Valorization of expired energy drinks by 1 designed and integrated ionic-liquid-based 2 aqueous biphasic systems

19 Expired energy drinks


INTRODUCTION
In developed countries an increasing amount of food is not consumed and ends up as waste along the food value chain, creating a relevant economic and environmental problem. 1 As disclosed by the Food and Agriculture Organization of the United Nations (FAO), one third of the food produced worldwide for human consumption (1.3 billion tonnes per year) is lost or wasted. 2 In the European Union, for instance, food waste is projected to rise to 126 million tons by 2020. 1 Currently, food waste constitutes a relevant concern, being linked to negative economic, societal and environmental impacts. 3rdingly, the valorization of food waste is a priority measure to reduce the carbon footprint of the food production chain 4 and to improve economy as the residues generated may contain high-value compounds. 5In the framework of circular economy, these evidences reinforce the need on the development of cost-effective and sustainable technologies to recover added-value compounds from food waste.Among food waste, energy drinks, particularly rich in stimulants and additives, play a significant role.These beverages contain high levels of caffeine (up to 500 mg per bottle) and are usually supplemented with taurine, glucuronolactone, and complex B vitamins. 6 of these high-value compounds maintain their biological activity, even after the expiration dates of energy drinks.In addition to the environmental concerns generated by this type of drinks, their discharge indirectly has an economic impact by increasing their waste management and production costs.Thus, the recovery and reuse of added-value and bioactive compounds from discharged energy drinks has a relevant environmental and economic influence on this market sector that registered global sales over €38 billion in 2015, being expected to reach €53.4 billion in 2020. 7ral methods, including liquid-liquid extraction, 8 nanofiltration 9 and solid-phase extraction 10 have been reported for the recovery of target compounds from diet samples and beverages.In addition to the extraction step, separation and purification processes are needed, which may comprise numerous drawbacks, including high energy and chemicals consumption. 11,12 urthermore, most of these methods are time consuming, labour intensive and use volatile organic solvents, contributing to a relevant environmental impact.Overall, cost-efficient and sustainable techniques able to provide high recovery yields and purity levels of valuable compounds recovered from food waste, ideally combining or integrating several steps, must be developed to meet the current society and environmental standards.
Aqueous biphasic systems (ABS) are downstream processing alternatives acting by liquid-liquid extraction, allowing to recover target products from complex samples. 13rdingly, this type of systems can be applied both in the extraction and purification steps of high-value compounds from food waste. 14Moreover, if properly designed, ABS may be biocompatible and of low cost. 15,16 ypical ABS consist of two immiscible aqueous-rich phases based on polymer/polymer, polymer/salt or salt/salt combinations.
In order to improve their separation performance, ABS formed by ionic liquids (ILs) have been extensively investigated. 15Besides other relevant properties, their fine-tuning by combining adequate IL cations and anions is one of the most significant. 15,17,18 I0][21] However, several concerns have been raised with the most studied ILs in this field, mainly imidazolium-based. 22,23 his trend is however changing, with novel classes of ILs being proposed for the creation of ABS. 19,21 mong these, cholinium-based ILs have been the main target since the IL cation is an important micronutrient source belonging to the B-complex vitamins, which may thus overcome the main drawback on the use of ILs in the food industry 24 .Cholinium chloride ([Ch]Cl) is currently classified as a safe substance by the U.S. Food and Drug Administration (FDA). 25Previous works reported the synthesis of cholinium-based ILs alongside with their toxicological and biodegradation potential, showing that when combined with appropriate anions, these ILs exhibit low toxicity and high biodegradability. 26][29] Some publications can be found in the literature regarding the use of IL-based ABS in the valorization of food waste; 25,27,30,31 yet, the majority of these works focused on ABS formed by imidazolium-based ILs and salts, thus compromising their green credentials, and none envisioned the use of ILs with similar biological features to enhance the biological properties of the recovered compounds, while avoiding the use of an additional step to recover the target compounds from the ILrich phase.The non-volatile nature of ILs, which is valuable when addressing it from an environmental perspective, is indeed a major drawback when attempting the recovery of target compounds from the IL-rich phase since a simple distillation step cannot be applied.Therefore, and although scarcely considered, the recovery of the target compounds from IL-rich phases has been achieved by the addition of anti-solvents, backextraction steps with organic solvents or by the use of solid-phase extraction. 32,33 g at developing a sustainable and cost-effective process for the recovery of addedvalue compounds (caffeine, taurine and niacin) from expired energy drinks, we here demonstrate the potential of ABS formed by cholinium-based ILs (4 synthesized ILs and 3 commercial ILs for comparison purposes) and polypropylene glycol with a molecular weight of 400 g.mol -1 (PPG 400) to directly extract the target compounds from the real samples.By being extracted to the IL-rich phase, and by using ILs with similar biological features, the additional separation step to recover the target compounds from the IL-rich phase can be avoided, and may result in an integrated process.The chemical structures and abbreviations of the investigated ILs are depicted in Figure 1.
The synthesized ILs comprise anions derived from natural sources, such as from plant natural acids (lactate and pyruvate), amino acids (taurate) and vitamins (nicotinate).These ILs were designed taking into account the target compounds to recover from expired energy drinks, which could have their biological properties enhanced if combined with IL anions with similar properties.Bearing in mind the potential reuse of the recovered compounds combined with adequate ILs, the ILs cytotoxicity towards human intestinal cell lines and their ecotoxicity by the microtox assay were evaluated.The recovery performance of the investigated ABS for caffeine (alkaloid), taurine (amino acid) and niacin (vitamin B3) from expired energy drinks was finally addressed.7][38][39]
The sample of energy drink (sugar free Red Bull®) was acquired from a local market in Aveiro (Portugal); it was used in all experiments with one month after the expiration date.

