Crystalline Zirconium Phosphate Research Articles

Polymer-encapsulated crystalline zirconium phosphates as NH4+ and K+ ion exchangers for application in sorbent dialysis cartridges

The ion exchange properties of crystalline ⍺- and γ-zirconium phosphates in the sodium and hydrogen forms were investigated. The zirconium phosphates were synthesized by a mechanochemistry-assisted protocol. Amongst the compounds, ⍺-Na2-zirconium phosphate and γ-H2-zirconium phosphate were found to be excellent ion exchangers for NH4+ and K+ ions, two key cations in renal sorbent dialysis systems. The maximum NH4+ uptake by ⍺-Na2-zirconium phosphate was 5.5 mmol/g, close to the theoretical limit of exchangeable sites. In multi-ion solutions, γ-H2-zirconium phosphate was a selective exchanger for K+ with total uptake capacity of 2.9 mmol/g. The as-synthesized microcrystalline zirconium phosphates were encapsulated by polyacrylonitrile to form spherical porous beads of tailorable sizes. Owing to the porosity, access to the ion exchange sites of the embedded zirconium phosphates particles was unaffected, enabling fast kinetics in the uptake of NH4+ and K+. In this form, the PAN/ZrP beads can be easily handled in sorbent cartridges. The activity of the PAN/ZrP beads could be fully restored by simple regeneration with the appropriate electrolyte.

Ionothermal synthesis of a highly crystalline zirconium phosphate proton conductor.

A highly crystalline one-dimensional zirconium phosphate, (NH4)2[ZrF(PO4)(HPO4)] (ZrP-3), was facilely synthesized by the ionothermal method. The robust structure and rich hydrogen-bonded network make ZrP-3 an excellent proton conductor by having a proton conductivity higher than 10-2 S cm-1 at 90 °C and 95% RH. The remarkable stability makes ZrP-3 a promising solid electrolyte material for proton exchange membrane fuel cells.

HF-Free Synthesis of α-Zirconium Phosphate and Its Use as Ion Exchanger for Separation of Nd(III) and Dy(III) from a Ternary Co–Nd–Dy System

The recovery of Nd and Dy from a ternary Co-Nd-Dy system using layered crystalline zirconium phosphate (alpha-ZrP) was investigated. alpha-ZrP was synthesized by the refluxing method, and subsequently characterized by sodium hydroxide titration, Fourier transform-infrared spectrometry, thermogravimetry, scanning electron microscopy, and X-ray diffraction. The selectivity and ion exchange kinetics of the alpha-ZrP material were determined with regard to the individual elements. The influence of solution pH on the uptake was studied in ternary 1 and 2 mM equimolar solutions. The results showed that in acidic solution (pH 1-3), very little Co was taken up, while Nd and Dy uptakes were at reasonable levels (0.5-0.6 meq/g). The uptake isotherms of Nd, Dy, and Co were measured separately at pH 2.5 and 4.5 in ternary equimolar solution series. At pH 4.5, the loading capacities were about 0.2 meq/g for Co, 1.1 meq/g for Nd, and 1.5 meq/g for Dy. Dy was thus clearly preferred over Nd by alpha-ZrP. The loading of an alpha-ZrP column showed a similar preferred pattern. Nitric acid eluent removed Co, Nd, and Dy, but there was no separation of the metals in the eluate. A mixture of nitric and phosphoric acids, however, produced a strong separation. Co was very weakly retained in the column, and the ratio Dy/Nd in the eluent was in the range of 2-7. Thus, the alpha-ZrP material showed encouraging ion exchange properties for the separation and recycling of Nd and Dy from a ternary Co-Nd-Dy system. Much more work is needed, however, to develop a practical separation flowsheet.

