Biosilica preparation from abundantly available African biomass Teff (Eragrostis tef) straw ash by sol-gel method and its characterization

This study reports preparation of biosilica from teff straw ash via sol-gel method. Teff straw ash prepared at different ashing temperatures (500, 700, and 900 °C) was treated with 2.5 N NaOH solution prior to acidification in order to extract biosilica in the form of sodium silicate solution (SSS). The effects of ashing temperatures on biosilica yield and physiochemical properties were studied. Physicochemical properties of extracted biosilica were determined by performing XRD, FE-SEM, EDX, and FTIR analysis. The carbon content and other impurities in extracted biosilica decreased with rise in ashing temperature. The biosilica yield increased with ashing temperature in the order 500 °C (49.5%) < 700 °C (70.2%) < 900 °C (84.5%). EDX, XRF, and FTIR analysis confirmed that the purity was > 99% for biosilica prepared from teff straw ash prepared at 900 °C.