ABS phase diagrams and recovery studies.
4][45] Details regarding phase diagram determination are given in the Supporting Information.Initial tests to address the real samples effect in the binodal curves was carried out, with no significant differences (within the experimental error) obtained between the phase diagrams determined with water or with energy drink samples.This fact is due to the low amount of additives present when compared to the amounts of IL and PPG 400 required to create ABS.
After addressing the ABS phase diagrams and compositions required to create two-phase systems, their recovery capability for the three biomolecules from expired drinks was evaluated at two mixture compositions: (15 wt% IL + 40 wt% PPG400 + 45 wt% expired energy drink) and (30 wt% IL + 30 wt% PPG400 + 40 wt% expired energy drink).The mixture compositions were chosen taking into account two common mixture points in the biphasic region of all systems, while varying the IL and PPG 400 contents to address their effects.Each biphasic system was prepared in 2 mL micro-centrifuge tubes by adding the appropriate amount of PPG 400, IL and energy drink sample to make up a final weight of 1 g.It should be remarked that a liquid energy drink sample is being used directly in the creation of ABS, thus allowing the integration of the extraction and purification steps.
Furthermore, by using designed ILs with similar chemical structures to the target compounds, the recovery step can be avoided, allowing to develop and integrated extraction-purification-recovery strategy.All systems were mixed vigorously using a vortex agitator (Reax Top, Heidolph, Germany) and left at 25 °C for 2 h.Each ABS was then centrifuged for 5 min at 2000 rpm to ensure the complete phase separation.The weights of the top and bottom phases were measured.
Recovery efficiencies of studied molecules (RE%) correspond to the percentage ratio between the amount of each biomolecule in a given phase (IL-or PPG-rich) and that in the total mixture, determined according to Eqs (1) and ( 2): where wIL, wPPG,

RESULTS AND DISCUSSION
In this work, cholinium-based ILs with anions presenting similar characteristics to the ones of the target high-value compounds, to recover from expired energetic drinks, were synthetized and characterized.The ILs were then applied in the creation of ABS to simultaneously extract and recover these compounds directly from the real samples.The ILs selection was based on the premise that the IL-rich phase will have a superior selectivity to the target compounds and that the activity of the recovered compounds could

