Green synthesis and adsorption performance of FeO/chitosan/polypyrrole composites for efficient removal of chromium ion.

In this study, FeO/chitosan/polypyrrole (FeO/CS/PPy) magnetic adsorbents were successfully synthesized using the chemical oxidation polymerization method. These adsorbents were characterized by SEM, FT-IR, TGA, and XPS. The results of batch adsorption experiments showed that the FeO/CS/PPy composite exhibited a maximum adsorption capacity of 193.23 mg g in a 100 mg L Cr(vi) solution at 298 K, with a pH of 2.0. The adsorption behavior of the adsorbent to Cr(vi) was in good agreement with the Langmuir isothermal model and the quasi-second-order kinetic model. Thermodynamic studies indicated that the process of adsorption was spontaneous and endothermic. The mechanism of adsorption may be attributed to electrostatic interactions and chemical reduction. After five cycles, the removal efficiency of the FeO/CS/PPy composite for Cr(vi) has consistently remained at 84.32%. Overall, the FeO/CS/PPy composite exhibits great potential as an adsorbent for effectively removing Cr(vi) from aqueous solutions.