Fluorescence drainage profiles of thin liquid films.
Fluorescence drainage-profiles of thin liquid films formed from Rhodamine solutions containing anionic, cationic and non-ionic surfactants have been investigated. It is found that the influence of system variables such as electrolyte concentration, dye concentration, film environment and solution viscosity can be evaluated by means of the profiles. The addition of sodium chloride leads to the expansion (non-ionic surfactant), or contraction (anionic surfactant) of the profiles. In the case of the cationic surfactant, it reduces the number of fringes in the profiles. The height of selected fringes changes linearly with dye concentration, and no fringes are observed when the films are submerged in non-polar solvents. The influence of solution viscosity on film thickness and drainage rate is demonstrated by the number and frequency of fringes in the profile. The formation of first and second "black films" from solutions containing varying concentrations of sodium chloride can be shown.
Formation constants for the complexes of 2-mercapto-3-phenylpropanoate with nickel(II) and hydrogen ions.
The system formed by 2-mercapto-3-phenylpropanoate (MPP), nickel(II) and hydrogen ions in 30% (v/v) ethanol-water at 25 degrees and I = 100mM (nitrate) has been characterized by means of glass-electrode potentiometry. Protonation constants for 2-mercapto-3-phenylpropanoate and formation constants for the complexes Ni(3)(MPP)(2-)(4) and Ni(MPP)(2-)(2) are reported.
A potentiometric and calorimetric study of the polynuclear and mononuclear complexes of Ni(II) and Zn(II) with 2-mercaptopropionic acid
Abstract The composition and stability constants of the complexes formed between Ni 2+ and Zn 2+ and 2-mercaptopropionic acid (thiolactic acid, TLA) were determined by a pH-metrical method at 25°C and in 0·5 M KNO 3 . For the system Ni 2+ /TLA, the complexes BA , BA 2 and B 3 A 4 were found. For the system Zn 2+ /TLA the same complexes as for Ni 2+ and also the complex B 2 A 2 were detected. The enthalpy and entropy changes, accompanying the formation of the complexes were calculated from calorimetric titrations.