College of Environmental Science and Engineering, Dalian Maritime University, Linghai Road 1, Dalian, 116026, People's Republic of China.
Environ Sci Pollut Res Int. 2021 Aug;28(30):41268-41282. doi: 10.1007/s11356-021-13543-z. Epub 2021 Mar 29.
In the present study, five magnetic multi-walled carbon nanotubes (MMWCNTs) with different diameters were prepared and their performance on the sorptive removal of methylene blue (MB) from water was investigated. Transmission electron microscope, scanning electron microscope, Fourier transform infrared spectrometer, X-ray diffraction, and vibrating sample magnetometer confirm that the surface of these MMWCNTs has been decorated by FeO nanoparticles, which renders the MMWCNTs superparamagnetic. Thus, these MMWCNTs can be easily separated from water after the adsorption. During the adsorption process, pH slightly affected the removal efficiency of MB and the adsorption performed better under weak alkaline conditions. Adsorption kinetics followed the pseudo-second-order kinetic model well, and the Dubinin-Radushkevich model fitted the isotherms best. The maximum adsorption capacity for MB reached 204.2 mg/g, and the values decreased with increasing diameters of MMWCNTs due to decreasing specific surface areas. The thermodynamics parameters indicated the spontaneous and exothermic nature of the adsorption. The reusability test showed that MMWCNTs could be used for 6 cycles without significant loss of the adsorption capacity. And common ions (K, Na, Ca and Al) and SDS in water did not show greatly effects on the removal efficiency of MB. Hence, MMWCNTs prepared in this study could be promising adsorbents for dyes removal from wastewater.
在本研究中，制备了五种具有不同直径的磁性多壁碳纳米管（MMWCNTs），并研究了它们对水中亚甲基蓝（MB）的吸附去除性能。透射电子显微镜、扫描电子显微镜、傅里叶变换红外光谱仪、X 射线衍射和振动样品磁强计证实，这些 MMWCNTs 的表面已被 FeO 纳米颗粒修饰，使其具有超顺磁性。因此，吸附后这些 MMWCNTs 可以很容易地从水中分离出来。在吸附过程中，pH 值对 MB 的去除效率略有影响，在弱碱性条件下吸附效果更好。吸附动力学很好地遵循了伪二级动力学模型，而 Dubinin-Radushkevich 模型最适合拟合等温线。MB 的最大吸附容量达到 204.2mg/g，由于比表面积减小，MWCNTs 的直径增大，吸附容量减小。热力学参数表明吸附是自发和放热的。重复使用测试表明，MWCNTs 在没有明显损失吸附容量的情况下可以使用 6 次。而且水中的常见离子（K、Na、Ca 和 Al）和 SDS 对 MB 的去除效率没有很大影响。因此，本研究中制备的 MMWCNTs 可能是去除废水中染料的有前途的吸附剂。
