Investigations on the preparation and application of some inorganic separators for the removal of the matrix activity in neutron-activated biological samples

For the selective removal of the matrix activity (²⁴Na,³²P and⁴²K) in the neutron activation analysis of biomedical samples the inorganic separators “hydrated antimony pentoxide”, zirconium phosphate, and titanium phosphate were prepared. The sorption parameters of the samples were determined via elution chromatography techniques, with appropriate tracers. The basic principles of the sorption processes were investigated, and the experimental conditions were optimized. These inorganic separators were then applied, combined with a distillation procedure and an ion-exchange separation, for the determination of the following trace elements in animal blood samples: Mn, Co, Cu, Fe and Zn.     

Uptake of inorganic acids on hydrogels of tetravalent hydroxides and its application for the preparation of some inorganic sorbents

The paper deals with the study of inorganic acid uptake on hydrogels of titanium, zirconium, and tin hydroxides prepared by the sol-gel method in the form of regular spherical particles. The aim of the work was the determination of the basic conditions for the preparation of inorganic ion exchangers by means of the conversion of the hydroxide gel. The results obtained prove that the exchange of hydroxide groups of the gel phase for the respective anions plays the decisive role in the uptake on zirconium hydroxide. With similar titanium and tin compounds, the main process affecting the uptake is the formation of adsorption compounds and the free diffusion of the electrolyte into the gel phase. The possibilities of the application of the sol-gel method for the preparation of inorganic sorbents are discussed.     

Mixed insoluble acidic salts of tetravalent metals IV. Crystalline mixed zirconium — Titanium phosphates

Mixed crystalline alpha zirconium — titanium phosphates with variable zirconium to titanium ratios have been prepared both by the well known gel reflux method and a modified HF method. Chemical analysis, X-ray, i.r. and thermal analysis were used to characterize the materials. Exchange capacities for these ion-exchangers have been evaluated by pH-titration combined with radioisotope tract technique for Na⁺, K⁺, Rb⁺ and Cs⁺.     

Effect of preparative conditions on the surface characteristics of mixed zirconium and titanium oxides

The surface characteristics of mixed zirconium and titanium oxides prepared from different starting materials are investigated. One mode of preparation entailed the use of zirconium sulfate and titanium oxysulfate as starting materials and ammonium hydroxide as precipitating agent. The produced oxides were washed to different extents to obtain samples with different sulfate content. A second preparative mode used zirconium oxychloride and titanous chloride as starting materials also with ammonium hydroxide as precipitating agent. The oxidation of the titanous to the titanic form for these oxides was carried out by means of oxygen gas. Resulting samples were heat treated at 400 °C and 600 °C, and textural characteristics determined from the adsorption of N₂ at 77 K, complemented by infrared and thermal studies. The samples precipitated from the oxychloride and chloride salts of zirconium and titanium, as well as those precipitated from the sulfate and oxysulfate salts and washed free of the sulfate ions displayed quite similar textural characteristics. The unheated samples and those heat-treated at 400 °C were mesoporous, with some microporosity, and relatively large surface areas in the order of 200–300 m²/g. Heat treatment to 600 °C led to a relative decrease in surface area, in the order of 100 m²/g, and to the disappearance of microporosity. The mixed zirconium and titanium oxides with a sulfate content of ≈17% displayed significantly lower surface areas, smaller than 10 m²/g, with a prevalence of micro and mesoporosity. Infrared and thermal studies indicated the presence of differently bounded sulfato groups, which seem to have a blocking effect on the pores, resulting in the observed smaller surface areas.     

New sol–gel processes in the synthesis of inorganic sorbents and ion exchangers based on nanoporous oxides and phosphates of polyvalent metals

The original competing-templating sol–gel method was proposed based on the idea that the formation of inorganic sols and gels always slower process than the formation of the corresponding precipitations; slowing down of solid phase formation (sol particles) can be realized by the competition with main reagents of the cations and anions added to one of starting precursors. This new sol–gel process can be conducted with water solutions only simplest salts, alkalis and acids without using chelating reagents. The date are also presented on the “oil-drop” and “air-drop” semi plant technologies for continuous sol–gel production of porous spherically granulated sorbents and inorganic ion exchangers such as amorphous titanium and zirconium phosphates. Here are represented also data about their porous structure and the role competing-templating triply charged cations (Al³⁺, Fe³⁺) in the ultra pores formation for selective sorption of heavy metals, radionuclides and uranium.     

