Crystalline Zirconium Phosphate Research Articles

ChemInform Abstract: ION EXCHANGE IN FUSED SALTS. PART VII. ION‐EXCHANGE ISOTHERMS FOR THALLIUM(I)‐POTASSIUM AND RUBIDIUM‐POTASSIUM ON CRYSTALLINE ZIRCONIUM PHOSPHATE IN MOLTEN THALLIUM NITRATE‐POTASSIUM NITRATE AND RUBIDIUM NITRATE‐POTASSIUM NITRATE MIXTURES AT 360°C

Chemischer InformationsdienstVolume 8, Issue 3 Physical Inorganic Chemistry ChemInform Abstract: ION EXCHANGE IN FUSED SALTS. PART VII. ION-EXCHANGE ISOTHERMS FOR THALLIUM(I)-POTASSIUM AND RUBIDIUM-POTASSIUM ON CRYSTALLINE ZIRCONIUM PHOSPHATE IN MOLTEN THALLIUM NITRATE-POTASSIUM NITRATE AND RUBIDIUM NITRATE-POTASSIUM NITRATE MIXTURES AT 360°C S. ALLULLI, S. ALLULLISearch for more papers by this authorN. TOMASSINI, N. TOMASSINISearch for more papers by this authorM. A. MASSUCCI, M. A. MASSUCCISearch for more papers by this author S. ALLULLI, S. ALLULLISearch for more papers by this authorN. TOMASSINI, N. TOMASSINISearch for more papers by this authorM. A. MASSUCCI, M. A. MASSUCCISearch for more papers by this author First published: January 18, 1977 https://doi.org/10.1002/chin.197703023AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume8, Issue3January 18, 1977 RelatedInformation

Catalytic and Acidic Properties of Crystalline Zirconium Phosphate

The catalytic property and the acidity of crystalline zirconium phosphate have been studied in order to clarify the origin of the acidity of metal phosphate catalysts. Crystalline zirconium phosphate (c-ZrPhos) is a good model catalyst of metal phosphates because its crystal structure is well known and, therefore, it was possible to make more detailed discussion.Infrared diffuse reflectance spectra, X-ray diffraction patterns, and TG-DSC curves of c-ZrPhos calcined at various temperatures have been measured to characterise the structural changes caused by the calcination. The acidity-strength distribution curves of c-ZrPhos were very sharp as shown in Fig.6; there were distinctly two kinds of acid sites. The number of acid sites of c-ZrPhos calcined at low temperature (6.4 mmol/g) was nearly equal to the number of POH groups (6.64 mmol/g). The amounts of both acid sites varied with calcination temperature, reflecting the changes in the residual crystal water and hydroxyl group as shown in Fig.11 and 12. IR spectra of adsorbed pyridine and the composition of butene isomers formed in the dehydration of 1-butanol suggest that c-ZrPhos has Briinsted acid sites. It was concluded from these results that the weak acid site is POH group with strong interaction with crystal water and the strong acid site is free POH. This conclu- sion and the published data about amorphous phosphate suggest that the acid sites of on amorphous phosphate arise from metal cation.

Ion-exchange mechanism of some bivalent transition-metal ions on half-converted sodium and lithium forms of crystalline zirconium phosphate

The ion-exchange processes of Ni2+, Co2+, Cu2+, Mn2+, and Zn2+ on half-converted sodium and lithium (MI) forms of crystalline zirconium phosphate, ZrHMI(PO4)2·nH2O, occur in two steps from 0 to 80% and 80 to 100% conversion of the exchanger. Different ion-exchange mechanisms operate for the first step of exchange, depending on the proton activity in solution. Measurements on mixtures of transition-metal ions and fully converted metal(II) forms of zirconium phosphate, ZrMII(PO4)2·nH2O, show that the exchange is a non-equilibrium process.

