Clean Ion-Exchange Technologies. I. Synthesis of Chlorine-Free Potassium Fertilizers by an Ion-Exchange Isothermal Supersaturation Technique

Muraviev, Dmitri; Хамизов, Р. Х.; Тихонов, Н. А.; Krachak, A. N.; Zhiguleva, and Tatyana I.; Fokina, O. V.

doi:10.1021/ie970690o

Cited by 15 publications

(9 citation statements)

References 13 publications

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“…In the case of Ca 2+ , the observed increase in the degree of conversion in comparison with the bi-phasic system may be attributed to the 'supersaturation' effect that occurs in the mixed bed system. This supersaturation stabilizes the solution within the column interstitial space and the eluate collected can start to crystallize either spontaneously, 27,28 or after a certain period of time. 10 Thus, both Ca 2+ and F − would benefit from such an effect, but it is only noticed for Ca 2+ because of its low values.…”

Section: Resultsmentioning

confidence: 99%

Calcium and fluoride release from ion exchange polyphasic systems

Torrado

Valiente

2003

J of Chemical Tech & Biotech

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The present study concerns the kinetics of ion exchange accompanied by CaF 2 precipitation in tri-phasic and quadri-phasic systems involving a weak base anionic exchanger and a carboxylic cationic exchanger in the F − and Ca 2+ forms, respectively, in contact with a solution of artificial saliva. It was shown that in both systems the rate of Ca 2+ release from the cationic exchanger is much lower than that of F − from the anionic one. The rate of release for both ions, controlled by intraparticle diffusion, has been characterized by a Fick's law model. The kinetic parameters of effective rate of release (B) and diffusion coefficient (D) of the respective ion in the resin phase depend on the type of resin and the presence of different numbers of phases. The amount of the precipitate crystallizing on the surface of the resin beads depends on the type of the ion exchange resin, its particle size and on the ratio of resin components. By varying this ratio and the particle size of the ion exchangers it is possible to accomplish the precipitation mostly on the larger surface of the ionic exchanger.

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Section: Resultsmentioning

confidence: 99%

Calcium and fluoride release from ion exchange polyphasic systems

Torrado

Valiente

2003

J of Chemical Tech & Biotech

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“…Three previous articles in this series were also focused on the development of GIET-type processes for (1) the ion-exchange synthesis of chlorine-free potassium fertilizers, 9 (2) the recovery of high-purity magnesium compounds from seawater, 10 and (3) the temperatureenhanced ion-exchange synthesis of potassium hydroxide. 11 The present work reports the results on the further development of the GIET concept obtained by the development of an optimal ion-exchange material for the self-sustaining process of the decalcification of highly mineralized waters (seawater).…”

Section: Introductionmentioning

confidence: 99%

Clean (“Green”) Ion-Exchange Technologies. 4. High-Ca-Selectivity Ion-Exchange Material for Self-Sustaining Decalcification of Mineralized Waters Process

Muraviev

Хамизов

Тихонов

et al. 2004

Ind. Eng. Chem. Res.

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This paper (the fourth in a series) reports the results of a theoretical and experimental study of the decalcification of seawater on different ion-exchange sorbents by simultaneous use of electroselectivity reversal and ion-exchange isothermal supersaturation (IXISS) effects. A detailed evaluation of the influence of the sorbent properties on the efficiency of the IXISS-based selfsustaining seawater decalcification process was carried out through a series of computer experiments using a mathematical model of the dynamics of ion exchange. It was found that the best sorbent to be used in the process is a modified A-type zeolite. The modification of the zeolite includes sequential treatment of the initial ion exchanger with dilute magnesiumcontaining solution (or seawater) and concentrated sodium salt solution. The first treatment was carried out at elevated temperature [15-20°C higher than the temperature at which the modified zeolite (MZ) is expected to be used, T ex ], and the second was performed at T ex . The complete regeneration of the MZ after the calcium sorption cycle was carried out with the calciumfree brine produced by the seawater desalination unit. The process is continuous and operates in the closed-cycle mode.

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“…The first two papers of this series reported the results obtained by studying the IE synthesis of chlorine-free potassium fertilizers (Muraviev et al, 1998a) and the high-purity magnesium compounds by using seawater as the initial magnesium source (Khamizov et al, 1998). The present (third) paper is dedicated to the IE synthesis of potassium hydroxide.…”

Section: Introductionmentioning

confidence: 99%

Clean Ion-Exchange Technologies. 3. Temperature-Enhanced Conversion of Potassium Chloride and Lime Milk into Potassium Hydroxide on a Carboxylic Ion Exchanger

Muraviev

Noguerol

Gaona

et al. 1999

Ind. Eng. Chem. Res.

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This paper reports the results obtained by studying the ion-exchange synthesis of potassium hydroxide from lime milk and carboxylic resin Lewatit CNP 80 in the K-form. Carboxylic resin has been shown to have several advantages in comparison with, for example, sulfonate ion exchanger, due to its higher selectivity toward Ca2+, which substantially enhances at elevated temperature. The increase of temperature from 293 to 333 K enhances the sorption of Ca2+ versus K+ that allows achieving far higher KOH concentration in the solution phase. The values of equilibrium separation factor, α, for Ca2+−K+ exchange have been determined at 293 and 333 K by varying the equivalent fraction of Ca2+ in the solution phase from 0.04 to 0.7. A remarkable increase of α values has been observed at higher temperatures and at low calcium content in the solution phase. The regeneration of the resin (conversion from Ca- to K-form) has been carried by using the mixtures of potassium chloride and potassium sulfate. The regeneration process under these conditions is accompanied by the ion-exchange isothermal supersaturation of calcium sulfate, which forms a stable supersaturated solution in the resin bed. After leaving the column, CaSO4 crystallizes spontaneously, which allows reuse of the regenerating solution following the complete elimination of the Ca2+ admixture with a small amount of K2CO3. The precipitates of calcium sulfate and calcium carbonate are the only wastes produced in the process. The complete regeneration of the resin has been shown to require a nearly 70-fold excess of the regenerant; nevertheless, the decrease in the degree of resin regeneration from 100 to 80% allows reduction of the amount of the regenerant by more than 2 times. The use of incompletely regenerated resin for the synthesis of KOH does not decrease remarkably the efficiency of the process. The flow sheet of the proposed process is presented and discussed.

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Clean Ion-Exchange Technologies. I. Synthesis of Chlorine-Free Potassium Fertilizers by an Ion-Exchange Isothermal Supersaturation Technique

Cited by 15 publications

References 13 publications

Calcium and fluoride release from ion exchange polyphasic systems

Calcium and fluoride release from ion exchange polyphasic systems

Clean (“Green”) Ion-Exchange Technologies. 4. High-Ca-Selectivity Ion-Exchange Material for Self-Sustaining Decalcification of Mineralized Waters Process

Clean Ion-Exchange Technologies. 3. Temperature-Enhanced Conversion of Potassium Chloride and Lime Milk into Potassium Hydroxide on a Carboxylic Ion Exchanger

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