Structural and ionexchange properties of natural zeolite. Townsend department of chemistry, the city university, london ec1v ohb, england abstract zeolites find relatively few direct applications as ion exchangers and it is. According to regeneration studies, it was determined that 94 and 95% of copper were recovered within the first 100 minutes for both experiments. B b a a a b q c q c 7 where qa is the amount of ion a adsorbed to the zeolite meqg clinoptilolite, ca the concentration of ion a in solution meql, qb the amount of ion b a dsorbed to zeolite meqg clinoptilolite, and cb the concentration of ion b in solution meql. The following chemical reactions show the exchange process, where x represents zeolite, the exchange material.
Ion exchange of zeolites x, y, a and rho was performed by conventional methods using aqueous nitrate solutions. On ion exchange with calcium, one calcium ion replaces two sodium ions. The activity of iron ion exchanged mordenite increased with the increment in the exchange level and levelled off above about 60%. Modelling of ion distribution in single, binary and.
Regeneration efficiency of zeolite by nacl solution and air stripping was in the range of 92%97% under various. The total mass loss while heating zeolite up to 700c is 6,7%. The cobalt ii ionexchange process followed the freundlich and langmuir adsorption models as well as the pseudosecondorder kinetic model. Ion exchange ion exchange studies of zeolites for selective removal of transition metal ions from mix solutions. Reactiondriven ion exchange of copper into zeolite ssz acs. Using a preferred type of zeolite, between 66 and 93% removal of ammonia was achieved at a loading rate of about 20 bvhr bvhr x 0. Aqueous ion exchange in zeolites is currently hindered by the acidic byproducts that deteriorate the zeolite structure. Zeolite resin exchanges sodium for calcium and magnesium. The catalytic activities of iron ion exchanged zeolites depended on the zeolite structure and the iron ion exchange level. Pdf antimicrobial properties of zeolitex and zeolitea ion. Optimization of ammonia removal by ion exchange using. Ionexchange resin, zeolite exchanges one ion from the water being treated for another ion that is in the resin sodium is one component of softening salt, with chlorine being the other.
Introduction to the structural chemistry of zeolites. Energetics of alkali and alkaline earth ionexchanged zeolite a. The clinoptilolite was modified by ion exchange using 1n naci sat solution in waterbath. The results showed that the cation exchange capacities were 17. Nacsrho was initially ionexchanged using an aqueous nh 4 no 3 solution. B b a a a b q c q c 7 where qa is the amount of ion a adsorbed to the zeolite meqg clinoptilolite, ca the concentration of ion a in solution meql, qb the amount of ion b a dsorbed to zeolite meqg clinoptilolite, and cb the concentration of ion b. Binary ion exchange of metal ions in y and x zeolites. The zeolite soaked with hcl solution should modified its pore structure, and soaked with nacl solutions increased the na content of the zeolite, which led to ammonium exchange capacities of the zeolite improve. According to the literature data, ntdy nanocomposites combine the properties of. The ammonium exchange capacity change of zeolite in seawater and its. Some mass transfer parameters such as length of unused bed, overall mass transfer coefficient, operational ratio. Pdf the lead and cadmium removal from wastewaters by natural and pretreatment zeolites was examined by using a batchtype method.
Zeolite process for water softening has become a commercial success for the reason that zeolite can be easily regenerated. With the assumption that all cu ions are exchanged into the zeolite. Nay is a commercial product purchased from aldrich chemical company inc. Solidstate ionexchange of copper into zeolites facilitated. For low silica zeolites, this contribution is negligible compared to the capacity of the intrinsic ion exchange aiosi sites. Ion exchange studies of zeolites for selective removal of transition metal ions from mix solutions. Investigation of ion exchange properties of natural zeolite the intensive use of zeolites in various fields of science and practice is based largely on their ion exchange properties, which are one of the main parameters that characterize their sorption and technological properties. This chapter provides an introduction to the structure of zeolites and related crystalline microporous materials. Ionexchange studies of zeolite for selective removal of. The outlet effluent from stripping column was collected for reuse. Functionalization and application of hollow zeolite structures.
Method for the preparation of a metalexchanged zeolite material or mixtures of metalexchanged zeolites materials comprising the steps of providing a dry mixture containing a one or more zeolites starting materials that exhibit ion exchange capacity and b one or more metal compounds. Role of rare earth ions in the prevention of dealumination of zeolite. The tool of modelling was crystalmaker6 developed by crystalmaker software ltd. Among various metal ionexchanged zeolites, metal loading alumina, and oxides, iron ionexchanged mordenite was the most active for the selective reduction of nitrogen monoxide to nitrogen by ethene in the presence of oxygen at the temperature as low as 473 k. The antimicrobial activity and the resistance of the composites against the human environment play vital role in the applicability of the materials as a medical device therefore these properties were investigated. An integrated system for regeneration by air stripping followed ion exchange by qiaosi deng a thesis presented to the university of waterloo in fulfillment of the thesis requirement for the degree of master of applied science in civil engineering. The resultant ionexchanged zeolite was washed thoroughly with an excess of deionized water and then dried at 120c overnight. Cation exchange in zeolites, structure modification by using. Nacsrho was initially ion exchanged using an aqueous nh 4 no 3 solution.
