It is studied the regeneration and utilization possibility of spent nitric acid solutions for copper and its alloys etching for the creating an environmentally clean closed-cycle production of regenerated electrolytes. It is established that some difficulties arise when using the electrochemical method in the regeneration process of these solutions: during copper electrodeposition from spent copper-containing nitric acid solutions, nitric acid decomposes with vigorous evolution of nitrogen dioxide, which prevents copper ions reduction. In order to suppress the side process, it was proposed to partially neutralize the solution, not reaching the pH of copper hydration (pH 4-5). It is revealed that a decrease in the concentration of metal cations occurs due to partial neutralization of the nitric acid contained in the solution by concentrated alkali solution. The pulsed electrolysis mode was used to increase the efficiency of the metal ions electrodeposition process from dilute solutions. It is established that the using of pulsed electrolysis can reduce diffusion difficulties that arise in a dilute spent nitric acid copper-containing solution, thereby intensify the process of copper electrodeposition. It is showed that the prospects of using ultrasound to increase the rate of the copper electrodeposition process and improve the quality of the resulting coating. It is studied the ultrasound field effect on nucleation during copper electrodeposition in a pulsed mode from a partially neutralized electrolyte simulating the spent nitrate solution of etching copper alloys on various materials by the potentiostatic. It is established an increase in the number of copper nucleus that form on the studied substrates (graphite, copper, steel) at the initial time under the action of an ultrasonic field. It is concluded that the use of ultrasound allows to intensify the process of metal electrodeposition. An increase in current efficiency during copper electrodeposition and an increase in the copper extraction degree using ultrasonic field are achieved at lower cathodic current densities in a pulse. It is substantiated using of graphite foil and steel as cathode materials in the copper extraction from the spent nitric acid etching solution.
Method of Controlling the Morphology of Cathode Deposit by Determining Electrochemical Resistance for Copper Electrodeposition Process
