Aromatic Liquids Research Articles

A packed bed Reactor Combined with Membrane Unit for the Elimination of Toluene Vapours using a Novel Packing Material

Toluene is a colorless and aromatic oily liquid primarily used in the petrochemical and polymer processing industries and has been used in this study as the target compound. Continuous experiments were performed in a biofilter on a laboratory scale, followed by a membrane reactor to monitor toluene as one single contaminant. This bioreactor device included a reactor with a packed bed and a membrane array. Pearl millet stacks and berl saddles have been used as packing material for the development of the attached microorganism. Toluene was efficiently treated, with toluene effluent concentrations held at less than 0.4 g m-3 and a Total Removal Efficiency (TRE) of more than 96 % achieved when fluctuating loads were faced by the packed bed reactor. The combined packed bed reactor system had a maximum RE of 93.8 g m-3 h-1, which was higher than the one obtained with the packed bed reactor alone. In this work the influences on gas membrane separation were also explored in the combined bioreactor and membrane fouling.

Transport coefficients of model lubricants up to 400 MPa from molecular dynamics.

In this paper, the predictive power of molecular dynamics methods is demonstrated for the cases of model paraffinic and aromatic lubricant liquids at pressures up to 400 MPa. The shear viscosity and self-diffusion coefficients are calculated for 2,2,4-trimethylpentane (C8H18) at 298 K and 1,1-diphenylethane (C14H14) at 333 K. Three force fields with different levels of accuracy are compared by the ability to predict the experimental data. The Stokes-Einstein correlation between viscosity and self-diffusion is demonstrated for both compounds.

Assessment of coke deposits on lamellar metal-modified MFI zeolites in ethylene transformation to aromatic liquids

The effects of meso-/microporous structure and metal-additive (Ga or Zn) of lamellar MFI catalysts on the characteristics of coke deposits during ethylene-to-aromatic liquids conversion were investigated. The nature, composition, and location of coke deposits in spent lamellar catalysts were analyzed and compared to those on the microporous MFI counterparts, using FTIR, UV–Vis, GC–MS, and argon adsorption-desorption. The total amount of coke and the changes in coke nature during catalyst regeneration were studied by MS/FTIR combined with temperature programmed oxidation. The lamellar meso-/microporous structure of MFI reduces the coke quantity and the heavy coke fractions. The coke preferentially deposites on external surface of lamellar zeolite due to the lower diffusion limitation for bulky coke precursors. Metal-additive changes the catalyst acidity and decreases the coke formation rate, especially when zinc is used. Therefore, the coke formation on zeolite can be tuned by modulating the textural and acidity properties of the metal-modified catalyst.

Antifungal effects of essential oils against Aspergillus niger in vitro and in vivo on pomegranate (Punica granatum) fruits

Essential oils are aromatic oily liquids obtained from some aromatic plant materials. In the present study, the inhibitory effects of eucalyptus, galbanum, thymus, and clove essential oils against Aspergillus niger were tested at various concentrations (0, 200, 400, 600, and 800 μL. L−1) in in vitro and in vivo. The in vitro results showed that the growth of A. niger was completely inhibited by the application of clove oil at concentrations of 200, 400, 600, and 800 μL. L−1 on the first and tenth days as well as thyme application with concentrations of 800 μL. L−1 on the tenth day. The in vivo results indicated that treated fruits with thyme oil at a concentration of 800 μL. L−1 had the lowest weight loss in comparison to eucalyptus, galbanum, and clove oil. Furthermore, among essential oils, treated fruits with thyme essential oil (800 μL. L−1) had the highest firmness. The highest anthocyanin content was obtained with eucalyptus essential oil at 800 μL. L−1 concentration and lowest value were found at a galbanum control treatment. The soluble solids content reached 13.08°Brix at 400 μL. L−1 and in the control treatment the soluble solids content of fruit was significantly increased with 14.50°Brix. The most acidity was observed at eucalyptus and clove essential oil (800 μL. L−1) and the lowest values were recorded at control treatments of eucalyptus and galbanum. The highest TSS/TA of fruit juice in 800 μL. L−1 clove essential oil treatment and its lowest was obtained in the control treatments of eucalyptus and galbanum essential oils. This research confirms the antifungal effects of eucalyptus, galbanum, thymus, and clove essential oils both in vitro and in vivo on pomegranate fruits postharvest. Therefore, the present study suggests that the use of essential oils especially thymus and clove may be a useful alternative to the use of synthetic fungicides.