Crystalline insoluble acid salts of tetravalent metals—XXVI: Ammonium and ammonia uptake on different ionic forms of crystalline zirconium phosphate

Ammonia and ammonium ion uptake by layered inorganic ion exchangers is of interest for potential use in the removal of ammonia and ammonium ions from human blood (renal dialysis machines) or from waste solutions. Data reported in the literature on the titration of Zr(HPO 4) 2·H 2O with (NH 4Cl + NH 3·H 2O) solutions seem indicate that H + NH 4 + exchange is possible and that contrary to the behaviour toward alkali metal ions, both the protons of the exchanger are exhibiting the same pK value toward ammonium ion. A detailed investigation on the mechanism of the formation of Zr(NH 4PO 4) 2·H 2O in the titration of Zr(HPO 4) 2·H 2O showed that this formation is not due to a direct H + NH 4 + exchange but to an addition of ammonia to the protons of the exchanger. The lack of direct H + NH 4 + exchange on Zr(HPO 4) 2·H 2O was ascribed to steric impediments since this exchange can be acheived on polyhydrated dihydrogen forms of crystalline zirconium phosphate where the steric impediments are overcome owing to their large interlayer distance. The Na + NH 4 + ion exchange isotherm on Zr(NaPO 4)(HPO 4)·5H 2O and the K + NH 4 + isotherm on Zr(KPO 4) 2·3H 2O also have been investigated and discussed. Polyhydrated dihydrogen forms of zirconium phosphate seem to be good materials for removal of both ammonia and ammonium ions.

Gas adsorption studies on ion-exchanged forms of crystalline zirconium phosphate

Gas-solid chromatography was used to measure the heats of adsorption of eight aromatic and aliphatic adsorbates on crystalline α-zirconium phosphates. Four cation-exchanged phosphates were examined. Evidence was that both aromatic and aliphatic hydrocarbons were physically adsorbed in such a manner as to be screened from the cations in the cavities that are present in the zirconium phosphates. Surface areas are measured to enable entropies to be calculated. Entropy values are used to suggest modes of adsorption on to the crystalline surfaces.

Crystalline insoluble acid salts of tetravalent metals—XXI ion exchange mechanism of alkaline earth metal: Ions on crystalline ZrHNa(PO 4) 2·5H 2O

The monosodium form of crystalline zirconium phosphate, owing to its interlayer distance being much larger than that of the dihydrogen form, is able to exchange large divalent cations such as Ba 2+ or hydrated Mg 2+. A detailed investigation of the ion exchange mechanism of alkaline earth ions with ZrHNa(PO 4) 2·5H 2O has been carried out. In neutral or slightly acidic medium it behaves as a monofunctional exchanger towards Mg 2+ and Sr 2+; only Na + being replaced to give the phases ZrHMg 0·5(PO 4) 2·3H 2O and ZrHSr 0·5(PO 4) 2·3·6H 2O. Ba 2+-exchange is more complicated since this ion is able to replace both H + and Na + from ZrHNa(PO 4) 2·5H 2O, so that several irreversible ion exchange processes, each giving different solid phases, occur simultaneously. However, by using suitable experimental conditions, the phases ZrHBa 0·5(PO 4) 2·4H 2O, ZrH 0·4Ba 0·8(PO 4) 2·2·5H 2O and even the full Ba 2+-form, ZrBa(PO 4) 2·2·5H 2O, have been prepared. Ca 2+-behaviour is intermediate between that of Sr 2+ and Ba 2+. All the examined processes occur with a discontinuous rearrangement of the crystal structure of ZrHNa(PO 4) 2·5H 2O and the phases formed have been characterized by their X-ray diffraction patterns. The rates of the ion exchange processes of Ca 2+, Sr 2+ and Ba 2+ were appreciably higher than that of Mg 2+. A very high selectivity of ZrHNa(PO 4) 2·5H 2O for alkaline earth metal ions was found; this indicates new practical applications for crystalline zirconium phosphate.

On the mechanism of ion exchange in zirconium phosphates—XIII: Exchange of some divalent transition metal ions on α-zirconium phosphate

The exchange of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) on crystalline zirconium phosphate has been examined. High loadings may be achieved by using dilute acetate solutions of the cations at elevated temperatures. The exchange does not represent a true equilibrium since “site binding” traps the ions within the crystal lattice. This is reflected in the essentially complete removal of ions from solution up to high loadings. Nickel ion represents an exception as it is only loaded to a modest extent. Possible explanations for the observed behavior are presented.

