Izvestiya Vuzov. Prikladnaya Khimiya i Biotekhnologiya

6-11

Authors: Aliev И.А. , Sinegovskaya L.M. , Trofimov B.A.

The purpose of this research was to develop a selective rapid method for verifying the presence of palladium. For the first time, 2-(4-ethilthiophenyl) pyrrole has been used as a reagent for palladium determination. The reagent was obtained by the Trofimov reaction from 4-ethylthiophenylketoxime and acetylene at atmospheric pressure (Potassium Hydroxide/Dimethyl Sulfoxide, 96 °С, 5 h). It is established that Pd (II) and 2-(4-ethilthiophenyl) pyrrole form a complex compound of yellow colour in hydrochloric solutions (6 M of HCl, with a pH of up to 5). This compound absorbs in the visible region, λ = 415 nm. The properties of the palladium pyrrole complex were studied by an extraction-photometric method. The limits of Pd (II) concentrations (0,5-5,0 μg/ml), obeying the basic law of photometry, were revealed. The developed method for verifying the presence of Pd has been tested on complex solutions and the samples of industrial catalyst RC-404. It is shown that the new reagent provides a high selectivity of Pd (II) determination in the presence of Ag (I), Mn (II), Zn (II), Pb (II) and Ni (II), Al (III), Fe (III), Bi (III), Th (IV), Pt (IV), (VI), W (VI) and (VI), with the accuracy of analysis being ± 4%. In comparison with other analytical reagents, 2-(4-ethylthiophenyl) pyrrole is characterized by a high accuracy and good reproducibility of results, as well as by the selectivity and promptness of the analysis (4-5 min).

17-24

Authors: Dragunskii A.V.

Research into the kinetics of processes associated with the regeneration of spent chromium-containing solutions primarily aims to determine such basic parameters, as the order and rate constants of the reactions involved, their activation energies and transference numbers. All these parameters determine the efficiency of the regeneration process and its power consumption values. In addition, knowledge of these dependencies is essential for the selection of optimal operating modes of a device for regenerating spent chromium-containing solutions, as well as for the development of mathematical models and engineering calculation methods describing such processes. On the basis of experimental data, a functional relationship between changes in the values of electric current intensity and transference numbers has been established. The optical density of samples was measured using a photoelectric concentration colorimeter KFK-2-UHL 4.2. The voltage and current intensity values were controlled and regulated using a power supply unit Mastech HY3005-2. It is shown that an increase in the intensity of electric current leads to a decrease in the mobility of chromium ions. This occurs because the gas is absorbed by the solution, which prevents the passage of electric cur-rent. In addition, an increase in the current intensity results in the deposition of chromium on the electrode. Optimal dependencies between the key kinetic characteristics and parameters of the re-generation process are provided. Diagrams are presented for calculating optimal parameters of the process and corresponding power consumption values, which can be helpful in carrying out the re-generation of spent chromium-containing solutions with a high efficiency.