Biodegradability Of Ionic Liquids Research Articles

Degradation of imidazolium-based ionic liquids by UV photolysis and pulsed corona discharge: The effect of persulfates addition

Ionic liquids (ILs) are salts with exceptional properties important for future development, although potentially hazardous for humans and aquatic life due to their high aqueous solubility and toxicity. Biodegradation of ILs depends on the anion nature and cation structure: many ILs are not readily degraded during conventional wastewater treatment, thus requiring alternative cost-effective and energy-efficient solutions. In this research, the degradation of aqueous imidazolium-based ILs by pulsed corona discharge (PCD) and UV photolysis combined with persulfates was studied, using peroxymonosulfate (PMS) and peroxydisulfate (PDS) as extrinsic oxidants. 1-Ethyl-3-methylimidazolium chloride ([Emim][Cl]), 1-methyl-3-octylimidazolium chloride ([Omim][Cl]), and 1-ethyl-3-methylimidazolium bromide ([Emim][Br]) were chosen as imidazolium-based ILs with different alkyl chain lengths and anions in oxidation experiments under variable operation factors - pH, concentrations of persulfates, pulse repetition frequency in PCD. Pulsed corona discharge has previously shown high energy efficiency in the degradation of micropollutants but has not yet been applied to ionic liquids. The experimental results showed the ability of PCD, PCD/oxidant and UV/oxidant combinations to completely degrade the ILs with the degradation rates in descending order [Emim][Cl] > [Omim][Cl] > [Emim][Br], indicating an impact of both the alkyl chain length and the type of anion on the oxidation rate. The strong activation of persulfates was observed in UV/oxidant combinations, whereas PCD demonstrated the effect of persulfates addition between slight acceleration and moderate deceleration of oxidation dependent on the concentration of extrinsic oxidants. The addition of the sulfate radicals’ scavenger, however, showed the presence of those in all combinations indicating a certain replacement of PCD-generated reactive oxygen species with secondary reactants formed from persulfates. The unassisted PCD and UV/PDS combination demonstrated similar energy efficiencies of about 54 and 26 mmol kWh−1 for [Emim][Cl] and [Emim][Br] degradation, respectively, while for [Omim][Cl] the UV/PDS combination showed energy efficiency 1.42 times higher than unassisted PCD.

Physicochemical Properties and Applications of Deep Eutectic Solvents for CO2 Capture

AbstractRising anthropogenic greenhouse gas concentrations, notably CO2 emissions, have led to environmental issues that affect both humans and ecosystems. CO2 separation makes it easier to reduce energy use and CO2 emissions, both of which are essential for combating the concern of global warming. The use of ionic liquids (ILs) as CO2 capture solvents is recommended. However, the high viscosity, toxicity, cost, and poor biodegradability of ILs limit their large‐scale application. In recent years, deep eutectic solvents (DESs) have been created with improved CO2 separation efficiency, lower preparation costs, and less negative environmental impact. The state‐of‐the‐art of the physicochemical properties of DESs in connection to their influence on CO2 capture processes and the studies of CO2 solubility in DESs are discussed. The absorption mechanism of CO2 in DESs and the effect of temperatures, pressures, and hydrogen bond donors (HBDs) on the solubility of CO2 in DESs are overviewed and analyzed, and future research directions on this topic are suggested.

Role of Fungi in Biodegradation of Imidazolium Ionic Liquids by Activated Sewage Sludge.

Ionic liquids (ILs), due to their specific properties, can play the role of persistent water contaminants. Fungi manifest the ability to decompose hardy degradable compounds, showing potential in the biodegradation of ILs, which has been studied extensively on sewage sludge; however, attention was drawn mainly to bacterial and not fungal species. The aim of the research was to determine the significance of fungi in ILs' biodegradation to extend the knowledge and possibly point out ways of increasing their role in this process. The research included: the isolation and genetic identification of fungal strains potentially capable of [OMIM][Cl], [BMIM][Cl], [OMIM][Tf2N], and [BMIM][Tf2N] degradation, adjustment of the ILs concentration for biodegradability test by MICs determination and choosing strains with the highest biological robustness; inoculum adaptation tests, and finally primary biodegradation by OECD 301F test. The study, conducted for 2 mM [OMIM][Cl] as a tested substance and consortium of microorganisms as inoculum, resulted in an average 64.93% biodegradation rate within a 28-day testing period. For the individual fungal strain (Candida tropicalis), the maximum of only 4.89% biodegradation rate was reached in 10 days, then inhibited. Insight into the role of fungi in the biodegradation of ILs was obtained, enabling the creation of a complex overview of ILs toxicity and the possibilities of its biological use. However, only an inoculum consisting of a consortium of microorganisms enriched with a selected strain of fungi was able to decompose the IL, in contrast to that consisting only of an individual fungal strain.

