Strength of Humic Acid Aggregates: Effects of Divalent Cations and Solution pH
Strength of Humic Acid Aggregates: Effects of Divalent Cations and Solution pH
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DOI：
10.1021/acsomega.9b00124
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发表时间：
2019-05
期刊：
影响因子：
4.1
通讯作者：
A. Hakim;Tomoharu Suzuki;Motoyoshi Kobayashi
中科院分区：
文献类型：
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作者：
A. Hakim;Tomoharu Suzuki;Motoyoshi Kobayashi
研究了钙芒硝腐殖酸（LHA）在CaCl 2和MgCl 2溶液中的聚集-分散性、荷电性和聚集体强度随pH和离子强度（I）的变化。腐殖物质（HS）团聚体的强度或抗破碎力是重要的，因为这种力通过HS团聚体作为运输单元的尺寸的变化影响污染物和营养物沿着HS的运输和分布。我们观察到的LHA聚集在高pH值比在低pH值的CaCl 2和MgCl 2溶液中的每一种情况下的优势。这一观察结果表明，这些二价离子在高pH值下的结合效率较高，但与电泳迁移率和LHA的聚集没有明显的关系。此外，我们首先揭示了HS聚集体的强度的数值，通过使用一个简单的实验装置下的聚集体破碎层流收敛流通过毛细管。LHA聚集体的强度的获得的值在CaCl 2溶液的存在下比MgCl 2溶液更高，并且强度随pH增加。LHA聚集体在30 mM（I）CaCl 2和MgCl 2溶液中的最高强度分别为约5.8和2.4 nN，在pH约9时。
Aggregation–dispersion, charging, and aggregate strength of Leonardite humic acid (LHA) were investigated in CaCl2 and MgCl2 solutions as a function of pH and ionic strength (I). The strength or the withstanding force of aggregates of humic substances (HSs) against breakage is important because this force influences the transport and distribution of pollutants and nutrients along with HSs through the change in the size of HS aggregates as a transport unit. We observed the dominancy of aggregation of LHA at high pH than at low pH in every case of CaCl2 and MgCl2 solutions. This observation suggests the higher binding efficiency of these divalent ions at high pH, though there was no obvious relation with electrophoretic mobility and aggregation of LHA. Further, we first revealed the numerical value of the strength of HS aggregates by using a simple experimental setup of aggregate breakup under laminar converging flow through a capillary tube. The obtained values of the strength of LHA aggregates were higher in the presence of CaCl2 solution than MgCl2 solution, and the strength increased with pH. The highest strengths of LHA aggregates in 30 mM (I) CaCl2 and MgCl2 solutions were around 5.8 and 2.4 nN, respectively, at pH around 9.