficient reaction time, they are more prone to exhibit a co-agglomeration effect in the presence of cations. This phenomenon can enhance the synergistic removal efficiency of these substances.
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