Enhanced separation of chlorogenic and gallic acids extracted from spent coffee grounds using a three-zone simulated moving bed process with partial feed and partial collection strategies

BACKGROUND Spent coffee grounds, a valuable source of phenolic compounds, are considered beneficial for human health because of their antioxidative properties. The liquid extract containing phenolic compounds (such as chlorogenic and gallic acids) can be obtained via extraction using environmentally friendly organic solvent. The separation of chlorogenic and gallic acids from the liquid extract was carried out using isocratic chromatography technique in a three-zone simulated moving bed (SMB). However, due to the low selectivity of separation, the productivity of three-zone SMB was sacrificed to meet the purity criteria. Hence this work aimed to enhance the productivity of three-zone SMB for the separation of chlorogenic and gallic acids via model simulation using partial feed operation and to improve the concentration of extract and raffinate products using partial collection strategy. RESULTS The full feed scenario was designed based on the triangle theory, and the partial feed patterns (initial feed, middle feed and late feed) were implemented for each operating point in the triangle diagram to investigate the possibility of increasing the feed flow rate. The maximum productivity was evaluated based on the purity criteria (>= 98%) for both extract and raffinate products. Under optimal conditions, productivity was doubled to 0.24 mg min(-1) L-1 for both middle feed and late feed patterns compared to that of the full feed scenario. The partial collection strategy applied to the optimal point for each operational mode significantly increased the raffinate concentration to approximately 0.02 g L-1 at the optimal time fraction for discarding the solvent. CONCLUSION This work could be a foundation for the valorization of spent coffee ground. (c) 2021 Society of Chemical Industry (SCI).

Automated summary

This study aimed to enhance the productivity of three-zone SMB for the separation of chlorogenic and gallic acids through model simulation and partial feed operation. The partial collection strategy significantly increased the concentration of raffinate products, showing potential for the valorization of spent coffee grounds.