ILs toxicity
Given the potential applications of the recovered ABS phases containing the target bioactive compounds, it is crucial to evaluate the ILs cytotoxicity.For this purpose, the epithelial human colon cell line (Caco-2) was used to study the intestinal cytotoxic effects of the investigated ILs.According to the given trend, it seems that the cholinium-based ILs act as the salting-out species over the moderately hydrophobic PPG 400.The salting-out aptitude of ILs is directly related to the hydration capacity of their ions. 32,51 ince all ILs share a common cation, cholinium, more hydrophilic anions with a higher charge density, such as [DHP] - , have a higher hydration ability and display stronger salting-out effects.However, it should be taken into account that the mechanisms behind the formation of ABS containing ILs and polymers are far more complex than those observed in ABS formed by salts and ILs. 45It was previously reported that the ABS formation in systems comprising higher melting temperature cholinium-based ILs, e.g.[Ch][DHP], [Ch][Ac] and [Ch]Cl, is mainly governed by their affinity for water. 52A higher affinity for water implies a higher ability to promote phase separation when dealing with systems involving polymers, where the ILs acts as the salting-out species.In the case of ABS based on ILs with lower melting temperatures (which will be the case of and polymers, the two-phase formation ability is not a main result of the IL ions to create hydration complexes, but yet the IL-polymer interactions play a significant role. 53anions hydrophobicity may be appraised by the logarithmic values of their octanolwater partition coefficients (logKow); for conjugated acids of the studied anions they are in the range from -2.77 to 0.22 (detailed values given in the Supporting Information).
The most hydrophilic anion is [Tau] -, justifying its higher affinity for water and saltingout ability.On the other hand, the most hydrophobic anion is [Nia] -, which shows the lowest ability to form ABS. However, the obtained trend of ABS formation does not [Nia], respectively). 54These results suggest that the ABS formation of these low melting ILs with PPG is governed by their ability to be solvated by water to act as salting-out species and by specific interactions with the polymer, being in agreement with the literature. 52For instance, [Ch][Nia] contains π electrons able to establish strong hydrogen bond interactions with the ether oxygen atoms of PPG, and this could be the major factor for the lower ability of [Ch][Nia] to promote the creation of ABS with PPG.
Tie-line (TL) compositions, tie-lines length (TLL) and slope were additionally determined for ABS formed with the synthesized ILs, being given in the Supporting Information.TL data are particularly relevant to have information on the compositions of the phases at which the extractions are carried out.
After addressing the phase-forming components compositions required to create ABS, the potential of these new ABS formed by cholinium-based ILs and PPG 400 to recover added-value compounds from expired energy drinks, namely caffeine, taurine and niacin (Vitamin B3), was investigated.The synthesized ILs were designed to have similar anions to the target products, which could be beneficial to improve selectivity and biological activity while ideally avoiding the need of the products recovery from the ABS phases.
The commercial energy drink contains aspartame, acesulfame K (110 g.L -1 ), caffeine (320 mg.L -1 ), taurine (4 g.L -1 ), vitamin B3 -niacin (80 mg.L -1 ) and other B complex vitamins (Figure S9 in the Supporting Information).The properties of the targeted compounds which can influence the partitioning in the proposed ABS and their stability in the ABS phases are given in the Supporting Information (Table S6 and Figure S10, respectively).
All studied bioactive compounds are stable in the ABS' phases and ILs/PPG 400 aqueous solutions.According to the chromatograms given in Figure S10 in the Supporting Information, it is shown that the retention times of taurine, niacin and caffeine do not change when compared to the standards and that no new peaks appear in addition to those already existing in the energy drink sample.
The extraction of the target compounds from the energy drink was performed at two ternary system compositions (identified in Figure 3  Caffeine can be used as an effective and valuable probe to characterize the relative hydrophobicity of a series of ABS, particularly when hydrophobic type interactions are predominant, since this alkaloid does not suffer speciation in a large range of pH values (pKa1/pKa2 = 0.12 / 10.5) while being moderately hydrophilic (logKow = -0.63). 55rding to the RE% values, caffeine preferentially partitions to the PPG-rich phase at both compositions, except in the case of the ABS composed of [Ch][Nia] and [Ch] [Pyr]  where caffeine preferentially migrates to the IL-rich phase (Figure 4).Recovery efficiencies of caffeine in the range from 16.19 to 55.38% toward the IL-rich phase and from 5.12 to 83.81% to the PPG-rich phase were obtained, meaning that the enrichment of caffeine in a given phase can be tailored by changing the IL chemical structure.In ABS (cf. the Supporting Information, tie-line data), thus justifying the inversion on the caffeine partitioning among the coexisting phases, and in agreement with the use of caffeine as a valuable probe to characterize the relative hydrophobicity of ABS phases. 49in (pKa=4.80) 57, unlike caffeine, is negatively charged in the pH range of the studied ABS (5.8-10.1).Moreover, niacin is the most hydrophilic compound (logKow values ranging from -2.03 to -2.93 in the pH range 5.8-10.1)and contains an acidic (-COOH) and a basic group (N from the pyridine core.In the same line, taurine (pKa=-1.49/9.06) 57 has a high hydrophilic nature (logKow values ranging from -5.27 to -6.23 in the pH range 5.8-10.1),and exists as a zwitterion or as negatively charged species at the working pH.
The results disclosed in Figure 4 show that niacin and taurine preferentially migrate to the IL-rich phase, which is the most hydrophilic phase in the ABS phases, mainly due to their hydrophilic character.
In summary, the ABS evaluated are able to remarkably recover added-value compounds directly from expired energy drinks.Furthermore, caffeine, taurine and niacin can be recovered in one phase or caffeine can be separated from the remaining target compounds only by changing the IL chemical structure.For the first strategy, the best ABS is formed by [Ch][Nia] that allows to recover all compounds in one step with RE% higher than 82.32%, whereas the best ABS able to separate caffeine from taurine and niacin is composed of the commercial IL [Ch][DHP].[Ch][Nia] exibits low citotoxicity and low ecotoxicity, while PPG 400 is approved as a food additive by FDA. 58Given the enviosioned target applications and assuming that no separation of caffeine from taurine and niacin is aimed, the results obtained reveal that the ABS formed by [Ch][Nia] and PPG 400 is the most efficient system to recover added-value compounds from expired energy drinks, which could be then reused in diverse industrial applications without the need of removing the IL or recovering the target compounds from the IL-rich phase.For instance, these compounds can be used together in food supplements and in cosmetic or pharmaceutical formulations.Despite our promising results, it should be stressed that a thorough risk assessment is required in order to demonstrate the safety use of the IL-rich phase directly by these industries.This assessment includes further in vitro and in vivo tests in order to evaluate the acute and chronic toxicity towards mammals and towards other test organisms from different trophic levels to guarantee that there are no hazards related with these products.
A schematic overview of the developed integrated platform, and within a circular economy perspective, to extract and recover added-value compounds from expired energy drinks without the need of recovering them from the IL-rich phase is shown in

