Surface Modification of Nano-Biosilica Extracted from Rice Husk using A Silane Coupling Agent

Abstract

Nano-biosilica extracted from rice husk, an abundant by-product of rice milling, has many potential applications in industry. However, the high amount of hydroxyl group in silica make it easy to adsorb moisture and form aggregates that are difficult to distribute in the hydrophobic matrices. This research aimed to modify the surface of nano-biosilica by using a coupling agent and characterize the changes in physical properties. Nano-biosilica was extracted using a sol–gel technique and treated with a silane coupling agent (bis-(triethoxy-silyl-propyl) tetrasulfide/TESPT) at concentrations of 0–20%. Characterization included colour (chromametry), weight increase (gravimetry), crystallinity (X-Ray Diffraction/XRD), microscopic structure (Scanning Electron Microscopy/SEM), functional groups (Fourier Transform – Infrared Spectroscopy/FT-IR), silica content (X-Ray Fluorescence Spectroscopy/XRF), and specific pore surface area (Brunauer Emmett-Teller/BET). Crystallinity decreased with the increase in silane concentration, indicating more amorphous structures of surface-modified nano-biosilica. This was confirmed by a more porous surface structure in the silane-treated nano-biosilica as shown under SEM observation. FT-IR analysis exhibited some peaks at methylene bounds at the surface-modified nano-biosilica demonstrating its interaction with TESPT. The silica content (SiO2) and the specific pore surface area of the treated nanobiosilica decreased, confirming the presence of TESPT on the surface. This study provides more potential applications of nano-biosilica as a filler agent.