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The variety of applications and expected growth in ionic liquid production are raising concerns about the release of these compounds into aquatic systems. Up to date, 103 studies have provided ecotoxicological data regarding the exposure effects of Ionic Liquids towards aquatic microorganisms and invertebrate species: 61 were devoted to freshwater species (n = 28), while marine species (n = 12) were mentioned in 42. The aim of this review, by gathering published studies on ionic liquids and model aquatic organisms, was to present the toxic effects described in distinct species and to understand which are the main factors influencing the toxicity of some ionic liquids. In accordance with the most recognized pattern, freshwater species were featured in a higher number of publications than marine ones. After literature analysis, algal species were the most represented organisms in aquatic toxicity assessments. Among tested compounds, the imidazolium cations in combination with long alkyl-chain anions, showed to be the most toxic one. In analytical terms, it is not straightforward to find the undissociated compound in a natural compartment, as ionic liquids are composed of ionic components, easily subjected to dissociation. Given the aforementioned, the present review paper points out the need of increasing the number of organisms being assessed in ionic liquids toxicity assays, in order to start defining monitoring procedures. Moreover, such would allow a better understanding of ionic liquids contamination status and, also, the opportunity to remark the effectiveness of new in silico methods for the ecotoxicity assessment of this kind of substances. [ABSTRACT FROM AUTHOR]

Amongst the current alternatives, algae were proven to be a promising source of biofuel, which is renewable and capable of meeting world demand for transportation fuels. However, a suitable lipid extraction method that efficiently releases the lipids from different algal strains remains a bottleneck. The multifarious pretreatment methods are prevalent in this field of lipid extraction, and therefore, this article has critically reviewed the various lipid extraction methods for ameliorating the lipid yield from algae, irrespective of the strains/species. Physical, mechanical, and chemical are the different types of pretreatment methods. In this review, methodologies such as homogenization, sonication, Soxhlet extraction, microwave treatment, and bead-beating, have been studied in detail and are the most commonly used methods for lipid extraction. Specific advanced/emerging processes such as supercritical CO 2 extraction, ionic liquid, and CO 2 switchable solvent-based algal lipid extraction are yet to be demonstrated at pilot-scale, though promising. The extraction of lipids has to be financially conducive, environmentally sustainable, and industrially applicable for further conversion into biodiesel. Hence, this paper discusses variable pretreatment for lipid extraction and imparts a comparative analysis to elect an efficient, economically sound lipid extraction method for pilot-scale biodiesel production. • Multifarious pretreatment methods for algal lipid extraction were reviewed. • Conventional methods like sonication, microwave, homogenization was discussed. • Chemical/solvent-based processes for various algal strains were critically analyzed. • Ionic liquids and CO 2 switchable solvent based algal lipid extraction was addressed. • Advances and mechanism in supercritical CO 2 extraction process was presented in-detail. [ABSTRACT FROM AUTHOR]

This paper reports on a detailed study of the influence of salinity on the biological activity of 1-alkyl-3-methylimidazolium chlorides on two green algae Oocystis submarinaand Chlorella vulgaris, one diatom Cyclotella meneghinianaand one blue-green alga Geitlerinema amphibium. All these organisms inhabit the Baltic Sea, an environment naturally varying greatly in salinity. The toxicity effects of ILs towards cyanobacterial and algal organisms were tested in fresh water and in water of four different salinities—8, 16, 24 and 32 PSU—reflecting the whole range encountered in the Baltic Sea. Increasing the salinity was found to exert a significant influence on ionic liquid toxicity in all cases. The lower toxicity is probably due to the reduced permeability of ionic liquid cations through the algal cell walls. Higher chloride concentrations offer a good ion-pairing environment for imidazolium cations, which therefore compete with hydroxyl or silanol functional groups in cell-wall structures. The results of this work indicate that at higher salinities algal growth is inhibited to a significantly lesser extent. With the same IL concentration, the toxicity decreases by eight–ten times in the algae or about three times in the cyanobacterium in the 0–32 PSU salinity range. [ABSTRACT FROM AUTHOR]

