Experiments On The Effect Of The Microwave Field On The Extraction Of The Active Ingredients From Medicinal Plants And Membrane Ultrafiltration

To discuss the enhancement mechanism of microwave on mass transfer of medicinal materials extraction, representative medicinal plants, Astragalus and Angelica were chosen as research object, water as solvent. The special heating characteristics of microwave, combining micro-structure of medicinal plants and the extract components of Chinese medicine were investigated in this paper. The molecular weight distribution characters of water extract, the micro-structure of medicinal materials and Angelica Polysaccharide content and the change of its molecular weight distribution characteristic were discussed. Also, the effect of microwave field on the process ultrafiltration of Astragalus water extraction using Polyethersulfone Membrane was discussed.The main work and results are as follows:1. Compare the characteristics of molecular weight distribution of Angelica extracting solution by microwave assisted extraction (MAE) and traditional refluxing extraction (TRE) and the results show that substances less than 2000 Dalton obtained by microwave methods with 15 minutes is 2.33 times more than that of TRE with 30 minutes, and it's 4.91 times of substances less than 10000 Dalton. Substances less than 2000 Dalton obtained by MAE with 60 minutes is 4.82 times more than that of TRE with 90 minutes, and it's 7.74 times of substances less than 10000 Dalton. It can be shown that the extraction efficiency of MAE is higher than that TRE. Microwave can reduce extraction time and increase extraction ratio, which have significant meanings to the research and development of Chinese traditional medicine modernization.2. Concerning the extraction of Angelica amylose, MAE is superior to the TRE. The Angelica amylose obtained by MAE methods with 600W, 20 minutes is 2.48 times more than that of TRE with 60 minutes. With the increase of microwave power from 200w to 900w level, the percentage composition of Angelica amylose with molecular weight 140000 to 0.45μm reduced from 58.97﹪to 37.72﹪, Angelica amylose with molecular weight 6000～70000 increase from 16.66﹪to 32.22﹪, Angelica amylose with molecular weight smaller than 6000 increase from 24.36﹪to 30.06﹪. Angelica amylose with large molecular weight can break down into amylose with smaller molecular weight, which is benefit to the extraction of amylose.3. After radiation 30 minutes under microwave field, the membrane flux down to 30.29﹪of original value, while without microwave field, the membrane flux is down to 57.36﹪of original value. Under the same driving pressure, the influence of temperature of the extraction is small. Microwave slow up descend of membrane flux and boost up the ultrafiltraction performance. The colloid substances on ultrafiltration membrane in microwave field reduced obviously, which indicate that microwave can boost up ultrafiltraction performance by weakening concentration polarization.