Ionic Liquids Toxicity-Benefits and Threats.

Ionic liquids (ILs) are solvents with salt structures. Typically, they contain organic cations (ammonium, imidazolium, pyridinium, piperidinium or pyrrolidinium), and halogen, fluorinated or organic anions. While ILs are considered to be environmentally-friendly compounds, only a few reasons support this claim. This is because of high thermal stability, and negligible pressure at room temperature which makes them non-volatile, therefore preventing the release of ILs into the atmosphere. The expansion of the range of applications of ILs in many chemical industry fields has led to a growing threat of contamination of the aquatic and terrestrial environments by these compounds. As the possibility of the release of ILs into the environment s grow systematically, there is an increasing and urgent obligation to determine their toxic and antimicrobial influence on the environment. Many bioassays were carried out to evaluate the (eco)toxicity and biodegradability of ILs. Most of them have questioned their “green” features as ILs turned out to be toxic towards organisms from varied trophic levels. Therefore, there is a need for a new biodegradable, less toxic “greener” ILs. This review presents the potential risks to the environment linked to the application of ILs. These are the following: cytotoxicity evaluated by the use of human cells, toxicity manifesting in aqueous and terrestrial environments. The studies proving the relation between structures versus toxicity for ILs with special emphasis on directions suitable for designing safer ILs synthesized from renewable sources are also presented. The representants of a new generation of easily biodegradable ILs derivatives of amino acids, sugars, choline, and bicyclic monoterpene moiety are collected. Some benefits of using ILs in medicine, agriculture, and the bio-processing industry are also presented.

Potential Application of Ionic Liquids in Pharmaceutical Dosage Forms for Small Molecule Drug and Vaccine Delivery System.

Ionic liquids are salts in which the ions are poorly coordinated, which causes them to exist in liquid form below 100°C, or at room temperature. Therefore, these are also defined as room temperature ionic liquids (RTILs). In ionic liquids, at least one ion has a delocalized charge and one component is organic, which prevents the formation of a stable solid form of crystal lattice. Physical properties of ionic liquids, such as melting point, viscosity, and solubility of starting materials and other solvents, are impacted by the substituents on the organic component and by the counterions. Many ionic liquids have even been developed to address specific synthetic problems and that is the reason these are also termed as "designer solvents". Ionic liquids are considered as "green solvents" that exhibit several unique characteristics such as high ionic conductivity, high solvation power, thermal stability, low volatility, and recyclability. Although very useful with several advantages, ionic liquids have some limitations that include high cost and ease of recycling. Moreover, the toxicity and biodegradability of ionic liquids are not yet well understood. Nonetheless, ionic liquids can potentially be used in the field of pharmacy in drug design and formulation development. In drug or vaccine dosage formulation development, ionic liquids can be used as a solubility enhancer, permeability enhancer, stabilizer, targeted delivery inducer, stealth property provider or bioavailability enhancer. In this article we reviewed the physical properties of ionic liquids and potential application of ionic liquids in developing formulations for vaccines and small molecule drugs (A table has been added).

A review of recent advances towards the development of QSAR models for toxicity assessment of ionic liquids

•Ionic liquids (ILs) are considered as an alternative to traditional organic solvents due to their unique physical and chemical properties. On the one hand, they have promising solvating characteristics, on the other hand, they are considered as environmentally friendly “green” solvents. Recent studies of ILs toxicity however questioned the safety of ILs.•Assessment of the toxicity of ILs based on laboratory testing is time-consuming and requires significant resources. Complementing this task by applying computational methods is an option for filling data gaps and allows predicting the toxicity of ILs that lack experimental data. Development and application of quantitative structure–activity relationships (QSARs) for innovative design of safe-by-design ILs became recently a research priority. In this review, we summarize the current knowledge on development of in silico models in predicting and classifying the hazards of ILs. In addition, we discuss biodegradability of ILs and assessment of mechanisms of toxicity of ILs based on the reported models.

