Aqueous zirconium nitrates

Most of the experimental studies that have contributed information about the formation of Zr-nitrate complexes also yielded information concerning Zr-chloride complexes as discussed in Section V.4.2. All of the studies have been re-interpreted in the present review, using a statistical (least squares) regression technique, since in the majority of cases either the model or the selected stability constants assigned by the authors are not fully supported by the data (see Appendix A) or no uncertainties were assigned in the original work. A summary of the available data, as reported in the 

Method Ionic Strength t (°C) (mol dm ) logic P (reported) logic P (re-interpreted) Reference 

Experimental data are available only at two different ionic strengths (2 and 4 M perchlorate/nitrate solutions). The limited number of available experimental data makes the extrapolation to infinite dilution relatively uncertain for the first association constant and impossible, based on experimental data alone, for the higher order complexes. 

The Gibbs energy of formation for the ZrNOj and ZifNOj) complexes are determined from the stability constant at zero ionic strength and the Gibbs energy of formation for Zr and NOj (Section V.2.1 and Chapter IV, respectively)  

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Figure 3.12 Schematic representation of the dispersion of Zr02 particles and the extent to which the silica support is covered in three Zr02/Si02 catalysts prepared by impregnation with an aqueous zirconium nitrate solution, and one prepared via an exchange reaction of the support with zirconium ethoxide. The rectangles represent 100 nm2 of silica support area, and the circles represent a half-spherical particle of Zr02 seen from above. See Table 3.3 for corresponding numbers (adapted from Meijers et al. [33]).

Dibasic tridentate Schiff bases derived from salicylaldehydes and 2-aminobenzoic acid658 or l-amino-2-mercaptobenzene659 react with aqueous zirconium nitrate to give monomeric complexes of the type [Zr(0H)2(L)(H20)]. IR spectra of these compounds support an ONO-or ONS-tridentate attachment of the (L)2 ligands. 

Fig. 3.13 Schematic representation of the dispersion of Zr02 particles and the extent to which the silica support is covered in three Zr02/Si02 catalysts prepared by impregnation with an aqueous zirconium nitrate solution, and one prepared via an...

It can be seen from Figure 5.18 that the KD values for zirconium are higher than those for hafnium at all nitric acid concentrations. This is because the dissolution of zirconium nitrate (Zr(N03)4) into zirconyl (Zr02+) and nitrate (NOj) ions takes place to a lower extent as compared to the corresponding dissolution of hafnium nitrate in an aqueous medium. Hence, separation is feasible. However, at higher nitric acid concentrations the separation factor is reduced significantly because the dissociation of hafnium nitrate (Hf(NOs)4) decreases sharply with increasing nitric acid concentration, with the result that the separation factor, p, falls off rapidly. Hence, the separation process calls for the adjustment of the nitric acid concentration to a suitably low value. 

Figure 3.10 XPS spectra in the range from 150 to 200 eV, showing the Zr 3d and Si 2s peaks of the 7.r02/Si02 catalysts after calcination at 700 °C. All XPS spectra have been corrected for electrical charging by positioning the Si 2s peak at 154 eV. The spectra labeled nitrate correspond to the catalysts prepared by incipient wetness impregnation with an aqueous solution of zirconium nitrate, and the spectrum labeled ethoxide to that prepared by contacting the support with a solution of zirconium ethoxide and acetic acid in ethanol. The latter preparation leads to a better Zr02 dispersion over the Si02 than the standard incipient wetness preparation does, as is evidenced by the high Zr 3d intensity of the bottom spectrum (adapted from Meijers et at, [33]).

Prepare the zirconium-alizarin red S paper as follows. Soak dry filter paper in a 5 per cent solution of zirconium nitrate in 5 per cent hydrochloric acid and, after draining, place it in a 2 per cent aqueous solution of sodium alizarin sulphonate (BDH Alizarin Red S ). The paper is coloured red-violet by the zirconium lake. Wash the paper until the wash water is nearly colourless and then dry in the air. 

Equilibrium constants for the formation of nitrate complexes at hydrogen ion concentrations of 2 and 4 M and metal ion concentrations of 5 X 10 M or less, were determined using ion exchange techniques (353, 465) (Table XVIII). Activity coefficient data for aqueous zirconium and hafnium species are scarce, although there is one report (319) of activity coefficients for metal nitrate solutions as determined by the isopiestic method. 

