Carbon nanotubes-based polymer nanocomposites: Bio-mimic preparation and methylene blue adsorption

The effective removal of environmental pollutants using nanomaterials and their composites has attracted great attention over the past few decades. Among them, carbon nanotubes (CNTs) have been extensively applied as adsorbents to remove various environmental pollutants for their small size, large surface areas and unique chemical structure. However, the adsorption performance of pristine CNTs is largely limited for their poor dispersibility and lack of functional groups. In this work, CNTs based composites (CNTs@poly(S-co-MA-DA)) have been successfully synthesized through combination of ring-opening reaction and mussel inspired chemistry. The pristine CNTs and as-prepared CNTs@poly(S-co-MA-DA) were characterized by transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS). The influence of various experimental factors on the adsorption process, such as contact time, initial MB concentration, solution pH and temperature, was studied. Experimental results show that adsorption capacity of CNTs@poly(S-co-MA-DA) is about 4 times that of pristine CNTs in same experimental conditions. The kinetics and isotherms studies suggest that pseudo-second-order kinetic and Freundlich isotherm models could well fit with the adsorption data. The thermodynamic studies imply that the adsorption process of MB onto CNTs@poly(S-co-MA-DA) is endothermic and spontaneous. The adsorption mechanism might be the synergistic action of physical adsorption of CNTs@poly(S-co-MA-DA) particles and electrostatic interaction between the MB and functional groups on the surface of CNTs@poly(S-co-MA-DA) composites, including carboxyl, acylamino, hydroxyl and aromatic moieties. These obtained results and facts indicate that the as-prepared CNTs@poly(S-co-MA-DA) could be utilized as high-performance adsorbents with great potential applications in environmental treatment.