Functionalization of halloysite nanotubes for the preparation of carboxymethyl cellulose-based nanocomposite films

Halloysite nanotubes (Hal) were treated with acid to prepare uniformly charged acid treated Hal (Hal-A). After acid treatment, the surface charge (zeta potential) of Hal changed from + 0.08 mV to − 32.65 mV. Functionalized Hal-A were prepared through adsorbing metal ions by immersing the Hal-A into saturated solutions of three different metal salts, silver nitrate, zinc nitrate, and copper acetate. The number of metal ions attached to the Hal-A and their functionality were dependent on the type of metal ions. The functionalized Hal-A exhibited strong antimicrobial activity against food-borne pathogenic bacteria, L. monocytogenes and E. coli. The CMC-based film showed a significant increase in mechanical, water vapor barrier, and thermal stability properties after forming a composite with Hal. In particular, CMC-based films incorporated with the functionalized Hal-A showed strong antimicrobial activity against both L. monocytogenes and E. coli.