Localized in situ polymerization on carbon nanotube surfaces for stabilized carbon nanotube dispersions and application for cobalt(ii) removal

We demonstrate a two-step in situ polymerization method to develop localized polymer coatings on the surface of carbon nanotubes (CNTs). CNTs show good chemical stability, relatively large specific area, porous and layered nanosized structures. However, difficulties in dispersion quality hinder the practical application of CNT-based composites. Poly(N,N-dimethylacrylamide) (PNDA) is a well-known soluble polymer and it has been proved to improve the sorption efficiency for some metal ions. With these in mind, the plasma-induced grafting polymer technique is used to improve the adsorption capacity and the dispersion property of CNTs. The synthesized multiwalled CNT/poly(N,N-dimethylacrylamide) (MWCNT/PNDA) composites are characterized. After attaching the polymer, the MWCNT/PNDA composites show highly stable dispersion in aqueous solutions and good properties in the preconcentration and separation of Co(II) ions from aqueous solutions. Co(II) ion sorption by MWCNT/PNDA composites obeyed the Langmuir model, attributed mainly to a outer-sphere surface sorption probably via coordination of Co d-electrons to amide and –O–Co and CC (π-electrons) bonds.