Insights into the interaction between cadmium/ tetracycline and nano-TiO2 on a zeolite surface

Abstract Titanium dioxide (TiO2) nanoparticles interact with organic–inorganic pollutants in the environment, and these interactions affect their environmental behavior. The mechanisms of the interaction between TiO2 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 Cd2+/tetracycline (TC), TiO2 nanoparticles, and a zeolite (Zeo). SEM, FT-IR, and XPS were also used to reveal the interaction mechanism between organic–inorganic pollutants and TiO2 on their stability and mobility in the environment. Compared to the single systems, the adsorption of Cd2+ and TiO2 in the Cd + TiO2 composite system decreased by 3.43% and 9.90%, respectively; the TC and TiO2 adsorption in the TC + TiO2 composite system decreased by 14.39% and 45.47%, respectively. The antagonism between Cd2+ and TiO2 was due to Cd2+ and TiO2 competing for the electrostatic attraction (-OH) and hydrogen bonding sites (Si-O), TC and TiO2 competing for the hydrogen bonding sites (-OH and C = O) on Zeo. The presence of TiO2 will increase the mobility of Cd2+ and TC on a clay surface, and this effect is more significant for organic pollutants TC. Compared with Cd2+, TC has a more significant boosting impact on the TiO2 mobility.