Insights into the interaction between cadmium/tetracycline and nano-TiO 2 on a zeolite surface

Titanium dioxide (TiO 2 ) nanoparticles interact with organic–inorganic pollutants in the environment, and these interactions affect their environmental behavior. The mechanisms of the interaction between TiO 2 and organic–inorganic pollutants on the surface of clay minerals are still unclear. In this work, isotherm adsorption was studied to explore the interactions between Cd 2+ /tetracycline (TC), TiO 2 nanoparticles, and a zeolite (Zeo). SEM, FT-IR, and XPS were also used to reveal the interaction mechanism between organic–inorganic pollutants and TiO 2 on their stability and mobility in the environment. Compared to the single systems, the adsorption of Cd 2+ and TiO 2 in the Cd + TiO 2 composite system decreased by 3.43% and 9.90%, respectively; the TC and TiO 2 adsorption in the TC + TiO 2 composite system decreased by 14.39% and 45.47%, respectively. The antagonism between Cd 2+ and TiO 2 was due to Cd 2+ and TiO 2 competing for the electrostatic attraction (-OH) and hydrogen bonding sites (Si–O), and TC and TiO 2 competing for the hydrogen bonding sites (-OH and C = O) on Zeo. The presence of TiO 2 will increase the mobility of Cd 2+ and TC on a clay surface, and this effect is more significant for organic pollutants TC. Compared with Cd 2+ , TC has a more significant boosting impact on the TiO 2 mobility.