Efficient CO 2 capture by chemical absorption is currently gaining interests for the control greenhouse gas emissions. In this work, a nonaqueous process was developed to regenerate CO 2 below 373 K by removing methanol first after the hybrid solvent of monoethanolamine (MEA) and methanol had absorbed CO 2 . A model was accordingly developed to analyze the performance of the desorption process. Experiments were performed to determine the missing reaction kinetics of nonaqueous solvent regeneration of CO 2 to help develop the model. The predicted gas concentration, axial velocity, energy consumption, and desorption efficiency agreed well with the stripper experimental data. A parametric analysis was conducted to investigate the effects of temperature, pressure, lean solvent loading, gas/liquid ratio, packing, and internals on the energy consumption and desorption efficiency. All analyses were performed under three defined desorption conditions: N 2 , methanol vapor, and steam as purge gases. Major energy savings were clearly identified because of feasible desorption temperatures below 373 K under nonaqueous desorption conditions. N 2 purge gas desorption conditions offered the minimum energy consumption of 2.28 GJ/t, being 24% below the typical value of 3.0 GJ/t. Additionally, it was found that the nonaqueous environment improved the desorption efficiency by 10% compared to that obtained by typical aqueous solution regeneration.

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Sodium fluoride-loaded gelatin microspheres (NaF-GMS) were prepared using double-phase emulsified condensation polymerization. The average diameter of microspheres was (11.33+/-5.56) microm. The drug content and encapsulation efficiency were 8.80% and 76.73%, respectively. The fluoride releasing profiles of NaF-GMS in physiological saline and artificial saliva (pH 4.5, pH 6.8) showed that NaF-GMS had a sustained-release property and fluoride release rate was increased in pH 4.5 artificial saliva. Experiments conducted in rabbits' oral cavity using NaF-GMS and NaF solution as control revealed NaF-GMS could maintain oral fluoride retention longer than NaF solution. Cariostatic abilities of NaF-GMS including demineralization prohibition in vitro, fluoride deposition in artificial dental plaque and the ability of targeting to cariogenic bacteria were investigated in artificial dental plaque. The results indicated NaF-GMS with lower fluoride concentrations could achieve equivalent cariostatic effect to the concentrated NaF solution, at the same time, could prolong fluoride retention in dental plaque. Microscopic observation showed that NaF-GMS carrying fusion protein of glucan-binding domain could adhere more bacteria than NaF-GMS and this might indicate the possibility of targeting to cariogenic bacteria when NaF-GMS were properly modified.

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