INTERACTIONS BETWEEN ACID DYE AND GELATIN IN AQUEOUS SOLUTION (II)

Abstract

The binding of five acid dyes, HAS, Acid Orange 7, Acid Orange 52, Acid Red 88 and Acid Blue 25, to gelation from the acidic solutions has been studied by polarography and equilibrium dialysis. The thermodynamic parameters were calculated from the temperature dependence. The following results were obtained:
(1) The binding of the acid dyes except Acid Orange 52 increase with the increase of pH.
(2) The binding at the constant pH decreases with temperature.
(3) The binding constants of the dyes are in the order, R-88>B-25>O-7>O-52>HAS, corresponding to the decrease of the inorganicity/organicity value of these dyes.
(4) The entropy change ΔS° is positive in the binding of R-88 or B-25. Hence, the hydrophobic bond seems to play a role in binding.