All of the members of the final review team contributed, if not text, then comments to all of the chapters of the book. Their primary responsibilities for the different sections/chapters were divided as follows. Paul Brown prepared the introduction, and the sections on elemental zirconium, the zirconyl ion, the gaseous zirconium oxides, zirconium hydride, the halogen compounds and complexes, the chalcogen compounds and complexes, the Group 15 compounds and complexes, zirconium carbides and silicates. He was assisted by Christian Ekberg in the interpretation of aqueous zirconium complexes in these sections. Some initial work was done by Ken Jackson on the zirconium sulphate, nitrate and phosphate compounds and complexes. Bernd Grambow was responsible for the drafting of the sections on zirconium hydrolysis, the ion and the section on crystalline and amorphous zirconium oxides. Enzo Curti drafted the section on the zirconium carbonates. 

Assume that the aqueous and organic phases are conpletely immiscible and that the densities of the two phases are both constant (volumetric flow rates are constant). For zirconium nitrate, Zr(N03)4, the equilibrium data are listed below for 60 volume % TBP in kerosene (Benedict and... 

Nitrates. Anhydrous zirconium tetranitrate [12372-57-5] Zr(N02)4, is prepared from zirconium tetrachloride and nitrogen pentoxide (201). The hydrated compounds are obtained from aqueous nitric acid (165) Zr0(N02)2 2H20 [20213-65-4] is most commonly used Zr(N02)4 5H20 [12372-57-5] can be produced from strong nitric acid. 

Zirconium ( > 100 mg in ca /. M sulphuric acid solution). Add freshly prepared 10 per cent aqueous diammonium hydrogenphosphate solution in 50-100-fold excess. Dilute to 300 mL, boil for a few minutes, allow to digest on a water bath for 15-30 minutes and cool to about 60 °C. Filter through a quantitative filter paper, wash first with 150 mL of 1M sulphuric acid containing 2.5 g diammonium hydrogenphosphate and then with cold 5 per cent ammonium nitrate solution until the filtrate is sulphate-free. Dry the filter paper and precipitate at 110°C, place in a platinum crucible and carefully burn off the filter paper. Finally heat at 1000 °C for 1-3 hours and weigh as ZrP207 (Section 11.51). 

Elemental composition (for anhydrous Zr(N03)4 Zr 26.89%, N 16.51, O 56.59%. The water of crystallization can be measured by thermogravimetric methods. The nitrate ion can be measured by ion-selective electrode or ion chromatography. Zirconium may be analyzed in an aqueous solution by flame... 

As was observed in the case of the extraction of zirconium and hafnium from nitrate media, it is probable that the different tendencies of the metals towards hydrolysis has some effect on the selectivity observed,298 313 expecially in view of the proved extraction of hydroxo complexes. The extraction of both metals decreases markedly in the presence of sulfate ions in the aqueous phase (a feature that is utilized in the stripping of the loaded hafnium with sulfuric acid), although the selectivity for hafnium over zirconium is simultaneously increased on account of the higher stability constants of the inextractable sulfato complexes of zirconium.298... 

Many procedures are available in the literature for the deprotection of 5,S -dialkyl thioacetals to their carbonyl compounds such as clay supported ammonium ion, ferric or cupric nitrates, zirconium sulfonyl phosphonate, oxides of nitrogen, DDQ, Se02/AcOH, DMSO/HCI/H2O, TMSI(Br), LiN(i-C3H7)2/THF, ceric ammonium nitrate in aqueous CH3CN, CuCb/CuO/acetone and reflux, Hg(C104)2/chloroform and m-CPBA/Et3N/Ac20/H20. 

Inorganic precursors are much cheaper and easier to handle than metal alkoxides. Therefore the industrial production of oxide powders for ceramics and catalysts is mainly based on the precipitation or coprecipitation of inorganic salts from aqueous solutions. Gibbsite, Al(OH)3, (see Aluminum Inorganic Chemistry) is precipitated from aluminate solutions. Ti02 powders are made via the controlled hydrolysis of titanium salts. Stabilized zirconia is coprecipitated from aqueous solutions of zirconium oxychloride, ZrOC, and yttrium nitrate, YlKOsjs. 

All salts of zirconium and hafnium tend to hydrolyze in aqueous solutions, though less so than those of titanium. In highly dilute solutions (<10 " M), Zr and Hf exist as the aqueous ions [M(OH) ] " " +, where n is pH-dependent. The hydration energies are 7001 and 7169kJ moU for Zr and Hf respectively. In chloride, perchlorate, and nitrate solutions, hafnium is less hydrolyzed than zirconium, while the reverse is true in sulfate solutions. This is connected with the lower solubility of hafnium compounds in sulfate solutions, even in only slightly acid media. It should be noted that the sulfate anion has a strong affinity for Zr and Hf... 

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