Removal of residual functionalized ionic liquids from water by ultrasound-assisted zero-valent iron/activated carbon

ABSTRACTNumerous applications of ionic liquids (ILs) are often accompanied by the generation of aqueous wastes. Due to the high toxicity and poor biodegradability of ILs, effective chemical treatment is of great importance for their removal from aqueous solution. In this work, an ultrasound-assisted zero-valent iron/activated carbon (US-ZVI/AC) micro-electrolysis technique was used to degrade residual functionalized ILs, 1-butyl-3-methyl benzimidazolium bromide ([BMBIM]Br) and 1-allyl-3-methylimidazolium chloride ([AMIM]Cl) in aqueous solution, and the degradation degree, degradation kinetics and possible degradation pathways were investigated. It was shown that the degradation of these functionalized ILs was highly efficient in the US-ZVI/AC system, and the degradation degree was as high as 96.1% and 92.9% in 110 min for [BMBIM]Br and [AMIM]Cl, respectively. The degradation of [BMBIM]Br could be described by the second-order kinetics model, and [BMBIM]+ was decomposed in two ways: (i) sequential cleavage of N-alkyl side chain of the cation produced three intermediates; (ii) the 2-positioned H atoms of the benzimidazolium ring were first oxidized, and then the imidazolium ring was opened. The degradation of [AMIM]Cl followed the first-order kinetics rule, and the 2,4,5-positioned H atoms of the imidazolium ring were oxidized to induce ring opening. In addition, the removal of total organic carbon was found to be >87%, which indicates that most of the ILs was mineralized in the degradation process. These results suggest that ultrasound-assisted ZVI/AC micro-electrolysis is highly effective for the removal of residual functionalized ILs from aqueous environment.

Effects of imidazolium chloride ionic liquids and their toxicity to Scenedesmus obliquus

The low volatility of ionic liquids effectively eliminates a major pathway for environmental release and contamination; however, the good solubility, low degree of environmental degradation and biodegradation of ILs may pose a potential threat to the aquatic environment. The growth inhibition of the green alga Scenedesmus obliquus by five 1-alkyl-3-methylimidazolium chloride ionic liquids (ILs) ([Cnmim]Cl, n=6, 8, 10, 12, 16) was investigated, and the effect on cellular membrane permeability and the ultrastructural morphology by ILs ([Cnmim]Cl, n=8, 12, 16) were studied. The results showed that the growth inhibition rate increased with increasing IL concentration and increasing alkyl chain lengths. The relative toxicity was determined to be [C6mim]Cl<[C8mim]Cl<[C10mim]Cl<[C12mim]Cl<[C16mim]Cl. The algae were most sensitive to imidazolium chloride ILs at 48h according to the results from the growth inhibition rate and cellular membrane permeability tests. The ultrastructural morphology showed that the ILs had negative effects on the cellular morphology and structure of the algae. The cell wall of treated algae became wavy and separated from the cell membrane. Chloroplast grana lamellae became obscure and loose, osmiophilic material was deposited in the chloroplast, and mitochondria and their cristae swelled. Additionally, electron-dense deposits were observed in the vacuoles.

Persistence of selected ammonium- and phosphonium-based ionic liquids in urban park soil microcosms

Knowledge about biodegradability of ionic liquids (ILs) in terrestrial systems is limited. Here, using urban park soil microcosms spiked with either ammonium- or phosphonium-based ILs [didecyldimethylammonium 3-amino-1,2,4-triazolate, benzalkonium 3-amino-1,2,4-triazolate, trihexyl(tetradecyl)phosphonium chloride, or trihexyl(tetradecyl)phosphonium 1,2,4-triazolate], we studied their (i) 300-day primary biodegradation, and (ii) influence on CO2 evolution from the microcosms. The primary biodegradation ranged from 21 to 33% of total compound in the dissolved phase. The evolution of CO2 from spiked microcosms was either lower or within the range of background soil respiration, indicating no or small mineralization of the parent compounds and/or their metabolites, and their negligible or small toxicity to soil microorganisms. Our results suggest the potential for persistence of the four studied ILs in urban park soils.