Synthesis and study of the chemical stability and strength of zirconium phosphates with the structure of langbeinite with imitators of high-level radioactive waste (HLRW)

Crystalline zirconium phosphates with the langbeinite structure containing macroquantities of elements that imitate high-level radioactive waste (HLRW) (Cs 4.6 wt %, Sr 6.2 wt %, La 10.0 wt %, or U4+ 11.6 wt %) have been synthesized. To impart finely the dispersed materials with the necessary rheological properties, they have been made more compact with the addition of an 2.4–4.4 wt % aluminophosphate binder. The rate of leaching (logR) of the prepared langbeinite samples in distilled water at room temperature for 100 days decreased to–6.1 (Cs),–5.4 (Sr),–5.5 (La), and–5.6 (U) g/(cm2 day) with a noticeable trend toward further reduction, which meets, in practical terms, the requirements for the matrix material used for HLRW management. The samples’ axial compression strengths after leaching tests varied from 600 to 1100 kg/cm2.

Thermodynamic properties of crystalline magnesium zirconium phosphate

Heat capacity \( C_{\text{p}}^{^\circ } \)(T) of crystalline magnesium zirconium phosphate was measured between 6 and 815 K. The experimental data obtained were used to calculate the standard thermodynamic functions \( C_{\text{p}}^{^\circ } \)(T), H°(T) − H°(0), S°(T), G°(T) − H°(0) over the temperature ranging from T → 0 to 810 K and standard entropy of formation at 298.15 K. The fractal dimension of Mg0.5Zr2(PO4)3 was calculated from experimental data on the low-temperature (6 ≤ T/K ≤ 50) heat capacity, and the topology of the phosphate’s structure was estimated. Thermodynamic properties of structurally related phosphates M0.5Zr2(PO4)3 (M = Mg, Ca, Sr, Ba, Ni) were compared.

Effect of treatment temperature on the immobilization of Cs and Sr to HZr2(PO4)3 using an autoclave

Abstract The proton-type crystalline zirconium phosphate, HZr 2 (PO 4 ) 3 , was used to immobilize Cs + or Sr 2+ by mixing HZr 2 (PO 4 ) 3 and an aqueous solution of CsNO 3 or Sr(NO 3 ) 2 in an autoclave at 160–400 °C. The Cs or Sr immobilized HZr 2 (PO 4 ) 3 was further kept in the open air at 300–700 °C. The effect of treatment temperature on the immobilized amount of Cs or Sr in HZr 2 (PO 4 ) 3 and the leaching rate of Cs or Sr from its immobilized HZr 2 (PO 4 ) 3 was discussed from the standpoint of crystalline structure. The immobilization and the stabilization of Cs or Sr in HZr 2 (PO 4 ) 3 produced in an autoclave at 250 °C were better achieved by additional thermal treatment in the open air at 700 °C.

Immobilization of alkali, alkaline-earth and rare-earth elements by crystalline zirconium phosphate HZr<sub>2</sub>(PO<sub>4</sub>)<sub>3</sub>

Immobilization of alkali, alkaline-earth and rare-earth elements by crystalline zirconium phosphate HZr<sub>2</sub>(PO<sub>4</sub>)<sub>3</sub>

Separation of lanthanum, hafnium, barium and radiotracers yttrium-88 and barium-133 using crystalline zirconium phosphate and phosphonate compounds as prospective materials for a Ra-223 radioisotope generator

Crystalline hybrid organic/inorganic ion exchangers based on zirconium phosphate and phosphonate compounds were evaluated for application in radium-223 generator for radiopharmaceutical applications. Various compositions were synthesized and the selectivity of these materials was determined for inactive lanthanum, hafnium and barium, and radiotracers yttrium-88 and barium-133. The hybrid materials show very efficient lanthanum/barium separation; the response for zirconium phosphate was even better. A small-scale column loaded with pelletized zirconium phosphate compound demonstrated excellent retention of (88)Y and release of (133)Ba.

