Effect of Magnetic Metal Ions on Properties of Carbon Nanotube Slurry Dispersed by Sodium Carboxymethylcellulose

A detailed study of the dispersion, rheological and adsorption behaviors between multi-walled carbon nanotubes (MWNTs) and sodium carboxymethylcellulose (CMC) at different metal ions solutions were presented. The experimental results suggested that the chelation between metal ions and CMC governed the adsorption amount and adsorption conformation of CMC onto MWNTs, which had a great influence on the dispersion stability of MWNTs slurries. The MWNTs slurry with Fe²⁺ had smaller average size, lower viscosity and better stability, which led the slurry to evolving from shear-thinning fluid. It can be seen form UV adsorption experiment that the chelation between Fe³⁺ and CMC was stronger than that of other divalent ion. And the chelation increased with the increase of the radius of the divalent ion. Raman and Thermo-gravimetry (TGA) results showed that the adsorption amount of Fe³⁺ was lower, which provided a lower electrostatic repulsive force. In the slurry with divalent ions, adsorption amount of CMC onto MWNTs were higher in the order of Ni²⁺, Co²⁺ and Fe²⁺, providing higher repulsive force, larger zeta potential on MWNTs surface. That’s the reason why Fe²⁺ had better dispersion stability. The microstructures were measured by TEM. It was found that uniform CMC adsorption layers were formed on the surface of MWNTs with divalent ions. However, for the MWNTs with Fe³⁺, MWNTs were wrapped by CMC agglomerates, resulting in poor dispersion stability.