Insights into the effect of humic acid on Ni(II) sorption mechanism on illite: Batch, XPS and EXAFS investigations
Insights into the effect of humic acid on Ni(II) sorption mechanism on illite: Batch, XPS and EXAFS investigations
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DOI：
10.1016/j.molliq.2017.10.146
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发表时间：
2017-12
影响因子：
6
通讯作者：
Xiaolan Zhao;Yun Wang;Hanyu Wu;Linchuan Fang;Jianjun Liang;Q. Fan;Ping Li
中科院分区：
文献类型：
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作者：
Xiaolan Zhao;Yun Wang;Hanyu Wu;Linchuan Fang;Jianjun Liang;Q. Fan;Ping Li
本文采用批量法、EXAFS和XPS研究了腐殖酸（HA）对Ni（II）在伊利石/水界面吸附机理的影响。结果表明，HA对伊利石吸附Ni（II）有明显的抑制作用，尤其是在中性至弱碱性条件下、短时间老化的情况下。在低pH条件下，离子交换（IE）和HA-桥接络合物是主要的吸附机制。在中性至弱碱性条件下，Ni（II）在伊利石表面的吸附在短期内逐渐由HA桥连络合物和表面沉淀物（如α-Ni（OH）2）主导。HA对Ni（II）吸附的抑制作用可能是由于HA与Ni（II）络合物的竞争作用和HA包覆的伊利石表面抑制了Ni（II）的表面诱导沉淀。随着时效时间的延长，HA对Ni-Al LDH和Ni（OH）2等表面析出物的抑制作用逐渐减弱。这可能是由于有效Al 3+的生长和Ni（II）的表面负载引起的。在强碱性条件下，β-Ni（OH）2是伊利石吸附Ni（II）的主要物种。本研究的这些发现为理解和预测富含天然有机质的土壤中Ni（II）的环境行为提供了深刻的见解。
In this study, the influence of humic acid (HA) on Ni(II) sorption mechanism at illite/water interface was investigated using batch, EXAFS, and XPS. The results showed that HA can apparently inhibit the sorption of Ni(II) on illite, especially at neutral to weak alkaline conditions under a short aging time. Under low pH conditions, ion exchange (IE) and HA-bridging complexes were the main sorption mechanisms. Under neutral to weak alkaline conditions, HA-bridging complexes and surface precipitates (such as α-Ni(OH)2) gradually became predominant for Ni(II) sorption on illite at a short term. The inhibition of HA for Ni(II) sorption was deduced that: (i) the competition of soluble HA-Ni complexes, and (ii) HA-coated illite surface restrained the formation of surface-induced precipitates. With the increasing aging time, the inhibiting effect of HA became weak with respect to the surface precipitates such as Ni-Al LDH and Ni(OH)2forming gradually. This might be caused by the growth of the available Al3 +and the surface loading of Ni(II). Moreover, β-Ni(OH)2was the dominant species for Ni(II) sorption on illite under strong alkaline conditions. These findings in this study are providing deep insights into the understanding and prediction of Ni(II) environmental behaviors in soils enriched with natural organic matters.