Work

Influence of phosphate on hexavalent chromium immobilization by ferrihydrite under light irradiation

Year: 2025

Type: article

Abstract: Ferrihydrite is an important geosorbent and catalyst that is ubiquitous in natural environments, and plays a critical role in regulating the speciation and migration of hexavalent chromium (Cr(VI)). Phosphate has a strong affinity for ferrihydrite surfaces, but it remains unclear how phosphate influences the immobilization of Cr(VI) by ferrihydrite in sunlight-influenced surface environments. Herein, the surface interactions of ferrihydrite and Cr(VI) in the presence of phosphate were studied under mercury lamp irradiation. Results showed that mercury lamp irradiation significantly attenuated the inhibitory effect of phosphate on Cr(VI) removal by ferrihydrite compared to that under dark conditions. X-ray photoelectron spectroscopic (XPS) analysis revealed that Cr(III) was the predominant chromium species immobilized on ferrihydrite surfaces. Specifically, the reduction of Cr(VI) produced CrPO 4 precipitates, whereas the released Fe(III) can also co-adsorb with phosphate (i.e., FePO 4 ) onto ferrihydrite surfaces. The reduction of Cr(VI) mediated by the generated Fe(II) species and photoelectrons effectively reduces the electrostatic repulsion between Cr(VI) and phosphate, thereby enhancing the immobilization of these two ions on ferrihydrite. Energy dispersive X-ray spectrometer (EDS) results provide direct quantitative evidence that mercury lamp irradiation substantially enhances the immobilization of Cr(VI) and phosphate by ferrihydrite. The above-described results account for the effect of phosphate on the light-induced coupling process of ferrihydrite reductive dissolution and Cr(VI) reductive immobilization, advancing our understanding of the geochemical cycle of Cr(VI) pollution in sunlight-influenced surface environments.

Source: Chemical Geology

DOI: 10.1016/j.chemgeo.2025.123144

Authors: Chaorong Chen, Sailan Wang, Yixuan Yang, Gaofeng Wang, Jing Liu, Qingze Chen, Fei Ge, Runliang Zhu

Institutions: Chinese Academy of Sciences, Guangzhou Institute of Geochemistry, Xiangtan University, Macau University of Science and Technology, State Key Laboratory of Lunar and Planetary Sciences

Language: English

Topic: Chromium effects and bioremediation

Subfield: Health, Toxicology and Mutagenesis

Field: Environmental Science

Domain: Physical Sciences

SDG: Clean water and sanitation

Open Access status: hybrid

Estimated APC paid: $3,550