Addition of graphene oxide to ZIF-8/HKUST-1 composite for enhanced adsorptive and photocatalytic removal of congo red in wastewater

Abstract

Ternary composites comprised of graphene oxide (GO), ZIF-8, and HKUST-1 with varying amounts of GO were successfully synthesized via the solvothermal method. Based on the photoluminescence characterization, the GO/ZIF-8/HKUST-1 composite presents a more efficient charge carrier separation and transfer compared to pristine HKUST-1 and ZIF-8. As a result, electron-hole recombination was hindered due to the presence of GO as an electron mediator in the heterojunction. The dark adsorption kinetics data for the removal of Congo Red (CR) dye fit well with the pseudo-second order model. The photocatalytic degradation performance of the GO/ZIF-8/HKUST-1 composite was investigated by means of degrading CR dye under UV-LED irradiation. The photodegradation efficiency of the GO(10)/ZIF-8/HKUST-1 composite for the removal of CR dye was 91.81% within 60 min of irradiation. The trapping experiments showed that hydroxyl and superoxide radicals are the main reactive species. The results of this study indicate that ternary composites comprised of MOFs as photocatalysts have great potential for degrading pollutants in aquatic environments.