Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5782699 | Chemical Geology | 2017 | 38 Pages |
Abstract
The incorporation of arsenate (As(V)) in the gypsum structure is an important process for arsenic (As) fixation during industrial effluent treatment and may influence the mobility and bioavailability of As in surface environment. However, spectroscopic evidence is still lacking for its species and local structure. The species and local structure of As(V) in a gypsum lattice were investigated using Fourier transform infrared (FTIR) spectroscopy, density functional theory (DFT) modelling, and full-potential multiple scattering (FPMS) simulations. Ascorbic acid-treated As(V)-gypsum co-precipitates were used to avoid the influence of amorphous calcium arsenate on the characterization. The lack of the FTIR band in the range of 750-860 cmâ 1 was an indicative that no AsO43 â species was incorporated into the gypsum structure. DFT calculations proved that the incorporation of AsO43 â was energetically much harder than HAsO42 â species. The FPMS structural refinement yielded the optimal AsO interatomic distances of 1.77, 1.67, 1.65, and 1.66 Ã
, with an average of 1.69 ± 0.057 Ã
, in agreement with the DFT and EXAFS results. Our work conclusively showed that HAsO42Â â dominated as the species of As(V) incorporated into the gypsum lattice, with the H atom in the HAsO42Â â group adjacent to water layer, regardless of pH.
Keywords
Related Topics
Physical Sciences and Engineering
Earth and Planetary Sciences
Geochemistry and Petrology
Authors
Shaofeng Wang, Danni Zhang, Xu Ma, Guoqing Zhang, Yongfeng Jia, Keisuke Hatada,