活性污泥对四环素的吸附性能研究

通过批量平衡法研究了四环素在活性污泥上的吸附行为.结果表明,污泥混合液浓度和四环素初始浓度对吸附平衡时间、污泥吸附量和污泥吸附率均有较大影响.伪二级反应动力学模型较伪一级反应动力学模型更符合本吸附实验.在10、25℃条件下,四环素在活性污泥上的吸附行为较符合Langmuir模型,最大吸附量分别是31.14、70.95 mg.g-1;在40℃下,符合Henry模型.应用D-R模型判定吸附类型,10℃(平均吸附能为9.13 kJ.mol-1)下,化学吸附占主导;40℃(平均吸附能为7.07 kJ.mol-1)下,物理吸附占主导.温度升高,污泥对四环素的吸附能力增大.离子交换是四环素在活性污泥上吸附的一种机制.四环素的初始浓度为5、10、20 mg.L-1,钠离子浓度由0 mol.L-1增加到0.1 mol.L-1时,吸附量分别下降15.32%、15.00%、20.12%.当pH在5～10之间时,pH为6的条件下污泥对四环素的吸附量最大.

Study on the Sorption Behavior of Tetracycline onto Activated Sludge

The batch sorption methods were employed to investigate the sorption behavior of tetracycline (TC) on the activated sludge. It was shown that the mixed liquor suspended solids (MLSS) and the initial concentration of TC had great impacts on equilibrium time, adsorption capacity and adsorption rate. Compared with pseudo first-order model, pseudo second-order model showed the better agreement. At 10, 25 degrees C, the Langmuir model was the best isotherm to describe the experimental data for adsorption of TC on activated sludge, and the maximum adsorption capacities were 31.14, 70.95 mg x g(-1) respectively; at 40 degrees C, the linear isotherm confirmed the agreement. The data were also modeled by D-R isotherm to determine the type of adsorption. At 10 degrees C (E was 9.13 kJ x mol(-1)), the dominant type was physical, and at 40 degrees C (E was 7.07 kJ x mol(-1)), the dominant type was chemical. With the temperature increasing, the adsorption capacity increased. Ion exchange is one mechanism for adsorption of TC on activated sludge. When the initial concentrations of TC were 5, 10, 20 mg x L(-1), with the Na+ concentration increasing from 0 mol x L(-1) to 0.1 mol x L(-1), the adsorption capacities decreased by 15.32%, 15.00%, 20.12% respectively. The maximum adsorption capacity was got at pH 6 when pH varied from 5 to 10.