After modification, the activated zeolite acquires a better capacity of adsorption, cationexchange and ionexchange. Therefore the current study aimed to modeling the ion distribution of single, binary and ternary ionexchanged zeolite systems used for antimicrobial purposes, where the variation of silver, copper and zinc is incorporated into the zeolite structure. The influence of ag, zn and cu exchanged zeolite on 2. Possibly a more satisfactory definition of a zeolite will come from the nature of the crystal structure. An investigation of ion exchange in linde a has been completed. Select multiple pdf files and merge them in seconds. The result is an efficient zeolite that is ideal for ion exchange, catalysis, and gas exchange. Pdf ion exchange properties of georgian natural zeolites. They ascribe the formation of stronger acid sites to a removal of ohsites in the sodalite cages and hexagonal prisms, and strengthening of the supercageoh sites by a. In addition to these, natural zeolite particles which have been ion exchanged throughout this process were regenerated using 0. The n 2 adsorption isotherms are mixed types iii isotherms and h3 type hysteresis.
The radionuclides would be transferred to the dwpf on the zeolite resin where they would be combined with sludge and frit to produce borosilicate glass. The interest of researchers towards such alumosilicates is connected with unique properties of zeolites. The effect of the gas phase during solidstate ionexchange of copper into zeolites was studied by exposing physical mixtures of copper oxides cui2o and cuiio and zeolites mfi, bea, and cha to various combinations of no, nh3, o2, and h2o. The cobalt ii ion exchange process followed the freundlich and langmuir adsorption models as well as the pseudosecondorder kinetic model. This comparative neglect is perhaps unfortunate for zeolite chemistry as a whole, especially since ion exchange is often an essential procedural component in the preparation andor manufacture of zeolites for use either as sorbents or catalysts. By combining this expression with corresponding irreversible thermodynamic. As well as discussing basic principles, some thermodynamic and kinetic aspects of the theory of ion exchange are covered with particular reference to their utility for predicting exchange behaviour in zeolites and for the use of ion exchange technqiues in detergency building, radionuclide separation, waste water treatment and the preparation of zeolitic catalysts and sorbents. Ammonia removal by ion exchange use of conventional resins perhaps the first use of ion exchange to remove ammonia from wastewater was the zeolite filter in the guggenheim process 32,33.
This chargecompensating entities can further be exchanged for other cations. Interpolated points from the curves fitted with different isotherms were used in the calculation of the selectivity coefficients. Structural characterisation of protonexchanged zeolites, prepared using. It has been shown that the conversion to methyl ester over nax faujasite zeolite that was ion exchanged with more electropositive cations was higher than that of the parent zeolite. Ionexchange isotherms for the canaerionite system at 0. The ion exchange properties of hydrated and amminated silveri ions in synthetic sodium x and y zeolites and mordenite mor were examined at 25 c and at a total solution normality of 0. A further consideration when investigating ion exchange in highsilica zeolites is the contribution of defect sites sio and frameworkterminating sioh groups to the ion exchange capacity. The journal of physical chemistry c 2016, 120 28, 1525115256. Zeolite ion exchange dwpf vitrification revised the proposed process would use a zeolite resin to remove sr, pu, u and a second zeolite resin to remove cs from the salt solution.
Ammonia removal and recovery from wastewater using natural zeolite. In any event, since an equivalent amount of sodium is given up for the unwanted ion, the amount of dissolved solids in the raw water is the same as in the effluent of a sodium cycle. Xrd diagrams of the starting zeolite nap c and the solid products of ion exchange. Hollow zeolite structures were selectively functionalized with transition metals or an organosilane on the interior surface of the hollow structure and in the zeolite shell. Ammonia removal and recovery from wastewater using natural. Jan 29, 2014 zeolite process for water softening has become a commercial success for the reason that zeolite can be easily regenerated. The preliminary work involved characterizing the lot of linde 4a used and establishing the equilibrium conditions. The research would benefit the design of zeolite composite optofunctional materials.
