Multifunctional quaternized chitosan@surface plasmon resonance Ag/N-TiO₂ core-shell microsphere for synergistic adsorption-photothermal catalysis degradation of low-temperature wastewater and bacteriostasis under visible light

Chitosan are deemed as a promising candidate to environmentally friendly materials owing to the inexpensive, biodegradable and rich reserves. Nevertheless, the application of chitosan materials still confronts chemical instability and low mechanical strength. In this study, we grow ultrafine nitrogen-doped TiO₂ nanoparticles (chitosan as nitrogen source) on the surface of hollow quaternized chitosan by electrostatic self-assembly, giving a unique core-shell structure. Then, Ag nanoparticles is deposited on the surface of quaternized chitosan@N-TiO₂ via a simple photo-deposition process. Our investigations indicate that chitosan has a great adsorption-photothermal catalysis degradation for low-temperature sodium dodecylbenzene sulfonate (SDBS) wastewater and gram-negative (E. coli) under visible light. The degradation rate of SDBS wastewater can reach 96.4% within 180 min and E. coli can be inactivated within 120 min. The outstanding degradation performance of QCS@Ag-TiO₂ is ascribed to the synergistic effect of the active site of quaternized chitosan, nitrogen doping and surface plasmon resonance of Ag nanoparticles. Our work provides a promising design to combine adsorption and photothermal catalysis to prepare a multifunctional material.