Ion exchange in fused salts. Part VII. Ion-exchange isotherms for thallium(I)–potassium and rubidium–potassium on crystalline zirconium phosphate in molten thallium nitrate–potassium nitrate and rubidium nitrate–potassium nitrate mixtures at 360 °C

Ion-exchange isotherms for Tl+–K+ and Rb+–K+ on crystalline zirconium phosphate in molten Tl[NO3]–K[NO3] and Rb[NO3]–K[NO3] mixtures are almost fully reversible processes which occur in several steps either via a two-phase transition or a solid–solution mechanism. There is a strong dependence of the gradients of the isotherms on the polarisability of the exchanging cations, and some of the equilibrium constants have been calculated.

Uptake of pyridine and n-butylamine by crystalline zirconium phosphate

The titration curve of the hydrogen form of crystalline α-zirconium phosphate with pyridine shows only one end point and a phase Zr(C 5H 5NHPO 4) 0·45(HPO 4) 1·55 · H 2O with a basal spacing 10·9 Å is formed. The titration titration curve with a stronger base n-butylamine exhibits two plataux, showing the amine uptake to be a two-step process, and two phases formed through the process are Zr(C 4H 9NH 3PO 4) 1·34(HPO 4) 0·66 · H 2O and Zr(C 4H 9NH 3PO 4) 2·0 · H 2O with basal spacings 18·2 and 18·8 Å, respectively. Sodium ion-exchanged forms of crystalline α-zirconium phosphates also form complexes with pyridine and n-butylamine. The pH values of the amine solutions in this case differ from the case of the hydrogen form of the phosphates. On the basis of the uptake behaviors of pyridine and n-butylamine, two mechanisms of the complex formation of crystalline α-zirconium phosphates with these amines are proposed as follows: (1) Exchange reaction of interlayer cations of crystalline α-zirconium phosphate with pyridinium and n-butylammonium cations; (2) Intercalation reaction of these unionized organic bases into the interlayer spaces.

Studies on the ammonium form of crystalline zirconium phosphate—I: Ammonium-sodium ion exchange isotherms

The isotherms for NH 4 +/Na + exchange on crystalline zirconium phosphate have been investigated at 25°C. The isotherms obtained show a hysteresis loop. When sodium ion replaces the ammonium ion in the exchanger, the exchange proceeds in two steps. First the formation of the intermediate phase is observed, and subsequently this is converted to the sodium form. As the two steps take place for the very close mole fractions of sodium ion in the solution, the process is observed as a single one. When ammonium ion replaces the sodium ion in the exchanger the sodium form is converted into the ammonium form directly.

Characterisation and electronic properties of some inorganic ion exchangers of the zirconium phosphate type containig transition-metal ions

A series of transition-metal-ion forms of crystalline zirconium phosphate of general formula ZrM(PO4)2·4H2O (M = ZnII, CuII, NiII, CoII, and MnII) has been characterised. The visible–near U.V. spectra of the copper, nickel, and cobalt species indicate the presence of an octahedral stereochemistry (tetragonally distorted in the case of CuII). The dehydration of the exchangers has been followed using thermal and X-ray powder techniques and electronic spectra. Magnetic-susceptibility measurements have also been used (where possible) to support structural assignment. Complete dehydration occurs only atca. 450 °C with a change in stereochemistry for the compounds of NiII and CoII. At higher temperature the layer structure is lost and the materials become double phosphates, MZr(PO4)2. Possible stereochemistries for the anhydrous forms are discussed.