Synthese von [SiW11O39MF]5– (M = Zr,Hf) – den ersten Heteropolyoxowolframaten mit terminal gebundenem Fluor

Synthesis of [SiW₁₁O₃₉MF]^5– (M = Zr, Hf) – the First Heteropolyoxotungstates with Terminal Bonded Fluorine The reaction of metal fluorides of Group 4 with lacunar [α-SiW₁₁O₃₉]^8– resulted in the formation of metal fluorides containing inorganic clusters. In the case of titanium all metal fluorine bonds are cleaved, while the corresponding reaction of zirconium and hafnium, respectively gave compounds having one metal fluorine bond. The new compounds contain an additional active NMR probe.     

Synthesis of mono and diesters using eco-friendly solid acid catalyst – zirconium titanium phosphate

Abstract

Amorphous zirconium titanium phosphate (ZTPA), an advanced inorganic ion exchanger of the class of tetravalent bimetallic acid (TBMA) salt, has been synthesized by sol gel route. ZTPA has been characterized by inductively coupled plasma atomic emission spectrometer (ICP-AES), Thermal analysis, Fourier transform infrared spectrometer (FTIR), and X-ray diffraction (XRD). The acid sites present in ZTPA indicate good potential to be explored as solid acid catalyst. The catalytic characteristics of ZTPA have been evaluated by determining surface area and surface acidity. The catalytic performance of ZTPA as a solid acid catalyst has been explored by studying esterification as a model reaction wherein mono and diesters have been synthesized. Crystalline zirconium titanium phosphate as well as amorphous and crystalline phases of zirconium phosphate and titanium phosphate have also been synthesized, characterized, and their catalytic performance investigated for comparative studies. TBMA salt exhibits enhanced catalytic activity compared to its single salt counterparts and amorphous phases exhibit higher catalytic activity compared to their crystalline phases.     

Recovery of137Cs from acidic fission products solutions

A procedure for the isolation of¹³⁷Cs from acidic fission products solutions, based on the use of silica gel and zirconium phosphate ion exchangers, is presented. The¹³⁷Cs recovered by the ion-exchange process is converted to powder by coprecipitation of cesium with ammonium molybdophosphate.¹³⁷Cs pellets have been prepared by compression of¹³⁷Cs ammonium molybdophosphate powder using a hydraulic press. An important aspect of this procedure is that it does not require neutralization of the Purex waste.     

Synthesis of dispersed silicon, titanium, and zirconium dioxides by pyrolysis of cellulose inorganic composites

The method of the synthesis of dispersed powders of silicon, titanium, and zirconium dioxides was developed, including formation of cellulose inorganic composites by impregnation of pressed granules of powdered cellulose with solutions of tetraethoxysilane and tetrabutoxy zirconium, hydrolysis of the organometallic constituent of the composite, pyrolysis of the cellulose matrix of the composite, and burning of its carbon constituent.     

Separation of zirconium from fission products in silica gel—nitric acid systems

A method for the separation of zirconium from fission products based on the system 100–200 mesh silica gel—2.0 M nitric acid is described. Decontamination factors are over 500 for ⁹⁵Nb, ¹⁰⁶Ru, ¹²⁴Sb, ¹³⁷Cs, molybdate and uranium(VI), and the yield of zirconium is 98 %.     

Synthesis and ion-exchange properties of crystalline titanium and zirconium phosphates

The preparation of novel types of inorganic ion-exchangers, titanium and zirconium phosphates and their ion-exchange properties towards strontium ions, are reported and discussed. Ti(HPO₄)₂·2H₂O is shown to be very stable to hydrolysis and to have high exchange capacity in strongly acid medium. In the case of zirconium phosphate, the titration curves with alkaline earth metal hydroxides are strongly affected by hydrolysis of the exchanger and precipitation of insoluble phosphate. The degree of conversion of the exchanger at which phosphate precipitation begins was found to be 80% for Sr²⁺. The comparison of Ti(HPO₄)₂·2H₂O with the corresponding zirconium phosphate dihydrated phase suggests that the former possesses a lattice structure different from that reported for the monohydrated exchanger.This revised version was published online in November 2005 with corrections to the Cover Date.     

