Synthesis and application of copper(II) dipyridyl chloride metal organic framework in the photodegradation of reactive blue dye and disinfection of Escherichia coli and Staphylococcus aureus

Abstract

In this study, the metal-organic framework (MOF) [Cu (4,4′-bipy)Cl]n was synthesized via a hydrothermal method using 4,4′-bipyridine as a ligand. The material was characterized through scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and elemental and structural analyses. The effect of initial pollutant concentration, photocatalyst mass, and solution pH were assessed. The reaction kinetics and stability of the MOF was evaluated over five reuse cycles. The disinfection performance was evaluated using disk diffusion method and bacteria in suspension test against E. coli and S. aureus. The Cu-MOF exhibited remarkable photocatalytic efficiency, achieving 93.7% degradation of reactive blue dye under natural sunlight and the optimal conditions included a dye concentration of 0.4 mg/l, 0.45 g of catalyst, and a pH of 10. The photodegradation process followed first order kinetics with a rate constant (k) of 0.076 min⁻¹. The control study showed reduction of the degradation to 30% in the dark due to adsorption and there was no change in dye concentration due to photolysis alone. The MOF maintained stable activity over five consecutive usage cycles, with minimal performance reduction, highlighting its durability. The Cu-MOF displayed significant antibacterial activity, producing inhibition zones of 21 and 23 mm against E. coli and S. aureus, respectively, for initial bacterial concentration of 1.2 × 10⁵ CFU/ml; with 99.99 and 99.999% reduction for E. coli and S. aureus, respectively. The Cu-MOF photocatalyst effectively degraded the pollutants under visible light and maintained good stability and durability; hence it is a promising photocatalyst for water and wastewater purification.