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51.
Spectrophotometric Determination of Rhenium(IV) with Thiocyanate,TX-100 and N,N′-Diphenylbenzamidine
A spectrophotometric method to determine rhenium(IV) at trace level is based on the extraction of Re(IV)-SCN? complex in sulphuric acid media with N,N′-diphenylbenzamidine(DPBA) in presence of a non-ionic surfactant triton X-100 (TX-100) in chloroform. The complex shows maximum absorbance at 435 nm with amolar absorptivity value of 4.24 × 104 L mol?1 cm?1 at an acidity range 3.5-6.5 M H2SO4. The method followed Beer's Law for the system Re(IV)-SCN?(TX-100)-DPBA upto 4.0 μg Re(IV) mL?1. The detection limit of the method is 5 ppb. None of the tested foreign ions, except molybdenum(VI), interfere with the determination of rhenium. The interference due to molybdenum could effectively be removed by prior precipitation with oxine. The effect of various analytical parameters on the extraction of the metal are discussed. 相似文献
52.
Summary The title reaction has been followed spectrophotometrically at 325 nm (max of [Mn(CN)6]3–) under pseudo-first order conditions with cyanide in a large excess at pH=10.0, I=0.1M (NaClO4) and 25°C. The reaction follows first-order kinetics in [MnEDTA(OH)]2– and exhibits variable-order dependence in [CN–] one at high cyanide concentration, and two at low cyanide concentration. The product of above reaction has been identified as [Mn(CN)6]3–.The kinetics of the reverse reaction,i.e., the reaction of [Mn(CN)6]3- with EDTA4– have also been followed spectrophotometrically. This reactions is first-order with respect to both [Mn(CN)
6
3–
] and [EDTA4–] and exhibits an inverse first-order dependence on [CN–]. A six-step mechanism has been proposed in which the penultimate step is rate-determining. The activation parameters have been obtained and support the postulated mechanism. 相似文献
53.
Anuradha Mishra Malvika Bajpai Sunita Pal Monika Agrawal Sushant Pandey 《Colloid and polymer science》2006,285(2):161-168
The application of Tamarindus
indica seed mucilage (Tam), a food grade polysaccharide, and its acrylamide grafted copolymer as flocculants was assessed for the first time for removal of various types of dyes from model textile wastewater containing azo, basic, and reactive dyes. Acrylamide grafted T. indica mucilage (Tam-g-PAM) was obtained by ceric ion initiated polymerization technique. A series of contact time experiments were conducted to assess the system variables such as concentrations of mucilage and dyes and pH. These flocculants reduce the dye concentration by flocculation and settling. The grafted copolymer, Tam-g-PAM showed better results for dye removal. The optimal flocculant concentration, which was required to effect flocculation, was independent of dye concentration within the range examined. Both the flocculants performed better for removal of azo dyes than for reactive and basic dyes. 相似文献
54.
Summary The kinetics of the silver(I)-catalysed oxidation of malonic acid by peroxodiphosphate (pdp) was studied in acetate buffers. The rate law as represented by-d[pdp]/dt = {(k
1
K
inf2
sup-1
[H+]2 + k
2[H+] + k
3
K
3)/ ([H+]2/K
2 + [H+] + K
3)}[pdp][Ag(I)] conforms to the proposed mechanism. The rate is independent of malonic acid concentrations. Acetate ions do not affect the rate; however, the rate decreases as the ionic strength increases. A probable portrait of reaction events is suggested. A comparative analysis of the reactivity pattern of malonic acid towards peroxodiphosphate and peroxodisulphate in presence of silver(I) has been made. 相似文献
55.
M. K. Mishra 《Colloid and polymer science》1982,260(5):508-510
In an attempt to modify fibrous protein, methyl methacrylate (MMA) has been graft copolymerized onto Mulberry silk in an aqueous medium by using peroxydiphosphate — fructose redox system. Graft copolymerizations were carried out at 45, 50, and 55 °C for a period from 1 to 6 hr. Percentage grafting was found to be dependent upon reaction temperature, time, concentration of monomer, acid, peroxydiphosphate and fructose. The rate of grafting (R
p
) and the induction period (I
p
of MMA was determined as a function of total initial monomer concentration. 相似文献
56.
K. C. Mishra B. N. Dev S. M. Mohapatra W. M. Gibson T. P. Das 《Hyperfine Interactions》1983,16(1-4):997-1000
The electronic energy levels and wave functions of fluorine and chlorine atoms adsorbed at the <111> surface of silicon are obtained by the Hartree-Fock procedure applied to clusters simulating the surface structure. Minimising the total energy with respect to the positions of the halogen atoms, the Si-Cl distance in the adsorbed system was found to be in good agreement with that from a recent SEXAFS measurement, there being no corresponding data presently available for fluorine on silicon surface. The calculated19 f * nuclear quadrupole coupling constants using the electronic wave functions for SiH3F and the larger cluster Si4H9F, simulating the surface, differed substantially in contrast to the situation for the Si-F distance, indicating that the quadrupole coupling is a more sensitive indicator of the adequacy of the cluster chosen to represent the surface system. Experimental results for the coupling constants are awaited for comparison with theory. 相似文献
57.
Jackson SN Mishra S Murray KK 《Rapid communications in mass spectrometry : RCM》2004,18(18):2041-2045
Matrix-assisted laser desorption/ionization (MALDI) was used for the on-line analysis of single particles. An aerosol was generated at atmospheric pressure and particles were introduced into a time-of-flight (TOF) mass spectrometer through a single-stage differentially pumped capillary inlet. Prior to entering the mass spectrometer, a matrix was added to the particles using a heated saturator and condenser. A liquid matrix, 3-nitrobenzyl alcohol (NBA), and a solid matrix, picolinic acid (PA), were used. Particles were ablated with a 351 nm excimer laser and the resulting ions were mass-separated in a two-stage reflectron TOF mass spectrometer. Aerosol particles containing the biomolecules erythromycin and gramicidin S were analyzed with and without the matrix addition step. The addition of NBA to the particles resulted in mass spectra that contained an intact molecular ion mass peak. In contrast, PA-coated particles did not yield molecular ion peaks from matrix-coated particles. 相似文献
58.
The preparation of polymer blends of poly(methyl methacrylate) and poly(vinylidene fluoride) in different weight percentages is described. Vickers microhardness measurements have been made to study the effects of load and compositional ratio of the two polymers in polyblend. It is observed that poly(vinylidene fluoride) acts as a plasticizer for poly(methyl methacrylate). Evidence of increasing and decreasing strength of polyblends has been obtained for different compositional ratios of the two polymers. 相似文献
59.