Experimental and computational insights into the CuFeMoO₄ modified CMC microbeads for effective removal of methylene blue from aqueous media

Abstract

Abstract CuFeMoO₄/CMC microbeads were synthesized by crosslinking CuFeMoO₄ with carboxymethyl cellulose using AlCl₃ as a crosslinker. The microbeads were used as a catalyst in the reduction of methylene blue (MB) by sodium borohydride (NaBH4). The catalyst was characterized with FT-IR, XRD, BET, SEM, EDX, and TEM techniques. It has a surface area of 34.88 m2g− 1 and a pore diameter of 1.9212 nm. Within 45 min, the catalytic efficiency of the CuFeMoO4 composite increased from 25.8% to 99.2% after modification with carboxymethyl cellulose (CMC). The reduction rate constant followed the order CuFeMoO4/CMC (0.9609 ± 0.0233 min− 1) > CMC (0.2274 ± 0.00592 min− 1) > CuFeMoO4 (0.1365 ± 0.00445 min− 1). The catalytic reaction was carried under several reaction conditions, including catalyst dose, dye and NaBH4 concentrations, pH, NaCl concentration, temperature, and a radical scavenger. The results fit well with the pseudo-first-order kinetics. No significant change in the catalytic efficiency of the CuFeMoO₄/CMC up to the fifth cycle of reusability, demonstrating its high stability during the reaction. The basis function 6–31 G++ (d, p) in conjunction with the DFT method was applied for the computational investigation. Molecular modeling was carried out in both the gas phase and in water solvent to precisely predict the molecular structure, physicochemical properties, and spectroscopic spectra of MB, thereby validating the experimental results. Computational FT-IR, time-dependent-DFT (TD-DFT), natural bond orbital (NBO), and molecular electrostatic potential (MEP) were all calculated. The computational data and the experimental findings were in good agreement. Based on the regeneration data, CuFeMoO4/CMC proved a promising catalyst in the removal of MB from water.