Effect of the preparation conditions of zirconium phosphate on the characteristics of Sr immobilization

The proton-type crystalline zirconium phosphate, HZr 2(PO 4) 3, was obtained by a thermal decomposition of NH 4Zr 2(PO 4) 3 at different temperatures from 400 to 800 °C, where NH 4Zr 2(PO 4) 3 was obtained in advance by a hydrothermal synthesis using a mixed solution of ZrOCl 2, H 3PO 4 and H 2C 2O 4 with different processing times from 5 to 72 h. Sr ion was immobilized to HZr 2(PO 4) 3 by treating the mixture of HZr 2(PO 4) 3 and Sr(NO 3) 2 aqueous solution in an autoclave at 250 °C. Immobilizing and leaching performance of St in HZr 2(PO 4) 3 were discussed.

ChemInform Abstract: Heterogeneous Catalysis of Nucleophilic Substitution.

The opening of an epoxide ring by attack of a nucleophile can be catalysed by the heterogeneous catalyst, crystalline polymeric zirconium phosphate.

Thermodynamic properties of crystalline phosphate Ba0.5Zr2(PO4)3 over the temperature range from T → 0 to 610 K

Abstract The temperature dependence of the heat capacity of crystalline barium zirconium phosphate Cpo = f(T) was measured over the temperature range 6–612 K. The experimental data obtained were used to calculate the standard thermodynamic functions Cpo(T), H°(T) − H°(0), S°(T), G°(T) − H°(0) over the temperature range from T → 0 to 610 K and standard entropy of formation at 298.15 K. The data on the low-temperature (6 ≤ T/K ≤ 50) heat capacity were used to determine the fractal dimension of Ba0.5Zr2(PO4)3. Conclusions concerning the topology of the structure of phosphate were drawn. Thermodynamic properties of M0.5Zr2(PO4)3 (M = Ca, Sr, Ba) were compared.

Immobilization of Cs and Sr to HZr2(PO4)3 using an autoclave

The proton-type crystalline zirconium phosphate, HZr2(PO4)3, was prepared by a thermal decomposition of NH4Zr2(PO4)3 at about 450°C, where NH4Zr2(PO4)3 was obtained in advance by a hydrothermal synthesis using a mixed solution of ZrOCl2, H3PO4 and H2C2O4. Cs or Sr ion was immobilized to HZr2(PO4)3 by mixing HZr2(PO4)3 with an aqueous solution of CsNO3 or Sr(NO3)2 under the molar ratio CsNO3/HZr2(PO4)3=1.0 or Sr(NO3)2/HZr2(PO4)3=0.5. The mixtures were treated thermally in an autoclave at different temperatures from 200 to 275°C and Arrhenius equation was applied to the Cs and Sr immobilization process to HZr2(PO4)3. The activation energy for the immobilization process of Cs or Sr was estimated as 179kJmol−1 and 186kJmol−1, respectively.

A comparative study on lead sorption by amorphous and crystalline zirconium phosphates

In the present study amorphous and crystalline zirconium phosphate (ZrP) were synthesized to explore their different behavior towards lead sorption. Both sorbents were characterized by X-ray diffraction (XRD), pH-titration and X-ray photoelectron spectroscopy (XPS). Lead sorption onto both sorbents was found to be pH-dependent due to the ion-exchange mechanism. Sorption isotherms onto both sorbents can be well correlated by Langmuir model. By comparison with crystalline ZrP, the amorphous one exhibited more favorable sorption of lead ion particularly in terms of high capacity and selectivity, as indicated by the qm values from Langmuir model (1.50mequiv./g for amorphous ZrP and 0.20mequiv./g for crystalline ZrP) and the distribution coefficients even several orders higher than crystalline ZrP when calcium ion coexisted at a high level in solution. Besides, rapid sorption kinetics were observed for both sorbents, and both lead-laden sorbents were amenable to an efficient regeneration by dilute HCl solution. Results indicated that amorphous ZrP can be selected as an ideal inorganic exchanger in the preparation of inorganic-polymer composites for heavy metals removal from water.

