Valorization of Expired Energy Drinks by Designed and Integrated Ionic Liquid-Based Aqueous Biphasic Systems

Abstract

Expired energy drinks are rich in bioactive value-added compounds that can be recovered and reused in order to valorize food waste within a circular economy perspective. However, to accomplish such requirements, it is necessary to develop sustainable extraction and recovery processes, which must consist of decreasing the number of steps required or developing integrated strategies. In this work, novel aqueous biphasic systems (ABS) composed of ionic liquids (ILs) and a biocompatible polymer polypropylene glycol (400 g·mol–1, PPG 400) were studied for the simultaneous extraction and recovery of three value-added compounds, namely, caffeine, taurine, and niacin, from expired energy drinks. ILs were designed and synthesized in order to have similar anions to the target compounds, thus allowing enhanced selectivity and biological activity, while avoiding an extra step of separation of these high-value compounds from the IL-rich phase. To this end, cholinium-based ILs comprising the anions lactate, pyruvate, taurate, and nicotinate were synthesized, and their cytotoxicity and ecotoxicity credentials were evaluated. Overall, taurine and niacin are majorly enriched in the IL-rich phase, while caffeine preferentially migrates in the majority of the cases toward the PPG-rich phase. However, caffeine also partitions to the IL-rich phase in the ABS formed by cholinium pyruvate or cholinium nicotinate. The ABS formed by cholinium nicotinate and PPG 400 is the best system identified, allowing the almost complete recovery (recovery efficiencies > 82%) of all target compounds into the IL-rich phase in one step. Furthermore, cholinium nicotinate exhibits marginal cytotoxic potential and is harmless from an ecotoxicological point of view. This system is thus a promising platform to simultaneously extract, recover, and reuse value-added compounds from expired energy drinks without the need of removing the IL or recovering the target compounds from the IL-rich phase, thus contributing to a sustainable and circular food economy.

Application of Ionic Liquids for Chemical Demulsification: A Review

“…Ionic liquids were first introduced by Paul Walden in 1914 when he discovered a special chemical-ethyl ammonium nitrate ([EtNH 3 ] [NO 3 ]) with a melting point of 12 °C [ 52 ]. Ionic liquids have been widely used in different fields like pharmaceutical, oil and gas, and chemical industries [ 53 , 54 , 55 , 56 , 57 , 58 ], such as in pharmaceutical products manufacturing [ 59 , 60 , 61 , 62 ], viscosity modifiers [ 63 ], desulfurization of liquid fuels [ 64 ], and liquid-liquid extraction [ 65 , 66 , 67 ]. Several types of ionic liquids, such as polymeric ionic liquids [ 68 , 69 , 70 ], double salt ionic liquids [ 71 ], dicationic ionic liquids [ 72 , 73 , 74 , 75 ], deep eutectic solvents [ 76 , 77 , 78 , 79 ], chiral ionic liquids [ 80 ], and solvate ionic liquids [ 81 , 82 ], have been synthesized for different aforementioned purposes.…”

Green Extraction Strategy Using Bio-Based Aqueous Biphasic Systems for Polyphenol Valorization from Grape By-Product

“…In the scientific literature, ILs are frequently designated as environmentally friendly alternatives to toxic organic solvents due to their stability and low vapor pressure, leading to a generalization of their benign nature [ 26 , 27 ]. In addition, it is well documented that ILs synthesized from carefully selected, safe, naturally-derived materials can be environmentally benign with enhanced biodegradability and biocompatibility [ 28 , 29 , 30 ]. Such ILs can be based on low-cost and non-toxic cations, thus opening doors for their application in bioactive molecule extraction and even their further preservation [ 31 , 32 ].…”

“…IL-ABSs can be applied in both the extraction and purification steps of high-value compounds from food waste. Moreover, through the wise selection of the phase-forming components and their compositions, IL-ABSs may be biocompatible, efficient, and low-cost [ 30 , 35 ]. Briefly, IL-ABSs consist of two aqueous-rich phases formed by mixing aqueous solutions of ionic liquid and a polymer or salt at appropriate concentrations [ 36 ].…”

“…Briefly, IL-ABSs consist of two aqueous-rich phases formed by mixing aqueous solutions of ionic liquid and a polymer or salt at appropriate concentrations [ 36 ]. Recent investigations have demonstrated that ILs with cholinium cations paired with appropriate anions present outstanding biodegradable and low-toxicity properties [ 30 , 37 ]. Moreover, some cholinium ILs possess a remarkable biomass dissolution ability and cellular disruption potential, which could be crucial assets in designing extraction platforms for polyphenol recovery [ 33 ].…”

Liquid–Liquid Extraction of Some Biomolecules in the ATPS {Ethyl Lactate (1) + Sodium Potassium Tartrate (2) + Water (3)} at 298.15 K and 0.1 MPa

“…Aqueous two-phase systems (ATPS), or aqueous biphasic systems (ABS), have been gaining relevance in the extraction of biomolecules such as proteins, – vitamins, – and lipids. – These ternary systems are constituted by water-soluble components, which become immiscible by the action of a salting out agent (such as a salt or a polymer), which is preferentially solvated by water. The classical combinations of components for ATPS include {polymer + salt + water}, {polymer + polymer + water}, and {solvent + salt + water}, but the most useful for the extraction of biomolecules is {solvent + organic salt + water} since this alternative allows for an easier separation of biomolecules from the solvents.…”