Extraction Mechanism In Synergetic Action Of Ultrasonic Field And Electrostatic Field

Ultrasonic extraction (UE) is a mature technique that is applied to extraction andseparation of natural ingredients and the active ingredient of herbal medicine in recent years,which gets more and more recognition. Ultrasonic cavitation and multi-level effect of theultrasonic wave generated by mechanical vibration, micro-jet, micro-acoustic streaming, candestroy the cell wall of the extract so that the effective material is prone to be extracted.Compared with traditional methods, UE has many advantages such as high extraction rate,short extraction time, low extraction temperature, energy saving and environmental protectionand so on. But the power intensity is dominated by the number of the ultrasonic probe in theexisting UE device, which is difficult to achieve the desired efficiency.In this dissertation, ultrasonic synergistic electrostatic field extract the glycyrrhizic acidfrom licorice, and the influence factors and the strengthening effect were investigated in detail,then their technical parameters were optimized, finally investigate the synergistic mechanismof the ultrasound and electrostatic field. The conclusions were as follows.Many factors exerted influence on USE of the glycyrrhizic acid from licorice, such assoaking time, the solvent soled-liquid ratio, ultrasonic power, ultrasonic frequency, extractiontime. In contrast, the extraction yield (EY) was less affected by the immersion time; The EYof the glycyrrhizic acid was helpful improved with the increasing amount of solvent, theproper going-up ultrasonic power; The EY was in the trend of earlier increasing and laterdescending with the increasing of ultrasonic time; Within a certain range, the EY was dropwith the ultrasonic frequency increases. Join the electrostatic field, the EY of glycyrrhizic acidhad improved significantly, which indicated that the electrostatic field has a catalytic role, andthere was a certain interaction between the electrostatic field and the ultrasonic field; The EYwas in the trend of earlier increasing and later descending with the static voltage increases.There was a critical value, in which the EY of glycyrrhizic acid was maximum.There was a synergistic effect between ultrasound and electrostatic field, and the EY wassignificantly improved after the introduction of the electrostatic field. The fognificance ofthese factors affecting EY was on the following order: the ratio of solid-liquid>ultrasonicpower>extraction time>static voltage. The optimal conditions for the EY of glycyrrhizic acidwere determined using the surface response method to be: the solid-liquid ratio30mL/g,extraction time28.92min, the ultrasonic power100W, the static voltage9.01kV, the predictedand experimental values of the EY of glycyrrhizic acid were11.01788%and11.01788%. Bythe Design-Expert software, quadratic polynomial regression model was derived. It further verified interaction by studying of the co-effect of ultrasound and electrostaticfield on the electrical conductivity of water. Their co-effect mechanism was discussed afterexploring the independent action of ultrasound and electrostatic field, and the conclusionswere: after the introduction of the electrostatic field in the ultrasound field, the collapse timeof cavitation bubble can be shortened, increasing the role of the ultrasonic frequency range,producing more transient cavitation, increasing the yield of the cavitation. The same time, theoriginal spherical cavitation bubble becomed ellipsoidal, and radius of bubble decreased, andpart of the steady-state cavitation was converted to transient cavitation. Due to the existenceof the electrostatic field, the solution would produce a certain micro-interference, so the largediameter bubbles of solution increased. Perturbation give the original ultrasonic field in ametastable to impose an randomly additional sound pressure, making cavitation nucleus in themetastable into the transient cavitation nucleus, which increased cacitation effect.