The process of delignification during the pretreatment of corn stover in supercritical CO2 with ethanol‐water as co‐solvent was investigated. After pretreatment, many lignin droplets were found deposited on the fiber surface which hinder cellulose digestibility. These lignin droplets were removed by ethanol‐water and after washing the optimal glucose yield increased significantly. Lignin degradation reactions competed with condensation reactions during pretreatment. The cleavage of ether bonds and the high solubility of lignin fragments in ethanol‐water co‐solvent were the key factors for lignin removal and degradation behavior during pretreatment.

Rutin and K3R (kaempferol-3-O-rutinoside) in tartary buckwheat are flavonol glycosides with high medical value. It is necessary to separate them from tartary buckwheat before utilization because of their different medical functions. However, they have very similar molecular structures, causing troubles in thorough separation. The adsorption equilibrium of rutin and K3R from supercritical CO2/methanol was investigated. The adsorption capacities were measured by the elution at characteristic point method at 308.15, 313.15, and 318.15 K with 0.450–0.693 g/cm3 CO2/methanol on CN-bonded silica. The adsorption capacity of rutin and K3R showed a decreasing trend with the increasing mobile phase density and temperature. The capacity of rutin is larger than that of K3R under the same conditions, indicating that rutin was an easily adsorbed component. The data obtained from adsorption equilibria were fitted by both Freundlich and Langmuir isotherm models, which showed that the latter one performed better. This single-component model can extend to binary component and describe the competitive behavior well. Data and models obtained can be used to simulate adsorptive separation processes so as to design and optimize the separation process of rutin and K3R with supercritical fluid chromatography.

The amount of trace organic acids must be controlled in the fuel ethanol product in order to reduce the chance to corrode automotive cylinder. Ion-exchange resin was investigated to remove acids from fuel ethanol in this paper. Industrial resins, D301R, 330, 201×7, and D201, were selected as candidates, and a series of experiments were carried out to determine which one is the best. Acetic acid was employed as a simulated compound in these experiments for it is the main residual acid in fuel ethanol product. The results showed that the 330 resin was the most effective one to remove acid from fuel ethanol, and then, both static and dynamic experiments were carried out to evaluate the performance of the 330 resin. It was found that equilibrium data can be well described by Langmuir isotherm during the temperature range from 25 to 35 °C. The kinetic data fitted well with the pseudo-second-order kinetic model. Furthermore, a bench scale fixed bed was set up to determine the optimal adsorption and regeneration conditions. When the initial concentration of acetic acid solution was 200 mg/L, the optimum operating conditions were as follows: A flux of 6.37 BV/h at a temperature of 30 °C. The optimum regeneration conditions were determined as follows: A 4% solution of sodium hydroxide, flux was 3.18 BV/h, and the temperature was 30 °C. A refined product with acidity under 56 mg/L was obtained under optimal operating conditions. At last, industrial fuel ethanol was used to test the selected resin and the established process conditions. No obvious difference was observed after five adsorption and regeneration cycles. Therefore, it can be concluded that the ion-exchange method would be a successful industrial process to remove acids from fuel ethanol.

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