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The experimental data reported in this paper suggest that titanium(IV) oxyhydroxyphosphate-based ion-exchange materials are potentially attractive for extraction of heavy metal cations from solutions. We have studied the time-dependent ion exchange activity of titanium phosphates for Zn2+, Co2+, and Ni2+ cations in relation to the liquid : solid ratio, temperature, and equilibrium pH of the cation exchange process. The results demonstrate that the selectivity of an ion exchanger for metal cations is determined by the ionic radii of the metals. Conditions for effective use of titanium phosphate materials for extraction of Zn2+, Co2+, and Ni2+ cations from solutions (liquid : solid ratio, temperature, and pH) have been optimized experimentally. [ABSTRACT FROM AUTHOR]

The results of studying of the nitric acid and NaOH + KOH alkalis' mixture recovery from concentrated solutions in filter-press-type electrodialyzers with anion-exchange, cation-exchange, and bipolar membranes are presented. The necessity of the technological solutions preliminary purification from calcium and boron compounds was established, in order to obtain crystalline boric acid (H3BO3) and gypsum (CaSO4·2H2O). The possibility of obtaining, from purified concentrated salt solutions, acids and alkalis with a concentration of ~300–600 g/L suitable for reuse is shown. This can be provided only by the electrodialysis with anion- and cation-exchange membranes, while electrodialysis with bipolar membranes is complicated by noticeable contamination of both acidic and alkaline solutions with salts. [ABSTRACT FROM AUTHOR]

The results reported in this paper suggest that titanium(IV) oxyhydroxyphosphates can be used for sorption extraction of valuable metal cations from solutions, followed by desorption and concentration of the metal cations and simultaneous regeneration of the titanium phosphate material for further use. Conditions for effective desorption processes (desorbing agent concentration and desorption time) have been studied and optimized. The sorption/desorption process effectiveness in the case of multistep use of the sorbent has been shown to decline as a result of steric hindrances associated with its dehydration. As the sorption properties of the sorbent degrade, it can be used for extraction of trace amounts of highly toxic metal cations and then buried. [ABSTRACT FROM AUTHOR]

This paper demonstrates the feasibility of using titanium(IV) oxyhydroxyphosphate-based materials for sorption extraction of heavy metal cations from solutions. We have determined Pb2+ and Cd2+ sorption characteristics of ion exchangers, examined the kinetics of Pb2+ and Cd2+ sorption on the titanium phosphate materials, and assessed the effect of ionic radius on the affinity of the sorption matrices for metal cations. Conditions for effective use of the ion exchange materials for extracting Pb2+ and Cd2+ cations from solutions (liquid : solid ratio and pH) have been optimized experimentally. [ABSTRACT FROM AUTHOR]

The possibility to synthesize titanium phosphate from crystalline titanium salts has been shown for the first time. Optimal synthesis conditions have been found to provide preparation of monophase product of composition Ti(HPO4)2 · H2O or TiO(OH)H2PO4 · 2H2O by heterogeneous reaction of titanium-containing precursors with phosphoric acid. The process has been found to proceed for 3–5 h at stoichiometric consumption of the components and provides more environmentally benign and profitable conditions as compared with the known methods of synthesis. [ABSTRACT FROM AUTHOR]

Sorbents based on titanium(IV) compounds have been shown to be potentially attractive for quantitative removal of antimony(III) anions from liquid radioactive waste with complex chemical composition. Evidence is presented that titanium(IV) oxyhydroxyphosphates have enhanced affinity for antimony(III) cations. Selectivity of sorption matrices increases with increasing solution acidity and with an increase in the concentration of hydrogen phosphate groups in the composition of the material. Having enhanced affinity for negatively charged antimony(III) ions, titanium(IV) oxyhydroxides are potentially attractive for extraction of anionic species. [ABSTRACT FROM AUTHOR]