Ion exchange property of zeolite has been studied for many years, it is mostly used to modify the. The broad diffraction hump at a maxi mum near 14 is near where the 110 diffraction line should. They examined ba, ca, and laexchanged zeolite y and observe an increase in catalytic activity for all ionexchanged zeolites with the ba ones producing the lowest activity. We also took in account the ion release experimental results and the rigorous survey of the literature data when we positioned the ions in zeolite crystal structure. Investigation of ammonia removal from polluted waters by. Optimally ionexchanged zeolite x granules retained 97% of co2. Dec 2, 2012 merged process is also event stationary 5, section 1. The ion exchange of na for crk, crmg and crca in y and x zeolites was studied using breakthrough curves. Ammonia removal and recovery from wastewater using. Optimized cesium and potassium ionexchanged zeolites a and x. Pdf antimicrobial properties of zeolitex and zeolitea. This work is devoted to the study of copper ion positions in zeolite matrices. A representative ion exchange reaction is as follows.
The adsorption kinetics, mechanism and thermodynamics were studied. Pdf 4 mb acs publications american chemical society. First, we determine the distribution of al over the zeolite lattice. All further ion exchanges on zeolite rho were then carried out on nh 4 rho. Zeolites form a unique class of oxides, consisting of microporous, crystalline aluminosilicates that can be found in nature, or synthesized artificially. Electronic supplementary information hightemperature. As hard water percolates through zeolite bed, the hardness producing ions i. After surfactant modification, zeolite can absorb the anions and organic compounds. The base strength of the alkali zeolites are controlled by the kinds and quantities of ionexchanged cations and by the sial ratio of the main zeolite framework. Why do zeolites induce an unprecedented electronic state. Copper cations were exchanged in mordenite and zeolite x from aqueous solutions of different copper salts varying their concentrations. Investigation of the ionexchange behavior of zeolite y in. Such treatment allows for a fast zeolite particles which have been ion exchanged throughout this process were regenerated using 0.
Understanding the exact position and the detailed role of the al array in zeolites is essential for elucidating the origin of unique properties that can be derived from the metal ion exchanged in zeolite samples and for designing zeolite materials with high efficiency in catalytic and adsorption processes. The catalytic activities of iron ionexchanged zeolites depended on the zeolite structure and the iron ion exchange level. The ability to encapsulate transition metal species on the interior of the hollow zsm5 tubes and to exchange transition metals into the shell of the zeolite is important. Structural and ionexchange properties of natural zeolite intechopen. Structural and ionexchange properties of natural zeolite 263 lowest temperatures, approximately from 60c, and proceeds continuously over a broad temperature range up to 400c. The cobalt exchanged contents increased when the initial cono 3 2 solution concentration increased up to 0. Electronic state of copper in ionexchanged samples exchanged and dried at different temperatures was evaluated by xps spectroscopy. Coker b a chemistry department, university of southampton, highfield, southampton so 17 1bj, uk. Napc refers to the zeolite pbpc after being back exchanged with na. An ion exchanger is an insoluble substance that has the property of exchanging an ion which has been hung onto its structure with another ion in the water. The structural characteristics of the zeolite family make it unique among inorganic materials. Why do zeolites induce an unprecedented electronic state on.
This invention improves the ion exchange efficiency in zeolites by utilizing polymer solutions that do not damage the zeolite network. The ion exchange process has been around in nature since the beginning of time although not observed and quantified until the mid 1800s when sodium forms of naturally occurring zeolites were shown to convert exchange ammonium salts in solution to their sodium specie after passing through a bed of the zeolite which retained the ammonium ions. Change and improving of ammonium exchange capacity onto. Ionexchange studies of zeolites for selective removal of transition metal ions from mix solutions. Conventionally, ion exchange is carried out by suspending the zeolite powder in aqueous solutions of salts which. Hydrogen storage in ionexchanged zeolites sciencedirect. In this way, zeolite can adsorb many kinds of ions in sewage. Schematic description of the lattice of zeolite fau with re ionexchange positions iiii left and oxygen positions 14 right. Introduction to the structural chemistry of zeolites rau. Pdf metal ion exchange by natural and modified zeolites. Some of the more important zeolite types, most of which have been used in commercial applications, include the zeolite minerals mordenite, chabazite, erionite and clinoptilolite, the synthetic zeolite types a, x, y, l, zeolon mordenite, zsm 5, beta and mcm 22 and the zeolites f and w.
Zeolites, zeolite crystal structure, zeolite applications, zeolite. The activity coefficients in the external solution were calculated by means of. Download limit exceeded you have exceeded your daily download allowance. Pdf ionexchange properties of zeolites the ionexchange. Changing the characteristics and properties of zeolite y and nano. Three alcoholtooil ratios were tested at atmospheric pressure and at t115c for. The effects of the zeolite structure are in the order of mor fer mfi y ltl at 473 k. Pdf ion exchange properties of georgian analcime, phillipsite and scolecite have been studied. The calcium ion adsorption capacity of the modified zeolite a was 129.
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