Views: 0 Author: Site Editor Publish Time: 2023-08-23 Origin: Site
The reaction system has an obvious thermal effect. The thermal analysis of the components of the material has confirmed that this is due to the violent thermal decomposition of the components. Based on the extraction rate, product characteristics and extraction mechanism of the material, a sub-supercritical system of the material was constructed. Extraction process model, the physical dissolution of low molecular substances in the material is carried out at less than 12o°C.
Extraction experiment The semi-continuous non-isothermal dynamic extraction experiment of wood was carried out on a solid material supercritical fluid extraction device made in Germany. The entire device can be divided into three parts: solvent supply system, material extraction system and product processing system. Wood in the extraction solution Cable content was determined using 205nfl UV spectrophotometry.
Thermal analysis experiments of wood and its components were carried out on a PCT-1 differential thermal balance (manufactured by Beijing Optical Instrument Factory). The heating rate was 10C/rain, the sample mass was about 5nag, and the atmosphere was still air.
Thermal Effect of the Extraction Process This experiment was completed on a solid material supercritical fluid extraction device manufactured in Germany. During the experiment, non-isothermal technology was used, the heating rate was kept constant, and it had a good temperature control system. However, during the experiment, it was found that In the 320-360℃ region, the heating rate is not very stable, and sometimes it is not easy to control at all. There is an abnormal phenomenon of rapid temperature rise and slow fall back. This shows that in this temperature range, the reaction system has obvious thermal effects.
For anhydrous ethanol extraction, the exothermic peak temperature is 355-359°C. As the pressure increases, the duration tends to shorten. When extracting with water-containing ethanol, the exothermic peak temperature moves forward. For example, when the mole fraction of water is 0.22 When, the exothermic peak temperature is 340°C; when the mole fraction of water is 0.39, the exothermic peak temperature is 306°C, and the duration is also shortened. From this, it seems to be inferred that high pressure and adding water can suppress the exotherm. In addition, the exothermic peak temperature is 306°C. When thermal phenomena occur, both the extract production rate and the gas production rate appear to have corresponding maximum values.
The above experimental phenomena can be scientifically and reasonably explained by the differential scanning calorimetry (osc) analysis results of wood. Wood has a heat flow peak in the range of 214-415qC, the thermal effect value is 5.2kJ/g, and the maximum heat flow temperature is 341qC. During wood extraction, The thermal bee temperature is 340359qC, which is quite consistent with the DSC analysis data of wood. It can be seen that wood and its various components almost all have obvious exothermic effects in the 300-360qC region, which is consistent with the Dsc curve of wood in a still air atmosphere.
