Coadsorption behaviour and mechanism of TiO2 NPs and OTC on different size particle components of Lou soil

The wide application of antibiotics and nanoparticles has made their coexistence in soil a new environmental problem, and the coexistence of multiple pollutants in soil may impact their environmental behaviour. In this study, by dividing soil into coarse particle (CP) and fine particle (FP) phases via differential centrifugation, oxytetracycline (OTC) and TiO 2 nanoparticles (NPs) were selected as two typical pollutants to study their coadsorption behaviour on Lou soil. The coadsorption mechanism of OTC and TiO 2 NPs on Lou soil was discussed through their morphology and characteristics by using SEM, XRD, BET specific surface, XPS and FT-IR analyses. The adsorption capacity of OTC on the FP phase was much greater than that on the CP phase. Hydrogen bonding and charge attraction are the main adsorption mechanisms of OTC on both the CP and FP phases. π-π interactions are another main adsorption mechanism of OTC sorption on the FP phase. Hydrogen bonding and charge attraction are the main mechanisms of TiO 2 NPs sorption on soil. OTC and TiO 2 NPs compete on the surface of soil particles through charge attraction and hydrogen bonding, thus inhibiting their adsorption.