Zr Phosphate Research Articles

Utilization of (Ca, Mg)-Zr phosphates adsorbents saturated by Cs+, Sr2+, Co2+ ions in NZP ceramic matrices

A novel approach to the utilization of (Ca, Mg)-Zr phosphate adsorbents saturated by Cs+, Sr2+, Co2+ ions was developed. The main stages include: (i) Cs+, Sr2+, Co2+ ions adsorption, (ii) the drying and shaping by cold pressing, (iii) the sintering. Metal ions leaching from the powder of the spent adsorbent were 0.2–26.5 % in distillation water (рН 4.0–10.0) and tap water, and increased to 6.4–68.2 % in seawater. Calcination of spent adsorbents at 1000 °C led to a decrease in Cs+, Sr2+, Co2+ ions leaching to less than 1.0 % in tap and seawater. The ceramic matrices with a Cs+, Sr2+, Co2+ content of 8.0–30.2 wt %, mechanical compressive strength of 2.9–260.9 MPa, leaching rate of 1.0×10−4 - 4.3×10−7 g/(cm2×day), density of 1.4–3.4 g/cm3 were obtained by cold pressing with subsequent sintering. The samples obtained at molar ratios Zr/(Ca+Mg) of 0.35 and 0.21 were characterized by the highest compressive strength and Cs+ and Sr2+, Co2+ leaching resistance, respectively. The obtained ceramic matrices fitted to the requirements of GOST R 50926–96 and NRC 1991 for solid high-level waste forms.

Kinetics of heavy metal ions removal from aqueous solutions using synthesised composite hybrid cation exchanger

ABSTRACT Hybrid organic–inorganic materials make it possible to combine beneficial organic and inorganic properties into a single molecular-scale composite. In this study, the removal efficiency of synthesized organic–inorganic hybrid cation exchanger: nylon-6,6, Zr (IV) phosphate with respect to Cu2+, Zn2+ and Cd2+ has been investigated in order to take into account its potential use to clean up wastewaters from heavy metals. Metal concentrations in solution of 0.02 and 0.2 mol/L were used in the batch technique. For both lower and higher initial concentration, the process was fitting to both first and pseudo-first-order-kinetic model, while it is also consistent with the intra-particle diffusion model. Particle diffusion is the rate-limiting step in the multistep process that is primarily controlled by external mass transfer. Moderate activation energy values confirmed that the process is a combination of both physisorption and chemisorption. The order of removal may be presented as Cu2+ > Zn2+ > Cd2+.

Developing a Selective Zirconium Phosphate Cation Exchanger to Adsorb Ammonium: Effect of a Gas-Permeable and Hydrophobic Coating.

A sorbent with a high enough capacity for NH4+ could serve as an oral binder to lower urea levels in end-stage kidney disease (ESKD) patients. A hydrogen-loaded cation exchanger such as zirconium phosphate Zr(HPO4)2·H2O (ZrP) is a promising candidate for this application. However, the NH4+ binding selectivity versus other ions must be improved. Here, we have developed a gas-permeable and hydrophobic surface coating on an amorphous form of ZrP using tetraethyl orthosilicate and methoxy-terminated polydimethylsiloxane. The hydrophobic coating serves as a barrier to ions in water solution from reaching the ion-exchanger's surface. Meanwhile, its gas-permeable nature allows for gaseous ammonia transfer to the cation exchanger. In vitro studies were designed to replicate the small intestine's expected ion concentrations and exposure time to the sorbent. The effectiveness of the coating was measured with NH4+ and Ca2+ solutions and uncoated ZrP as the negative control. X-ray photoelectron spectroscopy and scanning electron microscopy measurements show that the coating successfully modifies the surface of the cation exchanger─ZrP. Water contact angle studies indicate that coated ZrP is hydrophobic with an angle of (149.8 ± 2.5°). Simulated small intestine solution studies show that the coated ZrP will bind 94% (±11%) more NH4+ than uncoated ZrP in the presence of Ca2+. Meanwhile, Ca2+ binding decreases by 64% (±6%). The nearly fourfold increase in NH4+ selectivity can be attributed to the gas-permeable and hydrophobic coating applied on the ZrP surface. This work suggests a novel pathway to develop a selective cation exchanger for treating ESKD patients.

