Interest in ionic liquids for their potential in different chemical processes isconstantly increasing, as they are claimed to be environmentally benign – excellent, non-volatile solvents for a wide ...range of applications. The wide applicability of thesecompounds also demands reliable, relatively simple and reproducible analytical techniques.These methods must be applicable not only to different technical or natural matrices but alsoto the very low concentrations that are likely to be present in biological and environmentalsystems. In this review, therefore, methods for separating and analysing imidazolium- andpyridinium-type ionic liquids in aqueous matrices using high performance liquidchromatography (HPLC) and capillary electrophoresis (CE) are examined. The techniquesfor identifying ionic liquids are meant primarily to track the concentrations of ionic liquidsas residues not only in products and wastes but also in biological or environmental samples.The application of hyphenated techniques in this field is intended to selectively separate thequaternary entity from other cationic and non-ionic species present in the matrix, and toenable its fine-scale quantification. Nowadays, methods developed for cation analysis arebased mostly on reversed-phase high-performance liquid chromatography, ionchromatography, ion-pair chromatography and capillary electrophoresis, where variousbuffered mobile phases are used.
•Four cytostatic drugs were photooxidized over Bi-B co-doped TiO2 under solar light.•The photocatalytic oxidation of IF was similar effective for 3Bi-B-TiO2 and TiO2.•Photocatalytic oxidation pathway ...of IF was different over 3-Bi-BTiO2 and TiO2.•Dechlorination in contrast to mineralization was effective over 3Bi-B-TiO2.
The Bi-B co-doped TiO2 photocatalysts were prepared via a simple sol-gel method. Initially, the photocatalysts were applied to decompose ifosfamide (IF). 3Bi-B-TiO2 was found to be the most effective photocatalyst with regard to the cytostatic drug decay; it was also characterized by good sedimentation properties. For the constant concentration ratio of IF:catalyst, this photocatalyst was more effective in the removal of IF at low drug concentrations. The study employing scavengers, i.e. F− ions and isopropanol demonstrated that the modification of TiO2 with Bi and B co-dopants has a negative effect on the generation of OHfree radicals. The decomposition of the studied cytostatic drug was most likely connected to the reaction with OHads radicals generated at the catalyst surface. The quantitative and qualitative determination of IF intermediates during the photocatalytic decomposition in the presence of 3Bi-B-TiO2 showed that dechlorination was a more advanced process compared to the oxidation of organic matter.
Lastly, other cytostatic drugs such as, cyclophosphamide (CP), 5-fluorouracil (5-FU) and imatinib (IMA) decomposed in the presence of 3Bi-B-TiO2 under artificial sunlight and visible light irradiation. The rate and efficiency of photocatalytic decay of the aforementioned cytostatic drugs increased in the following order: CP≈IF<5-FU<IMA.
Commonly used alkylimidazolium ionic liquids are poorly to negligibly biodegradable, and some are toxic, with the potential to poison typical biological test systems. Therefore, when ionic liquids ...are present in technological wastewaters they could break through classical wastewater treatment systems into natural waters and become potentially persistent pollutants. A recent study investigating different advanced oxidation processes found that the H
2O
2/UV system degraded dissolved imidazolium ionic liquids with the greatest efficiency. In the present study, high performance liquid chromatography was coupled with electrospray mass spectrometry to separate, analyse and identify degradation products following the treatment of ionic liquid solutions with H
2O
2 in the presence of UV irradiation. It was found that hydroxylation in short-chain entities occurred mainly within the ring moiety, whereas in the case of longer alkylated cations, oxidation of the alkyl chain yielded several products. The potential transformation products were identified structurally by MS/MS analysis and are discussed in the light of their putative toxicity and biodegradability.
The effect of selected inorganic anions on the effectiveness of the Fenton advanced oxidative treatment of waters contaminated with methyl
t-butyl ether (MTBE) was examined. With respect to the ...chloride or phosphate ions used, inhibition of oxidation was clearly in evidence, whereas addition of sulfates or perchlorates influenced these rates to a much smaller extent. Anions suppress MTBE decomposition in the following sequence: ClO
4
−
<
SO
4
2−
<
Cl
−
<
H
2PO
4
−. There are very probably several mechanisms affecting oxidation. Complexation reactions with iron are likely to affect the distribution and reactivity of iron species with H
2O
2. Hydroxyl radicals may also be scavenged from less reactive inorganic radicals. Additionally, in order to explore the degradation mechanism of MTBE by Fenton's reagent in the presence of different salts, four intermediate products of MTBE oxidation were identified:
tert-butyl formate (TBF),
tert-butyl alcohol (TBA), acetone, and methyl acetate (MA).
The study examined the usefulness of a Fenton-like system for the degradation of ionic liquid residues in water. The ionic liquid was oxidized in a dilute aqueous solution of ...1-butyl-3-methylimidazolium chloride (bmimCl). The ionic liquid decomposes readily and rapidly in aqueous solution by chemical degradation in a Fenton-like system. Under chosen conditions the initial bmimCl solution was reduced by a factor of 0.973 within 90
min. Additional results showed that bmimCl degradations in a Fenton-like system in excess H
2O
2 could be interpreted as a combined oxidation–reduction mechanism. Preliminary investigations of the mechanism of such degradations have indicated that initial OH
radicals can attack any one of the three carbon atoms on the imidazolium ring. The intermediates of this reaction may be mono- di- or amino- carboxylic acids.