Enhanced extraction of phenol from model oils using ionic liquids elucidated with neutron diffraction.

Aromatic cation ionic liquids (ILs) based on alkylpyridiniums are shown to be good phenol extractants from model oils (hexane/toluene). ILs with hard basic anions are found to have best extraction efficiency consistent with tetraalkylammonium salts ([NR4]X). Key extraction interactions were analysed using small angle neutron diffraction. Trifluoromethanesulphonate ([OTf]- or triflate) anions provide the synergistic effects of reduced cation-phenol centre of mass (COM) distances and increased hydrogen bonding that are linked to the improved extraction efficiency. Increases in cation electron density (methylpyridinium ([Me-Py]+) vs. methylpicolinium ([Me-3-Pic]+)) also reduce cation-phenol COM interaction lengths consistent with small increases in extraction efficiency for the same ionic liquids.

Enhanced Electric Polarization and Polar Switching of Dipolar Aromatic Liquids Confined in Supramolecular Gel Networks.

Dipolar aromatic liquids confined in the interstitial domains of chiral organogels show significantly enhanced electric polarization, as compared with those of pure liquids alone or organogels formed with nonpolar liquids. Intriguingly, nitrobenzene gels showed a supramolecular polar switching phenomenon; i.e., hysteresis in the polarization (P)-electric field (E) curves was observed for the gel above the melting point of the solvent. This indicates that the nitrobenzene molecules confined in the chiral nanofibrous gel networks exert macroscopic polarization whose direction is inversed depending on the direction of the external electric field. The anomalously enhanced electric polarization and polar switching phenomenon of supramolecular gels in varied solvents are scrutinized by the positive-up-negative-down (PUND) measurements, and the interactions between the gel nanofibers and the polar solvent molecules play crucial roles for the emergence of the polar switching phenomenon. This work presents for the first time that dipolar liquid molecules filling the interstitial space of supramolecular gels exhibit a significant confinement effect. It provides a new perspective to design electric-field-responsive soft materials based on the functional liquid domains confined in their porous networks.

The mechanism study on aryl-substituted aromatic acid ionic liquid as the collector for quartz flotation

The mechanism study on aryl-substituted aromatic acid ionic liquid as the collector for quartz flotation

Delocalization of positive charge in aromatic liquids studied by subnanosecond near-infrared transient absorption spectroscopy

Transient absorption spectra of 1,2,4,5-tetracyanobenzene (TCNB) in aromatic liquids (benzene, toluene, m-xylene, and mesitylene) were measured in subnanosecond time resolution. Upon photoexcitation at 355 nm, exciplexes between TCNB and the aromatic liquids formed quickly, and we observed characteristic absorption bands due to a TCNB radical anion in the visible wavelength range and charge resonance (CR) absorption bands due to aggregate radical cations of the donor molecules in the near-IR wavelength range. The peak positions of the CR bands for the exciplexes differed significantly from those of the dimer radical cations of the corresponding donor molecules, indicating that positive charge was delocalized among more than two donor molecules. The TCNB radical anion decomposed efficiently within the lifetime of the exciplexes, and the positive charge remained in the aromatic liquids after the decomposition. Thus, we could observe CR bands due to positive charge (holes) in the aromatic liquids. From the peak positions of the CR bands, we were able to draw some conclusions regarding the delocalization of positive charge in aromatic liquids.

