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Simultaneous steam explosion and alkaline depolymerization was studied to develop an economic and green process for alkaline pretreatment of lignocellulose. Steam explosion facilitated alkaline delignification and decreased the amount of alkali used during pretreatment. Different amounts of lignin and hemicellulose were removed within 5 min by using different sodium hydroxide concentrations and steam explosion severity. The main component of lignin collected using our simultaneous process was acid-insoluble lignin, reaching a purity of 84 %. Structural analysis indicated that steam explosion and sodium hydroxide had a synergistic effect on the removal of lignin and hemicellulose from corncob. The effect to four simultaneous pretreatment process of delignification transformed cellulose I to cellulose II, enhancing the enzymatic conversion of cellulose to glucose from 22 % to 96 %. The process of simultaneous steam explosion and alkaline depolymerization shows a potential for application in the lignocellulose biorefinery. [ABSTRACT FROM AUTHOR]

A three-dimensional (3D) Euler-Euler gas-liquid two-phase mathematical model was developed for simulating the local transient fluid flow in a gas-induced pulsating flow bubble column using computational fluid dynamic (CFD) method, with multiple size group (MUSIG) model implemented to predict the bubble size distribution. Model simulated results such as local transient axial liquid velocities and time-averaged liquid turbulent kinetic energy distributions were validated successfully by corresponding experimental measurements under varied operating conditions, i.e. pulsating amplitudes and frequencies. It was found that the liquid turbulent kinetic energy increased with the increase in pulsating amplitude and frequency, and a maximum value appeared at an axial position of Z = 0.4 m, centerline of the column. Furthermore, local transient fluid flow characters such as the gas holdups, gas velocity fields and liquid velocity fields, as well as bubble size distributions were predicted reasonably by the proposed model. [ABSTRACT FROM AUTHOR]

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