Potentiometric Determination of Mercury Ions by Sol-gel Synthesized Multi-walled Carbon Nanotubes Zr (IV) Phosphate Composite Fabricated Membrane Electrode

Background: The nanocomposites are formed by introducing inorganic nano-clusters, fullerenes, clays, metals, oxides with numerous organic polymers. The assembly of these materials exhibits better properties such as catalytic, thermal stability and adsorption properties, etc. than the individual materials. Objective: The nanocomposite synthesized here by sol-gel method was primarily evaluated for cation exchange properties viz, elution concentration, elution behavior, effect of temperature on ion-exchange capacity. The synthesized composite was used as an electro-active component for fabrication of Hg2+ ion selective membrane electrode. Method : The sol-gel technique was used to synthesize multi-walled carbon nanotubes Zr(IV) phosphate composite cation exchanger. By the technique of solution casting the material as an electroactive part was used for the fabrication of mercury ion-selective membrane electrode. The potential response of the electrode was also investigated as a function of membrane composition and plasticizer. Results: The composite cation exchanger exhibited 1.8 meq g-1 ion-exchange capacity (IEC). It retained almost 65 % of its initial IEC upto a temperature of 400 °C. Distribution studies showed the selective nature of the composite for Hg(II) ions. The ion-selective membrane electrode exhibited typical Nernstian response towards Hg2+ ions in the concentration range 1×10-1 -1×10-7 M. Conclusion: The results discussed reveal that a new cation composite exchanger-multi-walled carbon nanotubes Zr (IV) phosphate exhibited excellent cation exchange properties and was found to be preferentially selective towards the Hg2+ ions. It was also used as an indicator electrode in the titration of Hg2+ using ethylenediaminetetraacetic acid as a titrant.

Synthesis, Crystal Structure, and Antibacterial Properties of Silver-Functionalized Low-Dimensional Layered Zirconium Phosphonates.

New insoluble layered zirconium phosphate carboxyaminophosphonates (ZPs), with the general formula Zr2(PO4)H5[(O3PCH2)2N(CH2)nCOO]2·mH2O (n = 3, 4, and 5), have been prepared and characterized. The crystal structure for n = 3 and 4 samples was determined ab initio from X-ray powder diffraction data. The structure for n = 3 was monoclinic in space group C2/c with the following unit cell parameters: a = 34.346(1) Å, b = 8.4930(2) Å, c = 9.0401(2) Å, and β = 97.15(1)°. The structure for n = 4 was triclinic in space group P1̅ with the following unit cell parameters: a = 17.9803(9) Å, b = 8.6066(4) Å, c = 9.0478(3) Å, α = 90.466(3)°, β = 94.910(4)°, and γ = 99.552(4)°. The two structures had the same connectivity as Zr phosphate glycine diphosphonate (n = 1), as previously reported. By intercalation of short amines, these layered compounds were exfoliated in single lamella or packets of a few lamellae, which formed colloidal dispersions in water. After a thorough characterization, the dispersed lamellae were functionalized with Ag nanoparticles, which were grown in situ on the surface of exfoliated lamellae. Finally, their antimicrobial activity was tested on several Gram-positive and Gram-negative bacteria. All of these systems were found to be active against the four pathogens most frequently isolated from orthopedic prosthetic infections and often causative of nosocomial infections. Interestingly, they were found to express powerful inhibitory activity even against bacterial strains exhibiting a relevant profile of antibiotic resistance such as Staphylococcus aureus ATCC 700699.

Synthesis, Temperature Behavior, and Hydrolytic Stability of Na–Zr and Ca–Zr Phosphate Molybdates and Phosphate Tungstates

Synthesis, Temperature Behavior, and Hydrolytic Stability of Na–Zr and Ca–Zr Phosphate Molybdates and Phosphate Tungstates

Unexpected structural/motional mode of water intercalated into an α-crystalline zirconium phosphate deduced by 31 P and 2 H solid-state MAS NMR spectra.

In developing the approach to understanding dynamics of intercalates in layered materials, crystalline-layered zirconium phosphate Zr (HPO4 )2 ·0.35D2 O has been prepared and characterized by the 1 H, 31 P, and 2 H solid-state MAS NMR spectra, including 31 P and 2 H T1 measurements. At temperatures >253 K, the intercalated water shows two spectrally-distinguished deuterons unprecedentedly with different DQCC's and 2 H T1 times, one of which is hydrogen bonded. The collected data allowed to identify an unexpected bonding/dynamic mode of water molecules, which experience fast rotation around the hydrogen bond, formed with a zirconium-coordinated oxygen. The low-temperature 2 H MAS NMR experiments have demonstrated the presence of additional hydrogen bond P(H)O˙˙˙ DO, population of which grows on cooling to 195 K corresponding to the doubly hydrogen-bonded immobile water molecule.

