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Copper-exchanged chabazite (Cu/CHA) catalysts have been found to be affected by alkali metal and alkaline earth ions. However, the effects of Na+ ions on Cu/SAPO-34 for ammonia selective catalytic reduction (NH3-SCR) are still unclear. In order to investigate the mechanism, five samples with various Na contents were synthesized and characterized. It was observed that the introduced Na+ ion-exchanges with H+ and Cu2 + of Cu/SAPO-34. The exchange of H+ is easier than that of isolated Cu2 +. The exchanged Cu2 + ions aggregate and form “CuAl2O4-like” species. The NH3-SCR activity of Cu/SAPO-34 decreases with increasing Na content, and the loss of isolated Cu2 + and acid sites is responsible for the activity loss. 相似文献
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The presence of pharmaceuticals in aquatic environments poses potential risks to the ecology and human health. This study investigated the removal of three widely detected and abundant pharmaceuticals, namely, ibuprofen (IBU), diclofenac (DC), and sulfadiazine (SDZ), by two magnetic ion-exchange resins. The adsorption kinetics of the three adsorbates onto both resins was relatively fast and followed pseudo-second-order kinetics. Despite the different pore structures of the two resins, similar adsorption patterns of DC and SDZ were observed, implying the existence of an ion-exchange mechanism. IBU demonstrated a combination of interactions during the adsorption process. These interactionswere dependent on the specific surface area and functional groups of the resin. The adsorption isothermfittings verified the differences in the behavior of the three pharmaceuticals on the two magnetic ion-exchange resins. The presence of Cl- and SO42- suppressed the adsorption amount, butwith different inhibition levels for different adsorbates. This work facilitates the understanding of the adsorption behavior andmechanismof pharmaceuticals onmagnetic ion-exchange resins. The results will expand the application of magnetic ion-exchange resins to the removal of pharmaceuticals in waters. 相似文献
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L. Trotignon M. -H. Faur A. Stietel C. Riglet-Martial M. Sardin P. Vitorge F. Lefvre 《Journal of contaminant hydrology》1997,26(1-4)
This work presents an intercomparison exercise between two geochemical migration codes, TRIO-EF (an object-oriented finite element code) and IMPACT (a chemical engineering code using mixing cells in series). The predictions of the two codes are compared with the reference experimental results obtained in a previous study of strontium transport in soil columns. This simulated geochemical system is well documented and includes ion exchange and dissolution-precipitation reactions. The solution transport is simulated by a one-dimensional advection-dispersion model. The predictions of TRIO-EF and IMPACT are both in good agreement with the experimental results. However, slight differences can be observed between the two codes, especially when concentration discontinuities are involved, such as precipitation fronts or changes in boundary conditions. These discrepancies between the two codes can mainly be attributed to the different discretisation approaches. 相似文献
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Shuang Tong Shaoxiang Zhang Yan Zhao Chuanping Feng Weiwu Hu Nan Chen 《环境科学学报(英文版)》2022,34(3):219-230
The discharge of slau ghterhouse wastewater(SWW) is incre asing and its wastewater has to be treated thoroughly to avoid the eutrophication.The hybrid zeolite-based ion-exchange and sulfur autotrophic denitrification(IX-AD) process was developed to advanced treat SWW after traditional secondary biological process.Compared with traditional sulfur oxidizing denitrification(SOD),this study found that IX-AD column showed:(1) stronger ability to resist NO3-pollution load,(2) low... 相似文献
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《环境科学学报(英文版)》2023,35(2):414-428
MXenes, a new family of two-dimensional transition metal carbides or nitrides, have attracted tremendous attention for various applications due to their unique properties such as good electrical conductivity, hydrophilicity, and ion intercalability. In this work, Ti3C2 MXene, or MX, is converted to MX-TiO2 composites using a simple and rapid microwave hydrothermal treatment in HCl/NaCl mixture solution that induces formation of fine TiO2 particles on the MX parent structure and imparts photocatalytic activity to the resulting MX-TiO2 composites. The composites were used for enrofloxacin (ENR), a frequently found contaminating antibiotic, removal from water. The relative amount of the MX and TiO2 can be controlled by controlling the hydrothermal temperature resulting in composites with tunable adsorption/photocatalytic properties. NaCl addition was found to play important role as composites synthesized without NaCl could not adsorb enrofloxacin well. Adding NaCl into the hydrothermal treatment causes sodium ions to be simultaneously intercalated into the composite structure, improving ENR adsorption greatly from 1 to 6 mg ENR/g composite. It also slows down the MX to TiO2 conversion leading to a smaller and more uniform distribution of TiO2 particles on the structure. MX-TiO2/NaCl composites, which have sodium intercalated in their structures, showed both higher ENR adsorption and photocatalytic activity than composites without NaCl despite the latter having higher TiO2 content. Adsorbed ENR on the composites can be efficiently degraded by free radicals generated from the photoexcited TiO2 particles, leading to high photocatalytic degradation efficiency. This demonstrates the synergetic effect between adsorption and photocatalytic degradation of the synthesized compounds. 相似文献
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离子交换法从兔肉中提取ATP无汞害新工艺 总被引:1,自引:0,他引:1
总结了用离子交换法从兔肉中生产ATP无汞害新工艺以取代汞盐法从兔肌生产ATP的老工艺,经试验及生产应用证明,新工艺成功地消除汞害和硫化氢的环境污染,提高原料的利用率和产品得率,降低生产成本和改善工人的劳动条件。 相似文献
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An activated carbon (AC) containing a high concentration (374 mg g−1) of Fe was prepared by carbonization of an ion-exchange resin. To examine its chemical reactivity as a catalyst to decompose 2,2′,4,4′,5,5′-hexachlorobiphenyl (PCB-153), the decomposition parameters of temperature and time were varied under air or N2. Decomposition at 350 °C was achieved within 15 min under air and 30 min under N2, and the efficiency of PCB-153 decomposition was 99.7% and 98.0%, respectively. An analysis of inorganic chloride ions revealed that PCB-153 was mineralized effectively during the decomposition. The Brunauer-Emmett-Teller (BET) surface area and pore volume of the AC were measured to assess the adsorption capacity before and after the decomposition. The differences between decomposition under air and N2 reflected the differences in the BET surface and pore volume measurements. A decomposition pathway was postulated, and the reactive characteristics of chlorine atoms loaded on the benzene rings followed the order of para > meta > ortho, which agrees with the calculated results from a density functional theory study. 相似文献
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Mourin Jarin Zeou Dou Haiping Gao Yongsheng Chen Xing Xie 《Frontiers of Environmental Science & Engineering》2023,17(2):16
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Regeneration of pure water is an important issue not only for the healthy life but also for the fine control of precise processes in various industries.One important issue in ultrahigh purified water is to reduce the amount of total organic carbon(TOC).Herein,we introduce a new approach to reduce the TOC using the surface silanized nanoparticles,in which the magnetic nanoparticles(mNPs) are silanized and then complexed with ion exchange resin(IER) beads.The Fe3O4 mNPs are s... 相似文献