Zinc oxide functionalized MOF-5 for the adsorptive removal of Pb(II) metal ions and photocatalytic degradation of methylene blue dye in aqueous medium

The composite of ZnO with MOF-5 (named ZnO@MOF-5) was synthesized through a solvothermal method for increasing the photocatalytic as well as adsorptive power of MOF-5. The synthesized compound was initially characterized through FT-IR, UV–visible, PXRD, TEM, and BET analyses. The efficacy of the synthesized compound toward the photocatalytic degradation of methylene blue and the adsorption of lead was analyzed through spectroscopic tools. The photocatalytic degradation study was conducted in direct sunlight irradiation and real-time monitoring of degradation was assessed through UV–visible spectroscopy in the presence and absence of H₂O₂. The photocatalytic degradation efficiency of ZnO@MOF-5 material has been greatly increased in the presence of sensitizer H₂O₂ molecules. The photocatalytic efficiency of MOF-5 was 97.47% in the presence of H₂O₂. The kinetic fitting models suggested that the degradation of methylene blue follows first-order kinetics. The efficiency of ZnO@MOF-5 towards the adsorptive removal of Pb(II) ions from aqueous solution was assessed using atomic absorption spectroscopy. The kinetic fitting studies for the adsorption process are unimolecular and follow pseudo-second-order kinetics.