Are ionic liquids eco-friendly?. (April 2022)

• Record Type: Journal Article
• Authors: de Jesus, Sérgio S.; Maciel Filho, Rubens
• Is Part Of: Renewable & sustainable energy reviews. Volume 157(2022)
• Publication Date: 2022-04
• Subjects: Biodegradability -- Ionic liquids -- Recovery -- Recycling -- Synthesis -- Toxicity; [2-HEAA] 2-hydroxyethylammonium acetate -- [2-HEAF] 2-hydroxyethylammonium formate -- 2-METHF 2-methyltetrahydrofuran -- [2-TEAA] Tris(2-hydroxyethyl)ammonium acetate -- Aliquat® 336 Methyl trioctyl ammonium chloride -- [AMIM][Cl] 1-allyl-3-methylimidazolium chloride -- [APBMIM][Glu] 1-(3-aminopropyl)-3-butylimidazolium glutamic acid -- [BMBIM][Br] 1, 3-dibutyl-2-methylimidazolium bromide -- [BMIM][Ace] 1-butyl-3-methylimidazolium acesulfamate -- [BMIM][BF4] 1-butyl-3-methylimidazolium tetrafluoroborate -- [BMIM][Br] 1-butyl-3-methylimidazolium bromide -- [BMIM][Cl] 1-butyl-3-methylimidazolium chloride -- [BMIM][HSO4] 1-ethyl-3-methylimidazolium hydrogen sulfate -- [BMIM][OAc] 1-butyl-3-methylimidazolium acetate -- [BMIM][OSO4] 1-butyl-3-methylimidazolium octylsulfate -- [BMIM][N(CN)2] 1-butyl-3-methylimdazolium dicyanamide -- [BMIM][NTF2] 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide -- [BMIM][PF6] 1-butyl-3-methylimidazolium hexafluorophosphate -- [BMIM][TfO] 1-butyl-3-methylimidazolium trifluoromethanesulphonate -- [BMPyrr][NTF2] 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide -- [BMPz][N(CN)2] 1-butyl-2-methylpyrazolium dicyanamide -- [BSMIM][HSO4] 1-(4-sulfobutyl)-3-methylmidazolium hydrosulfate -- [BVim][Br] 1-butyl-3-vinylimidazolium bromide -- CH2Cl2 Dichloromethane -- C2H4Cl2 1, 2-dichloroethane -- CH3CCl3 1, 2-dichloroethane. -- [C4(m-ABIM)2][PF6]2 1, 4-bis(3-(m-aminobenzyl)imidazole-1-yl)butane bis(hexafluorinephosphate) -- [C4(MIM)2][(2HSO4)(H2SO4)2] 1, 1-bis(3-methylimadazoilum-1-yl) butylene hydrogen sulfate-sulfuric acid cluster -- [C4Py][Br] 1-butylpyridinium bromide -- [C4Py][NTF2] 1-butylpyridinium bis(trifluoromethylsulfonyl)imide -- [C5C1IM][NO3] 3-pentyl-1-methyl imidazolium nitrate -- [ChCl]/urea Choline chloride/urea -- CPME Cyclopentyl methyl ether -- Cyphos® IL 101 Trihexyl(tetradecyl)phosphonium chloride -- [DIPEAc] Diisopropylethylammonium acetate -- [EAN] Ethylammonium nitrate -- [EIM][Cl] 1-ethylimidazolium chloride -- [EMIM][BF4] 1-ethyl-3-methylimidazolium tetrafluoroborate -- [EMIM][Cl] 1-ethyl-3-methylimidazolium chloride -- [EMIM][EtSO4] 1-ethyl-3-methylimidazolium ethylsulfate -- [EMIM][NTF2] 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide -- [EMIM][HSO4] 1-ethyl-3-methylimidazolium hydrosulfate -- [EMIM][OAc] 1-ethyl-3-methylimidazolium acetate -- [EMIM][SCN] 1-ethyl-3-methylimidazolium thiocyanate -- [EMIM][TFA] 1-ethyl-3-methylimidazolium trifluoracetate -- [EtOHMIM][PF6] 1-(2-hydroxyethyl)-3-methylimidazolium hexafluorophosphate -- [Et3N–SO3H][Cl] N, N-diethyl-N-sulfoethanammonium chloride (triethylamine-bonded sulfonic acid) -- [EtAN] Ethanolammonium nitrate -- EtOAc Ethyl acetate -- [Hbet][NTF2] Betainium bis(trifluoromethylsulfonyl)imide -- [HMIM][Cl] 1-hexyl-3-methylimidazolium chloride -- [HMIM][NTF2] 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide -- [HMPyrr][NTF2] 1-hexyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide -- [HSO3-bCPL][HSO4] 1-(4-sulfonic group) butylcaprolactamium hydrogen sulfate -- MeCN Acetonitrile -- [MMIM][DMP] 1, 3-dimethylimidazolium dimethylphosphate -- [MSBP][HSO4] 1-methyl-2-(4-sulfobutyl)-pyrazolium hydrogensulfate -- [OMIM][BF4] 1-octyl-3-methylimidazolium tetrafluoroborate -- [OMIM][Cl] 1-octyl-3-methylimidazolium chloride -- [P4444][OAc] Tetrabutylphosphonium acetate -- [PIP14][Br] 1-butyl-1-methylpiperidinium bromide -- [PyBu][OAc] N-butylpyridinium acetate -- [TBAB] Tetrabutylammonium bromide -- [TEA][HSO4] Triethylammonium hydrogen sulfate -- [TETAH][Lys] Triethylenetetramine l-lysine -- THF Tetrahydrofuran -- [THPC] Tetrakis(hydroxymethyl)phosphonium chloride; Renewable energy sources -- Periodicals; Power resources -- Periodicals; Énergies renouvelables -- Périodiques; Ressources énergétiques -- Périodiques; 333.794
• DOI: 10.1016/j.rser.2021.112039
• Languages: English
• ISSNs: 1364-0321

Abstract

Abstract: Ionic liquids are molten salts that have excellent chemical and thermal stability. Because they have qualities inherent to some precepts of green chemistry, they are identified as a potential substitute for traditional organic solvents. These useful physical and chemical properties have led to several promising applications in renewable energy technologies. Despite being classified as green solvents, these neoteric solvents present a number of problems related to their synthesis, toxicity and biodegradability, making their use questionable environment-wise. In this review, we analyzed the processes of synthesis, recovery and recycling, toxicity and biodegradability of different ionic liquids. A comparative analysis with some fossil-based solvents and organic-based green solvents was also undertaken. Through the construction of synthesis trees, it was found that all ionic liquids analyzed presented some problematic stage, mainly due to the use of volatile compounds containing C, N, S and halogens. On the other hand, several eco-friendly methodologies have been used for recovery and recycling, such as ultrafiltration and water extraction. One of the main critical points is related to toxicity and biodegradability, as most ionic liquids currently used are toxic and poorly biodegradable or non-biodegradable. Due to their infinite combination, computational modeling studies combined with life cycle assessment studies may, in the future, design new eco-friendly ionic liquids that largely comply with the 12 principles of green chemistry. Graphical abstract: Image 1 Highlights: Ionic liquids were analyzed for synthesis, recovery, toxicity, and biodegradability. Synthesis of ionic liquids involves several steps with highly toxic reagents. The recovery can be carried out by green processes and be reused for several cycles. Ionic liquids are mostly toxic and poorly biodegradable. Ionic liquids do not comply with the 12 principles of green chemistry.