Reusable and environmentally friendly cellulose nanofiber/titanium dioxide/chitosan aerogel photocatalyst for efficient degradation of tetracycline

Abstract

Tetracycline antibiotics are currently detected in most water sources. The presence of such pollutants in the environment is becoming increasingly common, and addressing this contamination is a significant challenge due to its potential threat to human health and ecosystem stability. This study successfully prepared cellulose nanofiber/titanium dioxide/chitosan (CNF/TiO2/CS) aerogels by directional freeze-drying technique for photocatalytic degradation of tetracycline-contaminated wastewater. The CNF/TiO2/CS aerogel photocatalysts have a three-dimensional mesh structure with a large specific surface area, which provides many active sites for the highly efficient photocatalytic degradation of tetracyclines. The CNF/TiO2/CS aerogel showed 99.5% tetracycline removal efficiency within 180 min. Free radical scavenging experiments investigated the adsorption and photodegradation mechanism of tetracycline by CNF/TiO2/CS aerogel. The critical participation of •O2-and h+ in the decomposition of tetracycline was verified, which provided experimental support for the photocatalytic reaction mechanism. In addition, the CNF/TiO2/CS aerogel has high stability and recyclability for photocatalytic degradation, which can be recycled 7 times, and the recycling process is environmentally friendly. An in-depth analysis of the intermediate degradation products using liquid chromatography-mass spectrometry (LC-MS) revealed two efficient photocatalytic degradation pathways. These findings strongly confirm the extensive potential of photocatalytically active aerogels for wastewater treatment.