Marina Cvjetko Bubalo

A brief overview of the potential environmental hazards of ionic liquids.

Over past decades ionic liquids, a promising alternative to traditional organic solvents, have been dramatically expanding in popularity as a new generation of chemicals with potential uses in various areas in industry. In the literature these compounds have often been referred to as environmentally friendly; however, in recent years the perception of their greenness dramatically changed as the scientific community began to proactively assess the risk of their application based on the entire life-cycle. This review gives a brief overview of the current knowledge regarding the potential risks linked to the application of ionic liquids - from preparation to their disposal, with special emphasis on their potential environmental impacts and future directions in designing inherently safer ionic liquids.

Imidiazolium based ionic liquids: Effects of different anions and alkyl chains lengths on the barley seedlings

We studied the effects of five imidiazolium based ionic liquids with different anions and length of alkyl chains linked to imidazolium ring on the early development of barley (Hordeum vulgare). The inhibitory effect depends on the ionic liquids concentration and chemical structure, whereby the most toxic one was [C10mim][Br], followed by [C7mim][Br], [C4mim][Br], [C4mim][CH3CO2] and [C4mim][BF4]. Both anion and cation structures affected the toxicity of ionic liquid indicating that selection of more biocompatible anions such as [CH3CO2] does not necessarily indicate lower toxicity. Alternation in the extent of oxidative stress and antioxidant enzymes activities were found in barley plants due to ionic liquid treatments. When seedlings were exposed to higher concentrations of ionic liquids, antioxidant system could not effectively remove reactive oxidative species, leading to lipid peroxidation and damage of the photosynthetic system. However, overall data indicated that the performance of barley seedling was improved when all measured enzymes involved in scavenging of reactive oxygen species (ROS) were increased with special emphasis on GPX activities. Since there are no studies about ionic liquid (IL) toxicity in plants, that simultaneously evaluates the antioxidative enzyme system in response to different ILs, this work is valuable for gaining knowledge about the protection mechanism of plants from oxidative stress caused by IL exposure.

Green extraction of grape skin phenolics by using deep eutectic solvents.

Conventional extraction techniques for plant phenolics are usually associated with high organic solvent consumption and long extraction times. In order to establish an environmentally friendly extraction method for grape skin phenolics, deep eutectic solvents (DES) as a green alternative to conventional solvents coupled with highly efficient microwave-assisted and ultrasound-assisted extraction methods (MAE and UAE, respectively) have been considered. Initially, screening of five different DES for proposed extraction was performed and choline chloride-based DES containing oxalic acid as a hydrogen bond donor with 25% of water was selected as the most promising one, resulting in more effective extraction of grape skin phenolic compounds compared to conventional solvents. Additionally, in our study, UAE proved to be the best extraction method with extraction efficiency superior to both MAE and conventional extraction method. The knowledge acquired in this study will contribute to further DES implementation in extraction of biologically active compounds from various plant sources.

Cytotoxicity towards CCO cells of imidazolium ionic liquids with functionalized side chains: Preliminary QSTR modeling using regression and classification based approaches

Within this work we evaluated the cytotoxicity towards the Channel Catfish Ovary (CCO) cell line of some imidazolium-based ionic liquids containing different functionalized and unsaturated side chains. The toxic effects were measured by the reduction of the WST-1 dye after 72 h exposure resulting in dose- and structure-dependent toxicities. The obtained data on cytotoxic effects of 14 different imidazolium ionic liquids in CCO cells, expressed as EC50 values, were used in a preliminary quantitative structure-toxicity relationship (QSTR) study employing regression- and classification-based approaches. The toxicity of ILs towards CCO was chiefly related to the shape and hydrophobicity parameters of cations. A significant influence of the quantum topological molecular similarity descriptor ellipticity (ε) of the imine bond was also observed.

Comparative in vitro study of cholinium-based ionic liquids and deep eutectic solvents toward fish cell line

With the advent of ionic liquids, much was expected concerning their applicability as an alternative to organic solvents in the chemical technology and biotechnology fields. However, the most studied and commonly used ionic liquids based on imidazolium and pyridinium were found not to be as environmentally friendly as it was first expected. Therefore, a new generation of alternative solvents named natural ionic liquids and deep eutectic solvents, composed of natural and/or renewable compounds, have come into focus in recent years. Since the number of newly synthesized chemicals increases yearly, simple and reliable methods for their ecotoxicological assessment are necessary. Permanent fish cell lines can serve as a test system for the evaluation of a chemicals cytotoxicity. This paper presents research results on the cytotoxic effects on Channel Catfish Ovary (CCO) cell line induced by fifteen cholinium-based ionic liquids and deep eutectic solvents. Based on the decrease in cell viability, the most obvious toxic effect on CCO cells was caused by ionic liquid choline oxalate, while other solvents tested exhibited low cytotoxicity. Therefore, we can conclude that cholinium-based ionic liquids and deep eutectic solvents are comparatively less toxic to CCO cells than conventional ionic liquids.

