Study On Extraction Of Kumquat Essential Oil By Subcritical 1,1,1,2-tetrafluoroethane And Its Dissolved Phase Equilibrium

Kumquat essential oil is a high value-added natural extract with anti-oxidation activity,antibacterial and anti-toxicity,anti-inflammatory analgesic activity and anti-tumor effects,which has a good application prospect in the field of medicine.As a green chemical technology,subcritical and supercritical fluid extraction technology has many advantages in the field of natural product extraction.1,1,1,2-Tetrafluoroethane(R134a)has a low critical pressure(4.06 MPa)and other excellent physical properties,which has excellent dissolving capacity in subcritical state.Therefore,R134a is preferred as an extractant for the sub(super)-critical fluid extraction process.At present,the phase equilibrium data and extraction process of subcritical R134a and kumquat essential oil system have not been found.Therefore,the phase equilibrium data of the system are determined experimentally,and the process of extracting kumquat essential oil by subcritical R134a is studied.In this work,D-limonene,the main component of Kumquat essential oil,was selected as the solute.The solubility data of D-limonene in subcritical R134a was measured by dynamic method at temperature between 308 K and 328 K and pressure from 6.0 MPa to 16.0 MPa.The influence of temperature and pressure on the solubility of solute was discussed.Eight semi-empirical models(Chrastil,K-J,Bartle,M-S-T,V-A,Tang,S-S and A-L)were selected to correlate solubility experimental data.The average absolute relative deviation(AARD)was used to evaluate the correlation accuracy of each model.In addition,based on the association theory and the phase equilibrium principle,a phase equilibrium model for calculating the solubility of solutes in sub(super)-critical fluids is derived,and a total of 887 sets of solubility data are used to verify the calculation accuracy of the model.The process conditions of subcritical R134a extraction of kumquat essential oil were studied.The effect of extraction pressure(6.0 MPa-14.0 MPa),mesh number of raw materials(20 mesh-100 mesh),extraction time(20 min-100 min),extraction temperature(313 K-333 K)and R134a flow(0.75 L·min'1-2.00 L·min-1)on the extraction rate of kumquat essential oil were investigated.In addition,the five-factor and four-level orthogonal experiment was designed to investigate the effect of various factors on the extraction rate of kumquat essential oil,obtaining the optimal extraction conditions within the experimental conditions.The main components of kumquat essential oil were analyzed and identified by gas chromatography mass spectrometer(GC-MS)and eight main substances were identified.