Round-the-Clock Adsorption-Degradation of Tetracycline Hydrochloride by Ag/Ni-TiO₂

The synergy of adsorption and photocatalysis is a good method to remove organic pollutants in wastewater. In recent decades, persistent photocatalysis has gained considerable interest for its ability to sustain the catalytic degradation of organic pollutants in the dark. Herein, we report three different TiO₂ nanomaterials to remove tetracycline hydrochloride (TCH) in solution. We found that the removal ability of TiO₂, Ni-TiO₂, and Ag/Ni-TiO₂ is 8.8 mg/g, 13.9 mg/g and 23.4 mg/g, respectively, when the initial concentration of TCH is 50 mg/L. Chemical adsorption could be the rate-determining step in the TCH adsorption process. Moreover, Ag nanoparticles dispersed on Ni doped TiO₂ surface act as traps to capture photo-generated electrons upon illumination with indoor light. The holes in Ag/Ni-TiO₂ serve as critical oxidative species in TCH degradation under dark conditions. This work provides new insights into the design of persistent photocatalysts that can be activated by weak illumination and degrade organic pollutants in wastewater after sunset.