Abstract
Using a new determination method of tannin by means of colloid-titration with methy-glycol-chitosan, the reactions between various tannins and hide powder were investigated from the viewpoint of absorption isotherm. The absorption mechanism of tannins such as qebracho (SO2 treatment), chestnut, myrobalan, and lignosulfonic acid can be represented by LANGMUIR's equ-ation, but in the case of tannins such as mangrove and Acacia Mollissima it may rather follow FREUNDLICH's equation. Or the basis of various data of absorption isotherm, it seems reason-able to assume that absorption of the tannins of the former group can be partly ionic, whereas that of the later group non-ionic.
