Optimization of preparation parameters for environmentally friendly attapulgite functionalized by chitosan and its adsorption properties for Cd2+

This work focused on using attapulgite and chitosan as raw materials to improve the adsorption capacity of Cd2+ from the aqueous phase by optimizing the preparation experimental parameters. The modification parameters (attapulgite-chitosan mass ratio, calcination temperature, and time) were specifically studied and optimized. The results indicated that the mass ratio of attapulgite to chitosan was 1:4, the calcination temperature was 300 degrees C, and the calcination time was 1 h. Both raw and functionalized attapulgite samples were characterized by nitrogen adsorption-desorption isotherms at 77 K, X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and zeta potential analysis. A series of adsorption experiments showed that the pseudo-second-order kinetic model and Langmuir adsorption isotherm better corresponded with the adsorption characteristics of the newly prepared adsorbent, and the maximum adsorption amount of Cd2+ was 109.30 mg/g. Moreover, the effects of the pH value and coexisting cations on the Cd2+ adsorption in aqueous solution were investigated. Adsorption mechanism of Cd2+ on adsorbent might attribute to complexation, ion exchange reaction, and self-polarization.

Automated summary

This study focused on improving the adsorption capacity of Cd2+ from the aqueous phase by using attapulgite and chitosan as raw materials and optimizing the experimental parameters. The results showed that the newly prepared adsorbent had a maximum Cd2+ adsorption amount of 109.30 mg/g, and the adsorption mechanism involved complexation, ion exchange reaction, and self-polarization.