Effects of lignin, hemicellulose, and cellulose of feedstock and pyrolytic temperature on the composition and properties of biochar-derived dissolved organic matter

Abstract

Biochar has been widely applied across diverse fields, and its derived dissolved organic matter (BDOM) is attracting growing research interest, particularly concerning the environmental fate and transport of various contaminants. However, systematic studies on BDOM produced from feedstocks with varying lignin, hemicellulose, and cellulose contents under different pyrolysis temperatures are still limited. Differences in the pyrolysis behaviors of these components may lead to significant variations in the BDOM properties, thereby influencing its environmental behaviors and application. To address this knowledge gap, six types of agricultural waste—walnut shell (WAS), corn cob (CC), peanut shell (PS), rice husk (RH), wheat husk (WHS), and corn stalk (CS) with distinct lignocellulosic components—were selected as raw materials to produce biochars at 300°C, 400°C, and 500°C. BDOM was extracted and comprehensively characterized. The results indicate that in addition to pyrolysis temperature, lignocellulosic components also significantly affect the quantity, aromaticity, and composition of BDOM, particularly in biochars produced at lower temperature (≤400°C). A higher cellulose content promoted the release of more BDOM in biochars pyrolyzed at 400°C, as confirmed by the detection of fulvic-like and humic-like substances through fluorescence spectroscopy and three-dimensional fluorescence spectroscopy coupled with parallel factor analysis. Additionally, two-dimensional correlation spectroscopy highlighted oxygen-containing functional groups as the most temperature-sensitive structural features. This study not only provides systematic evidence of the importance of lignocellulosic components on the properties and composition of BDOM, but also offers new insights into the potential applications of biochar in environmental remediation.