Microscopic algae occupies every photic niche on Earth and provides an efficient and inherently scalable sunlight energy capture and chemical storage mechanism. However, fuel production from algae remains outside economic viability due to limitations in biomass cultivation and feedstock extraction. In particular, extraction strategies require prohibitive energy inputs to breach the cell wall and separate lipids, while underutilizing polysaccharide- and protein-rich leftovers. Also due to focus on lipids, cultivars become either unstable or unproductive. Meanwhile, recent advances have demonstrated the synthesis of a variety of fuels and other chemicals from sugars and proteins. Here, the energy-efficient deconstruction of algae cell walls, resulting in release of cell contents, is reported. This occurs by dissolution and hydrolysis of wet algae biomass in ionic liquids without acids, bases or other catalysts. Deconstruction reached completion in ＜50 min regardless of algae species, at 100 to 140 °C and atmospheric pressure. Based on this finding, a simple process that converts wet algae biomass into constituent fractions is proposed and modeled. These results show it is possible to eliminate intensive energy demand currently hindering the economic viability of algae while co-producing sugar and protein feedstocks that tie into emerging fuel and chemical conversion paths. [ABSTRACT FROM AUTHOR]

Room temperature ionic liquids (ILs) are non-volatile organic solvents that are considered environmentally-friendly alternatives to traditional industrial solvents. However, the evidence of IL toxicity is mounting, while the mechanisms of toxicity to freshwater organisms remain poorly understood. ILs have been shown to have a wide-ranging toxicity to different taxa of freshwater algae, and differences in algal cell wall composition have been posed as one possible explanation for this variation. The cell wall is known to play a critical role in mediating the transport of materials into and out of algal cells, including potential toxins. The objective of our study was to determine the role of the cell wall in the toxicity of ILs to the freshwater phytoplanktor Chlamydomonas reinhardtii. We exposed wild-type (having a cell wall) and mutant (lacking a cell wall) strains of C. reinhardtiito a range of concentrations of five structurally-different ILs in 96-h standard toxicity bioassays. Our results suggest that the cell wall is involved in determining the susceptibility of C. reinhardtiito some but not all ILs, indicating that other factors, such as the base cation of the IL, are also involved. The alkyl chain length of an IL, a key factor in previous IL toxicity bioassays, does not appear to influence the ability of the cell wall to mitigate IL toxicity. The results of this study have important implications for predicting the effects of ILs in aquatic ecosystems and for extrapolating the effects of ILs across organisms. [ABSTRACT FROM AUTHOR]

Many studies done so far on the aquatic ecotoxicity of ionic liquids have dealt with phytoplankton organisms. Nonetheless, benthic organisms are just as important if we are to fully understand the prospective fate and effects of ionic liquids in the aquatic environment. An investigation was therefore undertaken into the toxicity of 1-alkyl-3-methylimidazolium ionic liquids towards the diatom Bacillaria paxilliferand the cyanobacterium Geitlerinema amphibium, species characteristic of the benthic environment. As in the first part of this study (A. Lataa, M. Ndzi and P. Stepnowski, Green Chem., 2009, 11, 580–588), five 1-alkyl-3-methylimidazolium chlorides (from ethyl to decyl) were chosen as the test kit compounds for examining the expected alkyl chain length effect, together with 1-butyl-3-methylimidazolium tetrafluoroborate, dicyanamide, trifluoromethanesulfonate and methyl sulfate and α-methyl[poly(oxy-1,2-ethanediyl)]sulfate for investigating the influence of anions on the toxicity of ionic liquids towards the algal species under investigation. A pronounced alkyl chain effect was found with both organisms. The results indicate that P. amphibiumis more sensitive than B. paxillifer.It was also found that the use of trifluoromethanesulfonate and dicyanamide as counteranions in the IL structure gave rise to the most pronounced toxic effects in comparison with the other anions tested. It is assumed that the greater toxicities of long alkyl chain ILs will most probably not pose a greater threat to benthic organisms, since these compounds will undergo rapid and very strong adsorption to sedimentary matter. Short-chain compounds, which are known to be reversibly bound to sediments, may still pose a significant risk to benthic ecosystems, however. [ABSTRACT FROM AUTHOR]