Essential oils of coriander and sage: Investigation of chemical profile, thermal properties and QSRR analysis

Essential oils (EOs) are aromatic oily liquids prepared from plant material. Many plants are rich in EOs, which usually consisted of different secondary metabolites such as terpenoids. The EOs or their components have been shown to exhibit antioxidant, antimicrobial, antiviral, antimycotic, antitoxigenic, antiparasitic and insecticidal properties, which is main reason for their ivenstigation. Coriander and sage essential oils, isolated by hydrodistillation, were analyzed using gas chromatography, differential scanning calorimetry and thermogravimetry techniques in order to correlate chemical composition and thermal behavior. Results showed that evaporation process of sage EO takes place in two steps, while coriander EO was evaporated in one step. The activation energy of the evaporation process of both EOs was in accordance to the evaporation enthalpy of dominant compounds in analyzed samples. The quantitative structure–retention relationship (QSRR) was employed to predict the retention time (RT) of essential oil compounds obtained by GC analysis, using five molecular descriptors selected by genetic algorithm. The selected descriptors were used as inputs of an artificial neural network (ANN), to build an RT predictive QSRR model. The coefficient of determination was 0.969, indicating that this model could be used for prediction of RT values for coriander and sage essential oil compounds.

Biochemical and Pharmacological Applications of Essential Oils in Human Health Especially in Cancer Prevention.

Essential oils (EOs) are aromatic, volatile and concentrated hydrophobic liquids extracted from plant material. EOs are also called as ethereal oils, volatile oils or aetherolea. EOs also play a crucial role in plant defence and signalling processes. They are mostly used in perfumes, cosmetics, soaps and other products for flavouring food, drinks, adding scents to incense and household cleaning products. EOs have a long medicinal history. Reported research literature and online contents related to the use of EOs for their biochemical pharmacological applications in cancer prevention therapy were reviewed. The most relevant and updated citations were included in this review. This review elaborates the various types of EOs, their biochemical characteristics, and pharmacology. Medicinal benefits of essential oil products range from various skin treatments to different types of therapies for cancer and are dependent entirely on historical backgrounds of use of EOs for these properties. EOs have antimicrobial, anticancer, antioxidant, antiparasitical, insecticidal, anti-inflammatory, viricidal, fungicidal, wound healing, antihypertensive, analgesic properties and other medicinal properties. The efficiency of EOs in medical treatments and treatment of cancers are these days a subject of interest in most countries. This review elaborated the potentials of EOs in regulating cancer cell growth and have explored the probable EOs that can be used in drug development.

Direct Observation of Carbon Nitride-Stabilized Pickering Emulsions.

Pickering emulsions are emulsions stabilized by solid particles located at surfaces/interfaces of liquid droplets that have promising applications for drug delivery and in nanomaterials synthesis. Direct observation of Pickering emulsions can be challenging. Normally, cryoelectron microscopy needs to be used to better understand these types of emulsion systems, but cryofreezing these emulsions may cause them to lose their original morphologies. In this work, we demonstrate that graphitic carbon nitride (g-C3N4) can stabilize oil-in-water (o/w) emulsions, with hexane illustrated as a typical oil phase. The g-C3N4-stabilized emulsions can act as an excellent platform for in situ study of emulsifying behavior from the mechanical point of view. Owing to its large lateral size and blue, stable fluorescence, the locations and motions of the g-C3N4 stabilizer can be finely in situ monitored by light microscopy, fluorescence microscopy, and confocal microscopy. Accordingly, we illustrate two stabilizing configurations of the g-C3N4 particles with respect to the emulsion droplets under static conditions. Further, we demonstrate the capability to manipulate emulsion droplets and investigate their response to external forces. We perform real-time observations of the g-C3N4 particles and the emulsion droplets that move in the continuous phase and study their adsorption kinetics toward each other. Finally, the π-π interaction between the stabilizer and aromatic liquid phase (e.g., toluene) is considered and studied as an influencing factor on emulsifying behavior.

