Title : Dissolution processes of metals during polarization with alternating current of industrial frequency
Abstract:
Our research is devoted to the electrochemical processes occurring during polarization by industrial alternating current with frequency of 50 Hz. The possibility of conducting targeted oxidation and reduction processes in the anode and cathode half-cycles of alternating current with the subsequent synthesis of a number of inorganic compounds is shown. Previously, it was considered impossible to purposefully carry out electrolysis under the action of alternating current and to obtain any compounds or substances, since the product obtained as a result of oxidation in the anode half-cycle would be reduced in the cathode half- cycle. As a result of our experiments, it was shown that during polarization with alternating current, the titanium electrode dissolves in aqueous acidic solutions. The discharge of hydrogen ions and partial reduction of the oxide film are possible in the cathode half-cycle. The surface of titanium, freed from the oxide film, is easily dissolved in acid by chemical reaction. The titanium electrode is electrochemically oxidized to form its ions in the anode half-cycle. It is established that after the polarization by alternating current in acidic aqueous solutions, the intensive dissolution of titanium occurs. In traditional electrolysis under the action of direct current, the titanium electrode does not dissolve anodically in aqueous solutions of inorganic acids, since an oxide film with semiconducting properties is formed on the metal surface during anodic polarization, and it passivates the electrode. In this regard, the established regularities of the dissolution of titanium in sulfuric acid and hydrochloric acid under alternating current polarization are new and promising.
A number of methods for the production of chlorides, sulfates, hydroxides and titanium dioxide have been developed, which are widely used in engineering and industry. Titanium (IV) hydroxide is an active sorbent in the chemical industry, titanium (III) chloride and sulfate are reducing agents and also serve as starting products in the synthesis of other important titanium compounds. Titanium dioxide serves as the starting material for the production of its other compounds, as well as titanium metal. The regularities of dissolution of lead, copper, iron, zinc, chromium, tungsten, platinum, silver, gold and some other metals under the action of alternating current have been established. The dissolution processes of lead, titanium, iron and copper at bipolar connection of electrodes under the alternating current action of industrial frequency have been investigated. In this case, the productivity of electrolysis increases 1.5-2.5 times. It is shown that during electrolysis under the action of alternating current, two half-cycles can be used simultaneously. This is achieved by the fact that two electrolyzers are connected to the circuit simultaneously and the electrodes are alternately dissolved in the anode half-cycle. The peculiarity of our research and their results is that the developed methods are simple in hardware design, they do not use current rectifiers, which are first, expensive, and second, cumbersome in industrial conditions. The processes take place at room temperature. Metal scrap (shavings, pieces, scraps) can be used as electrodes. The conducted research makes a significant contribution to the theory and practice of electrochemistry.
