The Study On The Producing Tea Polyphenols And Caffeine By 2-Stage Resin Pocess

In this paper, ultrafiltration process of tea extract, 2-Stepwise elution chromatography with macroporous adsorbent resin are studied to separate tea polyphenols (Tp) and caffeine. The 2mol.L-1 α acid eluted aqua and caffeine are recovered with the second stage macroporous adsorbent resin. A new process for producing TP and caffeine using ultrafiltration-two-stage-resin adsorption chromatography united process is developed, it proved to be simple, feasible, nontoxic, no pollution produced, safe, environmental benign.For the tea extract, ultrafiltration pilot unit is used to refine it. The experiment proved that ultrafiltration could prevent resin from being polluted and enhance the content of TP for 8.14%.Through experiments of adsorption, the optimal process is determined that caffeine and TP are 2-Stepwise chromatography eluted by 2molL-1 α acid and 85% alcohol aqua with XAD-7 resin. The feasibility of eluting caffeine using a acid and the performance of its elution are studied. The new analytic methods of Tp and caffeine in acidic condition are found. Adsorption mass transfer model for Tp with XAD-7 resin is also set up, the height of mass tranfer zone and total mass transfer coefficient in different operation conditions are calculated, which can provide important reference to the design of absorber.For the 2mol.L-1 α acid eluted aqua produced in the Stepwise chromatography using the first stage resin, the process of recovering a acid eluted aqua and caffeine with XDA macroporous adsorbent resin are studied.The content of Tp and caffeine of TP product are 94.42% and 3.19% respectively, the productivity of TP product reach 13%. The purity of by-product of caffeine is 46.24%, it can be refine by crystallization or sublimation.