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Cellulose extraction accounts for 70% of the total production cost required for the preparation of micro/nano cellulose. Conventional pretreatment methods cause equipment corrosion and generate non-recyclable waste liquids. Thus the industrial-scale preparation of micro/nano cellulose is limited. To overcome this limitation, herein, a method is proposed, where in a mild alkaline pretreatment is combined with the micro-nano bubble (MNB) treatment, for the extraction of cellulose from bagasse. A delignification rate of >92% was attained, micro/nano cellulose was exposed on the pulp surface owing to the MNB treatment; the 4-h MNB treatment resulted in the complete exposure of micro/nano fibers. The production cost for this process was only 3.19 USD/kg CNFs, about 70.9 times lower than that for TEMPO oxidation. An appropriate MNB treatment time (1 h, 2 h) allowed the retention of moderate micro-fibers, which enhanced the maximum tensile force and tensile strength of micro/nano cellulose paper by about 50%. The results revealed that the proposed method serves as an efficient, green, and sustainable strategy for the large-scale and low-cost production of micro/nano cellulose.

Ca 2+ transfer in the carbonation system of CO 2 -NH 4 OH-CaSO 4 ·2H 2 O-CaCO 3 is a complex multiphase mass transfer and reaction process. In this study, a kinetic model involving C O 3 2 - formation, CaSO 4 ·2H 2 O dissolution, and CaCO 3 crystallization was designed to describe the transfer. A gypsum disk was adopted as a raw material for dissolution, and Ca 2+ concentration was measured to determine the unknown kinetic parameters. The model was experimentally validated in a semibatch stirred reactor. A multistep transfer route from Ca 2+ to CaCO 3 via NH 2 COO − and C a C O 3 0 ion pair intermediates was described and divided into two parts by a ratio λ , which was defined as the relative net accumulated rate between total dissolved calcium and carbon. When λ > 0, NH 2 COO − hydrolysis controlled the transfer in the induction and nucleation periods. When λ 4 ·2H 2 O became dominant in the growth period. According to the rate-limiting steps, Ca 2+ transfer could be affected by the CO 2 flow rate and the impeller speed in different periods. Furthermore, as the impeller speed increased, the turbulence intensity was enhanced. As such, the nucleation rate was high, and the CaCO 3 particles were small.

A novel Corrugated Falling-Film Channel was developed in this work for application to industrial dust removal. Its pressure drop, inertial capture pattern, and grade capture efficiency were evaluated by simulation and experiments. The different inertial capture patterns were investigated on the windward side and leeward side by calculating aerosol particle trajectories, which show the particles captured on the leeward side get into the vortex first and then captured by the leeward wall with a certain probability. With the increase of particle diameter, the capture efficiency on the windward side increases gradually. However, the capture efficiency on the leeward side increases at first, then decreases to 0 due to the large size particle being too hard to be caught by the vortex. The increase of inlet gas Reynolds number will result in higher capture efficiency. The increase ratio of capture efficiency on the leeward side is higher when particles smaller than 9 μm, while on the windward side it is higher when particles size over 9 μm. Based on the simulation results, a new capture efficiency model was established and verified with experimental data.