Revealing the impact of pyrolysis temperature on dissolved organic matter released from the biochar prepared from Typha orientalis.

Biochars derived from wetland biomass have been extensively applied in water and wastewater treatments. This study investigated the quantity and chemical quality of dissolved organic matter (DOM) released from the biochar prepared from the typical wetland plant (Typha orientalis) at different pyrolysis temperatures (300-700 °C) by using fluorescence excitation-emission (EEM) spectrophotometry with parallel factor analysis (PARAFAC) and UV-Visible spectroscopy. The results showed that the content of DOM released from biochars at low pyrolysis temperatures (300-500 °C) was higher than that observed at high pyrolysis temperatures (600-700 °C). The distribution of DOM components (mainly including three humic acid-like substances, one fulvic acid-like substance and one tyrosine-like substance) varied significantly due to the increase of pyrolysis temperatures. The fulvic acid-like material was the key DOM component at the low pyrolysis temperature while the humic acid-like material became dominant at the high temperature. DOM quality indices also indicated that the percentage of the low molecular-weight DOM increased with the decreasing DOC concentration due to the higher temperatures. The results obtained in this study would be beneficial to guide the rational application of biochars in waste treatments.