| 摘要 |
PURPOSE:To efficiently obtain highly pure boric acid by arranging one or more cation exchange membranes to form a diffusive dialysio tank, charging a mineral acid into one of two compartments having the cation exchange membrane therebetween in the tank and charging an alkali metal borate aqueous solution into the other. CONSTITUTION:One or more, preferably plural, cation exchange membranes C are arranged at intervals to form a diffusive dialysis tank. The aqueous solutions of an alkali metal borate (e.g. sodium borate) is charged and circulated into alternate compartments A1, A2, A3 (hereinafter referred to as boric acid chambers), and the aqueous solution of a mineral acid (e.g. sulfuric acid) is also charged and circulated into the other compartments B1, B2, B3 (hereinafter referred to as mineral acid chambers) neighboring on the boric acid chambers A1, A2, A3 through the cation exchange membranes C, whereby hydrogen ions forming the mineral acids are transferred to the boric acid chambers through the cation exchange membranes C and alkali metal ions forming the alkali metal borate are also simultaneously transferred to the mineral acid chambers through the cation exchange membranes C. Boric acid is prepared in the boric acid chambers and the mineral acid is simultaneously converted into the alkali metal salt thereof in the mineral acid chambers. |
