Calix[4]arene-Modified Multi-Walled Carbon Nanotubes: Novel High-Efficient Sorbent for Organic Dyes

GRAPHICAL ABSTRACT

Abstract

The first example of calixarene-modified multi-walled carbon nanotubes was prepared in good yield. The absorption experiments for organic dyes indicated that it possessed excellent adsorption capacities for four tested organic dyes.

By simple esterification of hydroxyl carbon nanotubes (CNTs) with calix[4]arene carboxyl derivative 3, the first example of calixarene-modified multi-walled CNTs 5 was prepared in good yield. Its structure was characterized by Fourier translation infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetric analysis (TG). The absorption experiments for organic dyes indicated that calixarene-modified multi-walled CNTs 5 possessed excellent adsorption capacities for four tested organic dyes. The adsorption capacities for Orange G sodium salt, Brilliant ponceau 5R, neutral red and methylene blue were 0.572 mmol/g (258 mg/g), 0.434 mmol/g (262 mg/g), 0.865 mmol/g (249 mg/g) and 0.830 mmol/g (310 mg/g), respectively. The adsorption processes were exothermic and spontaneous, and obeyed pseudo second-order model and the Langmuir isotherm equation. The adsorption capacities kept stable in the range of pH = 3–10.

Keywords:

• Carbon nanotube
• Calix[4]arene
• Adsorption
• Dye

Acknowledgments

Financial support from the National Natural Science Foundation of China (No: 21406036), Fujian Natural Science Foundation of China (No. 2014J01034), Project of Fujian provincial department of education (JA11044, JA10056) and the Program for Innovative Research Team in Science and Technology in Fujian Province University were greatly acknowledged.