Interaction between poly-L-lysine and synthetic chrysotile asbestos

Abstract

The adsorption of poly-L-lysine (PLL) on synthetic chrysotile asbestos in aqueous solutions has been studied at 25°C. Adsorbed amount (mg g −1) of randomly coiled PLL (pH 8.5) was independent of its molecular weight (3900–47 000) and of the charge density of PLL and chrysotile. The adsorbed amount of helical PLL at pH 11 was five times more than that of randomly coiled PLL and its adsorbed amount increased with increasing molecular weight of PLL. The adsorbed amount of PLL increased linearly with increasing helix content, irrespective of pH and molecular weight. This suggests that ϵ-amino groups in the side-chains which are free from helical cores may be responsible for PLL adsorption. Nitrogen adsorption on a chrysotile sample with pre-adsorbed PLL at pH 11 indicated that PLL molecules in helical form would be also adsorbed on the inner surface of chrysotile.