Characteristics of Humic Acid-Iron Colloid Stability and Its Mechanism of Binding with As(III).

IF 2.2 4区 环境科学与生态学 Q3 ENVIRONMENTAL SCIENCES
Junfeng An, Conghui Wang, Jia Yu, Kaipian Shi, Youru Yao, Jingyi Zhang, Chonghong Zhang, Yuesheng Lin, Shiyin Li
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Abstract

The water-soil interface contains substantial amounts of dissolved organic matter (DOM) and iron minerals. However, the stability and aggregation behavior of DOM-Fe colloids under varying concentrations and mineral compositions remain unclear. Therefore, the binding behavior of these composite colloids with As(III) requires further investigation. This study analyzes the surface charge and particle size variations of the composite colloids to understand their stability and the binding process with As. Results indicate that the C/Fe molar ratio affects the dispersion of the three types of humic acid-iron (HA-Fe) composite colloids. As the C/Fe ratio increases, the Zeta potential of the composite colloids increases, and their particle size decreases, with a minimum size of 135, 232, and 188 nm. When the C/Fe molar ratio is below 4.7, sedimentation occurs, with the maximum sedimentation value (C/C0) reaching 0.7. As pH increases, the Zeta potential of all three HA-Fe composite colloids increases by 6.3, 8.1, and 6.2 mV respectively, and their particle sizes decrease, with average reductions of 336, 483, and 256 nm. The binding capacity with As(III) increases as the C/Fe ratio rises from 0 to 23.3. At a C/Fe ratio of 23.3, the binding coefficients (logKD) with As(III) are 2.42, 2.86, and 2.96 for the three composite colloids, respectively. Among them, the HA-FeO(OH) composite colloid shows the highest binding rate with arsenic at 92% when the C/Fe ratio is 23.3. The binding mechanisms include complexation, redox reactions, and cation bridge formation. The findings provide new insights into the environmental behavior of DOM-Fe at water-soil interfaces and their impact on pollutant migration.

腐植酸-铁胶体稳定性特征及其与As(III)结合机理
水-土壤界面含有大量的溶解有机质(DOM)和铁矿物。然而,DOM-Fe胶体在不同浓度和矿物组成下的稳定性和聚集行为尚不清楚。因此,这些复合胶体与As(III)的结合行为需要进一步研究。本研究分析了复合胶体的表面电荷和粒径变化,以了解其稳定性和与As的结合过程。结果表明,C/Fe摩尔比影响腐植酸-铁(HA-Fe)复合胶体的分散。随着C/Fe比的增大,复合胶体的Zeta电位增大,粒径减小,最小粒径分别为135、232和188 nm。当C/Fe摩尔比低于4.7时,发生沉淀,最大沉淀值(C/C0)达到0.7。随着pH的增加,三种HA-Fe复合胶体的Zeta电位分别增加6.3、8.1和6.2 mV,粒径减小,平均减小336、483和256 nm。随着C/Fe比值从0增加到23.3,与As(III)的结合能力增加。在C/Fe为23.3时,3种复合胶体与As(III)的结合系数(logKD)分别为2.42、2.86和2.96。其中,当C/Fe比为23.3时,HA-FeO(OH)复合胶体与砷的结合率最高,达到92%。结合机制包括络合、氧化还原反应和阳离子桥的形成。研究结果对DOM-Fe在水-土壤界面的环境行为及其对污染物迁移的影响提供了新的认识。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
CiteScore
5.60
自引率
3.70%
发文量
230
审稿时长
1.7 months
期刊介绍: The Bulletin of Environmental Contamination and Toxicology(BECT) is a peer-reviewed journal that offers rapid review and publication. Accepted submissions will be presented as clear, concise reports of current research for a readership concerned with environmental contamination and toxicology. Scientific quality and clarity are paramount.
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