Isolation of (+)-Catechin from Food Waste Using Ionic Liquid-Modified ZIF67 Covered Silica

Background: Food waste contains abundant (+)-catechin, but its efficient recovery remains challenging. This study aimed to prepare ionic liquid (IL)-modified sorbents and establish an efficient method for (+)-catechin recovery from chocolate waste via solid-phase extraction (SPE). Methods: Three series of IL-modified sorbents (Sil-IL, ZIF67-IL, Sil@ZIF67-IL) were synthesized. Their adsorption performance was evaluated under different conditions; adsorption isotherm and kinetic data were fitted to Langmuir/Freundlich and pseudo-first/second-order models, respectively. Sorbent stability and (+)-catechin recovery from chocolate waste extracts were tested. Results: Sil@ZIF67-Hmim showed the highest adsorption capacity (154.4 mg/g) at 25 °C within 120 min. Adsorption followed the Langmuir model (R2 = 0.99), indicating chemisorption. Sil@ZIF67-Hmim was subjected to repeated solid-phase extraction (SPE) for five consecutive days; the recovery rate ranged from 98.1% to 99.2%, and the relative standard deviation (RSD) was 3.2–4.4%. Conclusions: Sil@ZIF67-Hmim is a high-efficiency sorbent for (+)-catechin recovery from chocolate waste, providing a novel approach for food waste valorization and highlighting the application potential of IL-modified MOF-silica composites.