Meso/Macroporous Silica from Miscanthus, Cereal Remnant Pellets, and Wheat Straw

In the present study, the possibility of extracting biogenic silica from various European biomass materials was investigated. High-purity biogenic silica (>90 wt % SiO2) was obtained from energy crops (miscanthus), agro wastes (wheat straw), and other crop residues (cereal remnant pellets). Three different morphological forms of biogenic silica materials (ash) were obtained by a thermo-chemical treatment of these biomass sources. The wet biomass materials were leached using 5 M sulfuric acid for a defined period of time. After washing and drying the biomass materials, the leached samples were subjected to a heat treatment in a furnace with three sequential temperatures and time stages to determine the minimum combustion temperature of the organic compounds in the biomass materials. The final products were characterized by X-ray diffraction, X-ray fluorescence, carbon content analysis, differential thermal analysis, low temperature nitrogen adsorption, mercury intrusion porosimetry, and scanning electron microscopy. The obtained silica materials had a microstructure composed of accessible, interconnected, and intraparticle meso- and macropores with sizes ranging from 3 to 1500 nm.