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Selenium (Se) is an essential and crucial micronutrient for humans and animals, but excessive Se brings negativity and toxicity. The adsorption and oxidation of Se(IV) on Mn-oxide surfaces are important processes for understanding the geochemical fate of Se and developing engineered remediation strategies. In this study, the characterization of simultaneous adsorption, oxidation, and desorption of Se(IV) on δ-MnO mineral was carried out using stirred-flow reactors. About 9.5% to 25.3% of Se(IV) was oxidized to Se(VI) in the stirred-flow system in a continuous and slow process, with the kinetic rate constant k of 0.032 h, which was significantly higher than the apparent rate constant of 0.0014 h obtained by the quasi-level kinetic fit of the batch method. The oxidation reaction was driven by proton concentration, and its rate also depended on the Se(IV) influent concentration, flow rate, and δ-MnO dosage. During the reaction of Se(IV) and δ-MnO, Mn(II) was produced and adsorbed strongly on Mn oxide surfaces, which was evidenced by the total reflectance Fourier transform infrared (ATR-FTIR) results. The X-ray photoelectron spectroscopy (XPS) data indicated that the reaction of Se(VI) on δ-MnO produced Mn(III) as the main product. These results contribute to a deeper understanding of the interface chemical process of Se(IV) with δ-MnO in the environment.
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http://dx.doi.org/10.3390/ijerph18062902 | DOI Listing |
Biotechnol J
August 2025
Nanchang Key Laboratory of Microbial Resources Exploitation & Utilization from Poyang Lake Wetland, College of Life Sciences, Jiangxi Normal University, Nanchang, China.
Microbial reduction of toxic Se(IV) oxyanions to biogenic Se(0) has garnered considerable attention for detoxification. This study presents a comprehensive investigation of Se(IV) reduction by environmentally versatile Exiguobacterium genus through integrated physicochemical, genomic, and transcriptomic analyses. Exiguobacterium mexicanum PY14 demonstrated remarkable efficiency, reducing ∼1 mM selenite to extracellular Se(0) within 12 h under aerobic conditions, with broad adaptability to pH (7-9), temperature (30-37°C), and salinity (up to 40 g L NaCl).
View Article and Find Full Text PDFFront Plant Sci
June 2025
Key Laboratory of Alpine Vegetation Ecological Security in Tibet, Institute of Tibet Plateau Ecology, Tibet Agricultural and Animal Husbandry University, Nyingchi, China.
Introduction: Selenium (Se)-fortified foods have demonstrated efficacy in augmenting dietary Se intake and ameliorating human Se nutritional status. To mitigate Se deficiency-related health risks in Tibetan populations, systematic biofortification trials targeting highland barley, the primary staple crop in Tibet, are imperative.
Methods: Highland barley was subjected to soil-applied selenate (SeVI) and selenite (SeIV) at seven rates (0, 5, 15, 25, 50, 75, and 100 g·ha), followed by comprehensive evaluation of Se transfer dynamics within the soil-crop-diet continuum across Tibet's agricultural regions.
J Environ Manage
August 2025
Center for Advanced Process Technology and Urban Resource Recovery (CAPTURE), Department of Green Chemistry and Technology, Ghent University, Frieda Saeysstraat 1, 9052, Ghent, Belgium.
The removal of toxic selenium (Se) and arsenic (As) from sulfate-rich wastewater is challenging due to competition between sulfate ions and these contaminants. This study presents a simple, one-step method for creating an effective adsorbent. Unlike traditional methods that require separate chemical modifications, our approach includes the introduction of sodium carbonate, simultaneously forming Fe(OH) and cross-linking the alginate, while generating a porous structure by introducing sodium carbonate.
View Article and Find Full Text PDFJ Hazard Mater
September 2025
Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, Liaoning 110016, China.
Microalgae serve as effective carriers for selenium enrichment and accumulation within aquatic ecosystems. They possess the ability to convert inorganic selenium into organic forms, primarily selenium-containing amino acids and proteins, thereby playing a crucial role in transferring selenium through the food chain. However, the mechanisms underlying marine microalgae's responses to selenite (Se) and selenate (Se) remain unclear.
View Article and Find Full Text PDFJ Environ Sci (China)
October 2025
National Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China. Electronic address:
Microbial selenite (Se(IV)) reduction to elemental selenium nanoparticles (SeNPs) and chromate (Cr(VI)) remediation constitute effective detoxification processes. The strain Bacillus wiedmannii ES2-45 can efficiently reduce 5 mmol/L Se(IV) into SeNPs over 14 h and 1 mmol/L Cr(VI) within 36 h. Proteomic analysis and qRT-PCR revealed that reductases, including dithiol oxidoreductase (DsbA), Fe-S biosynthesis domain-containing protein (Fes), and aldose-6-phosphate reductase (Aldo), and bacillithiol (BSH) were involved in Se(IV) reduction.
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