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

• Published in: Sustainability 2023-03, Vol.15 (5), p.4626
• Main Authors: Maseko, Ncamisile Nondumiso, Enke, Dirk, Iwarere, Samuel Ayodele, Oluwafemi, Oluwatobi Samuel, Pocock, Jonathan
• Format: Article
• Language: English
• Subjects: Caustic soda; Citric acid; Electron microscopy; Ethanol; Fluorescence; Gels (Pharmacy); Pharmaceutical industry; Pharmaceutical research; Purity; Scanning electron microscopy; Silica; Silica gel; Sodium; Sodium hydroxide; Sodium silicates; Sol-gel processes; Solvents; Sugarcane; Surface active agents; Surfactants; Sustainability; Transmission electron microscopy; X-ray diffraction; X-ray fluorescence; X-ray spectroscopy; Xerogels
• ISSN: 2071-1050; 2071-1050
• DOI: 10.3390/su15054626

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.