Experimental and DFT investigation of ceria-nanocomposite decorated AC derived from groundnut shell for efficient removal of methylene-blue from wastewater effluent

• Ceria-decorated AC-derived groundnut shell was synthesized for removal of MB. • MB removal was significantly improved through adsorption at low-loadings of Ce. • Increased adsorption of MB on AC-Ce adsorbents was due to improved characteristics. • The MB removal efficiency of 99.9% (199.76 mg/g) was achieved within short period. • Ceria incorporation lowers energy gap and increases chemical softness of adsorbent. Removal of dyes is a significant aspect of environmental remediation to ensure clean water and atmosphere. In this study, we report an incorporation of nano ceria at different weight loadings via solid state impregnation on the highly porous activated carbon (AC) derived from groundnut shell to form nano-ceria decorated AC for effective removal of cationic dye (methylene blue). The adsorption capacity of MB within a short period is highly remarkable with 199.76 mg/g, corresponding to 99.9% efficiency in 400 ppm using 40 mg weight adsorbent. The adsorbent at relatively low loadings (0.5–1%) of nano-ceria of AC favors significantly adsorption of MB, owing to the high degree of dispersion of cerium with improved textural properties, acidity and surface chemistry. The adsorbents were characterized by the N 2 -sorption, spectroscopies; (XRD, FTIR and Raman), microscopies (SEM and TEM) and temperature programmed desorption (TPD) techniques. The isotherm and kinetics information reveals that the adsorption mechanism of MB is elucidated by the Langmuir and pseudo-second order models, respectively. Quantum chemical DFT calculations revealed that ceria incorporation lowers the HOMO-LUMO energy gap (ΔE), increases the chemical softness and enhances the adsorption capacity of AC with a theoretical adsorption energy of −18.5 kcal/mol.