Grape-like mesostructured silica nanoparticle-decorated single-walled carbon nanotubes: silica growth and dye adsorptivity

Abstract

ARTICLE This journal isSingle-walled carbon nanotubes (SWCNTs)-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, N 2 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 L -1 5 wt% S-MSN was able to adsorb 478 mg g -1 (q m ) of 50 mg L -1 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.

Facile synthesis methodology and characterization studies of silica‐decorated hybridized anisotropic nanotubes and nanosheets

“…The appearance of these peaks demonstrated the in situ silica decoration by hydrolysis and condensation of TEOS along with the formation of covalent bonding between the nanotubes and silane segments. The outcomes are in good agreement with the results as reported by Zhang et al 11 …”

“…The band found at 1405 cm −1 must be associated to –OH groups introduced during the acidification process. Besides, C‐N amide stretching has arisen for the nanohybrid owing to the interaction between –NH 2 groups of APTES and the existing carboxyl functionalities of acidified CNT 11 . Intensity of the characteristic peaks at 3400 and 1630 cm −1 declined for the CNS spectrum, confirming successful conversion of C=O and C–OH functionalities to C‐O‐Si.…”

“…Due to the porous nature of nanotube, the inserted silica precursors could be adsorbed onto the walls during the sol–gel process, and eventually, the nanoparticles physically anchored. On the other hand, as there are specific defect sites existing on the walls of acidified CNT (e.g., hydroxyl and carboxyl groups), some silica precursors could be covalently bonded to the surface 11 . The nanotube can be utilized as the chains to lock the attached silica layer altogether, and the assemblies might have attributed to the formation of unique hybrid nanostructures.…”

Visible‐light driven photodegradation of phenol over niobium oxide‐loaded fibrous silica titania composite catalyst

“…A few similar major absorption bands were identified for all catalysts: 1084 (Si-O-Si asymmetric), 964 (external Si-OH group), 530 (Si-O-Si asymmetric stretching), and 465 cm −1 (Si-O-Si bending vibration), all of which can be seen in the figures. 19,38 In order to further evaluate the rearrangement of the SiO 2 network, the region of Gaussian curve-fitting at 1000-900 cm −1 was determined ( Fig. S2) and the intensity of the peaks are illustrated in Fig.…”

Hydrothermal and activated synthesis of adsorbent montmorillonite supported porous carbon nanospheres for removal of methylene blue from waste water

“…Nowadays, dyes are widely used in textiles, printing, dye manufacturing, and food plants. [1][2][3] The extensive utilization of dyes in different kinds of industries oen lead to pollution problems by the discharge of dyes into environmental water bodies. 4 Dye effluents contain complex compounds, toxic synthetic substances and even the presence of trace amounts of organic dyes could induce a lot of signicant problems, such as toxicity and reducing light penetration of the effluent.…”