CONCLUSIONS
In this work, we proposed an integrated approach to extract and recover high-value and bioactive compounds from expired energy drinks using aqueous biphasic systems

Figure 1 .
Figure 1.Chemical structures of the investigated ILs and added-value compounds.

( 1 .
[Ch][Nia])41 and cholinium taurate([Ch][Tau])42 , were performed according to previously described protocols.Cholinium pyruvate ([Ch][Pyr]) was synthesized in this work for the first time by acid-base titration.The potentiometric acid-base titrations were performed by the slow addition of an aqueous solution of [Ch][OH] (at 1.7524 mol.L -1 ) to lactic, pyruvic, nicotinic and 2-aminoethanesulfonic acids.[Ch][OH] was added in small excess and then back titrated by adding the acid solution until the desired inflection point is obtained (pH values for [Ch][Lac] = 9.25, [Ch][Pyr] = 8.20, [Ch][Nia] = 7.95 and [Ch][Tau]= 9.02).Excess water was first removed from the synthesized ILs at 70°C using a rotational evaporator, and then under vacuum until constant weight was achieved.ILs were stored with P2O5 under vacuum for the following 72 h.The water content in the ILs was determined by Karl-Fisher titration and found to be ≤ 200 ppm in all ILs.The chemical structures and purities of the synthesized ILs, [Ch][Lac] (> 98 wt%), [Ch][Pyr] (>96 wt%), [Ch][Nia] (>99 wt%) and [Ch][Tau] (>99 wt%), were confirmed by 1 H and 13 C Nuclear Magnetic Resonance (NMR) and Fourier-transform infrared spectroscopy (FTIR) spectroscopy (Figures S1-S6 in the Supporting Information).NMR spectra were recorded in D2O at 25°C on a Bruker Advance III 400 MHz spectrometer.Tetramethylsilane was used as internal standard.FTIR spectra were recorded from (4000 to 650) cm -1 using a Thermo-Nicolet Nexus 670 spectrometer fitted with a Universal ATR Sampling Accessory.The chemical structures of the investigated ILs are given in Figure ILs cytotoxicity and ecotoxicity.The cytotoxicity of the synthesized ILs ([Ch][Lac], [Ch][Nia], [Ch][Pyr], [Ch][Tau]) alongside with the commercial ILs [Ch][Ace], [Ch]Cl and [Ch][DHP] was addressed in the human colon epithelial cell line (Caco-2).A stock solution of each IL was prepared in saline aqueous solutions and the test solutions were obtained by successive dilutions of the stock in culture medium, obtaining the final concentrations of 0.1, 1.0, 10, 30, 60, 90 g.L -1 of each IL.The epithelial human colon cell line (Caco-2) was grown in high glucose Dulbecco's modified Eagle's medium (DMEM-HG) containing 10% (v/v) fetal bovine serum (FBS), 100 units penicillin, and 50 μg.mL -1 streptomycin in a humidified atmosphere of 5% CO2 at 37°C.Cells were plated on polystyrene cell culture dishes at a density of 1x10 4 cells per well in 96 well culture plates.After 16 h, cells were treated with the different concentrations of the target ILs for 24h.dimethylthiazol-2-yl)-2,5diphenyltetrazolium bromide (MTT) assay.This assay is based on the ability of viable cells to convert MTT into a water-insoluble precipitate.Caco-2 cells were incubated with 0.5 mg.dm -3 of MTT in medium overnight at 37 °C.The precipitate was then dissolved in 10% (w/v) sodium dodecyl sulfate (SDS), and colorimetrically quantified (at 570 nm) using a microplate spectrophotometer.Each concentration was tested in five replicates of three independent experiments (n=3), except for [Ch]Cl for which the values correspond to five replicates of two independent experiments (n=2).In all experiments, a negative control corresponding to untreated cells was always included.The dose response curves and median effective concentration (EC50) calculations were performed using the GraphPad PRISM Software (version 8.0.1).The EC50 corresponds to the concentration of IL for