Tuneable solvents‐based extraction for the recovery of caffeine from coffee wastewater

Abstract

Tunable solvents represent a new generation of environmentally friendly solvents with potential applications in the effective extraction of bioactive compounds, including supramolecular solvents (SUPRAS). This study aimed to optimize caffeine extraction from coffee processing wastewater (CWW) using SUPRAS of various compositions. An extreme vertices design was employed to evaluate the SUPRAS composition. The synthesis of SUPRAS involved two amphiphiles (1‐hexanol and decanoic acid) in hydro‐organic solutions of tetrahydrofuran (THF). A statistical modeling approach was used to characterize the process and determine the optimal conditions for potential scale‐up within the coffee processing industry. The results indicated that SUPRAS offer a promising alternative to traditional solvents for extracting caffeine from CWW. The highest experimental extraction rate (~ 62%) was achieved using a 15% 1‐hexanol in a hydro‐organic solution of THF (47% v/v). This mixture corresponded to the optimum predicted by a special cubic statistical model (R2 = 0.9367; Adj‐R2 = 0.8608, and RSME = 3.2795). The percentage of caffeine extracted from CWW is considered acceptable, given the compound's affinity for water and the rapid (1 min) and straightforward approach employed. Moreover, the use of SUPRAS reduced solvent consumption, and the proposed statistical model identified conditions that maximized caffeine extraction while minimizing THF usage. This method can potentially lower process costs and solvent consumption. For large‐scale extraction, centrifugation can be substituted with spontaneous sedimentation. Overall, these findings have significant implications for the valorization of CWW, providing a sustainable and efficient method for the extraction of valuable compounds.