Electroanalytical techniques applied to monitoring the electro-Fenton degradation of aromatic imidazolium-based ionic liquids

In this study, the degradation of the ionic liquid (IL) 1,3-dicyclohexylbenzimidazolium chloride ([DCy6bim][Cl]) was carried out by applying an heterogeneous electro-Fenton (HEF) treatment using iron alginate spheres (FeAS) as catalyst. Initial trials were performed at current between 50 and 250 mA, different FeAS dosages (1–5 g), and [DCy6bim][Cl] concentrations (70–280 mg L−1) as key parameters for the characterization of the HEF process. Comparative experiments suggest that high current, low FeAS dosage and low [DCy6bim][Cl] concentration are the best conditions to yield near complete total organic carbon decay after 4 h. In order to evaluate the catalyst behaviour and iron leaching during the degradation of [DCy6bim][Cl], differential pulse voltammetry (DPV), a sensitive and selective electroanalytical technique, was used to monitor the IL degradation, by-products and iron evolution into the solution at high concentration levels. The profile of the voltammetric curves obtained by DPV suggests almost complete cleavage of the cation structure of [DCy6bim][Cl] during the first 120 min. At longer treatment times, DPV revealed the generation of iron complex with chloride and carboxylic acids. Finally, chromatographic analysis of these carboxylic acids and inorganic anions permitted to validate the results obtained by DPV and demonstrated the feasibility of the HEF process for IL degradation.

Striking Similarities in the Fluorescence Behavior between Carbon Dots and Ionic Liquids: Toward Understanding the Fluorescence Behavior of Carbon Dots

Despite several studies, convincing explanation for the fluorescence of carbon dots (CDs) and its excitation wavelength dependence behavior has not yet emerged. It may be noted that direct structure–property correlation can be misleading based on solely transmission electron microscopy micrographs as it does not fully reveal the possibility of heterogeneous nature of the samples in a sense that it does not fully reveal the possibility of having both carbonaceous nanoparticles as well as small organic molecular-based systems. The present work is undertaken specifically to address this issue. A detailed spectroscopic investigation comprising steady-state absorption, emission, time-resolved fluorescence, and fluorescence correlation spectroscopy (FCS) studies has been carried out on CDs, synthesized from two different sources. Similar investigations have also been carried out on the systems such as aromatic and aliphatic ionic liquids (ILs), which are known to be fluorescent in their neat conditions. Interes...

On the behavior of imidazolium versus pyrrolidinium ionic liquids as extractants of phenolic compounds from water: Experimental and computational analysis

The main goal of this work is to compare the ability of aromatic and non-aromatic ionic liquids (ILs) as potential solvents to extract phenolic compounds from aqueous systems. Although these liquid salts have been widely studied in the separation of organic compounds, especially aromatic hydrocarbons such as benzene, toluene, ethylbenzene, and isomer xylenes, their application to separate phenols from wastewater is still much less widespread. For that reason, in this work, the extraction efficiency of phenolic compounds in molecular form (phenol, o-cresol, and resorcinol) from water using non-aromatic (1-hexyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide, [HMpyr][NTf2]) and aromatic (1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [HMim][NTf2]) ILs was analyzed and discussed. Firstly, the optimal operating conditions (stirring and settling time, and phase volume ratio Vionic liquid/Vwater) were stablished and then other variables such as initial phenol concentration and temperature were also studied. This work was performed through equilibrium distribution studies and the tracking of the concentration of phenol was carried out by absorbance measurements using a UV/visible spectrophotometer. In order to provide a better understanding of the effect of the cation nature (aromatic and non-aromatic) as well as the role of the phenolic structure on the extraction ability of the ILs, the quantum chemical COSMO –RS method was used to seek an explanation in terms of molecular interactions between the solvents and the phenolic compounds. Overall results support that the aromatic nature of cations does not seem to be the predominant factor driving the extraction process, with hydrogen bonding significantly contributing to competitive solute-solvent interactions which promote the transfer of the phenolic compounds from the aqueous phase to the IL phase.

