Adsorption of Orange II to goat hair

On the adsorption of acid dye, Orange II, to goat hair, the effects of benz yl alcohol, glycine and hydroxy carboxylic acid in the medium of dye were s tudied quantitatively under Various conditions of pH and temperature. In the case of no benzyl alcohol, DeltaS's were negative and DeltaH's were in the region -25- -100 kJ mol(-1). These results suggested that the dye mi ght bind to the protein of goat hair with hydrogen bonds or ionic bonds. Th e DeltaH'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 go at hair adsorbed more dye in the lower pH medium, in which H3N+-CH2-COOH pr esented more than H3N+-CH2-COO-. Addition of benzyl alcohol with glycolic a cid in the medium of dye made both DeltaH and DeltaS positive. Penetration of benzyl alcohol into the goat hair enlarged the surface area for the adso rption of dye. Thereby, the velocity and the amount of adsorption sites inc reased as compared with the case of no benzyl alcohol. On the other hand, t he equilibrium constant decreased due to blocking the bond formation of dye to goat hair. Penetration of benzyl alcohol into the goat hair made diffic ult to speculate our results by a simple mechanism on the adsorption of dye according to Langmuir adsorption isotherm.