Heating temperature dependence of molecular characteristics and biological response for biomass pyrolysis volatile-derived water-dissolved organic matter.

The utilization of biomass pyrolysis volatile-derived water-dissolved organic matter (WOM, often called wood vinegar) determines sustainable recycling of biomass. Further, pyrolysis temperature significantly controls the cracking of biomass components, resulting in various molecular compositions and biological responses of WOM. Although it has been widely used in the agriculture, the relationship between molecular compositions and biological responses affected by heating temperature is still unclear. Here, it was observed that the WOM concentration increased with increasing temperatures and the pyrolysis of 1 g biomass can generate ~ WOM with 36.24 mg C. Moreover, with increasing pyrolysis temperatures, the generated WOM consisted of more phenols but fewer alcohols, furans, acids, and ketones, and demonstrated characteristics of higher aromaticity and lower m/z molecular weight. Due to the enhanced polarity, high temperatures promoted the solubility of WOM. Germination tests show that low pyrolysis temperatures-derived WOM (< 400 °C) with large-molecular-weight and low oxygen-containing (low O/C) promoted plant growth, while high temperatures-derived WOM (> 400 °C) with small-molecular-weight and high oxygen-containing (high O/C) inhibited growth. These results suggest that WOM can be separately collected at different pyrolysis temperatures to achieve sustainable recycling of pyrolysis volatile.