Adsorption of naphthols in the presence of different electrolytes and peptising agents and at different temperatures

Abstract

Adsorption of some dyestuffs of the Naphthol AS series by cotton fibre has been studied in the presence of alcohol, sodium hydroxide, sodium chloride, sodium sulphate, sodium phosphate, soap, gum tragacanth and agar-agar and at different temperatures to understand the mechanism of the process of dyeing. It is observed that adsorption of the dyestuffs decreases with increasing amount of alcohol, gum tragacanth and agar-agar, while it first increases, reaches a maximum and then decreases on adding increasing amounts of sodium hydroxide, sodium chloride, sodium sulphate, sodium phosphate and soap solutions. Regarding the effect of temperature on adsorption, it is found that (1) the rate of adsorption is greater at higher than at lower temperatures, (2) the equilibrium adsorption increases with the rise of temperature, and (3) the amount of increase of adsorption for a particular range of temperature is greater at lower than at higher temperatures. The results obtained become easily intelligible if it is assumed that the dye particles exist in colloidal condition and the process of dyeing is interpreted from that point of view.