Crystalline insoluble acid salts of tetravalent metals—XXIII: Preparation and main ion exchange properties of highly hydrated zirconium bis monohydrogen orthophosphates

The conversion of Zr(HPO 4) 2 · H 2O into ZrHNa(PO 4) 2 · 5H 2O, followed by regeneration with dilute solutions of HCl, yields a mixture of zirconium phosphate materials with various degrees of hydration and different interlayer distances. The relative amounts of the hydrated phases in the mixture were strongly dependent on the method of preparation of the employed Zr(HPO 4) 2 · H 2O. Under appropriate experimental conditions, 100% of a phase having an interlayer distance of 10.4 Å (already reported as Zr(HPO 4) 2 · 8H 2O and called ϑ-ZP) has been obtained. The stability of the various hydrated phases in HCl solutions of different concentrations was investigated and a valuation of their water content was attempted. The ion exchange properties of ϑ-ZP for alkali, alkaline earth and some divalent transition metal ions have been investigated in detail and a comparison with the ion exchange properties of Zr(HPO 4) 2 · H 2O is made. ϑ-ZP and other highly hydrated dihydrogen phases, owing to their expanded interlayer distance, can easily exchange several cations which are not, or only slowly, exchanged on the monohydrate dihydrogen form due to steric hindrance. This fact considerably enlarges the practical use of crystalline zirconium phosphate.

SODIUM ISOTOPIC EXCHANGE RATE BETWEEN CRYSTALLINE ZIRCONIUM PHOSPHATE AND MOLTEN NaNO3

Abstract The isotopic exchange rate of sodium ion between crystalline zirconium phosphate and molten NaNO3 has been measured at 312°C and 362°C by batch method. The equilibrium was reached within 20 minutes at either temperature, and the rate was very rapid as compared with that of sodium-potassium ion exchange.

Crystalline insoluble acid salts of tetravalent metals—XX Forward and reverse Cs +/H + and Rb +/H + ion exchange on crystalline zirconium phosphate

Forward and reverse Cs +/H + and Rb +/H + ion exchange have been investigated by the batch-procedure in 3rder to obtain both the titration and uptake curves, as well as X-ray diffractograms and water contents of the samples at the various Cs + or Rb +-loadings. The interlayer distance of the exchanger increases discontinuously with increasing Cs +-loading and three different phases, ZrHCs(PO 4) 2.2H 2O, ZrH 0·5Cs 1·5(PO 4) 2.3H 2O, and Zr(CsPO 4) 2.6H 2O with interlayer distances of 11·3, 11·7 and 14·2 Å, respectively, have been found in the forward process. For the analogous Rb +-ion exchange process the phases were ZrH 0·5Rb 1·52H 2O (10·6 Å) and Zr(RbPO 4) 2.H 2O (9·2 Å). Reverse ion exchange processes both for Cs + and Rb + ions showed a considerable irreversibility especially in the range of 0–50 per cent Cs + or Rb +-loadings. The replacement of both Cs + and Rb + ions by H + ions occurred together with the formation of solid solutions and therefore the large ion exchange hysteresis loops were ascribed to the formation of different phases in the forward and reverse processes. The X-ray diffraction patterns of the various Rb + and Cs +-phases dried under different conditions are reported. Finally, a general discussion of the Cs + or Rb +-ion exchange behavior on zirconium phosphate at various degree of crystallinity is made. It is concluded that the low, apparent selectivity of crystalline zirconium phosphate towards large monovalent ions is due to steric hindrance and therefore enlarged phases of this exchanger, such as Zr(HPO 4) 2.8H 2O (10·4 Å), are expected to have a high selectivity towards Cs + or even larger cations.

ChemInform Abstract: ION EXCHANGE IN FUSED SALTS PART 6, A NEW PHASE OF THE CRYSTALLINE DILITHIUM FORM OF THE ZIRCONIUM PHOSPHATE AND ITS INFLUENCE OF LI/K AND LI/NA ION EXCHANGE ISOTHERMS IN MOLTEN (LI‐K)NO3 AND (LI‐NA)NO3 MIXTURES AT 300 C

AbstractEine metastabile Dilithiumverbindung von kristallinem Zr‐phosphat wird röntgenographisch und durch DTA untersucht.