Effect of the porous structure of polymer on the kinetics of Ni<Superscript>2+</Superscript> exchange on hybrid inorganic-organic ionites

Hybrid organic-inorganic ion exchangers are obtained by incorporating amorphous zirconium hydrophosphate into the gel of strong acidic cation exchange resin. Hybrid organic-inorganic ion exchangers are obtained by modifying strong acidic cation exchange resin with amorphous zirconium hydrophosphate. The synthesized materials are studied by standard porometry contact. It is found that raising the inorganic component content to 34 wt % diminishes the microporosity of the samples and simultaneously enhances the of meso- and macropore volume. Experiments establish that modification of a polymer matrix lowers the self-diffusion coefficient of Ni²⁺ from 8.1 × 10⁻¹² to 2.4 × 10⁻¹²–4.1 × 10⁻¹² m² s⁻¹; nevertheless, an inorganic ion exchanger minimizes the inhibitory effect of co-ions on the Ni²⁺ → H⁺ exchange rate. One possible mechanism for of filling of the matrix by with particles of zirconium hydrophosphate is discussed.     

Structural studies on some inorganic ion exchangers

Ferrocyanides of zirconium(IV) and tin(IV), antimonates of cerium(IV) and titanium(IV), and cerium(IV) tungstate, has been shown to be useful materials as inorganic ion exchangers in radio- and analytical chemistry. These materials are sufficiently stable towards high dose of γ-radiations. Attempt is made to study some structural aspects and possible exchange sites of these materials using different techniques like thermal, Mössbauer and infrared spectroscopy.     

Study on the preparation of a137Cs/137mBa radionuclide generator

^137mBa has been applied successfully to dynamic studies for diagnosis in nuclear medicine for a long time. A variety of inorganic exchangers have been employed for the separation of^137mBa from its parent¹³⁷Cs. In the present study, cupric cobaltic ferrocyanide and amorphous zirconyl phosphate were synthesized and compared for use in a¹³⁷Cs/^137mBa generator. The results show that the former can adsorb¹³⁷Cs more efficiently and provide high elution yield of^137mBa with greater than 99.99% radionuclide purity. A new generator involving multimillicuries of^137mBa, in connection with a computerized detection system, has been constructed.     

Early (Ti,Zr)-late (Rh,Ir) heteronuclear complexes with bridging sulphido ligands

We report in this account on the controlled synthesis of novel d⁰–d⁸ early-late heteropolynuclear diolefin and carbonyl clusters. The synthetic approach was based on additive–deprotonation reactions involving the titanium and zirconium bis-hydrosulphido complexes of formula [Cp₂Ti(SH)₂] and [Cp^tt₂Zr(SH)₂] and appropriate rhodium and iridium diolefin and carbonyl compounds. The significant differences between the resulting early-late complexes and their structures coming from the titanium or zirconium metalloligand precursors are highlighted. The catalytic activity of some representative titanium–rhodium and zirconium–rhodium compounds towards alkene hydroformylation was explored. Interestingly, the heterotetranuclear ‘CpTi(μ₃-S)₃Rh₃’ structure was maintained as such under mild conditions. To cite this article: L.A. Oro et al., C. R. Chimie 6 (2003) 000–000.     

Spectrofluorimetric determination of titanium,zirconium and hafnium and their binary mixtures with biacetylmonoxime nicotinylhydrazone

The synthesis, characteristics and analytical applications of biacetylmonoxime nicotinylhydrazone are described. This compound forms fluorescent complexes with titanium(IV) (λ_ex = 430, λ_em = 540 nm), zirconium (λ_ex = 415 nm, λ_em = 505 nm) and hafnium (λ_ex = 400, λ_em = 500 nm) in an acidic medium. Titanium forms a 1:2 metal:ligand complex, whereas zirconium and hafnium form 1:2:1 metal:ligand:sulphate ternary complexes. Highly selective spectrofluorimetric methods for titanium (20–100 ng ml^?1), zirconium and hafnium (5–100 ng ml^?1) are proposed, and procedures for the analysis of binary mixtures of these ions are described.     

