Production and characterization of biochar produced from different type of bran

abstract

English

The aim of the research was focused on the production and characterization of biochar prepared from different type of bran. Bran is an outer layer of grains, and it is a side product of milling. It is a mass-produced sustainable material composed both of lignin, cellulose and hemicellulose. The motivation behind this research lies in the need for sustainable waste management strategies in the agricultural sector. Bran, a byproduct of grain processing, is typically underutilized and often considered as waste. General problem of milling industry lies in inefficient utilization of this materials, leading to environmental challenges and missed opportunities for resource recovery. This research aimed to address this issue by investigating the physicochemical properties of the biochar prepared by the pyrolysis under nitrogen atmosphere at 600 °C for 1h. Produced materials were subjected to the standard biochar physiochemical analysis with emphasis on the parameters described in European biochar certificate (EBC). Prepared biochars had a yield of 26% to 34%, consistent with previous findings. Comparing FTIR spectra confirmed adequate pyrolysis. However, the prepared biochars had a small specific surface area, which can be increased through physical or chemical activation. Surface modification is important for industrial use as an adsorbent. The high phosphorus and nitrogen content make biochars suitable for agriculture, enhancing plant production. None of the samples exceeded limits for hazardous elements, but only oat and rye bran biochars met the strictest criteria of the EBC. Rye bran biochar can be used in various sectors, except for the applications requiring high surface area. Oat biochar had low yield and exceeded PAH limits, limiting its use to industry and agriculture with process modifications. Wheat bran biochar meets EBC criteria for agriculture and industry, enhancing plant production in acidic soils. Spelt bran biochar has potential in all sectors, but zinc content restricts it to industrial applications. Rice bran biochar is suitable for agriculture, feed, and industry but exceeds PAH limits for certain categories. The prepared bran materials meet the conditions for being labeled as biochar, and some of the biochars also meet the strictest criteria of the European Biochar Certificate. Bran feedstock proved to be a suitable material for biochar production. Furthermore, it can be assumed that by modifying the pyrolysis process, the quality of the prepared material can be improved to meet even the lowest limits defined by the EBC. This possibility primarily applies to PAH content. By modifying the biochars themselves, the specific surface area and electrical conductivity can be adjusted, rendering the prepared sample a fully functional material suitable for application in agriculture as a fertilizer and feed, or in industry as an adsorbent for organic and inorganic contaminants, or as a component in construction materials, plastics, and textiles.

biochar, bran, pyrolysis, European biochar certificate

POŘÍZKA, J.; SLAVÍKOVÁ, Z.; GAJDUŠEK, M.; DIVIŠ, P.

12. 10. 2023

International Ecological Engineering Society

ZHAW Life Sciences und Facility Management, Grüentalstrasse 14, 8820 Wädenswil, Switzerland