Chitin-halloysite nanoclay hydrogel composite adsorbent to aqueous heavy metal ions

Halloysite nanoclay (HNC) was mixed with Chitin hydrogel film by phase inversion in water vapor atmosphere at room temperature. In the preparation, Chitin was dissolved in N,N-dimethyl acetamine/lithium chloride (DMAc/LiCl) and different amounts of HCN was dispersed well for the gelation process. The resultant Chitin-Halloysite nanoclay (CTH) hydrogel films containing HCN at 0, 0.1, 0.5, 1, and 4 wt % were used for the adsorbents of heavy metal ions. As the results, the tensile strength of the hydrogel composite was enhanced from 0.34 to 0.71 N/mm² while the elongation decreased from 66.43% to 49.93% with the increment of HNC concentration from 0 to 4 wt %. A reduction in the water content and the increment in the modulus confirmed the formation of highly dispersed nano-composites with improved interfacial interactions between nano-fillers and matrix. In the adsorption experiments of the ternary ion of Pb²⁺, Cu²⁺, and Cd²⁺, the removal capacity of Pb(II) was highly retained by the CTH hydrogel film relative to Cd(II) and Cu(II), shown Langmuir model with the maximum binding amount on the hydrogel composites were followed as order Pb (8.2 mg/g), Cu (4.2 mg/g), and Cd (2.1 mg/g). © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47207.