The Dyeing Property of Polyamide Fibre (V) The Effect of Electrolytes on the Adsorption of Levelling Acid Dyes by Amilan

摘要

The effects of addition of salts on the dyeing equilibriums useing four kinds of levellingacid dyes was studied.The dyebath was exchanged with the new dye liquor as the dyeing proceeds on， andAmilan was dyed to the point where the concentration of dye on the fibre was in equilibriumwith the initial concentration of dye and electrolyte in the last dyebath. lnvestigationsof the effect of various electrolytes (sodium chloride， sulphate， phosphate， formateand acetate) at varying pH values was made， and following results were obtained.1. The salts have three effects on the adsorption of dye.(I) In the cace of the adsorytion on Amilan was above its saturation value the desorptionof dyes due to the salt was remarkable.(II) In case the adsorption wes below the saturation value， the amount of dye on the fibrewas decreased by the salts according to the Gilbert-Rideal equation.(III) In case the adsorption being below the saturation value in the presence of a largeamount of salt， the amount of dye on the fibre was greater than the value calculated by theGilbert-Rideal equation. This effect must be attributed to the increase of the Donnan distributioncoefficient; the decrease of the electrical surface potential of fibre; and the decreaseof the hydration energy of dye ions with the addition of salts.2. The anions other than choride ion had lesser decreasing effect on the adsorption ofdye anion. This might be due to the effects of the dissociation constant and the hydrationof salt anions.3. In the case of the addition of phosphate buffer solution below mol./100， the effect ofthe salt was neglegiblly small on the adsorption of the acid dyes used. The data of theadsorption， therefore， from the dyebath of adjusted pH with the buffer solution can betreated according to the Gilbert-Rideal equation on effinity of the dye acids.4. The content of salts which is usually added as diluent in those commercial levellingacid dyes did not affect the amount of adsorption of dye on the fibre.