One-pot thermal synthesis of Ceria/Montmorillonite composite for the removal of hexavalent chromium from aqueous system

The thermal insertion of ceria into the structural framework of Montmorillonite (Mt) clay and the efficiency in Cr (VI) oxyanions removal from the aqueous medium are reported herein. CeO2/Mt adsorbent was synthesized via a one-pot thermal treatment operation. Fourier Transform Infrared (FTIR), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Energy-Dispersive X-ray (EDX), X-Ray Diffraction (XRD), and Point Zero Charge (PZC) were used for the material characterization. Incorporating cerianite into the clay mineral framework resulted in the overall charge-shift of the Mt/CeO2 composite and improved stability. Experimental data were analyzed using the non-linear kinetic and equilibrium adsorption isotherm equations. The values of the Chi-square (chi(2) <= 0.1167) showed that Cr (VI) uptake proceeded via chemisorption (similar to Lewis acid-base interaction) and monolayer adsorption. The change in the initial Cr (VI) concentration, the solution ionic strength, and pH value impacted the process efficiency for Cr(VI) removal. At low initial Cr (VI) concentration and initial solution pH value of 5.1, about 100% removal efficiency was achieved within 90 mins. The value of the Langmuir monolayer adsorption capacity obtained was 52.08 mg/g. The as-synthesized CeO2/Mt composite is a promising adsorbent for the treatment of water contaminated with Cr (VI) oxoanions.