Insoluble tannin preparation process, waste treatment process employing insoluble tannin and adsorption process using tannin

摘要

There is disclosed an insoluble tannin preparation process, in which a tannin is first dissolved in an aldehyde aqueous solution. Then, ammonia is added to the solution to produce a precipitate, and the resulting precipitate is subjected to aging. The insoluble tannin thus prepared is employed to treat a waste liquid. Furthermore, there is disclosed an adsorption process in which a tannin is first dissolved in a solution containing a material to be adsorbed. Thereafter, an aldehyde is added to the solution to produce a precipitate having tannin as a principal constituent. The material to be adsorbed is adsorbed to this precipitate.