Synergistic effects of photocatalysis-periodate activation system for the degradation of emerging pollutants using GO/MgO nanohybrid

Abstract

The combination between periodate (PI) activation and photocatalysis processes using heterogeneous catalysts can overcome the slow degradation rates related to photocatalysis and accelerate the degradation of organic pollutants. Thus, a nanohybrid of graphene oxide (GO) and magnesium oxide (MgO) (GO/MgO) was fabricated, characterized, and employed as a photocatalyst and an activator of PI for the degradation of reactive blue-222 (RB-222) dye, sulfamethazine (Sulfonamide antibacterial), and atrazine (Herbicide). Further, the optimization of operating parameters, the stability of the composite, the degradation mechanism, and the effects of water matrices were investigated. The bandgap decreased to 2.6 eV after merging between the GO and MgO, and the separation between charge carriers was improved in the case of the nanohybrid compared to single GO and MgO. The highest degradation percentage of RB-222 dye was achieved under the optimal operating conditions (pH 7, dye concentration of 6.4 mg/L, PI concentration of 1.5 mM, and catalyst dosage of 0.3 g/L) in the presence of light within 120 min. The nanocomposite was reused for five succeeding runs, where the degradation ratios decreased from 97.3% in the first run to 88% in the third run and declined to 81.25% in the fifth run which affirmed the high stability of the catalyst under three succeeding cycles. The degradation mechanism was explored showing that iodate radicals were the main reactive species. The degradation percentages of RB-222 decreased to 85.1% and 67.6% in the case of canal and sea water matrices, respectively. The degradation efficiencies of sulfamethazine and atrazine were 87.5% and 85%, respectively under the optimal conditions. The prepared composite exhibited high degradation performance towards different pollutants which affirmed the applicability of the proposed degradation system for degrading real industrial effluents.