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Effects of Calcium on Arsenate Adsorption and Arsenate/Iron Bioreduction of Ferrihydrite in Stimulated Groundwater
| Content Provider | MDPI |
|---|---|
| Author | Chen, Mengna Xie, Zuoming Yang, Yang Gao, Ban Wang, Jia |
| Copyright Year | 2022 |
| Description | The reduction and transformation of arsenic-bearing ferrihydrite by arsenate-iron reducing bacteria is one of the main sources of arsenic enrichment in groundwater. During this process the coexistence cations may have a considerable effect. However, the ionic radius of calcium is larger than that of iron and shows a low affinity for ferrihydrite, and the effect of coexisting calcium on the migration and release of arsenic in arsenic-bearing ferrihydrite remains unclear. This study mainly explored the influence of adsorbed $Ca^{2+}$ on strain JH012-1-mediated migration and release of arsenate in a simulated groundwater environment, in which 3 mM ferrihydrite and pH 7.5. $Ca^{2+}$ were pre-absorbed on As(V)-containing ferrihydrite with a As:Fe ratio of 0.2. Solid samples were analyzed by X-ray diffraction (XRD), scanning electron microscopic (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The results show that calcium and arsenate can synergistically adsorb on ferrihydrite due to the electrostatic interactions, and the adsorbed $Ca^{2+}$ mainly exists on the surface through the outer-sphere complex. Adsorbed $Ca^{2+}$ entering the stimulated groundwater was easily disturbed and led to an extra release of 3.5 mg/L arsenic in the early stage. Moreover, adsorbed $Ca^{2+}$ inhibited biogenic ferrous ions from accumulating on ferrihydrite. As a result, only 12.30% Fe(II) existed in the solid phase, whereas 29.35% existed without $Ca^{2+}$ adsorption. Thus, the generation of parasymplesite was inhibited, which is not conducive to the immobilization of arsenic in groundwater. |
| Starting Page | 3465 |
| e-ISSN | 16604601 |
| DOI | 10.3390/ijerph19063465 |
| Journal | International Journal of Environmental Research and Public Health |
| Issue Number | 6 |
| Volume Number | 19 |
| Language | English |
| Publisher | MDPI |
| Publisher Date | 2022-03-15 |
| Access Restriction | Open |
| Subject Keyword | International Journal of Environmental Research and Public Health Environmental Engineering Ferrihydrite Calcium Electrostatic Adsorption As Bioreduction Groundwater |
| Content Type | Text |
| Resource Type | Article |
