The Design of Three-Zone Simulated Moving Bed Process for the Separation of Chlorogenic and Gallic Acids Extracted from Spent Coffee Grounds

Abstract

Spent coffee grounds (SCG) are the agricultural waste generally eliminated by discarding or burning. It contains phenolic compounds with antioxidant properties (such as chlorogenic acid and gallic acid, etc.), which are beneficial in foods, cosmetics and pharmaceuticals. Apart from extraction, the purification of targeted antioxidative substances from the liquid extract is essential. This research presents the separation of chlorogenic and gallic acids using the three-zone simulated moving bed, which is based on the principle of liquid chromatography. Preliminary, SCG were extracted to assess the content of chlorogenic acid and gallic acid. After that, the adsorption behavior of both substances (chlorogenic acid and gallic acid) in a single chromatographic C18 column was studied. The suitable mobile phase was a mixture of acetonitrile, water, and acetic acid (80:20:1). The model simulation was carried out in the mono-component system to determine the adsorption parameters. Breakthrough curve experiments for a binary mixture were performed to validate the predetermined parameters. Then, a three-zone SMB was designed and the model simulation was used to optimize the operating conditions via response surface methodology based on purity and productivity. At the optimal conditions, the purity of chlorogenic acid and gallic acid were 99.27% and 98.43%, respectively.