Enhancement of 14C-phenanthrene mineralisation in the presence of plant-root biomass in PAH-NAPL amended soil

Investigations into the beneficial effects of the interaction between plants and soil microorganisms towards bioremediation of contaminated soil has been studied over the past 30 years. This subject has been summarized as the process where organic contaminants can be removed from the soil through the interaction between roots and catabolic microbial populations. This study assessed the tolerance of different plant species against polycyclic aromatic hydrocarbon-non aqueous phase liquid (PAH-NAPL) contaminated soil and the feasibility of the use of their root biomass to promote the biodegradation of 14C-phenanthene. Toxicity results showed that seeds germination was not affected by the presence of PAHs. Furthermore, mineralisation of 14C-phenanthrene was significantly enhanced by the addition of root biomass after at least two weeks incubation. Moreover, bacterial numbers did not show a significant relationship with 14C-phenanthrene mineralisation. Results showed that the higher mineralisation of 14C-phenanthrene is not related to an increase on the microbial numbers as is normally assumed.

Effect of essential oil supplement on milk yield and composition of lactating dairy cows

Essential oils (EO), an important group of plant extracts, which are concentrated extracts of aromatic oily liquids from various plant materials obtained by steam distillation. Plant-derived EO is a useful means to improve efficiency of nutrient utilization in ruminants and reduce the impact of their production on the environment. In recent years, more research has been directed toward evaluating the potential of EO to improve performance in dairy cows but according to the results the effect of EO on milk production is not consistent. Therefore, the study evaluated the effects of supplementing a mixture of EO (oregano, thyme, citrus, cinnamon, ginger, curcuma, pepper and an organic carrier) in the diet of lactating Holstein Friesian dairy cows (n=46) in late lactation on the intake, milk yield and composition in a dairy farm experiment. The average DIM at the start of the experiment was 156 days. Experimental treatments consisted of a mixture of EO (2 g cow-1 day-1) inclusion in a total mixed ration. There was a 3-week long preliminary and a 7-week long experimental period in the trial. Milk production was recorded every day. Chemical analyses were made from the morning milked samples once a week. Supplementation of dairy cows with mixture of EO significantly (P<0.05) increased the dry matter intake (control: 26.9±1.49 kg DM day-1 vs. experimental: 27.3±0.95 kg DM day-1) but had no effect on milk production (control: 38.3±4.99 kg vs. experimental: 37.9±4.93 kg) and milk composition (fat, protein, lactose). Results show that an intake of 2 g cow-1 day-1 mixture of EO may increase the feed intake but does not influence milk yield and composition in late lactation.

Biodegradation of representative ignitable liquid components on soil

A mixture containing 14 hydrocarbons representing six distinct compound types (e.g. normal alkanes, branched alkanes, cyclic alkanes, aromatics, polynuclear aromatics, and oxygenates) was deposited onto ninety grams of potting soil and allowed to remain for specified periods of time. Hydrocarbons remaining at the end of each time period were extracted by passive headspace concentration and analyzed by gas chromatography-mass spectrometry. No byproducts were observed to be formed or accumulate during biodegradation in this study. There was sizable loss of oxygenated compounds, normal alkanes, and toluene compared to poly-substituted aromatics, polynuclear aromatics, branched alkanes, and cyclic alkanes. The half-life for the cumulative loss of all components of the hydrocarbon mixture was calculated to be 3.15days. A half-life as short as 1.75days was determined for the integrated loss of a commercial ignitable liquid from the ASTM E1618 aromatic class ignitable liquid.

