活性污泥对四环素类抗生素的吸附特性研究

采用间歇吸附实验,研究了活性污泥对3种四环素类抗生素的吸附特性,探讨了吸附初始浓度、温度和溶液pH对吸附的影响。结果表明,当起始浓度为1～2 mg/L、pH为6、温度为25℃、污泥量为0.1 g时,盐酸四环素(TC)、盐酸土霉素(OTC)和盐酸金霉素(CTC)的吸附平衡时间分别为120、90和90 min。假二级动力学较假一级动力学能更好地模拟3种四环素类抗生素的吸附动力学,模型中TC、OTC和CTC的吸附容量qeq(mg/g)值分别为1.638、1.548和1.325,二级吸附速率常数k2×103g/(mg.min)]值分别为65.52,66.70和67.28。等温线模拟结果表明,Freundlich方程较Langmuir方程能更好地模拟等温吸附过程,TC,OTC和CTC吸附方程分别为qeq=8.485c1/0.915,qeq=8.170c1/1.063和qeq=7.573c1/1.076。活性污泥吸附3种四环素类抗生素的最优pH和温度分别为6.0和25℃,吸附容量随初始浓度的增加而增加,但达到吸附平衡的时间延长且平衡浓度上升。研究亮点:抗生素类污染物作为一种对人类和环境有潜在危险的微污染物直到最近才被引起重视,而常规的污水处理厂也不能很好地去除这类污染物。通过活性污泥对3种四环素类抗生素进行吸附研究,为将来进一步研究抗生素在污水处理工艺中的迁移转化提供参考。

Research on adsorption characteristics of tetracycline antibiotics with activated sludge

Tetracycline antibiotics removal by adsorption with activated sludge from wastewater was accomplished in this paper,and adsorption characteristics,adsorption kinetics,and adsorption equilibrium were investigated in a batch system.The effects of initial concentration,temperature and solution pH on adsorption were also discussed.The results indicated that adsorption equilibrium of TC,OTC and CTC can be reached at 120,90 and 90 min respectively under the conditions that the initial concentration of antibiotics was 1-2 mg/L,pH was 6 and temperature was 25 ℃.The adsorption kinetics of all three antibiotics followed pseudo-second order rather than pseudo-first order,and the corresponding adsorption capacity q_eq（mg/g） of TC,OTC and CTC were 1.638,1.548 and 1.325,and the second adsorption rate constants k₂ ×103g/（mg·min）] of TC,OTC and CTC were 65.52,66.70 and 67.28 respectively.The Freundlich model fitted the experimental data better than the Langmuir model,and the isotherm equations of TC,OTC and CTC were q_eq=8.485c1/0.915,q_eq=8.170c1/1.063 and q_eq=7.573c1/1.076 respectively.The optimal pH and temperature of all three kinds of antibiotics were 6.0 and 25℃.The higher the initial concentration was,the higher the adsorption capacity was,while it needed more time to reach equilibrium and the equilibrium concentration increased.