Mathematical Modeling and Experimental Studies of the Joint Electrodeposition of Gold and Silver from Sulfuric Acid Thiourea Solutions on Flow-Through 3D Electrode Taking into Account Its Nonstationary State

Mathematical models of electrochemical processes in reactors with flow-through 3D electrodes for the electrodeposition of metals from a polycomponent electrolyte solution have been presented. The parameters of the process and electrode, such as the flow rate of the electrolyte, porosity, specific surface, and the specific conductivity of the electrode and solution, at each electrode point during electrolysis have been taken into account. The mathematical models and methods for determining the electrochemical and hydrodynamic parameters of multicomponent electrochemical systems have been described. The data have been used to calculate industrial electrochemical processes in flow-through 3D electrodes. The adequacy of these methods has been shown. The experimental and calculated data on the electrodeposition of gold and silver from sulfuric acid thiourea solutions to carbon-graphite fiber cathodes have been analyzed. The dependences of electrodeposition parameters on the electrolysis conditions, the initial properties of the electrode-solution system, and the concentration ratio of gold and silver in the solution taking into account the joint reduction of hydrogen ions and molecular oxygen have been examined. The current and resulting regularities of the processes have been revealed. The adequacy of the mathematical models for industrial joint electrodeposition of gold and silver from sulfuric acid thiourea solutions on flow-through 3D electrodes taking into account the side electrode reactions has been shown. The appearance of anode zones on a cathode polarized carbon fiber flow electrode during the deposition of metals from multicomponent systems has been considered.