Effect of Zr(IV) to phosphorus ratio on U(VI) adsorption by diethylenetriamine-pentamethylene phosphate Zr(IV) hybrids

Abstract In this work, diethylenetriamine pentamethylenephosphonic acid (DTPMP) was ultilized into preparing of Zr(IV) organophosphates hybrids (Zr-DTPMP-x, x was the molar ratio of Zr(IV)/DTPMP in the synthetic process, x = 0.5, 1, 2, and 3) using a hydrothermal method. The physical and chemical properties of Zr-DTPMP-x were characterized by SEM&EDS, FT-IR, XRD, Zeta potential, XPS, TGA and contact angle analysis. Moreover, the adsorptive performances of Zr-DTPMP-x for U(VI) were investigated. The adsorption results showed that the optimum molar ratio of Zr(IV) to phosphine, pH, equilibrium time, and dosage was 0.5, 4.0, 180 min, and 10 mg, respectively. Besides, the adsorption of U(VI) was in accordance with the pseudo-second-order kinetic model and Sips isothermal model. Moreover, the adsorption capacity determined by Sips isothermal model was 181.34 mg g−1 for Zr-DTPMP-0.5. Furthermore, the adsorptive selectivity of Zr-DTPMP-0.5 for U(VI) was superior than the others. Zr-DTPMP-0.5 may be a powerful candidate for diminishing the contamination of U(VI).

Cs absorption capacity and selectivity of crystalline and amorphous Hf and Zr phosphates

Removal of radioactive Cs from sodium-rich solutions is a technical challenge that goes back to post World War II nuclear waste storage and treatment; and interest in this topic was reinvigorated by the Fukushima-Daiichi nuclear power plant disaster, 10 years ago. Since the 1960′s there has been considerable focus on layered Zr phosphates as robust inorganic sorbents for separation of radionuclides such as Cs. Here we present synthesis and characterization, and direct comparison of Cs sorption capacity and selectivity of four related materials: 1) crystalline α-Zr phosphate and α-Hf phosphate, and 2) amorphous analogues of these. Powder X-ray diffraction, thermogravimetry, solid-state 31P magic angle spinning nuclear magnetic resonance (MAS-NMR) spectroscopy, and compositional analysis (inductively coupled plasma optical emission spectroscopy and mass spectroscopy, ICP OES and ICP MS) provided formulae; respectively M(HPO4)2⋅1H2O and M(HPO4)2⋅4H2O (M = Hf, Zr) for crystalline and amorphous analogues. Maximum Cs loading, competitive Cs-Na selectivity and maximum Cs-Na loading followed by the above characterizations plus 133Cs MAS-NMR spectroscopy revealed that amorphous analogues are considerably better Cs-sorbents (based on maximum Cs-loading and selectivity over Na) than the well-studied crystalline Zr-analogue. Additionally, crystalline α-Hf phosphate is better Cs-sorbent than crystalline α-Zr phosphate. All these studies consistently show that Hf phosphate is less crystallize than Zr phosphate, when obtained under similar or identical synthesis conditions. We attribute this to lower solubility of Hf phosphate compared to Zr phosphate, preventing ‘defect healing’ during the synthesis process.

Optimization of the synthesis of UiO-66(Zr) in ionic liquids

Abstract In order to rationalize the production of porous Metal-Organic Frameworks (MOFs) in ionic liquids (ILs) as main solvent, we selected the archetype UiO-66(Zr) to analyze its precipitation in four commercial candidates of ILs commonly used in the literature. We did the choice to investigate the reactivity of two hydrophobic salts, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Emim][NTf2]) and 1-butyl-3-methylimidazolium hexafluorophosphate [Bumim][PF6]), as well as two other salts considered as hydrophilic, ([Omim][Cl]) and 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ([Emim][TFO]). Whereas the synthesis in hydrophilic ILs gave rise to the crystallization of pure UiO-66(Zr), the solvo-thermal reaction (120 °C) performed in hydrophobic salts did not lead to the same results. In the case of [Bumim][PF6], we noted the precipitation of zirconium phosphate Zr(HPO4)2 H2O, while the synthesis in [Emim][NTf2] favored the formation of distinct zirconium terephthalate called hcp UiO-66. These different phases have been characterized by powder X-ray diffraction, BET, IR and SEM.

