Сopper powders formation in the cathodic and anodic half-periods with industrial alternating current

For the first time, an installation was created for producing copper powders in the anodic and cathodic half-periods of industrial alternating current with a frequency of 50 Hz. This device consists of two electrolytic cells interconnected in parallel, in each electrolyzer there are two copper electrodes. Two diodes are also included in the electrochemical circuit to allow current flowing in opposite directions. The influence of electrodes current density, sulfuric acid concentration, copper ions, on current output of copper powder formation in each cell was investigated. It was established that the current output increases within the current density from 2000-8000 A/m2 and decreases with further increase of this parameter. When sulfuric acid concentration was 100 g/l and copper ions concentration was 15 g/l, the maximum current output of powder in electrolyzes was 50.1-53.3%, and the total current output exceeded 100%. Using a JSM-661 LV scanning electron microscope, the shape and size of obtained powders were investigated. On the basis of the conducted studies and captured oscillograms, the mechanism for copper powders formation in the anodic and cathodic half-cycles of alternating current was established. For the first time it was shown that the proposed installation allows to obtain copper powders in two half periods of alternating current. It was established that at the same time ultrafine metal powders with particle sizes of 1.0-1.5 microns had been formed. © National Academy of Sciences of the Republic of Kazakhstan, 2019

Formation of selenium powder at reduction of seleniteions in hydrochloric acid solution on the surface of copper anode

The article shows the possibility of reduction of selenite ions in the presence of copper (II) ions with the formation of dispersed selenium powders. The effect of the concentration of hydrochloric acid, copper (II) ions, the current density at the copper anode and the solution temperature on the current efficiency (CE) of the formation of selenium powder has been studied. The current efficiency of selenium powder was calculated by the weight of the powder formed. It was found that with increase in concentration of copper (II) ions and the solution temperature, the current efficiency of the formation of elemental selenium in the form of a powder increases. It was shown that at the current density below 75 A/m2, the current efficiency of selenium powder exceeds 100%. Previous studies have shown that titanium (IV) ions cannot be used in the recovery of selenite ions. Using an electron microscope, micrographs of selenium powder were obtained. They indicate the formation of a finely dispersed selenium powder of spherical shape with an average particle size of 0.252 µm. © 2020, National Academy of Sciences of the Republic of Kazakhstan. All rights reserved