Significant role of carbonate radicals in tetracycline hydrochloride degradation based on solar light-driven TiO2-seashell composites: Removal and transformation pathways

TiO 2 -seashell composites prepared via a sol-gel method were used to generate carbonate radicals (•CO 3 − ) under solar light irradiation. •CO 3 − , a selective radical, was employed to degrade the target tetracycline hydrochloride contaminant. A series of characterizations was carried out to study the structure and composition of the synthesized TiO 2 -seashell composite. This material exhibits excellent solar light-driven photochemical activity in the decomposition of tetracycline hydrochloride. The possible pathway and mechanism for the photodegradation process were proposed on the basis of high-resolution electrospray ionization time-of-flight mass spectrometry experiments. Finally, we investigated the reusability of the TiO 2 -seashell composite. This study is expected to provide a new facile pathway for the application of •CO 3 − radicals to degrade special organic pollutants in water.