Study on an alternative approach for the preparation of wood vinegar from the hydrothermolysis process of cotton stalk

The yield and pH of the refined aqueous product (RAP) prepared by the hydrothermolysis of cotton stalk (CS) were investigated using response surface methodology with the variation of three parameters: CS/water ratio of 0.05-0.15w/w, temperature of 180-280 °C, and retention time of 0-30 min. At the best formulation (0.05w/w, 264.36 °C and 0 min), the yield and pH of RAP were 82.8% and 3.95, respectively. Additionally, the organic compounds contained in RAP prepared under the respective optimal formulation (pH: 0.05w/w, 251.43 °C and 0 min, yield: 0.05w/w, 280.00 °C and 0 min) were determined by gas chromatography and mass spectrometry. The results show that the kinds of compounds in RAP are identical or similar to those in the wood vinegar (WV), but their contents is slightly higher than that of the WV. In sum, it is feasible that RAP has the enormous potential to be utilized as WV probably because of its higher quality and value than WV.