Some Uptake Studies of Metal Ions and the Formation of Cu₂0 Particles in Wool
This research programme is concerned with the uptake studies of Cu2+, Zn2+ and Mn2+ at different conditions, by merino wool fibres and also uptake studies of Cu2+ ions by chemically modified wool fibres. Cu2O particles and Cu complexes are formed within merino wool by an in situ reaction with sodium borohydride and thioglycoloic acid respectively. The d-block elements have the ability to bind chemically to certain functional groups present within the keratin protein of wool. The absorption of the Cu2+, Mn2+ and Zn2+ from solution by wool fibres under different conditions notably, time, temperature and initial concentration have been studied. The optimum temperature and reaction time to give highest absorption of the Cu2+ by the wool fibre was found to be 90 oC and one hour without modifying the nature of the wool, from a solution of Cu2+ concentration of 450 mg L-1. Cu2+ was found to give the greatest absorption by the wool fibres, whereas Zn2+ and Mn2+ were found to be absorbed the least. The absorption of Cu2+ ions increases with increasing temperature. At the higher temperature of 90 oC, the -S-S- bonds in the cystine amino acids break more readily, generating thiol and cysteic acid groups to bind with copper ions. The uptake of Cu2+ by ethylenediaminetetraacetic dianhydride (14 mg g-1 of wool) or thioglycolic acid (42.5 mg g-1 of wool) or sodium borohydride (41.8 mg g-1 of wool) treated merino wool fibres increases with respect to unmodified wool (8 mg g-1 of wool). NaBH4 treated merino wool reduces Cu2+ ions to Cu2O particles which form within the wool fibres by an in situ reaction. TGA treated merino wool provides additional functional groups to bind with copper ions and Cu2O particles also likely to be formed within TGA treated wool composites. The metal ions were absorbed into the fibres under various conditions and the extent of absorption was quantified. The form and binding of the Cu2O particles or Cu2+ ions onto the wool fibres are studied using UV-Visible, FTIR, XRD, SEM, EDS and TEM methods.