Effect of aromatic/aliphatic based ionic liquids on the phase behavior of methane hydrates: Experiments and modeling

Abstract In this study, eight ionic liquids (ILs) from the two varieties of ILs, namely, aromatic and aliphatic ILs, have been considered to carry out experimental studies for their effect on the phase behavior of methane hydrate. We have employed five aromatic based ILs with several cations, such as 1-butyl-3-methyl imidazolium, 1-hexyl-3-methyl imidazolium, 1-octyl-3-methyl imidazolium and various anions, such as [Cl]−, [Br]−, [HSO4]−, and three aliphatic based ILs with various cations, such as di-ethyl-ammonium, tri-propyl-ammonium, tri-butyl-ammonium and [HSO4]− anion. All the experiments were performed in the hydrate equilibrium pressure and temperature ranges of 3.86–7.66 MPa and 276.68–283.18 K, respectively. It has been observed that all the investigated ILs have shown inhibition effect on methane hydrate system. Aromatic ionic liquids have shown their dominance over aliphatic ionic liquids in terms of methane hydrate inhibition. ILs with similar class of cation with varying carbon chain length have not shown significant improvement in hydrate inhibition. However, the replacement of anion by [HSO4]− in imidazolium-based ILs improves methane hydrate inhibition. 1-butyl-3-methyl imidazolium sulphate ([BMIM]+[HSO4]−) found to be the best methane hydrate inhibitor among all investigated ILs. In addition, a phase behavior model incorporating a single tuning parameter has been proposed to predict the phase behavior of methane hydrate in the presence of various ionic liquids and salt solutions. The absolute average deviation in pressure (AARD-P, %) for proposed model with an experimental data generated in this work and for various data sets from the literature has been found to be within ±2.90% of the experimental values. Both cation and anion of the ionic liquids have shown to exhibit inhibition effect on the methane hydrate phase stability. The study indicates that the selection of ionic liquids with tunable cation and anion may provide an opportunity to design the best inhibitor for methane hydrate.

Effects of essential oil (blended and single essential oils) on anti-biofilm formation of Salmonella and Escherichia coli

BackgroundBiofilms were the third-dimensional structure in the solid surface of bacteria. Bacterial biofilms were difficult to control by host defenses and antibiotic therapies. Escherichia coli (E. coli) and Salmonella were popular pathogenic bacteria that live in human and animal intestines. Essential oils are aromatic oily liquids from plant materials and well known for their antibacterial activities.MethodThis study was conducted to determine effect of essential oil on anti-biological biofilm formation of E. coli and Salmonella strains in in vitro experiment. Two kinds of bacterial strains were separated from 0.2 g pig feces. Bacterial strains were distributed in 24 plates per treatment and each plates as a replication. The sample was coated with a Bacterial biofilm formation was.ResultPhotographic result, Escherichia coli (E. coli) and Salmonella bacteria colony surface were thick smooth surface in control. However, colony surface in blended and single essential oil treatment has shown crack surface layer compared with colony surfaces in control.ConclusionIn conclusion, this study could confirm that essential oils have some interesting effect on anti-biofilm formation of E. coli and Salmonella strains from pig feces.

Chromatographic and spectroscopic studies on β-cyclodextrin functionalized ionic liquid as chiral stationary phase: Enantioseparation of NSAIDs

Recently, we reported a new chiral stationary phase prepared using β-cyclodextrin functionalized with aromatic ionic liquid which is aimed to enhance the performance of enantioseparation of flavonoids and β-blockers. In this paper, the characteristics and performance of previously prepared chiral stationary phase denoted as β-CD-BIMOTs were compared with the newly synthesized chiral stationary phase denoted as β-CD-DIMOTs. β-CD-DIMOTs were prepared by functionalization of β-cyclodextrin with aliphatic ionic liquid. The obtained β-CD-BIMOTs and β-CD-DIMOTs stationary phases were compared with native β-CD stationary phase for the enantioseparation of non-steroidal anti-inflammatory drugs (NSAIDs) (ibuprofen, indoprofen, ketoprofen and fenoprofen). The β-CD-BIMOTs stationary phase showed greater chiral resolution capabilities rather than β-CD-DIMOTs and native β-CD stationary phases. Further, in order to understand the interaction of enantioseparation, the inclusion complex formation between NSAIDs and β-CD-BIMOTs was studied using 1H NMR, NOESY and UV/Vis. The enantioseparated NSAIDs were found to form multiple interactions with β-CD-BIMOTs-CSP.