THE UPTAKE OF A REACTIVE DYE BY BLEACHED COTTON AND ITS EFFECT ON THE ELECTRICAL-PROPERTIES OF THE INTERFACE .1. ELECTROKINETIC PROPERTIES

An experimental investigation on streaming potential, sorption, and electrical conductance of porous plugs of bleached cotton in aqueous solutions of a reactive dye, Remazol brilliant blue R (RBB-R), at varying temperatures is described. The absolute value of the (negative) zeta potential of cotton decreases appreciably when temperature is increased at concentrations of RBB-R in solution up to ca. 10** minus **4 mole/liter, the reverse trend being observed at higher dye concentrations. Similar behavior was deduced for the surface charge density of the fiber. The uptake of dye by the fiber is favored by the increase in temperature, this fact being in accordance with the chemical nature for the bonds involved. However, physical contributions, mainly H-bonds, cannot be neglected at the lowest temperatures studied. The effective dyeing surface has been found to increase linearly with temperature. Surface conductance, k//s, predominates in the total electrical conductance of the system, k, at low concentrations of dye in solution, while it is the bulk component, k//b, which predominates in the higher concentration range.