Discharge of hydronium ions on metal cathodes in the presence of pyridine

In this work, studies have been carried out on the electrochemical reduction of hydrogen (hydronium ion) from acidic aqueous solutions in the presence of an organic substance – pyridine. Electrolysis was carried out in an electrolyte with a sulfuric acid content (0.18; 0.36 M) with a pyridine additions of 8.4·10-3 M. Potentiostatic studies were carried out on a Potentiostat P-30Jcom Elins potentiostat using a three-electrode cell. Working electrodes (cathodes) were made of M1 copper with an area (S) of 0.09 cm2; aluminum (AD1) S – 0.125 cm2, zinc (Ts0A) S – 0.35 cm2, lead (Cl) S – 0.20 cm2, auxiliary (anode) – from a platinum plate with an area of 0.20 cm2, reference electrode – silver chloride (AgCl/Ag). In potentiometric measurements, the results are presented according to the average data obtained for 30 s of electrolysis in the potential range (-950 ÷ -1100 mV for AgCl/Ag), and in studies in the galvanostatic mode at current densities from 0 to 110 mV/cm2, the results are presented as average data, obtained in the initial 5 s of the process. The paper presents comparative data on the electrokinetic parameters studied under the same conditions of hydrogen discharge reactions at different cathodes in electrolytes with a sulfuric acid content of 0.36 M. It is shown that the highest discharge current density of the hydronium ion (Н3О+) is achieved at the copper electrode, and the lowest at the lead electrode. With the addition of 8.4∙10-3 M pyridine to the electrolyte, the reduction of hydrogen cations is somewhat reduced on the electrodes used, except for lead. The transfer coefficients of the hydrogen discharge at all electrodes are low, and with the addition of pyridine they decrease even more. The low transfer coefficients indicate that the process of the hydronium ion discharge proceeds in a non-activation mode. The lowest exchange current is recorded at the copper and lead electrode. At the zinc electrode, the exchange of current is one to two orders of magnitude higher than at the other electrodes, so it can be noted that at this electrode the system under consideration is closer to the equilibrium of state. The order of the reaction of the course of electrolysis by the hydronium cation on the copper, aluminum and zinc electrodes is close to unity. The addition of pyridine leads to a slight decrease in the order of the reaction. This is due to the fact that pyridine molecules in acidic solutions exist in the form of pyridinium ion, which is reduced at the cathode. In this case, a significant amount of hydrogen is absorbed, which should explain the decrease in the order of the reaction with respect to the hydronium ion in the presence of pyridine additives. The obtained low values of the transfer coefficients indicate that, during the discharge of hydronium ions, the process is limited to a greater extent by the concentration polarization. The diffusion nature of the reduction of hydronium ions in electrolytes with a sulfuric acid concentration of 0.18 and 0.36 M is also evidenced by data taken in a dynamic mode.

Study on Microetching Performance of Hydrogen Peroxide / Sulfuric Acid System

In order to get the optimum technological conditions of the hydrogen peroxide /sulfuric acid system,the static corrosion method was used to study the related parameters including compositions of the microetching system and the operation temperature. The results of the experiment show that the microetching performance of the hydrogen peroxide /sulfuric acid system was excellent under optimum conditions of maintaining temperature at 30~35, copper concentration about 25 g/L, hydrogen peroxide 30~40 g/L and sulfuric acid content 70~90 g/L . The process of microetching is stable and controllable.

Sulfonación de ésteres metílicos derivados del aceite de palma

<p class="Corpoica">En la presente investigación se estudió la sulfonación con trióxido de azufre (SO3) de ésteres metílicos fabricados mediante una transesterificación de la estearina hidrogenada de palma. La generación del agente sulfonante (SO3) mediante calentamiento, agitación y burbujeo de nitrógeno sobre óleum permitió establecer las condiciones de procesamiento. La materia prima se caracterizó mediante cromatografía de gases y espectroscopia infrarroja, y a través de titulaciones volumétricas se determinó el porcentaje de materia activa (Hyamina 1622) y del ácido sulfúrico contenido en el producto. Se determinaron el aceite libre mediante extracciones con éter de petróleo, y la coloración mediante espectrofotometría (420 nm). Se sugieren valores de las condiciones de proceso con miras a un escalamiento piloto. Las variables que tienen una influencia más determinante sobre las propiedades finales del producto son: el caudal de reactante líquido, la razón molar SO3/metiléster, la fracción molar de SO3 (o el porcentaje volumétrico) en la corriente sulfonante, la temperatura del proceso. </p><p class="Corpoica"> </p><p class="Corpoica"><strong>Sulfonation of methyl esters derived from palm oil </strong></p><p class="Corpoica">Sulfonation with sulfur trioxide (SO3) of methyl esters produced by a transesterification of hydrogenated palm stearin, was studied in the present research. The generation of sulfur trioxide (SO3), by heating, stirring and bubbling nitrogen on oleum, helped establish the conditions for processing. Through gas chromatography and infrared spectroscopy, raw materials were characterized; and with volumetric titrations, the percentage of active substance (Hyamina 1622) and sulfuric acid content in the product were determined, oil-free through drawings with petroleum ether, and coloring was also determined in a spectrophotometer (420 nm). Recommendations were developed from the standpoint of the process used to identify the main variables for the functionality of the sulfonation plant to a scaling-level pilot. The flow of liquid reactant, the molar ratio SO3/methyl ester, the mole fraction of SO3 (or the percentage by volume) in the sulfonante gaseous flow, and the temperature process are the variables that have a more decisive influence on the conversion and properties of the product. </p>

DYEBINDING AND MUCOPOLYSACCHARIDE CONTENT IN CONNECTIVE TISSUE

The hyaluronic acid content of the mucoid layer of the rooster comb and the chondroitin sulfuric acid content of bovine nasal cartilage were determined in the fresh tissue, in the water extract of the tissue, and in the water-extracted residue. The binding of cationic dye by the tissue, the tissue extract and the residue was compared with the mucopolysaccharide content. The molar ratio of the bound dye to the anionic sites of the mucopolysaccharides varied between 1.1 and 1.8. In the comb extract this ratio was one. This indicates that, with the exception of the comb extract, anionic sites other than those of the mucopolysaccharides are also responsible for the dyebinding.