| 1. |
- Gao, Yuxi, et al.
(författare)
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Sulphation and ammonia regeneration of a Pt/MnOx-CeO2/Al2O3 catalyst for NOx-assisted soot oxidation
- 2018
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Ingår i: Catalysis Science and Technology. - : Royal Society of Chemistry (RSC). - 2044-4753 .- 2044-4761. ; 8:6, s. 1621-1631
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Tidskriftsartikel (refereegranskat)abstract
- The sulphur resistance and regeneration strategy of soot oxidation catalysts are critical to the application of catalytic diesel particulate filters (CDPFs). In the present work, Pt/MnOx-CeO2/Al2O3, Pt/Al2O3 and MnOx-CeO2/Al2O3 catalysts were sulphated and regenerated with ammonia. The soot oxidation activity of poisoned Pt/MnOx-CeO2/Al2O3 was recovered completely after 30 min reduction in 500 ppm NH3 at 550 degrees C. The amount, distribution and structure of sulphates were studied comprehensively for the sulphated and regenerated samples by thermogravimetric analysis (TGA), infrared (IR) spectroscopy, CO chemisorption and transmission electron microscopy (TEM). The NO oxidation of Pt catalysts was found to depend strongly on the particle size distribution, surface exposure and oxidation state of the precious metal. This, as well as the effect of the remaining surface sulphates, helped the regenerated catalysts achieve even higher catalytic activity for soot oxidation.
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| 2. |
- Li, Yu-Feng, et al.
(författare)
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Organic Selenium Supplementation Increases Mercury Excretion and Decreases Oxidative Damage in Long-Term Mercury-Exposed Residents from Wanshan, China
- 2012
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 46:20, s. 11313-11318
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Tidskriftsartikel (refereegranskat)abstract
- Due to a long history of extensive mercury mining and smelting activities, local residents in Wanshan, China, are suffering from elevated mercury exposure. The objective of the present study was to study the effects of oral supplementation with selenium-enriched yeast in these long-term mercury-exposed populations. One hundred and three volunteers from Wanshan area were recruited and 53 of them were supplemented with 100 mu g of organic selenium daily as selenium-enriched yeast while 50 of them were supplemented with the nonselenium-enriched yeast for 3 months. The effects of selenium supplementation on urinary mercury, selenium, and oxidative stress-related biomarkers including malondialdehyde and 8-ydroxy-2-deoxyguanosine were assessed. This 3-month selenium supplementation trial indicated that organic selenium supplementation could increase mercury excretion and decrease urinary malondialdehyde and 8-hydroxy-2-deoxyguanosine levels in local residents.
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| 3. |
- Li, Yunyun, et al.
(författare)
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Understanding Enhanced Microbial MeHg Production in Mining-Contaminated Paddy Soils under Sulfate Amendment : Changes in Hg Mobility or Microbial Methylators?
- 2019
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 53:4, s. 1844-1852
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Tidskriftsartikel (refereegranskat)abstract
- Elevated methylmercury (MeHg) production in mining-contaminated paddy soils, despite the high fraction of refractory HgS(s), has been frequently reported, while the underlying mechanisms are not fully understood. Here, we hypothesized that sulfate input, via fertilization, rainfall, and irrigation, is critical in mobilizing refractory HgS(s) and thus enhancing Hg methylation in mining-contaminated paddy soils. To test this hypothesis, the effects of sulfate amendment on Hg methylation and MeHg bioaccumulation in mining-contaminated soil-rice systems were examined. The results indicated 28-61% higher net MeHg production in soils under sulfate amendment (50-1000 mg kg-1), which in turn increased grain MeHg levels by 22-55%. The enhancement of Hg methylation by Hg mobilization in sulfate-amended soils was supported by two observations: (1) the increased Hg(aq) release from HgS(s), the dominant Hg species in the paddy soils, in the presence of sulfide produced following sulfate reduction and (2) the decreases of refractory HgS(s) in soils under sulfate amendment. By contrast, changes in the abundances/activities of potential microbial Hg methylators in different Hg-contaminated soils were not significant following sulfate amendment. Our results highlight the importance to consider enhanced Hg mobility and thus methylation in soils under sulfate amendment.
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