Mesoporous MOF composite for efficient removal of uranium, methyl orange, methylene blue, and Congo red dyes from aqueous solutions

The metal-organic framework (MOF) composites have significant applications in removing water pollutants and heavy metals from aqueous solutions. The MOF-2@Al2O3 composite was synthesized using zinc nitrate, 1,4-benzene dicarboxylic acid, and Al2O3 using an in-situ one-pot solvothermal method. Physicochemical properties of MOF-2@Al2O3 are characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX), and Brunauer-Emmett-Teller (BET). Batch mode adsorption studies were carried for uranium (VI) effectively from 5-M HNO3 solution with maximum adsorption of 300.3 mg/g. Furthermore, methyl orange (MO), methylene blue (MB), and Congo red (CR) dyes were removed from the aqueous solution using the fixed-bed column adsorption method at room temperature. The pseudo second-order model was well fitted to uranium adsorption rate on MOF-2@Al2O3 composite, which indicates that chemisorption is the primary mechanism for removing U (VI). Effects of parameters such as flow rate, bed height, initial concentration, time, and pH are studied for azo dyes and U (VI) adsorption. Experimental results indicate that MOF-2@Al2O3 can efficiently remove uranium and azo dyes with good reusability up to five cycles.