Fabrication of Gelatin-Zr (IV) Phosphate and Alginate-Zr (IV) Phosphate Nanocomposite Based Ion Selective Membrane Electrode

Gelatin- Zr (IV) phosphate nanocomposite (GT@ZPNC) and alginate- Zr (IV) phosphate nanocomposite (AG@ZPNC) ion exchangers has been prepared by sol-gel method. The nanocomposites are characterised by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The SEM results of GT@ZPNC and AG@ZPNC confirmed that after the binding of polymer matrix to inorganic part, morphology was completely reformed. TEM results confirmed the synthesised materials were nanocomposite in nature. The GT@ZPNC and AG@ZPNC ion exchangers have been explored to fabricate ion selective electrode for the detection of Cd (II) and Al (III) metal ions. Both ion selective membrane electrodes show wide working concentration and pH range with good response time.

Local Environment of Terbium(III) Ions in Layered Nanocrystalline Zirconium(IV) Phosphonate-Phosphate Ion Exchange Materials.

The structures of Zr(IV) phosphonate-phosphate based, unconventional metal organic framework materials have been determined using atomic pair distribution function analysis of high energy, X-ray total scattering diffraction data. They are found to form as nanocrystalline layers of Zr phosphate, similar to the bulk, but with a high degree of interlayer disorder and intermediate intralayer order extending around 5 nm. These materials are of interest for their high selectivity for 3+ lanthanide ions. To investigate the mechanism of the selectivity, we utilize difference pair distribution function analysis to extract the local structural environment of Tb3+ ions loaded into the framework. The ions are found to sit between the layers in a manner resembling the local environment of Tb in Scheelite-type terbium phosphate. By mapping this local structure onto that of the refined structure for zirconium-phenyl-phosphonate, we show how dangling oxygens from the phosphate groups, acting like nose hairs, are able to reorient to provide a friendly intercalation environment for the Tb3+ ions.

Efficient photocatalytic degradation of toxic dyes from aqueous environment using gelatin-Zr(IV) phosphate nanocomposite and its antimicrobial activity

In the present study, gelatin-Zr(IV) phosphate nanocomposite (GT/ZPNC) was synthesized by sol-gel method by mixing the gelatin gel into the inorganic part Zr (IV) phosphate (ZP). The GT/ZPNC was characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy (SEM), transmission electron micron scope (TEM), X-ray powder diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The photodegradation activity of GT/ZPNC was explored for the removal of methylene blue (MB) and fast green (FG) dyes from aqueous solution. It was found that 87.81% MB and 89.91% FG were degraded within five hours. Also, the kinetics of photocatalytic degradation for MB and FG was investigated via pseudo first-order kinetic model with higher regression coefficient values (R2). The antimicrobial efficiency of GT/ZPNC was investigated against E. coli.

Synthesis of lactic acid–Zr(IV) phosphate nanocomposite ion exchanger for green remediation

Lactic acid–Zr(IV) phosphate nanocomposite (LA/ZPNC) ion exchanger was synthesised by sol-gel method. The nanocomposite ion exchanger was characterized by different techniques such as Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy X-ray diffraction (XRD) and thermogravimetric analysis (TGA/DTA/DSC). LA/ZPNC was employed for different physicochemical properties such as ion exchange capacity, elution behaviour, effect of eluent concentration, pH titration and thermal stability. The ion exchange capacity of LA/ZPNC was higher as compared to their inorganic counterpart. pH results indicate the bifunctional nature of nanocomposite. A degradation efficiency of 89.47 % was attained in 4 h of illumination. The distribution coefficient (K d) studies of LA/ZPNC ion exchanger were investigated for eight different metal ions and found more selective for Al3+ with higher K d value. It was explored for photocatalytic study of methylene blue under solar illumination.

Synthesis, characterization, and electroanalytical studies of Pb2+-selective polypyrrole-Zr(IV) phosphate ion exchange membrane

Polypyrrole-Zr(IV) phosphate (PPyZP) composite cation exchange material was synthesized by chemical oxidative polymerization of pyrrole with the help of FeCl3 as oxidant in the presence of Zr(IV) phosphate particles. On the basis of distribution studies, it was found to be highly selective for Pb2+. Using PPyZP composite exchanger, a cation exchange membrane was prepared by solution-casting method. PPyZP composite and its membrane were characterized by the following instrumentation techniques: XRD, FTIR, SEM, EDX, and TGA. A Pb2+-selective membrane electrode with linear sensitive range from 3.2 × 10−6 M to 1.0 × 10−1 M, working pH range from 4 to 7, and response time of 40 s was fabricated. The kinetic studies on electrode were done at 40, 60, and 80 °C to calculate D 0, ΔE a, ΔS°, ΔH°, and ΔG°. The selectivity coefficient of electrode with other interfering ions was also calculated. The analytical utility of PPyZP electrode was established by employing it as an indicator electrode in potentiometric titration of Pb2+.