The crystallization of the lithium titanate Li4Ti5O12 powders during doping with lanthanum(III) cations is studied. The introduction of up to 4 wt % La(III) does not change the crystalline structure of the material and increases the powder dispersity, which may be due to the formation of structural defects that create microstresses and do not allow the formation of relatively large crystallites. An increase in the content of the introduced lanthanum(III) cations makes it possible to obtain a composite material based on lithium titanate Li4Ti5O12 and solid electrolyte Li0.5La0.5TiO3. Reducing the particle size of the powders during preparation of the modified crystalline powders of lithium titanate Li4Ti5O12 by doping with lanthanum(III) cations and the formation of solid electrolyte-containing composites provides an increase in lithium-ion conductivity. The resulting materials are characterized by high and stable values of the capacity of the battery layout during cycling in the "charge–discharge" mode. [ABSTRACT FROM AUTHOR]

It has been demonstrated that titanyl hydrogen phosphate-based sorption materials can be effectively used for the extraction of cesium and strontium radionuclides from liquid radioactive waste similar in chemical composition to seawater. We have optimized conditions (pH, liquid : solid ratio, and temperature) for the coextraction of cesium and strontium cations. The titanium(IV) cesium or strontium double phosphate formed after heat treatment of the spent sorbent ensures proper immobilization of the radionuclides. [ABSTRACT FROM AUTHOR]

The effect of temperature and the cesium concentration in the external solution on the sorption capacity of titanium phosphate obtained upon the heterogeneous interaction of the (NH4)2TiO(SO4)2 · H2O crystalline salt with phosphoric acid is studied. Sorption on titanium phosphate is shown to be best described by the Langmuir isotherm. When describing the sorption kinetics of solutions, it is necessary to consider both the possibility of diffusion and adsorption limiting the process rate. The use of the chemical kinetic models shows that the stage of chemical interaction of metal ions with functional groups of the sorbent also contributes to the overall rate of the process. [ABSTRACT FROM AUTHOR]

The method of solid-phase sintering was used to synthesize samples of lithium-conducting Li6.4Al0.2La3Zr2O12 solid electrolyte with a garnet structure. Higher technological efficiency of the method of synthesis was achieved owing to using low-melting nitrate crystalline hydrates of ZrO(NO3)2 · 2H2O and La(NO3)3 · 6H2O as initial substances: formation of the melt considerably intensified the interaction, caused a decrease in the duration and energy consumption of the method, and provided the presence of only a single phase of powdered solid electrolyte with a high Li-ion conductivity. The excess of the lithium-containing component (Li2CO3) in the mix was varied to compensate lithium losses in the course of the high-temperature treatment. Specific ionic conductivity of Li6.4Al0.2La3Zr2O12 was determined using the impedance spectroscopy technique and was 2 × 10–4 S/cm at the room temperature. [ABSTRACT FROM AUTHOR]

A technology for the synthesis of highly efficient titanium phosphate sorbents and materials for lithium-ion batteries was developed. The precursor in this synthesis is ammonium titanyl sulfate (ATS), a product of processing of titanite concentrate. A unified approach to the synthesis of materials of various purposes was proposed. This approach allows one to create a flexible engineering system in which one of the products can be the starting material for obtaining others. The mild single-step synthesis by the interaction of ATS with phosphoric acid gives a titanium dihydrophosphate sorbent, the efficiency of which was confirmed by the results of tests of hydrometallurgical process waste treatment. Sorption materials based on hydrated titanium phosphates—the products of the synthesis with ATS—are efficient precursors for obtaining electrode materials for lithium-ion batteries. Using titanite processing products will expand Russia's titanium resource base for manufacturing products in demand. [ABSTRACT FROM AUTHOR]

Heterogeneous exchange of the proton of hydrated titanyl hydrogen phosphate with Li, Na, K, Rb, and Cs cations in aqueous solutions was studied potentiometrically. The sorption equations were proposed. The concentration and thermodynamic equilibrium constants were calculated. The optimal pH range of the solution providing effective sorption of radioactive cesium on hydrated titanyl hydrogen phosphate was determined. The decrease in the efficiency of radiocesium sorption from liquid waste with a high content of competing nonradioactive alkali metal cations is due to a decrease in the pH of this solution in the course of the sorption. To provide efficient sorption removal of radiocesium, the pH should be maintained in the range 4-7, or the sodium form of the sorbent should be used. The selectivity of radiocesium sorption on TiOHPO4 in the presence of excess sodium cation was estimated. [ABSTRACT FROM AUTHOR]

