Experimental extraction of gallic acid from brown sumac seed (Rhus coriaria) using supercritical carbon dioxide and ethanol as co-solvent: Modeling and optimization

In this paper, the extraction of gallic acid (GA) from brown sumac seeds was evaluated using supercritical-CO2 (SC-CO2) fluid and ethanol as the co-solvent, as well as Soxhlet method. Response surface methodology (RSM) design and optimize the experiments with second order model with the adjusted coefficient of determination (adj. R2) of 95.7%. Then, the supercritical fluid extraction (SFE) process was modeled based on differential mass balances and the shrinking core model. To determine the equilibrium coefficient, four thermodynamic equations were used. Based on the results, the optimal temperature, pressure, CO2 flow rate and dynamic time were obtained as 35 degrees C, 30 MPa, 1.64 ml/min and 127.08 min, which resulted in 50.54% recovery (w/w), respectively. The mentioned mathematical model appropriately predicted the behavior of the process. Accordingly, the results obtained from thermodynamic equation of Peng-Robinson cubic plus association (PR-CPA) with adj. R2 of 93.12%, showed the highest accuracy.

Automated summary

This study evaluated the extraction of gallic acid from brown sumac seeds using supercritical-CO2 fluid and ethanol. Response surface methodology was employed to design and optimize experiments, resulting in a mathematical model that predicted the behavior of the extraction process. Thermodynamic equations were used to determine the optimal operating conditions.