Biodegradation of ionic liquids--a critical review.

The importance of biodegradation data as part of the design of safer chemicals is presented using ionic liquids (ILs) as a model study. Structural features that promote/impede IL biodegradation, IL design strategies, methods of biodegradation analysis, properties of IL/surfactant derivatives and computational methods of predicting biodegradation are discussed. The importance of metabolite studies as part of biodegradation assays is highlighted. The relevance of applying the lessons learned developing biodegradable ILs to other chemical classes is proposed. A comprehensive appendix of IL biodegradation data published since 2010 (∼300 ILs) has been compiled.

Bacterial consortium and axenic cultures isolated from activated sewage sludge for biodegradation of imidazolium-based ionic liquid

Extensive research and increasing number of potential industrial applications made ionic liquids (ILs) important materials in design of new, cleaner technologies. Together with the technological applicability, the envi- ronmental fate of these chemicals is considered and sig- nificant efforts are being made in designing strategies to mitigate their potential negative impacts. Many ILs are proven to be poorly biodegradable and relatively toxic. Bioaugmentation is known as one of the ways of enhancing the microbial capacity to degrade xenobiotics by addition of specialized strains. The aim of current work was to select microbial species that could be used for bioaug- mentation in order to enhance biodegradation of ILs in the environment. We subjected activated sewage sludge to the selective pressure of 1-methyl-3-octylimidazolium chloride ((OMIM)(Cl)) and isolated nine strains of bacteria which were able to prevail in these conditions. Subsequently, we utilized axenic cultures (pure cultures) of these bacteria as well as mixed consortium to degrade this IL. In addition, we performed growth inhibition tests and found that bac- teria were able to grow in 2 mM, but not in 20 mM solutions of (OMIM)(Cl). The biodegradation conducted by the isolated consortium was higher than conducted by the activated sewage sludge when normalized by the cell density, which indicates that the isolated strains seem specifically suited to degrade the IL.

Ionic liquids as lubricants or lubrication additives: An ecotoxicity and biodegradability assessment

This paper reports on the (eco)toxicity and biodegradability of ionic liquids considered for application as lubricants or lubrication additives. Ammonium- and pyrrolidinium-based cations combined with methylsulphate, methylsulphonate and/or (CF3SO2)2N− anions were investigated in tests to determine their aquatic toxicity using water fleas Daphnia magna, green algae Selenastrum capricornutum and marine bacteria (Vibrio fischeri). Additional test systems with an isolated enzyme (acetylcholinesterase) and isolated leukaemia cells from rats (IPC-81) were used to assess the biological activity of the ionic liquids. These compounds generally exhibit low acute toxicity and biological activity. Their biodegradability was screened according to OECD test procedures 301 B and 301 F. For choline and methoxy-choline ionic liquids ready biodegradability was observed within 5 or 10d, respectively. Some of the compounds selected have a considerable potential to contribute to the development of more sustainable products and processes.

Toxicity and biodegradability of ionic liquids: New perspectives towards whole-cell biotechnological applications

The potential of four ILs for whole-cell biotechnological processes was evaluated in terms of toxicity and biodegradability. From the four ILs tested, only Aliquat completely inhibited the microbial glucose uptake at a concentration of 5%, while [PEGMIM][PF 6] was completely soluble in water. Therefore, these ILs were discarded for further studies. On the other hand, [BMIM][PF 6] and [BMIM][NTF 2] were not toxic at a concentration of 5% (v/v) (specific concentrations of 170 and 180 g IL g Biomass −1, respectively), while IL addition at 10% (v/v) slightly inhibited the metabolic activity relative to controls deprived of IL. Addition of both [BMIM][PF 6] and [BMIM][NTF 2] produced an acclimation time of approximately 24 h before the microorganisms were able to uptake the substrate. Further experiments on IL toxicity due to long-term fluoride (F −) release showed that despite the fact that F − was detected in the aqueous phase, its concentration was very low (≤2.98 mg L −1) and hence not toxic for the microorganisms. Finally, short- and long-term biodegradability tests showed that neither [BMIM][PF 6] nor [BMIM][NTF 2] was biodegradable. Therefore, [BMIM][PF 6] and [BMIM][NTF 2] can be considered as compatible with whole-cell biotechnological processes.

