Effectiveness of Nickel Plate as Anode in Synthesis of Tetramethylammonium Hydroxide Solution by Electrolysis

摘要

The migration ability of monovalent, bivalent, and trivalent ions, which often contaminate the product during tetramethylammonium hydroxide (TMAH) synthesis by electrolysis, was studied. It was recognized that most of the ions having the shorter Stokes radii had the higher migration abilities through a membrane into the catholyte during electrolysis. It would be difficult for these ions to prevent their penetrations to the catholyte, because of the short Stokes radius value of TMAH. On the other hand for the ions having the longer stokes radii such as Ni(II), Fe(III) or Cr(III), their penetrations were successfully prevented only using with the membrane. This indicates that even if these ions were contaminated into the anolyte from a stainless steel used as a manufacturing apparatus, the membrane could successfully prevent their penetrations, and also indicates that a stainless steel apparatus could be used instead of the expensive one consisted of quartz or tefron.Availability of Ni-plate as the anode in electrolysis of tetramethylammonium hydrogencarbonate (TMAC) was also studied. After impressing 12 V for 15 h (2.5X10~5 coulomb), concentration of Ni(II) in the anolyte was 47 ppm, and amount of it was 19 mg. For the sake of the low concentration of Ni(II) in the anolyte, the amount of it through membrane to the catholyte was under 10 ppb, and this indicates that Ni-plate was able to be used as an anode in electrolysis of TMAC in stead of the conventional and expensive anolyte (Pt, IrO_2, etc).