Synthesis of Low Density and High Purity Silica Xerogels from South African Sugarcane Leaves without the Usage of a Surfactant

Abstract

Sugarcane leaves were used to produce high-purity and low-density silica xerogels through a sol–gel method. The biogenic silica produced through a thermochemical method was reacted with sodium hydroxide (NaOH) to form sodium silicate and the produced sodium silicate was titrated with 1 M citric acid to form silica gel. The formed silica gel was washed, subjected to a solvent exchange process and later dried at 80 °C to produce low-density and high-purity silica xerogels. The produced xerogels were characterized with energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), nitrogen physisorption, elemental analysis (CHNS), X-ray fluorescence (XRF), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The produced silica xerogels had an amorphous structure and purity of 99.9 wt%. In addition, the textural properties analysis showed that the xerogel has a BET surface area of 668 m2·g−1, an average pore diameter of 7.5 nm, a pore volume of 1.26 cm3·g−1 and a density of 0.23 g·cm−3.

Investigation of different deposition methods for synthesized gold nanoparticles on a South African sugarcane leaves derived silica xerogel support

“…The gel was covered with a parafilm and left in a fume hood to age for a period of 8 h at room temperature. The resulting gel was later washed and subjected to a solvent exchange method as reported by Maseko et al [34]. After solvent exchange, the surfactant removal was conducted as per the method reported by Jabariyan et al [29] except that in this study HCl was substituted with citric acid.…”

Comparative Study of Commercial Silica and Sol-Gel-Derived Porous Silica from Cornhusk for Low-Temperature Catalytic Methane Combustion

“…Sol-gel products benefit from favorable properties such as high surface area with a bimodal pore size distribution, allowing for adequate surface for the active species immobilization and unimpeded mass transfer of gaseous species (reactants and products) [43]. In addition, they exhibited high thermal stability and hydrophobicity that could reduce hydroxylation and water deactivation during catalysis operations [44]. According to Schwarz et al [45], sol-gel products have extremely low thermal conductivity, good texture, and excellent stability at high temperatures.…”