Humic acid sorption onto a quartz sand surface: A kinetic study and insight into fractionation.
Humic acid sorption onto a quartz sand surface: A kinetic study and insight into fractionation.
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DOI：
10.1016/j.jcis.2008.05.031
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发表时间：
2008-09
影响因子：
9.9
通讯作者：
A. Pitois;L. Abrahamsen;P. Ivanov;N. Bryan
中科院分区：
文献类型：
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作者：
A. Pitois;L. Abrahamsen;P. Ivanov;N. Bryan
奥德里奇腐殖酸吸附到石英砂表面上的动力学研究揭示了腐殖酸分子的初始快速吸收，随后是慢得多的吸附。采用耦合非对称流场流动分级-紫外/可见吸收分光光度法研究了腐殖酸在简单石英砂表面吸附的两个动力学步骤的分子量和化学分级。吸附后溶液中残留腐殖酸的分子量分布偏离了原来的分子量分布，表现出对某些分子量组分的优先吸附。在两个动力学步骤之后，这种分馏是不同的。腐殖酸分子，其特征在于低于4800 Da的分子量和重均分子量（Mw）为1450 Da的吸附后的快速动力学步骤，而腐殖酸分子的分子量范围为1400-9200 Da和Mw 3700 Da的吸附后的较慢的吸收。因此，低分子量腐殖组分的吸附首先发生，然后是较高分子量组分的吸附。化学吸附分馏，通过研究253 nm/203 nm的吸光度比随时间的推移，研究表明，芳香族组分优先吸附在快速动力学步骤。分馏模式可以解释由奥德里奇腐殖酸的物理化学特性和基本的吸附过程。在腐殖酸存在下，铕在石英砂表面的吸附动力学趋势与腐殖酸本身的吸附动力学趋势相似。
A kinetic study of Aldrich humic acid sorption onto a quartz sand surface has revealed an initial rapid uptake of humic acid molecules followed by a much slower sorption. The humic acid molecular weight and chemical fractionation resulting from adsorption onto the simple quartz sand surface were investigated for the two kinetic steps by coupled asymmetric flow-field flow fractionation-UV/visible absorption spectrophotometry. The molecular weight distribution of residual humic acid in solution after adsorption deviated from the original molecular weight distribution, showing preferential adsorption of certain molecular weight components. This fractionation is different after the two kinetic steps. Humic acid molecules characterised by a molecular weight below 4800 Da and with a weight-average molecular weight (Mw) of 1450 Da were adsorbed after the fast kinetic step, whereas humic acid molecules in the molecular weight range 1400–9200 Da and of Mw3700 Da were adsorbed after the slower uptake. Therefore, the adsorption of low molecular weight humic components takes place initially, and is then followed by the adsorption of higher molecular weight components. Chemical adsorptive fractionation, investigated by studying the 253 nm/203 nm absorbance ratio over time, shows that aromatic components are preferentially adsorbed during the fast kinetic step. The fractionation pattern may be explained by the physicochemical characteristics of the Aldrich humic acid and the underlying sorption processes. The trend for the sorption kinetics of europium onto the quartz sand surface in the presence of humic acid is similar to that of the humic acid itself.