Influence of chitosan characteristics on the properties of biopolymeric chitosan–montmorillonite

Chitosan–montmorillonite is a modified montmorillonite in which the sodium ions in montmorillonite layers are replaced by biopolymeric chitosan. The effects of characteristics of chitosan (i.e. molecular weight and degree of deacetylation) and the chitosan/montmorillonite mass ratio on the properties of chitosan–montmorillonite were investigated. Thermogravimetric analysis, zeta potential and X-ray diffraction results confirmed intercalation of chitosan into montmorillonite layers. An interaction between chitosan and montmorillonite was revealed by FTIR and the zeta potential. The amount of chitosan intercalated into the montmorillonite layers depended on the characteristics of chitosan, with the largest amounts of intercalated chitosan achieved by addition of chitosan with a molecular weight of 71,000 g/mol or a degree of deacetylation of 80% at a fixed chitosan/montmorillonite mass ratio of 2:1. The resulting chitosan–montmorilllonite had good adsorbent properties, especially for adsorption of cationic dyes, and also inhibited E. coli by almost 100%. The chitosan–montmorillonite may be useful as a functional material for dye adsorption and antibacterial applications.