Effective separation methods must be developed to generate fractions of similar polarity and to concentrate the undistillable compounds before bio-oils are to be a source of chemicals production. Phase separation is one effective pathway to realize initial separation of bio-oil. By adding a little salt (3 wt % of bio-oil) or aqueous salt solution (10 wt % of bio-oil) including LiCl, CaCl2, FeCl3, (NH4)SO4, K2CO3, and Fe(NO3)3, the pyrolysis bio-oil of rice husk would quickly form two phases (40−80 wt % of the upper phase, 20−60 wt % of the bottom phase). On the basis of elemental analysis, 13C NMR integrations and GC/MS analysis, it has been demonstrated that some major components in the bio-oil are concentrated in upper/bottom phases respectively. The upper layers exhibit high contents of water, acetic acid, and water-soluble compounds; low density, viscosity, and calorific values; and high distillable substances (up to 65%). The bottom layer consists of low water content, high lignin-pyrolysis compounds, and low distillable substances (<10%), with high viscosity and calorific values. The physiochemical properties of two phases from the phase separation depend on the nature and dosage of salt added.
Injectable and degradable PEG hydrogel was prepared via Michael-type addition between cross-linking monomer 4-arm-PEG-MAL and two cross-linkers of hydrolysis degradable PEG-diester-dithiol and non-degradable PEG-dithiol, and it had a porous structure with the uniform pore size. The biocompatibility assays in vitro indicated that PEG hydrogel had excellent biocompatibility and can be degraded naturally without leading to any negative impact on cells. The results of antibacterial experiments showed that PEG hydrogel can inhibit the growth of bacteria. Furthermore, the Cell Counting Kit-8 (CCK-8) assay, LIVE/DEAD cell staining, and scratch healing experiments proved that PEG hydrogel can promote cell proliferation and migration, which had been further confirmed in in vivo experiments on the rat wound models. All experimental results demonstrated that PEG hydrogel is an injectable antibacterial dressing, which can promote the process of wound healing and has great potential in the field of wound healing.
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