Valorization of Rice Husk for the Production of Porous Biochar Materials

Abstract

Rice husk (RH) is one of the most important crop residues around the world, making its valorization an urgent and important topic in recent years. This work focused on the production of RH-based biochars at different pyrolysis temperatures from 400 to 900 °C and holding times from 0 to 90 min. Furthermore, the variations in the yields and pore properties of the resulting biochars were related to these process conditions. The results showed that the pore properties (i.e., BET surface area and porosity) of the resulting RH-based biochar were positively correlated with the ranges of pyrolysis temperature and holding time studied. The maximal pore properties with a BET surface area of around 280 m2/g and porosity of 0.316 can be obtained from the conditions at 900 °C for a holding time of 90 min. According to the data on the nitrogen (N2) adsorption–desorption isotherms and pore size distributions, both microporous and mesoporous structures exist in the resulting biochar. In addition, the EDS and FTIR analyses also supported the slight hydrophilicity on the surface of the RH-based biochar due to the oxygen/silica-containing functional groups. Based on the findings of this work, the RH-based biochar could be used as a material in environmental applications for water conservation, wastewater treatment and soil amendment.

Preparation of Porous Biochar from Soapberry Pericarp at Severe Carbonization Conditions

“…As summarized above, the temperature should be the most important process parameter for determining the pore properties of the biochar products as more pores were generated in severe carbonization conditions. The findings were consistent with those reported by the other feedstocks such as cocoa pod husk [11], rice husk [12], goat manure [21], biogas digestate [33] and dairy manure [34]. The maximal BET surface area of about 300 m 2 /g can be obtained by using these feedstocks in the biochar production when the carbonization temperature reached 800 or 900 • C. In addition, the average pore diameter was obtained from the data on the BET surface area and the total pore volume assuming the pore is of cylindrical and uniform geometry, showing that the pore diameter of the SP-BC-800 product was close to the boundary limit (2.0 nm) between micropores and mesopores.…”

“…Concerning its porous structure and surface characterization, biochar has high adsorption potential for the removal of pollutants from water streams [3][4][5][6][7]. In recent years, there is an increasing interest in exploiting biochar as an excellent carbon material for environmental applications, or reusing different lignocellulosic feedstocks for producing biochar with high pore properties (e.g., specific surface area), which includes wood [8], oil palm shell [9], maize straw [10], cocoa pod husk [11], rice husk [12] and so on.…”

WITHDRAWN: Optimization and characterization of biochar obtained from weedy biomass of Calotropis gigantea by vacuum pyrolysis

“…In the present study, the H/C ratio is 0.08, which is less than 0.2; thus biochar is highly stable with shelf life more than 1000years. Biochar with H/C ratio less than 0.7 indicate high degree of aromatacity (greater fused aromatic ring) in compare to the higher H/C ratio greater than 0.7(Tsai et al 2021). O/C ratio was calculated as 0.15, thus showing increasingly aromatic property (Table3).…”

Cereal Husks: Versatile Roles in Grain Quality and Seedling Performance

“…Finally, husks are major crop residues produced in gigantic quantities worldwide, making their valorization a topical issue in recent years. The beneficial properties of husks as rich sources for minerals, growth factors, antioxidants, proteins and other beneficial substances should further stimulate its utilization as a by-product for various purposes, including soil amendment, animal feed, production of biochar, as well as a resource for valuable substances [81,82].…”