RSC Adv., 2015,5,71796

Grape-like mesostructured silica nanoparticledecorated
single-walled carbon nanotubes: silica
growth and dye adsorptivity†

Single-walled carbon nanotube (SWCNT)-mesostructured silica nanoparticle (MSN) adsorbents (S-MSNs)
were prepared through a simple one-step method with various loadings of SWCNTs. Their surface
properties were characterized by XRD, TEM, N2 physisorption, and FTIR spectroscopy. A grape-like
S-MSN was produced, for which the growth of MSNs became intense with increasing CNT loading. A
bimodal pore structure also developed, which increased the average pore size and pore volume, but
decreased the surface area. The increasing amount of CNTs was found to provide more sites for silica
growth that enhanced the adsorptivity of the S-MSNs toward methylene blue (MB) dye. Accordingly,
0.1 g L1 5 wt% S-MSN was able to adsorb 478 mg g1 (qm) of 50 mg L1 MB at pH 7 and 323 K. The
equilibrium data were evaluated using the Langmuir, Freundlich, Redlich–Peterson, and Dubinin–
Radushkevich isotherm models, with the Langmuir and Redlich–Peterson models affording the best fit to
the adsorption data. The adsorption was best described by a pseudo-second-order kinetics model and
thermodynamically favored the endothermic chemisorption process. These results indicated the
potential of S-MSN as an effective new adsorbent for dye adsorption.