Adsorption Behaviors of Oxytetracycline onto the Colloid in Sediments

In this study, sediment samples were collected from a typical tributary in the mid-Weihe River and a separation device was employed to separate sediment into colloid and solid particles. The Oxytetracycline (OTC) adsorption onto solid particles was compared with OTC adsorption onto colloid particles in terms of their impact on the factors of the processes (e.g. contact time, temperature, kinetic, thermodynamics characteristics) which were analysed systematically. Results showed that the adsorption of OTC onto colloid and solid particles reached equilibrium after about 12 hours and 48 hours respectively. The adsorption capacity of OTC onto colloid particles was 26 times than that of OTC onto solid particles with an initial concentration of 20.0 mg/L at 25 degrees C. The Langmuir isotherm model was more suitable to describe the adsorption behaviours of OTC onto both colloid and solid particles in sediment. The adsorption processes were feasible, spontaneous, entropy-increasing and endothermic in nature, the adsorption capacity increased with increasing temperature. The mechanisms controlling OTC adsorption onto colloid and solid particles were mainly physisorption, but physisorption had a lesser effect on OTC adsorption onto colloid particles.