Combination of cellulosic materials and metallic ions

Cellulosic materials (DP, SCP) and PVA fibers were treated with four kinds of metallic ions (Ca2+, Fe2+, Fe3+, Ce4+), and the adsorption behavior was studied to elucidate the manner in which the celluloses and the metallic ions were combined. The effects of treatment temperature, time, and concentration upon the amount of the metallic ions adsorbed were examined. With Ca2+ and Fe2+, the effects of such factors on the adsorption were slight, while with Fe3+ and Ce4+ the effects of time, temperature, and ion concentration were pronounced. Also, it was evident that the amount (molar) of equilibrium adsorption of Ca2+ or Fe2+ was approximately the same as the content of carboxyl groups in the cellulose sample, and the amount of equilibrium adsorption of Fe3+ or Ce4+ was approximately the same as that of total carbonyl group content. When the samples which had adsorbed these metallic ions were treated with 0.1N hydrochloric acid, the Ca2+ and Fe2+ were completely desorbed while about 80% of the adsorbed Fe3+ and Ce4+ remained. These results indicate that there are two types of combinations of cellulosic materials and metallic ions involved: one is thought to be an ionic bond, while the other is considered to be a chelate bond.