Determination of Mo,W and Zr in molybdates and tungstates of zirconium and titanium

Molybdate and tungstate of zirconium and titanium gels, used as matrices of ⁹⁹Mo/^99mTc and ¹⁸⁸W/¹⁸⁸Re generators, were synthesized under different conditions, in order to establish their performance and to choose the most appropriate gel to produce commercially. This type of generators demands a high content of Mo or W (>25%) in the matrices, since they use ⁹⁹Mo and ¹⁸⁸W of low specific activities. Therefore, it is of vital importance, to know the concentration of W and Mo in these gels, to determine their viability as matrices of the ⁹⁹Mo/^99mTc and ¹⁸⁸W/¹⁸⁸Re generators. There are different analytical methods to determine Mo and W, however, the presence of Zr and Ti in these gels, in many occasions, interfere in the analysis, imposing the previous separation of both metals before their determination. Therefore, the preparation time of the sample, the cost and the generation of chemical waste of these analyses are increasing. In order to eliminate these difficulties, the concentration of Mo, W and Zr of approximately 43 gels of molybdate and tungstate of zirconium and titanium, were evaluated by NAA without preparation of the samples. The results of this study reveal that the conditions of preparation of the gels influence directly their Mo and W content. In general, the titanium molybdate gels possess, on the average, a larger content of Mo (37%) than the zirconium molybdate gels (30%), while the titanium tungstenate gels contain only 8.5%.     

Coordination Cage-Based Emulsifiers: Templated Formation of Metal Oxide Microcapsules Monitored by In Situ LC-TEM

Metallo-supramolecular self-assembly has yielded a plethora of discrete nanosystems, many of which show competence in capturing guests and catalyzing chemical reactions. However, the potential of low-molecular bottom-up self-assemblies in the development of structured inorganic materials has rarely been methodically explored so far. Herein, we present a new type of metallo-supramolecular surfactant with the ability to stabilize non-aqueous emulsions for a significant period. The molecular design of the surfactant is based on a heteroleptic coordination cage ( CGA-3 ; CGA =Cage-based Gemini Amphiphile), assembled from two pairs of organic building blocks, grouped around two Pd(II) cations. Shape-complementarity between the differently functionalized components generates discrete amphiphiles with a tailor-made polarity profile, able to stabilize non-aqueous emulsions, such as hexadecane-in-DMSO. These emulsions were used as a medium for the synthesis of spherical metal oxide microcapsules (titanium oxide, zirconium oxide, and niobium oxide) from soluble, water-sensitive alkoxide precursors by allowing a controlled dosage of water to the liquid-liquid phase boundary. Synthesized materials were analyzed by a combination of electron microscopic techniques. In situ liquid cell transmission electron microscopy (LC-TEM) was utilized for the first time to visualize the dynamics of the emulsion-templated formation of hollow inorganic titanium oxide and zirconium oxide microspheres.     

State of phosphorus in sorbents based on titanium and zirconium phosphates from 31P NMR spectroscopy data

A ³¹P NMR method has been used to study sorbents based on titanium and zirconium phosphates synthesized by bulk mixing the reagents and treatment of x-ray amorphous TiO₂, rutile and ZrO₂ by phosphoric acid. In the bulk titanium and zirconium phosphates the phosphorus occurs in four different states, phosphate groups bonded through cross-linking oxygen atoms with one, two, and three atoms of the metal and molecules of phosphoric acid trapped in the matrix of the sorbent in the synthesis process. It is established that the method of grafting the phosphate groups to the surfaces of the hydrated TiO₂ and ZrO₂ is determined by the crystalline and chemical properties of the surfaces.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 24, No. 5, pp. 633–636, September–October, 1988.     

Determination of zirconium in zirconium-bearing sands and zirconium concentrates by a nondispersive x-ray fluorescence method

A nondispersive X-ray fluorescence; method for the rapid, nondestructive determination of zirconium in zirconium-bearing sands and zirconium concentrates is described. A ¹⁰⁹Cd source of primary radiation and compact geometry for measurements were used. The matrix effect from iron and titanium in sands was eliminated by measuring the fluorescent radiation of zirconium and the scattered primary radiation, and interpreting the data with nomograms. For concentrates, dilution with pure sand and measurement of the ratio of fluorescence to scattered radiation were used to reduce a matrix effect; a calibration curve was then satisfactory. Particle size effects were avoided by grinding to below 70 μ.