Search Results

You are looking at 1 - 10 of 231 items for :

  • Refine by Access: All Content x
Clear All

Abstract  

Two compounds of antimony trichloride and bismuth trichloride with valine are synthesized by solid phase synthesis at room temperature. Their compositions, determined by element analysis, are Sb(C5H10O2N)3·2H2O and Bi(C5H10O2N)2Cl·0.5H2O. The crystal structure of antimony complex with valine belongs to triclinic system and its lattice parameters are: a=0.9599 nm, b=1.5068 nm, c=1.9851 nm, α=92.270, β=95.050, γ=104.270. The crystal structure of bismuth complex with valine belongs to monoclinic system and its lattice parameters are: a=1.6012 nm, b=1.8941 nm, c=1.839 nm, β=99.73°. The far-infrared spectra and infrared spectra show that the amino group and carboxyl of valine may be coordinated to antimony and bismuth, respectively, in two compounds. The TG-DSC results also reveal that the complexes were formed.

Restricted access
Journal of Thermal Analysis and Calorimetry
Authors: P. Melnikov, F. J. dos Santos, S. B. Santagnelli, M. A. C. Secco, W. R. Guimarăes, A. Delben, and J. R. Delben
Restricted access

Abstract  

A radioanalytical method based on substoichiometric principles has been developed for the extraction and determination of antimony/III/ with 1-/2-pyridylazo/-2-naphthol /PAN/. Antimony/III/ forms a red complex with PAN in the presence of I or Br, which is extractable into benzene from sulphuric acid media.

Restricted access

and complexing agents. Their effect on central nervous system and on redox process on human body as well as their catalytic property toward enzyme activation and inhibition has also been reported [ 13 , 14 ]. Owing to properties of ligands antimony

Restricted access

Abstract  

A vitreous form of antimony orthophosphate has been obtained using antimony polyphosphate as a precursor. Morphologically, it is composed of small uniform grains having ellipsoidal shapes. Prolonged thermal treatment leads to the transformation into a crystalline variety. According to TG curves, both forms start to evaporate at 920°C without decomposition. Melting point of crystalline SbPO4 has been determined to be 877°C. Thermomechanical study reveals plastic behavior due to the capacity to flow under shearing stress. Ceramics formation in the system Sb2O3-SbPO4 is discussed. The presence of glass domains in this system has not been confirmed.

Restricted access

Abstract  

Two antimonic acid samples were prepared and designated as hydrolyzed (H-SbA) and refluxed (R-SbA) antimonic acids. Their structure and ion exchange behavior towards Na+ as a simple ion is investigated. R-SbA samples showed higher degree of crystallinity and slightly higher ion exchange capacity than the other sample although it had slightly lower water content. Thermal treatment of both samples showed an increase in their ion exchange capacity on heating up to 200 °C. On further heating up to 400 °C the capacity is appreciably decreased. Equilibria measurements of both samples in dilute solutions showed almost an ideal ion exchange behavior. The obtained data are discussed in detail.

Restricted access

Abstract  

The uptake of fission products 137Cs, 85Sr, 57Co, onto an antimony silicate, and its Na, K, Ca ion-exchanged forms have been studied. Distribution coefficients have been determined as a function of the concentrations of sodium, potassium and calcium nitrate solutions (0.01, 0.1 and 1M). Plots of log distribution coefficients against concentrations enabled the elucidation of exchange mechanisms in some cases. Potassium had the least, and calcium the most effect on isotope uptake when present as macro ions. The presence of sodium promoted hydrolysis that also affected the exchange selectivity.

Restricted access

Abstract  

Four ethylenediamine-N,N,N′,N′-tetraacetate complexes with Sb(III)-M-Sb(III) polynuclear structure (M=Co(II), La(III), Nd(III), Dy(III)) are synthesized. [Sb24-(EDTA)2Co(H2O)2]·5.15H2O is characterized by single crystal X-ray diffraction. The crystal structure of [Sb24-(EDTA)2Co(H2O)2]·5.15H2O belongs to monoclinic system, space group P21/n, lattice parameters: a=6.9969(2), b=20.8705(4), c=10.8106(2) Å, β=90.031(1)°, V=1578.66(6) Å3, Z=2, M r=1007.76, D c=2.120 g cm−3, F(000)=1001, μ=2.323 mm−1, the final R=0.0235 and wR=0.0629 for 3480 observed reflections (I>2σ(I)). The powder X-ray diffraction patterns of the complexes are also measured. Elemental analyses, FTIR spectra, TG-DSC and DTA of [Sb2(EDTA)2Ln]NO3·nH2O are performed. FTIR spectra reveal that the antimony and other metallic ions were connected through the carboxylate bridges. The thermal analysis can demonstrate the complex formation of the antimony, other metallic ions and EDTA. The possible pyrolysis reactions in the thermal decomposition process of the complexes, the experimental and calculated percentage mass losses are also given.

Restricted access

Abstract  

The redox titration of antimony(III), labeled with125Sb(III), by potassium iodate was radiometrically investigated using the burette method and the standard series method. The stoichiometry of the redox process was determined. The redox valence (the number of equivalents per mol) of potassium iodate for the oxidation of antimony(III) to antimony(V) was found to be 6, differing from the results obtained using the usual visual indicator method, where the value was shown to be 4. This disagreement in the equivalents of potassium iodate for the oxidation of antimony(III) is discussed.

Restricted access

Abstract  

Antimony has been determined in a number of nonmetallic dental materials currently used for tooth restoration. The method applied was instrumental neutron activation analysis. The concentration of antimony in some of the brands tested was found to be as high as 900 fold that in the normal hard dental tissues.

Restricted access