Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
Glycine and L-Tryptophan, a Comparative Investigation on Interactions in Cu(II) Binary and Ternary Complexes in Aqueous Solution
American Journal of Biochemistry , 2012, DOI: 10.5923/j.ajb.20120203.04
Abstract: The acidity and stability constants of M(Trp) M: Cu2+, Cu(Bpy)2+, and Cu(Phen)2+ complexes, were determined by potentiometric pH titration. It is shown that the stability of the binary Cu(Trp) complex is determined by the basicity of the carboxylate group on one side and amino group on the other side. It is demonstrated that the equilibrium, Cu(Har)2+ + Cu(Trp) Cu(Har)(Trp) + Cu2+, is displacement due to the well known experience that mixed ligand complexes formed by a divalent 3d ion, a heteroaromatic N base and an O donor ligand possess increased stability. The other part of this displacement, which amount on average to an increased stability of the mixed ligand Cu(Bpy)(Trp) and Cu(Phen)(Trp) complexes of about 0.97 or 1.31 log unit. The stability constants of the 1:1 complexes formed between Cu2+, Cu(Bpy)2+ or Cu(Phen)2+ and Trp2 , were determined by potentiometric pH titration in aqueous solution (I = 0.1 M, NaNO3, 25℃). The order of the stability constants was reported. The results show following order for Trp, Cu(Trp) < Cu(Bpy)(Trp) < Cu(Phen)(Trp), and Gly, Cu(Gly) > Cu(Bpy)(Gly) ≤ Cu(Phen)(Gly). A comparative investigation between ternary complexes of Trp and Gly is made. The comparison of stability constants of these ternary complexes show that Cu(Har)(Gly) exist in open form but Cu(Har)(Trp) is found near 100% in closed form. The differences between the above mentioned stability constants based on stacked form of Cu(Har)(Trp). The stacked form provides for increased stability.
On the applicability of the uniquac method to ternary liquid - liquid equilibria
Alvarez Juliá,J.; Barrero,C.E.; Corso,M.E.; Grande,M.C.; Marschoff,C. M.;
Anales de la Asociaci?3n Qu?-mica Argentina , 2004,
Abstract: the use of the uniquac method for correlating experimental data in ternary liquid-liquid equilibria and its predictive capability is considered. it is concluded that parameters obtained by direct correlating techniques have large uncertainties. hence, for predictive purposes the original approach should be used.
Prediction of ternary vapor-liquid equilibria for 33 systems by molecular simulation,  [PDF]
Y. -L. Huang,J. Vrabec,H. Hasse
Physics , 2009,
Abstract: A set of molecular models for 78 pure substances from prior work is taken as a basis for systematically studying vapor-liquid equilibria (VLE) in ternary systems.All 33 ternary mixtures of these 78 components for which experimental VLE data is available are studied by molecular simulation. The mixture models are based on the modified Lorentz-Berthelot combining rule that contains one binary interaction parameter which was adjusted to a single experimental binary vapor pressure of each binary subsystem in prior work.No adjustment to ternary data is carried out. The predictions from the molecular models of the 33 ternary mixtures are compared to the available experimental data.In almost all cases, the molecular models give excellent predictions of the ternary mixture properties.
Thermal analysis and prediction of phase equilibria in ternary Pb-Zn-Ag system  [PDF]
?ivkovi? D.,Mini? D.,Manasijevi? D.,?estak J.
Journal of Mining and Metallurgy, Section B : Metallurgy , 2011, DOI: 10.2298/jmmb1101023z
Abstract: Ternary Pb-Zn-Ag system is typical for some physicochemical processes going on in refining phase in the extractive metallurgy of lead. Therefore, investigation of mentioned system is important from both theoretical and practical research of the phenomena occurring during the lead desilverizing process. The results of experimental investigation using differential thermal analysis (DTA) and thermodynamic calculation of phase equilibria in Pb-Zn-Ag system according to CALPHAD method, in the sections with Zn:Ag mass ratio equal to 90:10, 70:30 and 50:50, are presented in this paper.
Potentiometric Determination of Stability Constants of Sulphathiazole and Glycine-Metal Complexes  [PDF]
Awad A. Al-Rashdi, A. H. Naggar, O. A. Farghaly, H. A. Mauof, A. A. Ekshiba
American Journal of Analytical Chemistry (AJAC) , 2018, DOI: 10.4236/ajac.2018.93009
Abstract: Binary and ternary complexes of (Fe(III), Pb(II), Co(II), Al(III), La(III), Sr(II), Cr(III), Ti(II) and Zr(II)) with sulphathiazole (as primary ligand) and amino acid glycine (as secondary ligand) have been studied potentiometrically at 25°C ± 0.1°C and I = 0.1 M NaClO4 in 25% (v/v) pure ethanol-water medium. Although there are many methods available to study the stability of metal-ligand complexes, pH-metry is most frequently used. In extension of our study on solution equilibria, we used Calvin-Bjerrum method for the calculation of stability constants. Stoichiometries and stability constants of binary systems containing the above metal ions in a 1:1 and 1:2 and/or 1:3 ratios were also determined to compare the effect of the secondary ligand on (1:1) Metal:Sulphathiazole system. The protonation constants of the complexes were evaluated for the system M:Sulphathiazole:Glycine = 1:1:1. The order of stability of the binary and ternary complexes was examined. It was found that glycine adds preferably [M-Sulfathiazole] rather than to the aqueous complexes of metal ions. In all cases 1:1:1 complex was formed.
