Oxytetracline (OTC) is a widely-used antibiotic, which could transport into aqueous and soil systems. The coexistence of heavy metals, such as copper (II) [Cu (II)], may change the adsorption behaviors of OTC onto soils. This study investigated the simultaneous adsorption behaviors of OTC Cu (II) onto loess soil, which is ubiquitous in the northwest of China. The kinetics experiments were conducted in single and binary systems for OTC and Cu, and the results showed that the kinetics data of

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... OTC and Cu could be well fitted by the pseudo-second-model model. The co-adsorption might increase the adsorption rate of both OTC and Cu. However, the effects of the complexation of OTC and Cu (II) on their adsorption amounts onto loess soil were quite different. The presence of Cu (II) could increase the uptake of OTC from pH 3.0 to 10.0. By contrast, the coexistence of OTC would decrease the uptake of Cu (II), especially at pH > 5.0. Hence, it is proposed that the migration of OTC might be slowed down by the coexistence of Cu (II), whereas the transportation of Cu (II) would be accelerated by the presence of OTC.