Lithium cobaltate with stoichiometric composition (LiCoO2) is synthesized by the sol–gel method. The physical parameters (particle size, specific surface area, and specific static conductivity) of studied samples are found and their dependence on the calcination temperature is revealed. The following three conduction mechanisms are shown to contribute to the conductivity value: frequency-independent σ0, ionic transport in the sample bulk σsv, and ionic transport at the electrode/ionic conductor interface σdl. The optimal modes of thermal treatment that allow the highly developed specific surface of LiCoO2 to be retained are determined. [ABSTRACT FROM AUTHOR]

The stability of the LiCoPO4 electrode material in contact with a NASICON-type lithium ion conducting solid electrolyte having the composition Li1.5Al0.5Ge1.5(PO4)3 (LAGP) and a wide range of electrochemical stability has been studied for the first time. We have found the optimal temperature at which there is no reaction between the starting components of the composites and they retain their chemical and thermal stability. Cosintering a mechanical mixture of synthesized single-phase LiCoPO4 and LAGP powders with a submicron particle size at 750°C, we have obtained a stable LiCoPO4/LAGP two-phase composite whose room-temperature electrical conductivity is three orders of magnitude higher than that of the lithium cobalt double phosphate. Composites based on LiCoPO4 and the LAGP ionic conductor can be regarded as promising cathode materials for all-solid-state lithium ion batteries. [ABSTRACT FROM AUTHOR]

Methods of X-ray diffraction analysis, impedance spectroscopy, and scanning electron microscopy were used to examine how thermal treatment modes affect the transport properties and microstructure of a lithium-conducting oxide ceramic of composition Li0.33La0.56TiO3, produced from powders synthesized by the sol-gel method. It was found that the cubic structure of Li0.33La0.56TiO3 can be stabilized as a result of quenching after the high-temperature of sintering at 1150°C. The conditions were determined in which Li0.33La0.56TiO3 ceramic samples can be obtained with bulk ion conductivity of ∼1 × 10−3 S cm−1 at 20°C, which corresponds to the maximum values for the ceramic based on lithium-lanthanum titanate. [ABSTRACT FROM AUTHOR]

We have proposed compositions of titanyl hydrogen phosphate-based sorption materials modified with zirconium(IV) cations and containing both cation and anion exchange functional centers, represented by НРО and OH– groups, respectively. The synthesized materials were tested in sorption of antimony(III) cations and anions from high-salt solutions. Increasing the concentration of functional groups in ion exchange matrices has been shown to increase their affinity for antimony(III) ions. Such compositions can be regarded as promising ion exchange materials for efficient extraction of antimony radionuclides from multicomponent high-salt liquid radioactive waste. [ABSTRACT FROM AUTHOR]

We have studied the hydrolytic stability of titanyl hydrogen phosphates in relation to their composition, the synthesis procedure, and the nature and concentration of the electrolyte. The chemical stability of these compounds can be improved by increasing the electrolyte concentration and decreasing the degree of hydration of metal cations in solution and also by modifying their composition with metal cations differing in acid-base properties from titanium(IV). We have found conditions that maximize the hydrolytic stability of the titanyl hydrogen phosphates. [ABSTRACT FROM AUTHOR]

Solid solutions KTi1-XHfXOPO4 (х = 0.008 - 0.107) possessing the KTiOPO4 structure, have been synthesized in molten system K2O-P2O5-TiO2-HfF4. The crystal growth experiment of Hf-doped KTP crystal has been reported. The X-ray powder diffraction data and chemical analysis are also presented. It has been shown that KTiOPO4 crystal structure slightly changes when Hf incorporates into the framework. Transmission/absorption spectra of KTi0.974Hf0.026OPO4 crystals have been recorded. The incorporation of Hf ions shifts the optical absorption edge in the UV-visible spectrum towards the long-wavelength region with absorption near 387 nm. [ABSTRACT FROM AUTHOR]