Liquid - liquid equilibria of the water + butyric acid + decanol ternary system
Kirbaslar, S.I.;
Brazilian Journal of Chemical Engineering , 2006, DOI: 10.1590/S0104-66322006000300010
Abstract: liquid-liquid equilibrium (lle) data for the water + butyric acid + decanol ternary system were determined experimentally at temperatures of 298.15, 308.15 and 318.15 k. complete phase diagrams were obtained by determining the solubility curve and the tie lines. the reliability of the experimental tie line data was confirmed with the othmer-tobias correlation. the unifac method was used to predict the phase equilibrium of the system using the interaction parameters for groups ch3, ch2, cooh, oh and h2o determined experimentally. distribution coefficients and separation factors were evaluated for the immiscibility region.
三元体系MgCl2SrCl2H2O 323 K及348 K相平衡
Phase equilibria in the ternary system MgCl????2?? SrCl????2?? H????2??O at 323 K and 348 K

- , 2015,
Abstract: 采用等温溶解平衡法研究了323 K及348 K时三元体系MgCl????2?? SrCl????2?? H????2??O的相平衡关系. 根据实验数据, 绘制了相应的三元体系相图, 并确定了该体系共饱点的液相组成及对应的平衡固相. 该三元体系在323 K及348 K条件下均属于简单共饱型, 无复盐及固溶体生成, 相图均由一个共饱点, 两条单变量曲线和两个结晶区构成, 平衡固相均为MgCl????2???6H????2??O和SrCl????2???2H????2??O. 并对该三元体系在323 K和348 K时的相平衡进行了比较和讨论.
Phase equilibria in the ternary system MgCl????2?? SrCl????2?? H????2??O at 323 K and 348 K were studied by isothermal solution saturation method. Using the experimental data, the phase diagrams of ternary system at 323 K and 348 K were obtained, respectively. The solubilities of salts and the corresponding equilibrium solid phases of the ternary system were determined. The phase diagrams of the ternary system at both 323 K and 348 K belong to a simple type, and are without complex salt and solid solution. It can be found that in all cases there are one eutectic point, two univariant curves and two regions of crystallization corresponding to MgCl????2???6H????2??O and SrCl????2???2H????2??O. The phase equilibria in this ternary system at 323 K and 348 K are compared and discussed
Phase equilibria in the In–Sb–Bi system at 300 oC
Journal of the Serbian Chemical Society , 2006,
Abstract: Binary thermodynamic data, successfully used for phase diagram calculations of the binary systems In–Sb, Bi–Sb and In–Bi, were used fort the prediction of phase equilibria in the ternary system In–Sb–Bi at 300 oC. The predicted equilibria were compared with the results of SEM–EDX analysis.
Surface Analysis of Carbon Steel Protected from Corrosion by a New Ternary Inhibitor Formulation Containing Phosphonated Glycine, Zn2+ and Citrate  [PDF]
Boyapati Venkata Appa Rao, Madala Venkateswara Rao, Sirugudu Srinivasa Rao, Bojja Sreedhar
Journal of Surface Engineered Materials and Advanced Technology (JSEMAT) , 2013, DOI: 10.4236/jsemat.2013.31005
Abstract: Studies on surface analysis of carbon steel protected from corrosion in low chloride and nearly neutral aqueous environment by a synergistic mixture containing N,N-bis(phosphonomethyl) glycine (BPMG), zinc ions and citrate ions are presented. The effect of addition of citrate to the binary system, BPMG-Zn2+, is quite significant and is well explored through various studies. The surface protective nature is maintained in the pH range 5 - 9. Potentiodynamic polarization studies inferred that the ternary inhibitor is a mixed inhibitor. Impedance studies of the metal/solution interface indicated that the surface film is highly protective against the corrosion of carbon steel in the chosen environment. X-ray photoelectron spectroscopic (XPS) analysis of the surface film showed the presence of the elements namely iron, phosphorus, nitrogen, carbon, oxygen and zinc. Deconvolution spectra of these elements in the surface film inferred the presence of oxides/hydroxides of iron(III), Zn(OH)2 and [Fe(III), Zn(II)-BPMG-citrate] heteropolynuclear multiligand complex. This inference is further supported by the reflection absorption Fourier transform infrared spectrum of the surface film. Analysis by scanning electron microscopy (SEM) is presented for both the corroded and protected metal surfaces. Based on all these results, a plausible mechanism of corrosion inhibition is proposed.
Electrodeposition of Tin from Tartrate Solutions
Torrent-Burgués,J.; Guaus,E.;
Portugaliae Electrochimica Acta , 2005,
Abstract: the electrodeposition of tin in presence of tartrate ions has been analysed by electrochemical techniques, mainly chronoamperometry, and by scanning electron microscopy (sem). the obtained values of nucleus density with both techniques have been compared and discussed. the electrodeposition process follows an instantaneous nucleation with 3d growth under diffusion control at the initial times of the process, but a second nucleation process occurs at higher times. the influence of tartrate and of agitation conditions is also inferred from the crystal morphology.
Page 1 /100
Display every page Item

Copyright © 2008-2017 Open Access Library. All rights reserved.