INTERACTION OF WOOL KERATEINE AND ITS DERIVATIVES WITH HEAVY METAL IONS. I. PREPARATION AND PROPERTIES OF CROSSLINKED KERATEINE-GELS

Abstract

Chemical processings of waste wool fiber to prepare solid gel-particles (crosslinked kerateine gels), and their basic characteristics as adsorbent for heavy metal ions were investigated. A series of kerateine gels having different thiol (SH)-contents were obtained by gentle oxidation of kerateines which were brought into solution by reducing disulphide bonds of wool fiber. The oxidation was made by dialyzing the kerateine solution against water. The kerateine gels showed very high uptakes of metal ions, specific to Hg²⁺, from aqueous media in comparison with those by commercially available adsorbents and native wool. In acid media, a relation was found between the SH-content and Hg²⁺ uptake: the uptake increased with increasing SH-content. The Hg²⁺ uptakes strongly depended on the pH of the media, showing a maximum around pH 2.5 and then a gradual increase in the uptake at pH values higher than 5. The adsorption isotherm did obey the Freundlich equation in acid media but not in alkaline media in a range of lower Hg²⁺ concentrations.