ADSORPTION BEHAVIOR OF METAL IONS BY SILK YARNS ON METAL SALT TREATMENTS, WITH REFERENCE TO ITS INFLUENCE FOR PHOTODEGRADATION

Abstract

The adsorption of metal cations on domestic and eri silk spun yarns treated with salts of transition metals such as Mn, Fe, Co, Ni and Zn and their effect on the photodegradation of the silk yarns was investigated.When the silk yarns were treated with an aqueous solutions of Mn-, Fe-, Co-, Ni- or Zn-salt, the adsorbed amount of Mn2+, Co2+, Ni2+ and Zn2+ ions was larger in the case of eri silk than that of domestic silk but the adsorbed amount of Fe3+ ions was larger in domestic silk.The adsorbed amount of each metal cations increased with the increase of pH by the addition of NH4OH in the metal salt solutions. The relations between the adsorbed amount of metal cations and treating time can be classified into three types according to the extent of metal hydroxide formation by the adding of NH4OH.Some metal salts showed maximum adsorption of cations at a specific concentration. As for other metal salts, the adsorbed amount of cations increased with the incaease of the metal salt concentrations, and the adsorbed amount of cations continued to increase until their adsorption were saturated. This different phenomena are related to the extent of pH decrease due to the increase in melal salt concentration.The adsorption of Mn2+ and Ni2+ ions in the treated silk yarns showed only slight inhibive effect on their photodegradation when the deterioration was tested by the fade meter irradiation. On the contrary, Fe3+ and Zn2+ ions adsorbed in the treated silk yarns accelerated their deterioration.