The heat capacity and standard thermodynamic functions of Ni0.5Zr2(PO4)3 phosphate over the temperature range from T → 0 to 664 K

The temperature dependence of the heat capacity of crystalline nickel zirconium phosphate C°p = f(T) was measured over the temperature range 6–664 K. The experimental data obtained were used to calculate the standard thermodynamic functions of Ni0.5Zr2(PO4)3 from T → 0 to 664 K. The standard entropy of phosphate formation from simple substances at 298.15 K was calculated from the absolute entropy of the compound. The data on the low-temperature heat capacity were used to determine the fractal dimension of Ni0.5Zr2(PO4)3 over the temperature range 30–50 K. Conclusions concerning the heterodynamic characteristics of the structure of Ni0.5Zr2(PO4)3 were drawn.

Immobilization of Harmful Metallic Elements in HZr2(PO4)3

Several harmful metal ions (M=Mn(II), Cu(II), Zn(II), Cd(II) and Pb(II)) were completely immobilized in the crystalline zirconium phosphate, HZr2(PO4)3, by thermal-treating the mixture of M(NO3)2 and HZr2(PO4)3 under the molar ratios of M(NO3)2/HZr2(PO4)3=0.1-0.5 at 700°C for 5 h. The XRD analyses suggested that all the M(II) immobilized products have the same structure as that of the NASICON-type HZr2(PO4)3. Such immobilized products were subjected to the leaching test of M(II) ion in 1 mol•dm-3 HCl at 160°C for 24 h. For the M(II) immobilized products with the ratio of M(NO3)2/HZr2(PO4)3=0.5, the leaching rate was decreased with the increase in ionic radius of M(II).

Hydrothermal synthesis and characterization of microporous crystals of trivalent metal-containing zirconium phosphates

Two organically templated trivalent metal-containing crystalline zirconium phosphate materials FeZrPO-8 and AlZrPO-8 have been prepared hydrothermally by using fluoride as a mineralizer, and 1,6-diaminohexane (DAH) as templates. The powder XRD patterns indicate that the as-synthesized products are new materials. Substitutions of Al 3+ or Fe 3+ into Zr 4+ sites were confirmed by a combination of powder X-ray diffraction (XRD) and nuclear magnetic resonance (NMR) studies. The thermal behavior of the title compounds have been investigated using TG-DTA and X-ray thermodiffractometry, which indicated that the inorganic framework of the compounds are thermally stable up to ∼400 °C.

Sensitization of Luminescence of Europium Compounds on Solid Matrices by Terbium (III) Ions

The conditions of sensitization of the luminescence of Eu(III) by Tb(III) ions in complexes with inorganic (Na2WO4) and organic (nalidixic acid) ligands in sorbates on solid matrices (zeolite CaX and crystalline zirconium phosphate (ZrP)) and in coprecipitation with CaWO4 have been investigated. It has been established that the maximum sensitization of the europium luminescence is attained in the case where Eu and Tb are present in a 1:0.5 ratio. In this case, the integral intensity of luminescence of Eu(III) (the band with λmax = 612 nm) in the sorbate of its complex with nalidixic acid on ZrP accounts for more than 60% of the luminescence intensity of the industrial photoluminophor Y2O3:Eu (FL-612) possessing red luminescence, and the intensity of Tb(III) luminescence (the band with λmax = 545 nm) accounts for about 40% of the luminescence intensity of the photoluminophor Gd2O2S:Tb possessing green luminescence.