Poly (3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS) Zr(IV) phosphate composite cation exchanger : sol-gel synthesis and physicochemical characterization

An organic-inorganic composite cation exchanger poly (3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS) Zr(IV) phosphate was prepared by the sol-gel method for removal of cadmium, a toxic heavy metal pollutant causing adverse effects on human health. The synthesized material was characterized by various techniques such as thermo gravimetric analysis/differential thermal analysis/differential thermo gravimetry (TGA/DTA/DTG), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR). Organic polymer PEDOT:PSS binds with the inorganic counterpart and prevents the leaching of the inorganic parts, hence PEDOT:PSS Zr(IV) phosphate composite cation exchanger has improved ion exchange capacity than inorganic ion exchanger. The composite cation exchanger was found selective towards Cd(II) ions. The nature and composition of contacting solvents influence the selectivity of composite cation exchanger. The composite cation exchanger may be used for the removal of cadmium a toxic heavy metal ion.

Mechanism of ion transport in hybrid materials based on MF-4SC perfluorinated sulfonation-exchange membranes and acid zirconium phosphate nanoparticles

The relationship between the transport properties of various salt forms (H+, Li+, Na+, Cs+) of MF-4SC hybrid membranes containing nanoparticles of crystalline acid zirconium phosphate Zr(HPO4)2 at various relative humidities are investigated with the use of impedance studies and NMR spectroscopy. Modification of the membranes leads to a marked increase in ion mobility, and the maximum effect is observed under reduced humidity conditions. The conductivity of a modified membrane at a relative humidity of 10% is 1.6 × 10−4 Ω−1 cm−1, that is, almost 1.5 orders of magnitude greater than the conductivity of an initial membrane under the same conditions.

Comparative Studies of Kinetics of Nanocomposite Poly-o-toluidine Zr(IV) Phosphate and Fibrous Nylon-6,6 Sn(IV) Phosphate Cation Exchange Materials

An organic-inorganic composite, poly-o-toluidine Zr(IV) phosphate and nylon-6,6 Sn(IV) phosphate was chemically synthesized by mixing ortho-toluidine and nylon-6,6 into the gel of Zr(IV) phosphate and Sn(IV) phosphate in different mixing volume ratios. The particle diffusion mechanism is confirmed by the linear � (dimensionless time parameter) vs. t (time) plots. This study revealed the exchange process controlled by the diffusion within the exchanger particles. Some physical parameters like self-diffusion coefficient (D 0), activation energy (E a) and entropy of activation ( �S°) have been evaluated under conditions favoring a particle diffusion-controlled mechanism.

Heavy toxic metal ion exchange kinetics: Validation of ion exchange process on composite cation exchanger nylon 6,6 Zr(IV) phosphate

Nernst–Planck equation was applied to study the heavy metal ion exchange kinetics over the surface of nylon 6,6 Zr(IV) phosphate at various temperatures under particle diffusion controlled phenomena. Various useful ion exchange kinetic parameters such as self-diffusion coefficient (Do), energy of activation (Ea), and entropy of activation (ΔS*) were evaluated to validate the ion exchange process for practical applicability of this composite cation exchanger in remediation processes of the environment. This study is also supported for the good selectivity of Cu(II) to validate the practical application of this cation exchanger in environmental analysis.

Adsorption thermodynamics studies of 2,4,5-trichlorophenoxy acetic acid on poly-o-toluidine Zr(IV) phosphate, a nano-composite used as pesticide sensitive membrane electrode

2,4,5-Trichlorophenoxy acetic acid (2,4,5-T) is used in forestry and in agriculture as a systemic herbicide (for eradication of undergrowth, etc). Adsorption behaviour of 2,4,5-T on the surface of poly-o-toluidine Zr(IV)phosphate was studied and some thermodynamic parameters such as Freundlich constants and Langmuir constants were determined on the surface of cation-exchanger. In this work, the adsorption of 2,4,5-T on cation-exchanger from aqueous medium was studied with respect to pH and initial 2,4,5-T concentration. The experimental data were analyzed by the Freundlich isotherm, and the Langmuir isotherm. The results indicated that the cation-exchanger is very effective for the adsorption of 2,4,5-T from aqueous solutions. Pesticide sensitive membrane electrode was fabricated by using an electro-active composite material poly-o-toluidine Zr(IV) phosphate. The sensitivity towards the 2,4,5-T was monitored.