Adsorption and photodegradation of tetracycline by mannose-grafted chitosan composite films: Performance, mechanism and availability

The world faces increase in water scarcity and water pollution. A combined effect of adsorption and photodegradation is potential way to remove pollutants from water. In this work, mannose grafted chitosan (CSMan) films were synthesized due to Schiff base. To improve the adsorption and photodegradation capacity of films, graphite carbon nitride-zinc oxide (gCNMZnO0.3) was introduced into a system through solvent volatilization to remove tetracycline (TC). Comfortingly, the composite films of CSMan-gCNMZnO0.3-1 displayed outstanding adsorption capacity and excellent activity of degrading organic pollutant by visible light in water. The maximum adsorption capacity of CSMan-gCNMZnO0.3-1 was 164.627 mg g−1 through surface complexation, cation exchange, electrostatic attraction, hydrogen bonding, π–π interaction and plane strengthening effect. The analysis revealed that OH and h+ were the crucial radicals in photodegradation process. Meanwhile, CSMan-gCNMZnO0.3-1 possessed superior reusability and broad applicability in five distinct types of water. The simulation experiment of silicone tube showed the combined effect had a removal ratio of 84.3 % in 120 min, and the adsorption-photodegradation efficiency was constant in operating after five continuance usages.