which 50% of the cells are viable.Cell viability results are expressed as percentage of the control (i.e.unexposed cells).The ecotoxicity of the synthetized ILs was evaluated using the Standard Microtox liquidphase assays.This test evaluates the inhibition of the luminescence of the marine bacteria Vibrio fischeri and was performed using a range of diluted aqueous solutions (from 0 to 81.9%) of IL, where 100% of the compound corresponds to a known concentration of a stock solution (ca. 10 g.L -1 ).After 5, 15, and 30 min of exposure to IL, the light output of the luminescent bacteria was determined and compared with the light output of a blank control sample.The toxicity was evaluated on the basis of the percentage decrease in the bacteria luminescence relative to the blank control.The final output of this test is the EC50 parameter, which represents the effective concentration of a given IL that produces 50% of inhibition of light emission.Analyses were performed with the MicrotoxOmni TM Software version 4.3.0.1.
[]  and []  are the weights of the IL-and PPG-rich phases and the concentration of each biomolecule in the IL-and PPG-rich phases, respectively; m0 corresponds to the mass of each biomolecule present in the overall ABS.At the conditions used in this work, the top phase corresponds to the PPG-rich phase while the bottom phase corresponds to the IL-rich phase.According to the product label, the used energy drink contains ca.320 mg.L -1 of caffeine, 4000 mg.L -1 of taurine and 80 mg.L -1 of niacin.The amount of each studied alkaloid (caffeine, niacin and taurine) in Red Bull was confirmed by HPLC using the respective standards and calibration curves.The experimentally determined amounts of these compounds are in accordance with the amounts labelled in the energy drink sample (FigureS9in the Supporting Information).The stability of caffeine, niacin and taurine in the ABS phases after extraction was also evaluated by HPLC (FigureS10in the Supporting Information).Caffeine and niacin in each ABS were quantified by HPLC-DAD.The HPLC analysis was performed using an Agilent 1100 liquid chromatograph (USA) with a Zorbax XDB-C18 column (4.6 mm × 250 mm, 3.5 μm particle size).The mobile phase was composed of 18% methanol and 82% water, at a flow rate of 1.5 mL.min −1 , with an injection volume of 20 µL and temperature oven at 25°C.Quantification was carried out at 273 nm for caffeine and at 261 nm for niacin.The system was controlled by the Chemstation software.The taurine concentration was determined by HPLC including a pre-column derivatization with DNFB due to low absorption of taurine in the UV-Vis region.The procedure of derivatization is described elsewhere.46,47Briefly, 100 μL of the sample, 200 μL of the 0.01 M carbonate buffer (pH 9), 500 μL of DMSO and 10 μL of DNFB were added into an Eppendorf tube, vigorously mixed using a vortex agitator at 2500 rpm for 30 s and placed in a water bath at 40 °C for 15 min.Then, 650 μL of 0.01 M phosphate buffer (pH 6) was added.The mobile phase was a mixture of 0.01 M phosphate buffer pH 6 (A) and acetonitrile (B) and the following gradient profile was run: 0-10 min, 90% A and 10% B; 10-15 min, 75% A and 25% B; 15-19 min, 50% A and 50% B; from 19 min, 90% A and 10% B at flow rate of 1 mL min -1 with a sample injection volume of 20 μL and detection wavelength at 360 nm.
be enhanced, while avoiding a final step to recover these target compounds from the ILrich phase.The ILs correspond to [Ch][Lac], [Ch][Nia], [Ch][Tau] and [Ch][Pyr].Three commercial ILs, namely, [Ch][DHP], [Ch][Ac], [Ch]Cl, were also used for comparison purposes.The chemical structures of the investigated ILs and target added-value compounds are depicted in Figure 1.

