Synthesis of core/shell structured magnetic carbon nanoparticles and its adsorption ability to chlortetracycline in aquatic environment
核壳式磁性碳纳米吸附剂的制备及其对水环境中金霉素的吸附研究

Magnetic carbon nanoparticles with core/shell structure (Fe3C/Fe@ C) and large surface areas were synthesized via hydrothermal method followed with heat treatment under N2 atmosphere. The adsorbent has strongly magnetic cores and graphitized carbon shell. The removal efficiency of chlortetracycline (CTC) from aquatic environment by Fe3C/Fe@ C was investigated. The results showed that Fe3C/Fe@ C exhibited ultrahigh adsorption ability to CTC. The adsorption behavior of CTC on Fe3C/Fe@ C fitted the pseudo-second-order kinetic model, and the adsorption equilibrium was achieved within 24 h. The adsorption ability of CTC increased with solution pH at pH 3.5-7.5, but decreased with further increase of pH (pH 7.5-8.5). CTC adsorption decreased with solution temperature and increased with ionic strength. As the concentration of coexisting humic acid in solution ranged in 10-50 mg·L-1, the adsorption ability of CTC on Fe3C/Fe@ C was only decreased by 10%-20%. Under the optimal conditions (pH=7.5,T=293 K), the maximum adsorption capacity of CTC on Fe3C/Fe@ C calculated by Langmuir was 909 mg·g-1, which was significantly higher than those obtained on sediment or minerals. More importantly, Fe3C/Fe@ C adsorbed with CTC can be collected from water sample under a magnetic field rapidly for special disposal, which avoids secondary pollution of water. These results indicate that Fe3C/Fe@ C is a potentially efficient, green adsorbent for removal of tetracycline antibiotics from aquatic environment.