Influence of microbial adaption and supplementation of nutrients on the biodegradation of ionic liquids in sewage sludge treatment processes

As ionic liquids are winning more attention from industry as a replacement of more hazardous chemicals, some of their structures have the potential to become persistent pollutants due to high stability towards abiotic and biotic degradation processes. Therefore it is important to determine the hazard associated with the presence of ILs in the environment, for example biodegradation under real conditions. Standard biodegradation testing procedures generally permit pre-conditioning of inoculum but do not allow for pre-exposition to the test substance. These are usually conducted in a mineral medium which does not provide additional organic nutrients. Though very valuable, as a point of reference, these tests do not fully represent real conditions. In in situ conditions, for example in wastewater treatment plants or natural soils and water bodies, the presence of readily available sources of energy and nutrients as well as the process of adaptation may often alter the fate and metabolic pathways of xenobiotics. Our results have shown that these are the opposing processes influencing the biodegradation rate of ILs in sewage sludge. The results have significant practical implications with respect to the assessment of biodegradability and environmental fate of ILs and other xenobiotics in environmental conditions and their potential remediation options.

Biodegradability of Ionic Liquids – Test Procedures and Structural Design

AbstractDie biologische Abbaubarkeit ist ein zentraler Parameter bei der Einschätzung des Risikopotenzials einer Chemikalie und legt die zeitliche und räumliche Ausbreitung und die mögliche Anreicherung in der Umwelt von Substanzen fest. Insbesondere die Abbaubarkeit von ionischen Flüssigkeiten (ILs) scheint ein Flaschenhals bei der Entwicklung von umweltfreundlichen ILs zu sein, weil sich die hohe thermische und (elektro)chemische Stabilität vieler Vertreter dieser Substanzklasse auch in deren Stabilität gegenüber abiotischen und biologischen Abbauprozessen in der Umwelt widerspiegelt. Dieser Übersichtsartikel gibt eine Einführung in Testverfahren und einen Überblick zum Stand des Wissens zur Abbaubarkeit von ILs. Hierbei soll der Schwerpunkt auf Struktur‐Abbaubarkeits‐Beziehungen liegen und herausgestellt werden, welche Strukturmerkmale die Abbaubarkeit von ILs erhöhen bzw. senken. Die Diskussion dieser Ergebnisse soll das zukünftige Design von Verbindungen mit einem reduzierten Gefahrenpotenzial für Mensch und Umwelt unterstützen.

The Biodegradation of Ionic Liquids - the View from a Chemical Structure Perspective

The idea of green or sustainable chemistry is to develop highly efficient technical processes and applications using chemicals with a reduced or zero hazard potential for man and the environment. This approach is perfectly applicable to ionic liquids (ILs). These substances have potential applications in different fields (economic interests), and so far millions of possible structures have been designed, thousands of which have actually been produced, providing a broad base for the structural design of ILs with optimal technological properties and at the same time posing a reduced hazard to humans and the environment. In parallel with the rapidly growing (eco)toxicological knowledge regarding ILs, the available data regarding their biodegradability are also increasing. The following sections introduce the reader to biodegradation test procedures and present an overview of existing aerobic and anaerobic biodegradation data concerning ILs. Besides pure biodegradation kinetics, this discussion covers data on biological degradation products (metabolites) and abiotic degradation processes. Throughout this review special emphasis will be placed on structure-biodegradability relationships and the question whether the 10th principle of Green Chemistry, namely, Design chemicals and products to degrade after use: design chemical products to break down to innocuous substances after use so that they do not accumulate in the environment, is or is not fulfilled for some IL structures. The discussion of this data should help to improve the future design of inherently safer ILs, thereby reducing the risks they may pose to humans and the environment. Keywords: Biodegradation, metabolization, organic cations, structure-biodegradability relationships, sustainable design, weakly coordinating anions, cellulose dissolution, aluminum plating, gas compression, dye-sensitized solar cells, abiotic degradation processes, concentration of inoculum, rotifers