Figure 2 . 50 commercialFigure 3 .Figure 3 .
Figure 2. Caco-2 cell viability after 24 h of exposure to the ILs (average values with straight follow the logKow values; according to this rank, [Ch][Pyr] (logKow= -1.24) should be a stronger salting-out agent than [Ch][Lac] (logKow= -0.70).On the other hand, the trend of low melting cholinium-based ILs to induce ABS follows the decrease in the anion polar surface, which is the surface sum over all polar atoms (80.39, 60.36, 57.20 and 50.19 Å 2 for [Ch][Tau], [Ch][Lac], [Ch][Pyr] and [Ch] ): (A) 15 wt% of IL, 40 wt% of PPG 400 and 45 wt% of expired energy drink, and (B) 30 wt% of IL, 30 wt% of PPG 400 and 40 wt% of expired energy drink.The composition of the ternary mixtures was selected based on the phase diagrams previously determined, and close to the binodal curve of the ABS with lowest ability to undergo liquid-liquid demising aiming at improving their sustainability, i.e. requiring lower amounts of the phase-forming components (IL and PPG 400).The obtained recovery efficiencies (RE%) in the IL-rich and PPG-rich phases for niacin, caffeine and taurine are depicted in Figure 4 (detailed results are provided in the Supporting Information).At the conditions investigated, taurine and niacin from the expired drink preferentially migrate to the IL-rich phase in all ABS, whereas caffeine shows an opposite pattern in most of the systems investigated (preferential migration towards the PPG-rich phase, with the exception of [Ch][Pyr]-, [Ch][Nia]-and [Ch]Cl-based ABS) -cf.

Figure 5 .
Figure 5.This strategy envisions the direct use of the IL-rich fraction with enhanced

Figure 5 .
Figure 5. Schematic representation of the proposed integrated platform to extract and composed of cholinium-based ILs and PPG 400.A set of cholinium-based ILs was synthesized, characterized and used.[Ch][Lac] exhibits the lowest toxicity towards the human epithelial colon cell line (Caco-2), followed by [Ch][Pyr] and [Ch][Nia].[Ch][Tau] exhibits the highest cytotoxic character, being comparable to the commercial ILs [Ch]Cl and [Ch][DHP].A similar profile with [Ch][Tau] exhibiting the highest toxicity was obtained for the ecotoxicity tests, with this IL being considered moderately toxic.[Ch][Nia] is harmless to the marine bacteria V. fischeri, whereas [Ch][Lac] and [Ch][Pyr] were considered as practically harmless.The ABS phase diagrams were determined at 25°C and atmospheric pressure, in which the ILs in ABS formation followed the order: [Ch][DHP] > [Ch][Ac] > [Ch]Cl > [Ch][Tau] > [Ch][Lac] > [Ch][Pyr] > [Ch][Nia].In the studied ABS, taurine and niacin preferentially migrate to the IL-rich phase, while caffeine migrates in the majority of the cases towards the PPG-rich phase.However, an opposite behaviour on the partition of caffeine was achieved with ABS formed by [Ch][Pyr] or [Ch][Nia], in which caffeine also partitions to the IL-rich phase.The system composed of [Ch][Nia] and PPG 400 allows the almost complete recovery (RE% >82.32%) of all the target compounds into the IL-rich phase in one-step.Given that [Ch][Nia] exhibits lower cytotoxic potential and is considered harmless from an ecotoxicological point of view, this system can be considered a promising platform to simultaneously extract, recover and reuse added-value compounds from expired energy drinks and thus contribute to a more sustainable and circular food economy.ASSOCIATED CONTENT Supporting Information.Supplementary Information available: [NMR and FTIR spectra; information on the determination of the ABS phase diagrams; Caco-2 cytotoxicity dose response curves; Microtox toxicity results; Ternary phase diagrams and binodal weight fraction data of ABS, TLs and TLLs; HPLC chromatograms; Recovery efficiencies].