tin iv sulfate formula
The present invention relates to an electrolytic process for producing tin iv sulfate by means of which tin iv sulfate can be obtained in a very concentrated form from a practical point of view and where the electrolysis proceeds using a diaphragm. This diaphragm is composed of an inorganic, ceramic material which has been densified by sintering at above 1,000 deg C and where the anode space is separated from the cathode space by this diaphragm.
After a voltage is applied between the two tin electrodes, tin ions in a sulfuric acid solution are transferred from the anode to the cathode and bivalent and quadrivalent tin ions are transferred from the cathode to the anode. The bivalent tin ions are absorbed by the anode and the bivalent tin ion concentration in the electrolyte solution increases. This ion concentration, which is the result of the solubility of bivalent tin in a given concentration of sulfuric acid, causes the formation of a tin-containing coating at the anode and thus increases the voltage and oxygen is evolved at the anode almost simultaneously or soon after.
The tin iv sulfate solutions produced are very low chloride and tin (IV) content solutions, which are very economical to use as galvanic anodes. These galvanic tinning baths are used for the electrolytic deposition of bivalent and quadrivalent tin onto objects such as plastics or metal alloys. Such galvanic tinnings have been carried out in the industrial sector for many years and have been successful for example in the dyeing of aluminum.