Amorphous carbon nanotubes as a potent remover of textile dyes: methylene blue and malachite green

In view of increasing threats related to water pollution by textile effluents, this article reports the photo-catalytic removal of different cationic dyes by amorphous carbon nanotubes (a-CNTs). a-CNTs, were synthesized by a simple low-temperature, solid-state reaction between ferrocene and ammonium chloride. The amorphous nature of the a-CNTs was confirmed by XRD where the presence of a broad hump centering around 26° suggests the graphitic nature of the sample, whereas electron microscope images confirmed the 1 dimensional morphology of the material having diameter around 120 nm. Raman and Fourier transformed infrared spectroscopic analysis speculates different bonds existing in the sample. The sample shows an excellent ability to remove different cationic dyes like methylene blue, Malachite Green, or a mixture of dyes under UV light (wavelength λ = 254 nm) of wattage 30 W. a-CNTs show removal ability with efficiency around 90% within 70 min in case of methylene Blue. Whereas for Malechite green the efficiency comes little lesser. The sample performs most efficiently in basic medium with pH value 11. The dye mixture also shows a systematic decrease in adsorption peak under UV irradiation. The kinetics of the reaction has also been studied both considering the first as well as pseudo second order mechanism, and it found that the reaction is more likely to follow pseudo–second order kinetics with values of regression coefficient of linear fit as high as 0.999.