| Summary: | 碩士 === 國立成功大學 === 地球科學系碩士在職專班 === 105 === Summary
Arsenic is a widespread toxicant in the soil or aquifer in the global environment. Humic acid contains multiple functional groups capable of chelating with heavy metals. In this study, Fourier transform infrared (FTIR), X-ray photon spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) were used to study the bonding between the groups. The degree of bonding between humic acid and arsenic was investigated in this study. The bond distance and coordination number were analyzed by XAS, the binding energy of the humic acid-iron-arsenic complex was determined by XPS, and the functional groups of humic acid were analyzed by FTIR. The results of this study provide the binding properties of iron, arsenic, humic acid interactions. In the cationic state, iron may bind with humic acid and arsenic more easily between the bonds. This information could be valuable to understand the arsenic pollution in the soil or water due to its release or mobilization. The results proved that humic acid in the presence of iron ions can form a bidentate ternary complex. The bond distance and coordination number of Fe-As are 3.27~3.29 Å and 2, respectively. The Fe-As bonds of HA-Fe-As complex were subjected to break under strongly acidic conditions (pH=2), but not significantly affected by changing oxidation-reduction potentials (25, 0, -25, -50, -120 mV)
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