FIRST CHARACTERIZATION OF HUMIC-LIKE SUBSTANCES ISOLATED FROM MAIZE STRAW BIOCHAR

摘要

Biochar plays a crucial role in mitigation of climate change, improvement of soil fertility, enhancement of crop productivity, and remediation of contaminated soil. The roles of biochar in the environment can be partly ascribed to the presence of humic-like substances in biochar. In this study, the quantitative and qualitative characteristics of humic-like substances isolated from a commercial maize (Zea mays L.) straw biochar were described using chemical and spectroscopic methods. Compared with raw maize straw, the carbon contents of humic-like acid and fulvic-like acid fractions in maize straw biochar were lower, while the carbon content of humin-like fraction was higher. The ratios of H/C, alkyl C/O-alkyl C, aliphatic C/aromatic C and hydrophobic C/hydrophilic C were 1.2, 1.1, 0.8 and 2.6 for humic-like acid from maize straw biochar, and 1.5, 0.2, 2.1 and 0.7 for humic-like acid from maize straw, indicating that the aromaticity, alkylation and hydrophobicity degrees of humic-like acid were higher in maize straw biochar than in maize straw. With respect to humic-like acid, the elemental composition of humin-like fraction was more similar to their respective feedstock. The humin-like fraction in maize straw biochar was more aromatic and less polar than that in maize straw. Meanwhile, the humin-like fraction was also more aromatic and less polar than the humic-like acid in maize straw biochar. The present study revealed the essential differences between humic-like substances from maize straw biochar and raw maize straw. The results are important for understanding the possible mechanism of biochar functions in the environment.