In order to obtain an alkali insoluble ion exchanger from the regenerated humic acid prepared by oxidation of Miike coal with nitric acid, pyrolysis of metal salts of the regenerated humic acid has been investigated.
By heating Ca and Mg salts of the regenerated humic acid at 300°C for 1 hr in a stream of nitrogen, the pyrolyzed products became insoluble in an alkaline solution of pH 11. But the amount of carboxyl group (determined by Ca (CH3COO) 2 method) in the regenerated humic acid decreased only from 3.2meq/g to 2.2meq/g by the pyrolysis of Ca salt of regenerated humic acid.
The ion exchange capacity of the pyrolyzed product was not less than that of the original regenerated hurnic acid. Therefore, this pyrolyzed product can be used as an ion exchanger for treatment of the alkaline waste water containing heavy metal ions.
