Separation And Purification Of Sapindus Saponin

Sapindus saponin is a natural surfactant and has many bioactivities such as antimicrobial, spermicidal, antiulcer, hepatoprotective, fungicidal and anti-inflammatory activity. However, there are few researches about separation and purification of sapindus saponin. In present work, the macroporous resin adsorption and foam fractionations were adopted to purify sapindus saponin. A main objective was to develop new efficient methods for scale-up separation of sapindus saponin for its wide pharmaceutical use.Batch adsorption experiments have been carried out to determine the adsorption thermodynamics and kinetics of sapindus saponin onto macroporous resins. It was found that AB-8 resin offered the highest adsorption capacity among three different resins of AB-8,HZ-816,S-8, and its saturated adsorption capacity reached 518mg·g-1 at 328K and the initial adsorption solution pH value of 4.5. Its adsorption equilibrium data consisted with Langmuir model very well at different temperatures. Adsorption enthalpy of sapindus saponin onto macroporous resin was 12.25kJ·mol-1, which implies that the.adsorption is a physisorption and endothermic process. The negative value of△G and the positive value of△S reveal that the adsorption is spontaneous. The adsorption kinetic data fitted best to the pseudo first-order equation, and intraparticle diffusion is the rate-determining step.The results of dynamic adsorption-desorption experiments revealed that the saturation adsorption capacity of sapindus saponin on AB-8 resin achieved 568 mg·g-1 when the crude sapindus saponin water extracts (pH4.5) through the glass column (ratio of height to diameter of resin column 5.4:1) at the velocity of flow of 1mL·min-1. The desorption parameters were as follows:95% ethanol aqueous solution for 1.5 batch volume at 1mL·min-1. The sapindus saponin content at the ultimate product was 93.60%, with a recovery yield of 83.48%. In addition, stability of AB-8 resin was fine and it was able to be reused for eight times.In a continuous foam fractionation column, the effects of various operation conditions, such as operation procedure, the dimension of bubble, pH value, and gas flow rate, liquid flow rate, feed concentration and heighten, etc. on separation of sapindus saponin were investigated. It was found that the distillation tower and big bubble size will be propitious to foam separation. The yield and purity of sapindus saponin increased with increasing the gas flow rate, feed concentration and heighten, while the enrichment ratio decreased. The proper operating conditions of foam separation process were determined with the orthogonal test. The result suggested when feed concentration of saponins is 20mg·L-1, pH value 4.50, gas flow rate 600mL·min-1, liquid flow rate 35mL·min-1, feed heighten 40cm, the enrichment rate, yield and purity of isolated sapindus saponin was 591.17, 23.64%,90.27%, respectively. In addition, a mass transfer mathematical model described the concentration distribution of the whole tower in the process of foam separation was established by analysis of the drainage and axial dispersion: h>hf:c/cD=1.7808×10-4+0.4808exp[0.0208(h-hf)] h