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

Abstract The metal‐organic framework (MOF) composites have significant applications in removing water pollutants and heavy metals from aqueous solutions. The MOF‐2@Al 2 O 3 composite was synthesized using zinc nitrate, 1,4‐benzene dicarboxylic acid, and Al 2 O 3 using an in‐situ one‐pot solvothermal method. Physicochemical properties of MOF‐2@Al 2 O 3 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 HNO 3 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@Al 2 O 3 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@Al 2 O 3 can efficiently remove uranium and azo dyes with good reusability up to five cycles.