水浮莲干粉对离子型染料的吸附机理研究

Study on adsorption mechanism of ionic dyes by dried Pistia stratiotes L.

通过研究等温吸附行为、动力学特征和pH值影响以及红外光谱、扫描电镜表征等对水浮莲干粉吸附活性艳红K-2BP、亚甲基蓝两种不同类型的离子型染料的机理进行探讨。结果表明:水浮莲干粉对亚甲基蓝的吸附符合Langmuir等温方程,而Freundlich等温方程更适合活性艳红K-2BP的吸附。Lagergren准二级动力学方程能很好地描述两种染料的吸附动力学行为。pH值是影响染料吸附的重要因素,酸性环境利于阴离子型染料活性艳红K-2BP的吸附,而碱性环境则利于阳离子型染料亚甲基蓝。表征结果显示:吸附前后样品基本没发生变化,可能主要为物理吸附。

The dried Pistia stratiotes L. used as an adsorbent for the removal of two kinds of ionic dyes （methylene blue, MB and reactive brilliant red K-2BP, RBR K-2BP） from simulated wastewater was investigated. The adsorption mech- anisms of Pistia stratiotes L. for the ionic dyes were studied by dynamics analysis,effect of initial pH and characterization of fourier transform infrared spectroscopy （FT-IR） and scanning electron microscope （SEM）. Results showed that the pH was the key factor that affecting the adsorption and lower pH was conducive to RBR K-2BP adsorption, but was not suit- able for MB adsorption. The adsorption data showed that the characteristics of MB adsorption isotherms corresponded well with the Langmuir equations, while the process of RBR K-2BP adsorption fitted the Freundlich adsorption isothermal equa- tion quite well The dynamic behaviors of the two kinds of ionic dyes＇ adsorption were all well agreement with the Lagerg- ren pseudo-second-order kinetics equation. There were no significant differences of the Pistia stratiotes L. between before and after adsorbing MB,which proved through the characterization by fourier transform infrared spectroscopy and scanning electron microscope. The adsorption of Pistia stratiotes L. for ionic dyes was mainly a physical adsorption.