Ion exchange in fused salts—VI: A new phase of the crystalline dilithium form of the zirconium phosphate and its influence of Li/K and Li/Na ion exchange isotherms in molten (LiK)NO 3 and (LiNa)NO 3 mixtures at 300°C

A metastable dilithium form of crystalline zirconium phosphate, obtained by percolating molten LiNO 3 at 300°C on the dipotassium form, has been characterized by X-ray and DTA analyses. Reversible Li/K and Li/Na ion exchange isotherms in molten (LiK)NO 3 mixtures at 300°C have been obtained by employing the metastable dilithium form as starting material. The calculated equilibrium constants show that, for the equilibrium Zr(LiPO 4) 2 ⇌ ZrLiMe(PO 4) 2, the order of selectivity is Li ⩾ Na > K. The results indicate a strong influence of the interlayer spacing of the exchanger on its ion exchange behaviour.

Recent progress in the field of synthetic inorganic exchangers having a layered or fibrous structure

In the first part, recent results on crystalline insoluble acid salts of tetravalent metals having a layered structure are critically examined. The dependence of the interlayer distance of crystalline zirconium phosphate on its water content and counter ions is discussed and an ion-exchange mechanism for monovalent and divalent ions, in both aqueous and molten salt mediam, is proposed. Furthermore, the effect of the degree of crystallinity of zirconium phosphate on its ion-exchange properties and electrical conductivity, the dependence of its selectivity for large cations on steric hindrance and the catalytic effect of small amounts of sodium ions on the exchange of large hydrated cations are also discussed. Other layered exchangers, such as zirconium arsenate and titanium phosphate, are also considered and some general points on their ion-exchange properties as a function of the tetravalent metal ion and polybasic acid groups involved are made. The second part deals with the synthesis and ion exchange properties of fibrous inorganic ion exchangers with special regard to fibrous cerium(IV) phosphate. In the third part, some practical applications of the exchangers examined, in both ion-exchange and electrochemical processes, are reported.

ChemInform Abstract: CRYSTALLINE INSOLUBLE ACID SALTS OF TETRAVALENT METALS, PART 18, ION EXCHANGE PROPERTIES OF CRYSTALLINE ZRNAH(PO4)2.5H2O TOWARDS ALKALI METAL IONS

AbstractEs zeigt sich, daß im pH‐Bereich 3 bis 5 das H ‐ Ion nicht ausgetauscht wird und nur das Na ‐ Ion gegen Alkalimetalle ausgetauscht wird.

The Ion-exchange Behavior of Some Cations on Crystalline Zirconium Phosphate

Abstract The distribution coefficients of Ag+, Tl+, K+, NH4+, Mg2+, Ca2+, Sr2+, Ba2+, Co2+, Zn2+, Y3+, and Ce3+ have been determined on a crystalline zirconium phosphate ion-exchanger in chloride solution media, and the affinity sequences are presented. pH titration curves and X-ray powder diffraction data were obtained for calcium and barium ions. The ion-exchange capacity of the exchanger for barium ions was found to be 4.4 meq/g, but the X-ray powder patterns were rather unusual as compared to those of other ions studied previously.

Crystalline insoluble acid salts of tetravalent metals—XVIII: Ion exchange properties of crystalline ZrNaH(PO 4) 2. 5H 2O towards alkali metal ions

The ion exchange behaviour of crystalline ZrNaH(PO 4) 2. 5H 2O towards alkali metal ions has been investigated. It was found that, in the pH range 3–5, hydrogen ion is not exchanged and only Na +-alkali metal ion exchanges take place. Forward and reverse Na +-K +, Na +-Li +, K +-Li + and Na +-Cs + ion exchange isotherms have been determined and discussed comparatively with the results obtained previously with fully-substituted alkali metal ionic form of zirconium phosphate. The exchanges occur with phase transitions and small hysteresis loops have been observed between the isotherms of the two opposite processes. The sequence of decreasing alkali metal ion preference is K + > Cs + > Na + > Li + and a very high selectivity towards K + or Cs + ion has been found. Thus, differently from Zr(HPO 4) 2. H 2O, the monosodium form exhibits preference for large cations and this different behaviour may be due to the large difference in the interlayer distances of the two ionic forms (7·56 and 11·8 Å respectively). The uptake of large ions by enlarged crystalline zirconium phosphate discloses new practical applications for such an exchanger.