PURPOSE: To manufacture and adsorbent with a high selective adsorbability for soluble metal ions by the reaction of EGTA and a specific polyisocyanate in the presence of a soluble metal salt in a polar non-protic solvent of a specific permittivity or more.
CONSTITUTION: EGTA (ethyleneglycol-bis(2-aminoethylether)-N,N,N',N'-tetraacetic acid) and a soluble metal salt are dissolved in a polar, non-protic solvent, e.g., N-methyl-2-pyrolidone, etc., having a permittivity of more than 30, and then the solution is added with stirring to a solution of a polyisocyanate of the formula (1) in the same polar non-protic solvent as the precious solution and heated at 80 to 120°C in a current of dry nitrogen. The high polymer gel thus obtained is treated with a 1 to 5N hydrochloric acid solution to elute coordination metals, and then washed with sufficient water to remove acid in order to use it for adsorption treatment as carboxyl type adsorbent. Furthermore, the adsorbent can be used as an alkali metal salt type adsorbent after being treated with an alkali. The n as shown in the formula is 0, 1, 2, and 3.
SAKAMOTO TOSHIO
ONO YOSHIKO
