Abstract
Nanocomposites of silica gel (SG) and multiwalled carbon nanotubes (MWCNTs) of relatively low concentrations (0.25, 0.50, and 0.75 wt%) were characterized before and after annealing. Adsorption is a surface phenomenon, and based on this, the morphology of the composites was investigated by scanning electron microscopy (SEM). The produced images show that the MWCNTs were embedded into the silica gel base material. Fourier transform infrared (FTIR) transmittance spectroscopy showed that MWCNTs were not functionalized within the matrix of silica gel and MWCNT composites. However, after annealing the composites at 400 °C for 4 h in air, evidence of activation was observed in the FTIR spectrum. The effects of the embedding of MWCNTs on porosity, specific surface area, and pore size distribution were studied using Raman spectroscopy. The Raman spectra of the prepared composites were mainly dominated by characteristic sharp scattering peaks of the silica gel at 480, 780, and 990 cm−1 and a broad band centered at 2100 cm−1. The scattering peaks of MWCNTs were not well pronounced, as the homogeneity of the composite is always questionable. Nanosizer analysis showed that at 0.25 wt%, the distribution of MWCNTs within the silica gel was optimal. Vickers hardness measurements showed that the hardness increased with the increasing weight percent of MWCNTs within the composite matrix, while annealing enhanced the mechanical properties of the composites. Further studies are required to investigate the pore structure of silica gel within the matrix of MWCNTs to be deployed for efficient cooling and water purification applications.
Highlights
The identity of the discoverers of carbon nanotubes (CNT) is a subject of some controversy
All of the results indicated that the modification method has a reasonably benign effect on the ordered crystal structure of Multiwalled carbon nanotubes (MWCNTs) and is advantageous for the preservation of their superior mechanical capabilities [15]
scanning electron microscopy (SEM) micrographs and Energy-dispersive X-ray spectroscopy (EDX) showed that silica gel and MWCNT composites were mixed, with the lengthy MWCNTs tangled and the silica gel particulates immersed between the nanotubes
Summary
The identity of the discoverers of carbon nanotubes (CNT) is a subject of some controversy. Multiwalled carbon nanotubes (MWCNTs) are becoming increasingly attractive from a practical point of view, due to their greater diameter and reduced strain in addition to their economic value. They have superior mechanical properties, electrical conductivity [4], and high heat transfer performance [6]; based on these properties, they have been deemed appropriate for use as reinforcing fillers for high-performance polymer nanocomposites [7,8]. It has been observed that introducing MWCNTs, with their high surface area along with other physical properties, to the porous structure of SiO2 results in the enhanced adsorbing performance of cooling chillers [8]. The study will allow us to determine how to further employ the current composites or, otherwise, develop an efficient cooling system and other related applications
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