Poly(acrylic acid) grafted multiwall carbon nanotubes by plasma techniques for Co(II) removal from aqueous solution

Poly(acrylic acid) grafted multiwall carbon nanotubes (MWCNT-g-PAA) was synthesized by using plasma techniques, and was applied as a adsorbent to remove Co(II) from aqueous solution. Fourier transferred infrared spectroscopy (FT-IR) and thermo gravimetric analysis (TGA) demonstrate that poly(acrylic acid) was successfully grafted on the surface of MWCNTs. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) show that the bulk properties of MWCNTs were not changed after plasma treatment. The sorption capacity of Co(II) is improved conspicuously after plasma treatment due to the oxygen-containing functional groups. The removal of Co(II) by MWCNT-g-PAA occurs rather quickly, which can be well described by the pseudo-second-order model. The sorption of Co(II) is strongly dependent upon the pH values. The sorption isotherms fit the Langmuir sorption model well. The thermodynamic data (ΔH0, ΔS0 and ΔG0) are calculated from the temperature-dependent sorption isotherms, and the results suggest that the sorption process of Co(II) on MWCNT-g-PAA is spontaneous and endothermic.

MWCNT-g-PAA was synthesized by using plasma technique; compared with the raw MWCNTs, the sorption capacity of MWCNT-g-PAA for Co(II) was greatly enhanced.Figure optionsDownload as PowerPoint slideHighlights
► MWCNT-g-PAA was synthesized by using plasma techniques.
► The sorption capacity of MWCNT-g-PAA for Co(II) was higher than that of raw MWCNTs.
► The sorption of Co(II) was highly dependent on the pH value.
► The sorption of Co(II) was endothermic and spontaneous.