| 摘要 |
PURPOSE:To efficiently recover nitric acid and/or hydrofluoric acid from its soln. by using an anion exchange membrane comprising a specified aromatic polymer as a diffusion dialysis membrane. CONSTITUTION:Nitric acid and/or hydrofluoric acid are recovered from a soln. containing nitric acid and/or hydrofluoric acid and metal ions by using an anion exchange membrane to separate the metal ions. In this membrane separation method, a membrane consisting of a specified polymer having a crosslink structure is used as the anion exchange membrane. This polymer substantially consists of aromatic rings and linking groups and contains -X-Ar-Y- structure (wherein X and Y are O or S and Ar is an aromatic ring) in the recurring unit. An anion exchange group is introduced into this aromatic ring. Since this anion exchange membrane can be used at rather high temp., nitric acid and/or hydrofluoric acid can efficiently be recovered. |