Synthesis of the novel layered amorphous and crystalline zirconium phosphate–phosphonates Zr(HPO4)[O3PCH2N(CH2CH2)2O]·nH2O, Zr(HPO4)[O3PCH2N(CH2CO2H)2]·nH2O, zirconium phosphonates Zr[(O3PCH2)NCH2CO2H]·nH2O and the catalytic activities of their palladium complexes in hydrogenation

Abstract The layered amorphous and crystalline samples of zirconium [ N -(phosphonomethyl)morpholine-phosphate] Zr(HPO 4 )[O 3 PCH 2 N(CH 2 CH 2 ) 2 O]· n H 2 O (1a, 2a), zirconium [ N -(phosphonomethyl)iminodiacetic acid-phosphate] Zr(HPO 4 )[O 3 PCH 2 N(CH 2 CO 2 H) 2 ]· n H 2 O (1b, 2b) and zirconium [ N , N -di(phosphonomethyl) acetic acid] Zr[(O 3 PCH 2 ) 2 NCH 2 CO 2 H]· n H 2 O (1c, 2c) were synthesized for the first time with zirconium oxychloride, sodium dihydrogen phosphate and H 2 O 3 PCH 2 N(CH 2 CH 2 ) 2 O, H 2 O 3 PCH 2 N(CH 2 CO 2 H) 2 or (H 2 O 3 PCH 2 ) 2 NCH 2 CO 2 H in the absence and presence of hydrofluoric acid. The samples were comparatively characterized by XRD, IR, TG and elemental analysis. XRD data showed that the crystalline samples 2a, 2b and 2c are highly crystalline with interlayer spacings of 1.606, 1.538 and 1.239 nm, respectively. The amorphous and crystalline samples lost nearly the weight calculated for their organic component over the same broad temperature range of 172–664, 184–680 and 176–668 °C, respectively. XPS data indicated that the coordination bonds formed between nitrogen and palladium in the palladium complexes. Their palladium complexes possessed good activities for the hydrogenation of the carbon–carbon double bond. The catalytic activities of the palladium complexes of amorphous 1a, 1b and 1c is 1.5–3.1 times as high as that of the palladium complexes of crystalline 2a, 2b and 2c.

Swift heavy ion irradiation of zirconium phosphate of various forms

The zirconium phosphate and its various derivatives have good resistance against ionization radiation, as it was found earlier during the irradiation of them with γ-rays of high energy. Continuing these experiments amorphous and crystalline (both α- and γ-forms) zirconium phosphate, its monosodium, and propylamine intercalated forms were irradiated with a fluence of 10 11–10 14 ion cm −2 with swift heavy ions of 203Bi and 84Kr. The irradiation was also performed with Si containing zirconium phosphate. The structure of the materials was characterized by XRD method. The comparison of the powder diffraction patterns reveals that the irradiation has practically no effect on the α-zirconium phosphate, while the other materials more or less destroyed and some of them became amorphous. The propylamine intercalate form of zirconium phosphate is decomposed on α-ZrP and organic radical.

Immobilization of strontium by crystalline zirconium phosphate

Mixtures of HZr2(PO4)3 with varying amounts of Sr(NO3)2 were thermally treated at 600–1200 °C in order to investigate the immobilization of radioactive Sr. When the Sr(NO3)2 / HZr2(PO4)3=0.2 mixture was thermally treated at 700 °C, the main product was postulated to be SrZr4(PO4)6 from the XRD results. The Sr(NO3)2/HZr2(PO4)3=0.2 immobilized product thermally treated at 700 °C containing the maximum amount of immobilized Sr (a 0.2 molar ratio of Sr(NO3)2/HZr2(PO4)3 equates to approximately 4 wt.% of Sr) had minimal Sr leaching rates in several solvents at 160 °C in an autoclave. The leaching rate of Sr ion from that product was <10−6, 1.3×10−4, 1.4×10−4, 1.1×10−3, 2.0×10−3, 8.8×10−3 and <10−6 g m−2 day−1 in deionized water, sea water, 0.1 mol l−1- HCl, 0.5 mol l−1- HCl, 1 mol l−1- HCl, 1.5 mol l−1- HCl and 1 mol l−1- NH3 in an autoclave at 160 °C, respectively, indicating that HZr2(PO4)3 reacts with Sr(NO3)2 to give a stable Sr-immobilized product.