Efficient biodegradation of common ionic liquids by Sphingomonas paucimobilis bacterium

The biodegradation of ionic liquids (ILs) was evaluated by an indirect impedance technique, through which carbon dioxide production was measured during bioassay time. The biodegradation study was focused on finding a microorganism able to efficiently degrade common IL compounds. For the first time, a bacteria strain of Sphingomonas paucimobilis was employed in biodegradability tests of ILs, carried out for 37 commercial imidazolium-, pyridinium-, pyrrolidinium-, ammonium- and phosphonium-based ILs, including in the sample 12 different anions and 14 different cations. Remarkably, more than half of ILs studied (54% of the sample) exhibited a biodegradation percentage ≥60% after a 28-day incubation period with S. paucimobilis at 45 °C; therefore, they behave as easily biodegradable compounds from the indirect impedance test. In summary, current results suggested the possibility of biotreatment for the rapid and ultimate mineralisation of widely used ILs, such as BmimNTf2, BmimPF6, etc., which were noted as recalcitrant to biodegradation in previous standard tests with other microorganisms.

Anaerobic biodegradability of ionic liquid cations under denitrifying conditions

Biodegradability and ecotoxicity of ionic liquids (ILs) are key properties for determining the greenness of IL applications, and have been increasingly investigated during the last few years. Former studies on the biodegradability of ILs were solely focused on the aerobic side. Nevertheless, the anaerobic biodegradation of many compounds plays an important role in the environment. Anaerobic respiration, especially nitrogen reduction, is widespread in the environment and is commonly used for waste water treatment. Therefore, we investigated in this study, whether ILs can be biodegraded under nitrogen reducing conditions. The primary anaerobic biodegradability of nine different imidazolium, pyridinium and dimethylaminopyridinium based IL cations was monitored via HPLC-UV over a time period of 11 months. Only for the 1-(8-hydroxyoctyl)-3-methyl-imidazolium cation (IM18OH), and a degradation could be observed and several metabolites were identified using LC-MS. Co-metabolism is sometimes the only way to degrade difficult substances. However, a possible co-metabolism of the substances by using acetate was not observed. All in all, the biodegradability of the tested ILs seems to be even worse under denitrifying conditions compared to aerobic ones. Nevertheless, the present paper aims to fill the gap concerning the biodegradability of ILs in waste water treatment plants. It gives a first insight into the biological degradation of ILs in the absence of oxygen, and provides further data for an appropriate hazard assessment.

Further studies on the biodegradation of ionic liquids

Download options Please wait... Supplementary files Further experimental data PDF (1686K) Article information DOI https://doi.org/10.1039/C0GC00082E Article type Paper Submitted 05 May 2010 Accepted 11 Aug 2010 First published 07 Sep 2010 Download Citation Green Chem., 2010,12, 1783-1789 BibTex EndNote MEDLINE ProCite ReferenceManager RefWorks RIS Permissions Request permissions Further studies on the biodegradation of ionic liquids L. Ford, J. R. Harjani, F. Atefi, M. T. Garcia, R. D. Singer and P. J. Scammells, Green Chem., 2010, 12, 1783 DOI: 10.1039/C0GC00082E To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page. If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given. If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page. Read more about how to correctly acknowledge RSC content. Social activity Tweet Share Search articles by author Leigh Ford Jitendra R. Harjani Farzad Atefi M. Teresa Garcia Robert D. Singer Peter J. Scammells

Biodegradation studies of ionic liquids

Ionic liquids are highly polar solvents with negligible vapour pressure and low flammability that offer a potentially "green" alternative to volatile organic compounds (VOCs). However in order to confidently label this class of solvents as "green", their affect on the environment must be thoroughly examined. As a result various toxicity, ecotoxicity and biodegradation studies have been carried out on ionic liquids. Although toxicity evaluations of ionic liquids have been widely reported in the literature, biodegradation data are comparatively scarce. In this tutorial review we present an overview of studies into the biodegradability of ionic liquids, including the various methods of biodegradation assessment, trends observed for structurally related ionic liquids, and applications of biodegradable ionic liquids in synthetic chemistry.