Toxicity mechanisms of ionic liquids

Abstract Over the past three decades a growing awareness of environmental protection prompted the development of so-called green and sustainable technologies. Therefore, academic and wider community intensively explores new chemicals and safer, more energy efficient processes based on a rational compromise between economic, social, and environmental requirements. Due to low volatility and stability, ionic liquids emerged as a potential replacement for traditional volatile and harmful organic solvents. Various studies have been carried out to validate the green character of ionic liquids, whereby data published suggest that these compounds, due to their relatively high toxicity and poor biodegradability, could have an extremely negative impact on the environment. This paper presents the current knowledge on the toxicity of ionic liquids, with a special emphasis on the mechanisms by which this group of compounds causes changes in the morphology and physiology of organisms at different organisational levels of the ecosystem.

Antimicrobial, cytotoxic and antioxidative evaluation of natural deep eutectic solvents

Natural deep eutectic solvents (NADES) are a new generation of green solvents. They are mixtures of two or three compounds such as choline chloride as a cationic salt and alcohols, acids, amides, amines or sugars as hydrogen-bond donors. Although the majority of NADES’ components are of natural origin and therefore NADES are often presumed to be non-toxic, the evaluation of their toxicity and biodegradability must accompany the research on their synthesis and application. Therefore, the aim of this work was to investigate the effect of ten synthesised NADES towards bacteria (i.e., Escherichia coli, Proteus mirabilis, Salmonella typhimurium, Pseudomonas aeruginosa, Staphylococcus aureus), yeast (i.e., Candida albicans) and human cell lines (i.e., HeLa, MCF-7 and HEK293T). In addition, oxygen radical absorbance capacity (ORAC) method was used to determine the antioxidative activity of the tested NADES. Differences in toxicity response between microorganisms and cell lines were observed, and only NADES that contained organic acid showed toxicity towards the test systems. Furthermore, the NADES containing compounds that possess antioxidative activity also showed antioxidative activity. However, research whose primary purpose is the synthesis and application of NADES must be followed by an evaluation of their biological properties (e.g., antimicrobial activity, toxicity towards animal cells and antioxidative or other biological activity) to find the solvent with the best profile for wider industrial applications.

Extraction of Proanthocyanidins and Anthocyanins from Grape Skin by Using Ionic Liquids

In this study, eight different types of imidazolium-based ionic liquids (ILs) were applied as new solvents in the extraction of flavonoids from grape skin, and compared to the conventional organic solvent extraction that was not reported earlier. The structure of anions, cations and concentration of ILs significantly affected extraction yields. The highest mass fractions of proanthocyanidins and anthocyanins were obtained with 2.5 mol/L of 1-butyl-3-methylimidazolium bromide [C4mim][Br] and 2.5 mol/L of 1-ethyl-3-methylimidazolium bromide [C2mim][Br], respectively. The studied ILs provided an excellent preliminary result in the extraction of anthocyanins. Significantly higher mass fractions of total and all free anthocyanins were extracted with 2.5 mol/L of [C2mim][Br] and 2.5 mol/L of 1-methylimidazolium hydrogen sulfate [mim][HSO4] than with conventional solvent with the exception of anthocyanin-3-O-acetylmonoglucosides in the latter. On the other hand, 2.5 mol/L of [C4mim][Br] and 2.5 mol/L of 1-(4-sulfobutyl)-3-methylimidazolium hydrogen sulfate [sC4mim][HSO4] showed significantly higher selectivity towards anthocyanin-3-O-acetylmonoglucosides and anthocyanin-3-(6-O-p-coumaroyl)monoglucosides.

