A Comprehensive Chemistry Experiment for Undergraduates to Investigate the Photodegradation of Organic Dyes by ZnO/GO Nanocomposite

Thedangers of organic dye pollutants and environmentalpollutionimprovement through photocatalytic degradation are important coursesin applied chemistry programs in universities. Zinc oxide (ZnO)-basednanomaterials are potent catalytic agents against organic dyes, butfew experiments are available for students to understand their roleand mechanism in class. Herein, we designed a comprehensive experimentacross 24 class hours for undergraduates to investigate the photodegradationof colored organic dyes, including methylene blue, methyl orange,methyl violet, rhodamine B, basic fuchsin, and thymolphthalein, bya nanocomposite composed of ZnO-coated graphene oxide (ZnO/GO). Thisnanomaterial was prepared using a facile heating reflux method within1 h. Scanning electron microscopy, Fourier transform infrared spectroscopy,and X-ray diffraction were introduced to students to characterizethe synthesized products. Students could observe the time- and dose-dependentdegradation as well as the reusability of ZnO/GO. Additionally, theaddition of t-butanol, benzoquinone, and triethanolamine, scavengersof hydroxyl radical ((OH)-O-& BULL;), superoxide anion (O-& BULL;(2-)), and hole (h(+)), respectively,to the degradation system allowed them to master the underlying catalyticmechanism of ZnO/GO. This experiment improves students' understandingof the photocatalytic effect of ZnO nanomaterials and stimulates themto engage in the field of applied chemistry and thus is worth recommendingto undergraduates.