The current cellulosic biofuel process generates “un-hydrolyzed fermentation residue” waste that contains primarily lignin and other non-hydrolysable components. Any technology that could turn this wet lignin-rich waste material into a valuable product would be highly desirable. Here, we present our recent experimental study demonstrating the conversion of un-hydrolyzed cornstover residue into surface-oxygenated biochar through hydrothermal carbonization (HTC) and wet ozonization. The un-hydrolyzed residue from fermentation of corn stover was converted by HTC to an oily HTC liquid and biochar with an average biochar yield of 45.4%. The HTC biochar was wet ozonized (in presence of HTC liquid). A series of analytical methods were used to characterize the resulting wet ozonized biochar material and HTC liquid. The wet ozonized biochar pH was measured to be 5.86 while the control biochar pH was 7.07. The wet ozonization increased the HTC biochar cation exchange capacity (CEC) from 6.63 cmol/kg to 11.88 cmol/kg, indicating surface-oxygenation of the biochar through the ozonization process. The dissolved organic content (DOC) of the HTC liquid before and after ozonization was measured and a DOC bioassay was conducted using the cyanobacteria <i>Synechococcus elongatus </i>PCC 7942. Our preliminary results showed that the ozonized HTC liquid DOC at a concentration of 25 ppm slightly promoted the cyanobacteria growth. Whereas, the cyanobacteria growth was inhibited by both the HTC liquid and the ozonized HTC liquid at their higher DOC concentrations (75, 150 and 300 ppm).<br/>

Turning un-hydrolyzed cellulosic lignin residue into surface-oxygenated biochar through hydrothermal carbonization and wet ozonization

255th National Meeting (2018)

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