Construction of a recyclable chitosan-based aerogel-supported TiO2 catalyst for treating high-concentration surfactants

As high-concentration anionic surfactants easily form micelles, powdery catalysts exhibit low photocatalytic performance for treating anionic surfactants and are difficult to recycle. In this study, a recyclable chitosan-based aerogel-supported TiO2 catalyst was constructed to effectively treat high-concentration anionic surfactants using adsorption destroying micelles and in situ photocatalytic degradation of surfactants. Carboxylated carbon nanotubes/TiO2 (CCNT/TiO2) were loaded onto the skeleton of polyethyleneimine (PEI)-chitosan (CS) aerogel (PCA) by impregnation to prepare the CCNT/TiO2@PCA composite photocatalyst. CCNT/TiO2@PCA had a porous structure, and the catalyst particles were distributed on the skeleton. Sodium dodecylbenzene sulfonate (SDBS), a widely used anionic surfactant, was selected as the molecular probe. CCNT/TiO2@PCA exhibited excellent adsorption performance for SDBS (qm = 3154.5 mg g−1) and could destroy the micelles formed by a high concentration of SDBS (500 mg L−1). The SDBS removal rate by CCNT/TiO2@PCA reached 91.2% under UV light irradiation, which was 10 times faster than that of CCNT/TiO2. The excellent removal efficiency was mainly ascribed to the synergistic interaction between the electrostatic adsorption and photocatalytic degradation. The toxicity assessment indicated that the toxicity of the degradation intermediates was significantly lower than that of SDBS. After ten cycles, the removal of SDBS by CCNT/TiO2@PCA was 90.1%. Therefore, this study offers new insights into the construction of highly active photocatalysts for the treatment of high-concentration organic pollutants.