The sorption process in the zeolite chabazite
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(1) The changes in the zeolite chabazite during sorption have been investigated by means of X-ray examination of single crystals and of powders. (2) The heats of sorption for very small additions ammonia to the zeolite have been measured. (3) A theory has been advanced to explain the results.Keywords:
Chabazite
Dilution
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Chabazite
Thermal Stability
Hydrothermal Synthesis
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Clinoptilolite
Chabazite
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Chabazite
Sodalite
Mordenite
Ferrierite
Nanoporous
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This paper presents the systematic studies of the sorption capacity of natural zeolite with respect to In3+ and Ga3+ cations in the model systems “natural zeolite–In3+–H2O” and “natural zeolite–In3+–Ga3+–H2O”, while varying a number of the main process factors. The patterns of sorption of In3+ and Ga3+ cations by the natural zeolite of the Shankanai deposit are revealed, depending on the zeolite vs. solution ratio, temperature, and time. It is shown that the sorption of In3+ cations by natural zeolite can be controlled by the process duration. The longer the process, the less the sorption by natural zeolite. It has been found that the sorption of In3+ cations in the “natural zeolite–In3+–Ga3+–H2O” model system depends on the amount of zeolite and temperature, and the sorption of Ga3+ cations depends on the temperature and time. The physicochemical characteristics of the spent sorbents confirm the sorption of the cations, present in the systems under study.
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Chabazite
Analcime
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Zeolite Phi is synthesized by two methods reported previously. Results from X-ray powder diffraction and scanning electron microscopy suggest that the materials are physical mixtures of chabazite and offretite; one sample has a small amount of phillipsite. The X-ray powder diffraction data from these samples, and those reported previously, are indexed and their unit-cell parameters compare well to those obtained from a physical mixture of chabazite and offretite. These samples show multiple particle morphologies that are indicative of physical mixtures. Zeolite Phi is concluded to be a physical mixture of chabazite and offretite and we suggest that the use of the name zeolite Phi be discontinued.
Chabazite
Powder Diffraction
Particle (ecology)
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The interzeolite conversion of faujasite (FAU-type) zeolites to chabazite (CHA-type) zeolite in the presence of N,N,N-trimethyladamantammonium and N,N,N-dimethylethylcyclohexylammonium cations was investigated over a large compositional range by carefully controlling the reaction mixture compositions. Highly crystalline CHA zeolites were also obtained by the transformation of several zeolite types including EMT, LTL, LEV, RTH, and MFI frameworks. The formation of CHA zeolite from FAU zeolite precursors was substantially faster than that from zeolite L with a similar composition. High-silica CHA zeolites were also produced successfully using a mixture of TMAda with a number of less expensive organic structure-directing agents. The CHA zeolite materials have been synthesized with high crystallinity and with a Si/Al ratio ranging from 5 to 140. Our data support the importance of structural similarity between the zeolite precursors, nucleation/crystallization processes, and the zeolite product in the interzeolite conversion compared to conventional amorphous aluminosilicate gels. Our synthetic methods could be used to prepare other 8-membered ring zeolites such as AEI and AFX frameworks, potential candidates for selective catalytic reduction of NOx, light olefin production, and CO2 abatement.
Chabazite
Faujasite
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(1) The changes in the zeolite chabazite during sorption have been investigated by means of X-ray examination of single crystals and of powders. (2) The heats of sorption for very small additions ammonia to the zeolite have been measured. (3) A theory has been advanced to explain the results.
Chabazite
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Iron coated zeolite is made and its adsorption characteristics are compared with activated alumina and zero-valent iron to get further understand of the new adsorbent. The results show that iron coated zeolite removes As(V) in the similar with that by activated alumina with removal rate of 50% in first 5min's adsorption but slower after 60 mins' adsorption and faster than that by zero-valent iron during the whole adsorption process. Iron coated zeolite sorption fits Langmuir model the best. Capacities of activated alumina, iron coated zeolite and zero-valent iron for As(V) adsorption are 7.3mg/g, 3.9mg/g and 3.3 mg/g, respectively. XRD analysis shows that main components on the surface of the used iron coated zeolite in this paper is FeOOH. To improve the adsorption efficiency of iron coated zeolite, diameter of the zeolite should be decreased and iron should be coated more tightly on the zeolite.
Zerovalent iron
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