Green solvents for green extraction of biologically active compounds

I this study, decontamination and detoxification effects of non-thermal atmospheric pressure and low-pressure plasma systems were investigated on hazelnuts artificially contaminated with 7.9±0.06 log (CFU/mL) of Aspergillus parasiticus (A. parasiticus) and 7.8±0.06 log (CFU/mL) of Aspergillus flavus (A. flavus) spores. Different plasma parameters for atmospheric plasma (plasma frequency: 16-20-25 kHz, reference voltage: 40-100, plasma jet velocity: 50-100 m/min, gas flow rate: 3000-5000 L/h, raster offset: 3-5 mm, cycle time: 5, temperature, gases: high purity air or nitrogen) and low-pressure plasma (treatment time, gases: high purity oxygen, air or nitrogen) were tested for decontamination purposes. Optimum parameters for both plasma systems were determined according to remained viable spores counted after plasma treatments. Additionally, the effects of optimum plasma conditions on different concentration of aflatoxin B1(1-1000 ppb) and total aflatoxins (B1+B2, 1-1000.39 ppb) were also determined and compared with the effect of gamma radiation (10 kGY Cobalt-60 for 10 min). Improved spore inactivation of 5.6 and 4.7 log (CFU/mL) in A. paraciticus and A. flavus, respectively were achieved after 100 W-30 min of low pressure plasma treatment by using air as the plasma forming gas. Similarly, 5.5 and 5.4 log (CFU/mL) in A. paraciticus and A. flavus, respectively, were achieved after atmospheric pressure air plasma at 100 voltages, 25 kHz frequency, 3000 L/h flow rate, 60 m/min plasma jet velocity, 3 mm raster off set and 5 cycle time. 89-90% of AFB1 reduction was achieved when 10-50 ppm of pure AFB1 was treated with low-pressure air plasma at optimum conditions. On the other hand, highest AFB1 reduction of 75 % was achieved when 50 ppb of AFB1 was treated atmospheric pressure air plasma at optimum conditions.A common problem encountered in the use of grain sorghum is the milling process before the seeds can be used as food, feed or others. Milling aims to remove layers of sorghum pericarp and testa layer contains tannin from the endosperm. The layer can reduce protein digestibility in the stomach and the feeling of constipation. Institute for Agricultural Technology (BPTP East Java in cooperation with Indonesian Center for Agricultural Engineering Research and Development (ICAERD) Serpong, Banten) have developed a simple sorghum polishing machine with a diesel engine and abrasive stones type with a working capacity of 50-100 kg/hour. The purpose of this activity is to design the prototype machine polishing grain sorghum with the main objectives, namely: (i) Develop a milling system with a stone abrasive; (ii) Produce sorghum with the appearance of an intact form and bright colors. The design of sorghum polishing machine is done with the method and stage activities are divided into: the preparation stage, the stage of fabrication, testing, and reporting stage. The test results showed that the optimum milling capacity (2 × milling) is 100 kg/hour with tannin content of 0.09% and 3-5% broken grains and whiteness reached 44.66% (whole bean and bright appearance).S and their properties are playing an increasingly significant role in the industrial application. In general, materials are used according to their property requirements such as elasticity, strength, heat resistance or to meet other requirements such as corrosion resistance. However, traditional surfaces are often not able to meet the ever-increasing demands of today ́s applications in automotive, textile, medical and food industry. Thus, in recent years, advances have been made using functional coatings to exceed limitations of material to make surfaces more attractive for specific industry applications. Hygienic and efficient automation technologies are key aspects of a successful production process for example in the food and beverage industry. Requirements regarding the clean ability and durability of surfaces that are in food contact are key factors. The approach of this study was to design functional surfaces with easy to clean and/ or self-cleaning coatings that enable automation components to be easily or less cleaned. For coating procedure, physical vapor deposition was carried out to facilitate separation of the vaporized coating material to the substrate. Substrates used are aluminum, stainless steel, and plastics, for example, polyamide or polyethylene. Analytical descriptions of surface characteristics were performed using scanning electron microscopy, contact angle, and roughness. Different surfaces were successfully coated with easy to clean coatings and characterized analytically. In addition, a coating of automation components consisting of varied materials was realized and coating adhesion was improved. First application tests showed a clear improvement of material properties relating to chemical resistance and clean ability compared to today’s standard materials used.

Hyperspectral imagery as a supporting tool in precision irrigation of karst landscapes

This research was carried out in an experimental vineyard grown in artificially transformed karst terrain (Croatia). The experimental design included four water treatments in three replicates: 1) fully watered or based on 100% evapotranspiration (ETc) application; 2) regulated deficit irrigation based on 75% and 50% ETc applications; and 3) non-watered. Hyperspectral images of grapevines were taken in the summer of 2016 using two spectral-radiance (W·sr −1 ·m −2 ) calibrated cameras, covering wavelengths from 409 to 988 nm and 950 to 2509 nm. The four treatments were grouped into two new sets: 1) drought (NO); and 2) watered (the remaining three treatments). The watered group was then split into two new sets: 1) 50% treatment; and 2) 75+100% treatment. The images were analyzed using Partial least squares – discriminant analysis (PLS-DA), and Single Vector Machines (SVM). The PLS-DA demonstrated the capability to determine levels of grapevine drought or watered groups with 70 - 80% accuracy. A similar success rate was achieved in distinguishing the 50% group from the 75+100% group.