Percorrer por autor "Marques, Rafael Alves"
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- Choline-based ionic liquids as mass separation agents in the fractionation of terpene mixturesPublication . Marques, Rafael Alves; Martins, Mónia; Zuber, AndréEssential oils (EOs) are valuable natural products widely used in food, cosmetic, pharmaceutical, and fragrance applications. Their processing is often limited by the challenging separation of chemically similar compounds, while conventional fractionation methods are typically energy-intensive and rely on volatile organic solvents. These limitations have motivated the search for sustainable alternatives based on green chemistry principles. In this context, this work investigates the potential of choline-based biocompatible ionic liquids (ILs) as innovative separation agents, focusing on the fractionation of the representative limonene/linalool binary mixture found in citrus essential oils. The activity coefficients at infinite dilution (𝛾𝑖∞), of 38 organic solutes in choline acetate (ChOAc) were determined by inverse gas chromatography (IGC) over the temperature range of 373.15 – 393.15 K. The experimental data were used to evaluate thermodynamic functions at infinite dilution and to estimate selectivity, capacity, and solvent performance indices for the separation of terpene and terpenoid mixtures. ChOAc exhibited a strong affinity for oxygenated terpenoids and a negligible affinity for terpene hydrocarbons, resulting in high selectivities, including values above 20 for the limonene/linalool system. The thermodynamic analysis revealed that the separation mechanism is governed by unfavorable enthalpic and entropic contributions for terpene hydrocarbons, whereas oxygenated terpenoids benefit from more favorable interactions with the IL. Conductor-like Screening Model for Real Solvents (COSMO-RS) model correctly reproduced the experimental performance trends, although quantitative deviations were observed. Overall, the results demonstrate that choline acetate is a promising and sustainable separation agent for the fractionation and valorization of essential oils, supporting the development of greener processing technologies for the citrus industry.