Adsorption of Orange II to Goat Hair

Norihiro KATO*, Misako ARAI, Yasuzo SAKAI, Joji MITAMURA and Fujio TAKAHASHI

Department of Applied Chemistry, Faculty of Engineering, Utsunomiya University; 7-1-2 Yoto, Utsunomiya-Shi 321-8585 Japan
Beauty-care Research Laboratories, LION Corporation; 7-13-12, Hirai, Edogawa-ku, Tokyo 132-0035 Japan

On the adsorption of acid dye, Orange II, to goat hair, the effects of benzyl alcohol, glycine and hydroxy carboxylic acid in the medium of dye were studied quantitatively under various conditions of pH and temperature.
In the case of no benzyl alcohol, ΔS's were negative and ΔH's were in the region −25 − -100 kJ mol−1. These results suggested that the dye might bind to the protein of goat hair with hydrogen bonds or ionic bonds. The ΔH's shift more negative in the cases using glycolic acid and lactic acid than in the case using phosphoric acid. In the case of glycine, the goat hair adsorbed more dye in the lower pH medium, in which H3N+-CH2-COOH presented more than H3N+-CH2-COO. Addition of benzyl alcohol with glycolic acid in the medium of dye made both ΔH and ΔS positive. Penetration of benzyl alcohol into the goat hair enlarged the surface area for the adsorption of dye. Thereby, the velocity and the amount of adsorption sites increased as compared with the case of no benzyl alcohol. On the other hand, the equilibrium constant decreased due to blocking the bond formation of dye to goat hair. Penetration of benzyl alcohol into the goat hair made difficult to speculate our results by a simple mechanism on the adsorption of dye according to Langmuir adsorption isotherm.

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