Suberin, a plant polyester, consists of polyfunctional long-chain fatty acids and glycerol and is an intriguing candidate as a novel antimicrobial material. We purified suberin from cork using ...ionic-liquid catalysis during which the glycerol bonds that ensure the polymeric nature of suberin remained intact or were only partially cleaved—yielding the closest to a native configuration reported to date.
The chemistry of suberin, both in situ (in cryogenically ground cork) and ex situ (ionic-liquid extracted), was elucidated using high-resolution one- and two-dimensional solution-state NMR analyses. Centrifugation was used to isolate suberin particles of distinct densities and their monomeric composition, assembly, and bactericidal effect, inter alia, were assessed.
Analysis of the molecular structure of suberin revealed the relative abundance of linear aliphatic vs. acylglycerol esters, comprising all acylglycerol configurations and the amounts of total carbonyls (CO), free acid end groups (COOH), OH aliphatics, and OH aromatics. Suberin centrifuged fractions revealed generic physiochemical properties and monomeric composition and self-assemble into polygonal structures that display distinct degrees of compactness when lyophilized. Suberin particles—suberinsomes—display bactericidal activity against major human pathogenic bacteria.
Fingerprinting the multifunctionality of complex (plant) polyesters such as suberin allows for the identification of novel polymer assemblies with significant value-added properties.
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Pesticides are used as plants protection products. Among those, insecticides serve as agents to control insects. When incorrectly applied, however these substances may negatively affect people's ...health and natural environment. Administration routes of insecticides depend on many factors and vary from spraying to fertilizers. These different methods influence how insects prey and how pests develop. Additionally, too frequent use of the same chemicals can lead to development of resistance of insects to these insecticides. In order to prevent occurrence of negative effects of insecticides on surroundings, the effects of these compounds should be studied
This paper presents cytotoxicity data of selected imidazolium ionic liquids evaluated in vitro on the human tumor cell line HeLa. It was found that for 1-n-butyl-3-methylimidazolium entities the ...toxicity depends strongly on the associated anion; EC50 values are lowest for tetrafluoroborate. No direct dependence of the reduced effect concentration was found on elongating the short, methyl chain to ethyl or n-hexyl. Only for the ionic liquid with an n-decyl chain, the longest one studied, did higher hydrophobicity result in a EC50 one order of magnitude lower than that obtained with the n-butyl entity. The effect concentrations of imidazolium ionic liquids in the HeLa system used are lower than the values obtained for conventional organic solvents such as dichloromethane, toluene or xylene.
Current research indicates that replacing organic solvents with room-temperature ionic liquids may lead to remarkable improvements in well-known processes. Ionic liquids have already been utilized as ...alternative solvents in organic synthesis and catalysis, and also in electrochemistry and in separation sciences. Their wide applicability will soon result in their production on an industrial scale. Therefore, analytical methods applicable to various matrices for product control and environmental monitoring will be very much in demand. In this study, the usefulness of π...π interactions between alkylimidazolium and pyridinium cations and the aromatic π...π active moiety of the stationary phase was investigated for the selective separation and analysis of some ionic liquids. With phenyl-bonded phases, very good separations of the cations were achieved. Special attention was paid to the short-chain hydrophilic entities, known to be poorly separated on conventional reversed-phase columns. Further, the nature of the interactions occurring in the system under study was investigated by varying the content of methanol/acetonitrile used as organic modifiers in the mobile phases. The analytical method developed here is simple and reproducible, and its quantitative analytical performance was excellent. The paper also discusses the applicability of the method for monitoring degraded cations of 1-butyl-3-methylimidazolium salts obtained in the Fenton process.
► The explanation influence of IL composition on electrochemical oxidation at BDD anode. ► Identification of IL oxidants in different electrolyte. ► Two pathways of ILs transformation at BDD anode. ► ...Influence of halide ions on ILs electrooxidation at BDD. ► Identification of by-products for imidazolium salts with the different anions.
The electrochemical oxidation of ionic liquids (ILs) in aqueous solutions on boron-doped diamond was investigated with the aim of explaining the influence of the IL composition Cl-,Br-,BF4-,PF6-,CF3SO3-,CH3C6H4SO3-. By keeping the cation (1-butyl-3-methylimidazolium) constant and varying the anion, a comparative study of their oxidizability could be carried out. The experimental data suggest that hydroxyl radicals were the dominant oxidant reacting with the IL ionic pair. The chloride ion enhanced imidazolium cation degradation, whereas CH3C6H4SO3- competed with the cation for anodically produced hydroxyl radicals. The nature of the background anions (Na2SO4, NaCl, NaBr) also influenced the efficiency of the electrochemical process. The addition of trace halides further decreased chemical oxygen demand (COD). The results suggest that different oxidation mechanisms prevail at different halide concentrations. However, peroxodisulphate generated at the BDD anode in a Na2SO4 supporting electrolyte did not play a significant role in imidazolium salt oxidation. The intermediates found in the single compartment reactor after 3h of electrolysis suggest that O2- also occured and governed in part the electrochemical oxidation of IL.
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