Charcoal adsorption of phenolic compounds present in distilled grape pomace

Charcoal adsorption of phenolic compounds with antioxidant activity from distilled grape pomace pressing liquors (DPPL) and distilled grape pomace autohydrolysis liquors (DPAL) was carried out under anoxic conditions using commercially available activated charcoals (AC) in powdered, granulated or pelletized form. The adsorption kinetics followed a pseudo-second order rate, and equilibrium was reached in less than 15 h. The Langmuir and Freundlich model have been used to describe the equilibrium adsorption data. The maximum adsorption capacity was 239.4 mg/g AC. Fixed-bed adsorption and desorption experiments were carried out to assess the recovery and fractionation of products from exhausted AC beds and the AC susceptibility to regeneration. Recovery yields up to 20% were achieved in experiments with 96% ethanol, but neither the purity nor the antioxidant activity of the eluted fractions was affected. Five successive adsorption–desorption cycles with DPPL were performed without loss of adsorption capacity.