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

Synthesis of Core/Shell Structured Magnetic Carbon Nanoparticles and Its Adsorption Ability to Chlortetracycline in Aquatic Environment

采用水热法和热处理法制备了高比表面积的核壳式磁性碳纳米吸附剂(Fe3C/Fe@C).该吸附剂具有强磁性内核和石墨碳外壳.考察了Fe3C/Fe@C对水环境中金霉素(CTC)的去除能力.结果表明,Fe3C/Fe@C对CTC表现出极强的吸附性能,其吸附行为符合准二级动力学模型,24 h内吸附达到平衡.CTC的吸附能力随溶液pH(3.5～7.5)的增加而增加,但当pH在7.5～8.5时吸附能力下降.CTC的吸附随溶液温度的增加而降低,随离子强度的增加而增加.溶液中共存腐殖酸浓度为10～50mg.L-1时,CTC的吸附仅降低了10%～20%.在最佳条件下(pH=7.5,T=293 K),由Langmuir吸附模型拟合的CTC最大吸附容量为909 mg.g-1,该吸附容量远大于沉积物和矿物对CTC的吸附.吸附CTC后的Fe3C/Fe@C在磁场作用下可以快速从水样中收集,便于进一步处理,避免对环境的二次污染.这些结果表明,Fe3C/Fe@C可作为水环境中四环素类抗生素去除的一种潜在的高效、绿色吸附剂.

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.