Improvement of the carbon yield from biomass carbonization through sulfuric acid pre-dehydration at room temperature.

The pre-dehydration of a woody biomass waste (Douglas fir, DF) with 4.6-32 wt% of diluted sulfuric acid solutions was carried out mainly at room temperature aimed to improve the carbon yield from the thermal carbonization of pre-dehydrated biomass at 500 °C. By comparison (based on the raw DF), the pre-dehydration at room temperature increased the biochar yield and carbon retention up to about 32 wt% and 54%, respectively from that of about 22 wt% and 39% without pre-dehydration. When the pre-dehydration temperature increased to 90 °C, the biochar yield and carbon retention were sharply promoted to about 44 wt% and 76%, which was about two times higher than that of the biochar obtained without pre-treatment. This work for the first time proved the effectiveness of improving the carbon yield from lignocellulosic biomass via diluted sulfuric acid-assisted pre-dehydration at low or even room temperature.