Synthesis and characterization of Bi2O3/ZIF-67 nanocomposite integration with capacitive deionization system in the degradation tetracycline

A Bi2O3/ZIF-67 heterostructure was synthesized as a novel and highly active photocatalyst by the hydrothermal method. The as-synthesized catalysts were identified by XRD, SEM, EDX, FTIR, TEM, UV-Vis DRS, BET, and PL analyses. The two-component composite showed a significant improvement in photoactivity compared to Bi2O3 and pristine ZIF-67 due to its unique characteristics such as increased specific surface area and visible light adsorption, as well as reduced bandgap and recombination rate of electron-hole. The optimum values of the processing variables for the contaminant degradation efficiency were determined for photocatalytic process (catalyst concentration= 0.4 g/L, pH= 9, tetracycline (TC) initial concentration= 20 mg/L, and time= 120 min) and capacitive deionization system (CDI) (L=5 mm, voltage=1.8 V, and TC concentration=20 mg/l) and the maximum pollutant removal efficiency under optimal conditions for catalyst adsorption, photocatalytic process, and CDI systems were obtained 12%, 84% and 69%, respectively. The identification of a kinetic study confirmed that the TC removal followed the pseudo-first-order model. According to kinetic studies, the combination of photocatalysis and CDI system (PCS) has a significant effect on the efficiency of the contaminant removal, and the reaction rate constant is increased by about 1.5 and 2.4 times compared to the photodegradation process and the CDI system, respectively. As the results show, the PCS system is a promising way of removing contaminants and dramatically increasing the removal efficiency. Experimental results showed a great chemical stability and reusability of the photocatalyst and the graphite electrode after five cyclic usage.