复配膨润土颗粒对水中诺氟沙星的动态吸附研究

Removal of Norfloxacin by Compound Bentonite Particles in a Fixed Bed Column

  • 摘要: 将经过阴阳离子表面活性剂复配插层后的钙基膨润土造粒,并利用响应面优化法制成颗粒吸附剂。在降流式固定床柱中研究水中诺氟沙星(NOR)的动态吸附,分别考察了空床接触时间、床层高度以及溶液进水pH值对吸附过程的影响。综合考虑实际应用的经济性和高效性,选取吸附柱的最佳运行条件:初始ρ(NOR)为2 mg·L-1、溶液pH=3、空床接触时间(EBCT,TEBC)为20 min、床层高度(H)为15 cm、流速(Q)为1.33 mL·min-1,在此条件下NOR的去除率均可达到70%以上,复配改性膨润土颗粒(C/S-Mt)对NOR的穿透时间增加270 min,最大吸附量(qt)增大约910 μg,平衡吸附量比未改性的原土颗粒(Ca-Mt)提高约330 μg·g-1。利用Thomas和Yoon-Nelson模型对吸附柱性能进行评估,结果表明2种模型分别可以较准确地对吸附柱的平衡吸附量和50%的穿透时间进行预测分析。

     

    Abstract: The low-cost calcium-based bentonite modified by anionic and cationic surfactants was granulated and a particulate adsorbent was prepared by response surface optimization. The dynamic adsorption behavior of norfloxacin (NOR) in water was studied in a downflow fixed bed column. The effects of the contact time of empty bed, the height of the bed and pH value of the solution influent on the adsorption process were investigated. Considering the economy and high efficiency of the practical application, the optimal operating conditions of the adsorption column were selected in the experiment. The initial concentration of NOR was 2 mg·L-1, the solution pH was 3, the contact time of empty bed (EBCT) was 20 min, the bed height (H) was 15 cm, and the flow rate (Q) was 1.33 mL·min-1. The experimental results show that the removal rate of NOR can reach to more than 70% under these conditions. And the penetration time of NOR by the modified bentonite particles (C/S-Mt) was increased by 270 min. The maximum adsorption amount(qt) increased by about 910 μg while the equilibrium adsorption amount was about 330 μg·g-1 higher than the unmodified native soil particles (Ca-Mt). The performance of bed column was estimated by Thomas and Yoon-Nelson models. The analysis indicate that the two models can accurately predict the adsorption quantity and the breakthrough curves, respectively.

     

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