Removal of Acetaminophen (Paracetamol) from Water Using Aqueous Two-Phase Systems (ATPSs) Composed of Choline-Amino Acid Ionic Liquids

Abstract

Emerging contaminants, such as pharmaceutical compounds, are often bioaccumulative and can have toxic effects on the environment; therefore, there is a need to find efficient techniques to extract these hazardous species from water bodies. In this work, five aqueous two-phase systems (ATPSs) composed of choline-amino acid ionic liquids (CAAILs) and phosphate salts were studied to remove acetaminophen (a common active pharmaceutical ingredient, API), constituting a sustainable extraction approach. The CAAILs cholinium L-alaninate ([Ch][Ala]), cholinium glycinate ([Ch][Gly]), cholinium leucinate ([Ch][Leu]), and cholinium Lserinate ([Ch][Ser]) were successfully synthesized, and their chemical structures were confirmed by infrared spectroscopy and density measurements. Partitions of acetaminophen were performed in the systems {[Ch][Ala] or [Ch][Gly] or [Ch][Ser] (1) + K 2 HPO 4 (2) + water (3)} and {[Ch][Ala] or [Ch][Leu] (1) + K 3 PO 4 (2) + water (3)}, at 298.15 K and 0.1 MPa. Of these, four ATPSs showed good results in the extraction of acetaminophen: {[Ch][Ala] or [Ch][Gly] (1) + K 2 HPO 4 (2) + water (3)} and {[Ch][Ala] or [Ch][Leu] (1) + K 3 PO 4 (2) + water (3)}. Acetaminophen migrated preferentially to the top (IL-rich) phase, obtaining partition coefficients (K) higher than unity and extraction efficiencies (E) larger than 90%. The most promising extraction efficiencies (E) were attained for the largest tie-line lengths (TLLs) of {[Ch][Ala] or [Ch][Gly] (1) + K 2 HPO 4 (2) + water (3)}, with E = 97.5% for TLL = 82.18 m % and E = 79.3% for TLL = 85.05 m %, respectively, while {[Ch][Ala] or [Ch][Leu] (1) + K 3 PO 4 (2) + water (3)} only obtained E = 97.9% for TLL = 75.35 m % and E = 97.50% for TLL = 85.23 m %, respectively.

Water Purification Using Choline-Amino Acid Ionic Liquids: Removal of Amoxicillin

“…Following other works of the research group, , the partition coefficients were validated by performing a mass balance to the added solute. Hence, amoxicillin mass losses ( L s ) in quantification were determined in each tie-line using eq . L normals , i = m normals 2 , i − m normals 1 , i m s 1 , i · 100 where i is the number of tie-line, m s1 is the added mass of amoxicillin in the system for each feed, and m s2 is the quantified mass of amoxicillin, which was calculated using eq . m normals 2 , i = C normalT , i V normalT , i + C normalB , i V normalB , i where i is the number of tie-line, C is the concentration of amoxicillin obtained from the UV–vis absorbance calibration curve (in g·mL –1 ), T and B refer to the top and bottom phases, respectively, and V is the phase volume, which was calculated using eq . V f , i = m f , i ρ f , i where i is the number of tie-line, f refers to the top or bottom phase, m is the measured phase mass, and ρ is the measured liquid density.…”

“…The chemical structures of the obtained CAAILs were studied by means of FTIR spectroscopy within the wavenumber of 4000–400 cm –1 , using a PerkinElmer spectrum two FT-IR spectrometer. Then, the determined structures were confirmed with computational chemistry using density functional theory, following previous works of the research group. , More precisely, the IR spectrum of each IL was predicted using the GAUSSIAN G09.63 software with the combination B3LYP hybrid functional/6-311+G­(*,*) basis set …”

“…In the synthesis of the CAAILs, which was based on a previous work, 20 each amino acid ( l -alanine, glycine, or l -serine) and an excess of potassium hydroxide (KOH) were mixed with 500 g of ethanol in a stirred reactor for 3 h at 303.15 K and 0.1 MPa until complete dissolution of KOH. Then, choline chloride was added in stoichiometric proportions regarding the amino acid salt, and the mixture was stirred continuously for approximately 12 h (overnight) at the same temperature and pressure.…”

“…Despite ILs being considered “green solvents”, the most common cations ( e.g. , imidazolium and pyridinium) and anions (often fluorine-based) show scarce biodegradability and biocompatibility. , Therefore, ILs based on amino acids and choline, which are nontoxic and biodegradable, were developed, which are known as choline-amino acid ([Ch]­[AA]) ILs [or choline-amino acid ILs (CAAILs)] . CAAILs are seen as the most promising and secure ILs since they present lower toxicity, higher biocompatibility, and higher biodegradability, as well as more abundant raw materials …”

“… 18 , 19 Therefore, ILs based on amino acids and choline, which are nontoxic and biodegradable, were developed, which are known as choline-amino acid ([Ch][AA]) ILs [or choline-amino acid ILs (CAAILs)]. 20 CAAILs are seen as the most promising and secure ILs since they present lower toxicity, higher biocompatibility, and higher biodegradability, as well as more abundant raw materials. 21 …”