• Cu and Cr can be mostly incorporated into CuFexAlyCr2−x−yO4 with a spinel structure.• Spinel phase is the most crucial structure for Cu and Cr co-stabilization.• Compared to Al, Fe and Cr are easier to be incorporated into the spinel structure.• ‘Waste-to-resource’ by thermal process at attainable temperatures can be achieved. Chromium slag usually contains various heavy metals, making its safe treatment difficult. Glass-ceramic sintering has been applied to resolve this issue and emerged as an effective method for metal immobilization by incorporating heavy metals into stable crystal structures. Currently, there is limited knowledge about the reaction pathways adopted by multiple heavy metals and the co-stabilization functions of the crystal structure. To study the Cu/Cr co-stabilization mechanisms during thermal treatment, a simulated system was prepared using a mixture with a molar ratio of Al2O3:Fe2O3:Cr2O3:CuO= 1:1:1:3. The samples were sintered at temperatures 600–1300°C followed by intensive analysis of phase constitutions and microstructure development. A spinel phase (CuFexAlyCr2−x−yO4) started to generate at 700°C and the incorporation of Cu/Cr into the spinel largely complete at 900°C, although the spinel peak intensity continued increasing slightly at temperatures above 900°C. Fe2O3/Cr2O3 was more easily incorporated into the spinel at lower temperatures, while more Al2O3 was gradually incorporated into the spinel at higher temperatures. Additionally, sintered sample microstructures became more condensed and smoother with increased sintering temperature. Cu / Cr leachability substantially decreased after Cu/Cr incorporation into the spinel phase at elevated temperatures. At 600°C, the leached ratios for Cu and Cr were 6.28% and 0.65%, respectively. When sintering temperature was increased to 1300°C, the leached ratios for all metal components in the system were below 0.2%. This study proposes a sustainable method for managing Cu/Cr co-exist slag at reasonable temperatures. 相似文献
We implemented the online coupled WRF-Chem model to reproduce the 2013 January haze event in North China, and evaluated simulated meteorological and chemical fields using multiple observations. The comparisons suggest that temperature and relative humidity (RH) were simulated well (mean biases are–0.2K and 2.7%, respectively), but wind speeds were overestimated (mean bias is 0.5 m?s–1). At the Beijing station, sulfur dioxide (SO2) concentrations were overpredicted and sulfate concentrations were largely underpredicted, which may result from uncertainties in SO2 emissions and missing heterogeneous oxidation in current model. We conducted three parallel experiments to examine the impacts of doubling SO2 emissions and incorporating heterogeneous oxidation of dissolved SO2 by nitrogen dioxide (NO2) on sulfate formation during winter haze. The results suggest that doubling SO2 emissions do not significantly affect sulfate concentrations, but adding heterogeneous oxidation of dissolved SO2 by NO2 substantially improve simulations of sulfate and other inorganic aerosols. Although the enhanced SO2 to sulfate conversion in the HetS (heterogeneous oxidation by NO2) case reduces SO2 concentrations, it is still largely overestimated by the model, indicating the overestimations of SO2 concentrations in the North China Plain (NCP) are mostly due to errors in SO2 emission inventory.
Incorporating the missing heterogeneous oxidation of S(IV) by NO2 into the WRF-Chem model. Sulfate production is not sensitive to increase in SO2 emission. The newly added reaction reproduces sulfate concentrations well during winter haze. We implemented the online coupled WRF-Chem model to reproduce the 2013 January haze event in North China, and evaluated simulated meteorological and chemical fields using multiple observations. The comparisons suggest that temperature and relative humidity (RH) were simulated well (mean biases are -0.2K and 2.7%, respectively), but wind speeds were overestimated (mean bias is 0.5 m?s−1). At the Beijing station, sulfur dioxide (SO2) concentrations were overpredicted and sulfate concentrations were largely underpredicted, which may result from uncertainties in SO2 emissions and missing heterogeneous oxidation in current model. We conducted three parallel experiments to examine the impacts of doubling SO2 emissions and incorporating heterogeneous oxidation of dissolved SO2 by nitrogen dioxide (NO2) on sulfate formation during winter haze. The results suggest that doubling SO2 emissions do not significantly affect sulfate concentrations, but adding heterogeneous oxidation of dissolved SO2 by NO2 substantially improve simulations of sulfate and other inorganic aerosols. Although the enhanced SO2 to sulfate conversion in the HetS (heterogeneous oxidation by NO2) case reduces SO2 concentrations, it is still largely overestimated by the model, indicating the overestimations of SO2 concentrations in the North China Plain (NCP) are mostly due to errors in SO2 emission inventory. 相似文献
To understand the household C02 emission level in China, as well as how much the neighborhoods' socio-economic or design factors could influence the CO2 emission, 23 neighborhoods in Jinan were investigated in 2009 and 2010. These neighborhoods fall into four different types: superblock, enclave, grid and traditional. The household CO2 emission includes sources of both in- home energy use and passenger transportation. The average CO2 emission per household is 7.66 t.a^-1, including 6.87 t in-home operational emission and 792 kg transportation emission. The household CO2 emission by neighborhood categories is 10.97, 5.65, 6.49, 5.40 t-household-1. a-1 for superblock, enclave, grid and tradi- tional respectively. Superblock has the highest average emission and also the highest percent (more than 25%) of transportation emission among four different types of neighborhoods. The residential CO2 emission of superb- lock neighborhoods in Jinan has already reached the level in developed countries nearly ten years ago. It is predictable that more superblock neighborhoods would be built in China with the fast urbanization. How to avoid the rapid household CO2 emission growth in the future would be a systematic issue. The study also found that in addition to income and apartment area, household density, land use mix and accessibility to public transportation are three primary factors which have significant impacts on CO2 emission. High density, mixed land use and convenient accessibility to public transportation tend to reduce household CO2 emission. 相似文献