Synthesis and characterization of silica aerogel from sugarcane bagasse with ambient pressure drying method / Muhammad Al-Fateh Mohd Sofian

In this study, silica aerogel was prepared from sodium silicate extracted from sugarcane bagasse ash (SCBA) at ambient pressure drying. In brief, SCBA was boiled in NaOH and neutralized with HCl, which yielded silica as sodium silicate. Surface modification was achieved by ageing alcogel with sylilating agents, Trimethylsilyl chloride (TMCS) prior to drying at 100 °C for 1 h. The sodium silicate and synthesized sugarcane bagasse aerogel were characterized using several spectroscopic techniques and chemical analysis such as Inductively Coupled Plasma-Optical Emission (ICP-OES), Attenuated Total Reflectance-Fourier-Transform Infrared (ATR-FTIR), X-ray diffraction (XRD) and oil absorption test. The prepared sugarcane bagasse aerogel ICP-OES results showed that the concentration of silica in the extracted sodium silicate at different pre-treated temperatures of 400 °C and 600 °C was 139.1625 and 144.5625 ppm, respectively. This presumably due to at higher temperature, high dissolution of silica can be achieved. The ATR-FTIR spectrum show the peaks near 3449 cm-1 and 1647 cm-1 for both samples that corresponds to the Si-OH (silanol) groups that forms due to condensation reaction during drying. For the SCBA sample synthesized at 400 °C, the bands near 2827 cm-1 and 2894 cm-1 indicate the presence of OC2H5 terminal group, that exhibited a decreasing in peak intensity as temperature increases to 600 °C. To conclude, ATR-FTIR pattern of the synthesized SCBA aerogel is comparable that of reported commercial silica aerogel. Despite the crystalline nature of the silica product, the XRD pattern at 2θ = 22°–25° in SCBA samples at 400 °C and 600 ° confirms the amorphous nature of the synthesized sugarcane bagasse aerogel. The results of oil absorption tests showed that the maximum oil absorption capacity of the prepared sugarcane bagasse aerogel at 400 °C and 600 °C is 2.73 g/g and 2.50 g/g respectively that was greater than its initial weight. The findings proves that the SCBA-synthesized silica aerogel outperformed reported commercial absorbents (Polycaprolactone, 3.9 g/g to 0.3 g/g) in terms of absorption.