Cu/CuO改性碳纳米管对亚甲基蓝的吸附特征

为探讨Cu/CuO改性碳纳米管对亚甲基蓝的吸附特征,采用Cu/CuO对碳纳米管进行了改性,通过SEM、XRD和比表面积-孔径分析仪对改性前后碳纳米管进行表征。以改性前后碳纳米管为吸附剂,研究了改性前后碳纳米管对亚甲基蓝的吸附动力学和吸附等温线,并且分析了环境因素包括温度、pH和离子强度对吸附的影响。结果表明:改性前后碳纳米管对亚甲基蓝的吸附过程符合准二级动力学方程,且在2 h左右达到吸附平衡,吸附等温线符合Freundlich模型,改性之后碳纳米管对亚甲基蓝的吸附能力增强。改性前后碳纳米管对亚甲基蓝的吸附量随温度的增加而降低,随pH和离子强度的增大而增大。研究表明,Cu/CuO改性碳纳米管对亚甲基蓝的吸附效果优于原始碳纳米管,Cu/CuO改性碳纳米管去除溶液中的亚甲基蓝主要通过疏水性相互作用、静电相互作用和铜与亚甲基蓝之间的络合作用。

Characterization of adsorption of methylene blue by Cu/CuO-modified carbon nanotubes

The adsorption characteristics of methylene blue in both Cu/CuO-modified and pristine carbon nanotubes were evaluated using a batch technique. Both the modified and pristine carbon nanotubes were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD) and the specific surface area was determined via a pore size analyzer. Using methylene blue as the absorbent, the effects of reaction time, temperature, pH, and ionic strength on the adsorption by the modified and pristine carbon nanotubes were investigated. Results showed that the pseudo-second-order equation was more suitable for the adsorption kinetics than the pseudo-first-order equation. The adsorption equilibrium was reached in about 2 h. The adsorption isotherms of the two kinds of carbon nanotubes conformed to the Freundlich model. The adsorption capacity of the carbon nanotubes increased with increasing pH and ionic strength in the medium. However, the adsorption capacity of the carbon nanotubes decreased as the temperature increased. Our results indicate that the adsorption mechanisms mainly include hydrophobicity interaction, electrostatic interaction, and complexation between copper and methylene blue.