Influence of multi-walled carbon nanotubes on textural and adsorption characteristics of in situ synthesized mesostructured silica

• CNT–MSN composites with improved physicochemical properties were developed.
• A CNT–MSN composite adsorbed 524 mg g−1 (qm) MB at 303 K.
• The bimodal pore structure of CNT–MSN plays an important role in MB adsorption.
• The adsorption obeyed Langmuir isotherm and pseudo-first order kinetic models.
• MB adsorption is a thermodynamically favored exothermic physical process.

Carbon nanotubes–mesostructured silica nanoparticles (CNT–MSN) composites were prepared by a simple one step method with various loading of CNT. Their surface properties were characterized by XRD, N2 physisorption, TEM and FTIR, while the adsorption performance of the CNT–MSN composites were evaluated on the adsorption of methylene blue (MB) while varying the pH, adsorbent dosage, initial MB concentration, and temperature. The CNTs were found to improve the physicochemical properties of the MSN and led to an enhanced adsorptivity for MB. N2 physisorption measurements revealed the development of a bimodal pore structure that increased the pore size, pore volume and surface area. Accordingly, 0.05 g L−1 CNT–MSN was able to adsorb 524 mg g−1 (qm) of 60 mg L−1 MB at pH 8 and 303 K. The equilibrium data were evaluated using the Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich isotherm models, with the Langmuir model affording the best fit to the adsorption data. The adsorption kinetics were best described by the pseudo-first order model. These results indicate the potential of CNT–MSN composites as effective new adsorbents for dye adsorption.

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