Electrolytic refining

Electrolytic refining:  It is the process of refining of metal in which impure metal is made the anode and a thin strip of pure metal is made the cathode. A solution of metal salt is used as an electrolyte. The apparatus is shown in the figure given below. When electric current is passed through the electrolyte, the impure metal from the anode is dissolved in the electrolyte and an equal amount of pure metal from the electrolyte is deposited on the cathode. The soluble impurities go into the solution whereas the insoluble impurities settle down at the bottom of the anode which is known as anode mud. Following diagram shows the electrolytic refining of copper in which anode is impure copper and cathode is thin strip of pure copper while the electrolyte used is the copper sulphate solution.