A research on the purification of catechin from green tea waste with macroporous adsorption resins

In this study, the possibilities of purification of catechins with macroporous adsorption resins from green tea wastes obtained from Eastern Black Sea region were investigated. First, the adsorption and desorption characteristics of the 9 macroporous adsorption resins with different physicochemical properties were determined. Among these 9 different resins, the catechins in the extracts obtained from green tea wastes were adsorbed with resin NKA-2 with the highest adsorption capacity of 87.8 mg EGCG/g resin. Static and dynamic adsorption experiments were carried out with NKA-2 coded resin in later stages. It has been observed that NKA-2 coded resin has better adsorption characteristics of catechins through the macroporous adsorption resins. The reason of this is the better interaction between the polar NKA-2 coded resin and polar structured catechins in green tea wastes. Then, the adsorption isotherms were formed as a result of the experiments performed at different temperatures (25 °C, 35 °C and 45 °C) with the selected resin. At the same initial EGCG concentration, there was a decrease in the adsorption capacity of resin with increasing temperature. The adaptation of the adsorption isotherms formed in these three different temperatures to the Langmuir and Freundlich models was investigated and it was revealed that the Langmuir model could better explain the adsorption process. Dynamic adsorption and desorption experiments were carried out with NKA-2 coded resin and it was determined that desorption of 83% of the EGCG adsorbed in the first bed volume was possible with 70% ethanol. As a result, it has been determined that it is possible to purify catechins with macroporous adsorption resins from green tea wastes.