Tetrabutylphosphonium Bromide Research Articles

Demulsification of water in crude oil emulsions via phosphonium-based ionic liquids: Statistical modeling and optimization

In the present study, the performance of two ionic liquids namely Tetrabutylphosphonium bromide (TBPB) and Tetraoctylphosphonium bromide (TOPB) as the demulsifying compounds are investigated in the demulsification operation of water in light and medium crude oil emulsions for the first time. The response surface methodology (RSM) is employed to evaluate the impact of temperature, pH, water content, demulsifier concentration, and settling time on the demulsification efficiencies of studied demulsifiers. In order to design the requisite experiments and optimize the effective factors on the water removal efficiency, the central composite design (CCD) is applied. To determine the optimal conditions of input parameters, four exact models are created by utilizing the responses of 184 experiments to predict the demulsification efficiencies of two demulsifiers for two types of crude oils based on statistical tests of different models using the analysis of variance (ANOVA). High R2 coefficient values imply that the developed models could reproduce the experimental results of the studied demulsifiers appropriately. At the optimal conditions, the water in light and medium crude oil emulsions are completely broken in the samples containing TOPB. Moreover, TBPB agent presents high and acceptable demulsification efficiencies for both types of crude oils at the optimal values of process parameters i.e. 98.078% and 96.025% for light and medium crude oil emulsions, respectively. The superior demulsification performance of TOPB with respect to TBPB can be ascribed to the longer alkyl chain length of TOPB.

Deep Eutectic Solvent + Water System in Carbon Dioxide Absorption.

In the present work, deep eutectic solvents (DESs) were synthesized in a one-step process by heating the hydrogen bond acceptors (HBAs) tetrabutylammonium bromide and tetrabutylphosphonium bromide, along with two hydrogen bond donors (HBDs) ethanolamine and N-methyldiethanolamine, which were mixed in certain molar ratios. This mixture was then mixed with water to form a DES + water system. The densities of the prepared DES + water systems were successfully measured using the U-tube oscillation method under atmospheric pressure over a temperature range of 293.15-363.15 K. The CO2 trapping capacity of the DES + water systems was investigated using the isovolumetric saturation technique at pressures ranging from 0.1 MPa to 1 MPa and temperatures ranging from 303.15 K to 323.15 K. A semi-empirical model was employed to fit the experimental CO2 solubility data, and the deviations between the experimental and fitted values were calculated. At a temperature of 303.15 K and a pressure of 100 kPa, the CO2 solubilities in the DES + water systems of TBAB and MEA, with molar ratios of 1:8, 1:9, and 1:10, were measured to be 0.1430 g/g, 0.1479 g/g, and 0.1540 g/g, respectively. Finally, it was concluded that the DES + water systems had a superior CO2 capture capacity compared to the 30% aqueous monoethanolamine solution commonly used in industry, indicating the potential of DES + water systems for CO2 capture.

Enhanced corrosion protection of the ionic liquid doped-polypyrrole/MWCNT composite coating on stainless steel

Composite coatings were deposited on type of 430 stainless steel (SS) by one-step electrochemical process by adding Tetra Butyl Phosphonium Bromide (TBPB) ionic liquid and Multi-Walled Carbon Nanotube (MWCNT) to the sulfuric acid-polypyrrole medium. The coating conditions were optimised by changing potential range, scan rate and number of cycles. The protectivity of all polypyrrole/TBPB and polypyrrole/TBPB-MWCNT composite coatings was investigated in NaCl (3.5%) and 0.5 M sulfuric acid solution. The composite electrode prepared in 0.02 M TBPB and 5.0 mg MWCNT medium was found to be the best protective coating. Electrochemical measurements were performed by using potentiodynamic polarization (PDP) and electrochemical-impedance-spectroscopy (EIS) techniques. Althougt the corrosion protection efficiency of the coating was higher than its initial value in both media during long-term immersion until 504 h, the steel coated with the polypyrrole/TBPB/MWCNT composite was represented more protective efficiency in H2SO4 compared to NaCl solution.

A general strategy for recycling polyester wastes into carboxylic acids and hydrocarbons

Chemical recycling of plastic wastes is of great significance for sustainable development, which also represents a largely untapped opportunity for the synthesis of value-added chemicals. Herein, we report a novel and general strategy to degrade polyesters via directly breaking the Calkoxy-O bond by nucleophilic substitution of halide anion of ionic liquids under mild conditions. Combined with hydrogenation over Pd/C, 1-butyl-2,3-dimethylimidazolium bromide can realize the deconstruction of various polyesters including aromatic and aliphatic ones, copolyesters and polyester mixtures into corresponding carboxylic acids and alkanes; meanwhile, tetrabutylphosphonium bromide can also achieve direct decomposition of the polyesters with β-H into carboxylic acids and alkenes under hydrogen- and metal-free conditions. It is found that the hydrogen-bonding interaction between ionic liquid and ester group in polyester enhances the nucleophilicity of halide anion and activates the Calkoxy-O bond. The findings demonstrate how polyester wastes can be a viable feedstock for the production of carboxylic acids and hydrocarbons.

Combined Use of Ionic Liquid-Based Aqueous Biphasic Systems and Microfluidic Devices for the Detection of Prostate-Specific Antigen.

Prostate cancer (PCa) is one of the cancer types that most affects males worldwide and is among the highest contributors to cancer mortality rates. Therefore, there is an urgent need to find strategies to improve the diagnosis of PCa. Microtechnologies have been gaining ground in biomedical devices, with microfluidics and lab-on-chip systems potentially revolutionizing medical diagnostics. In this paper, it is shown that prostate-specific antigen (PSA) can be detected through an immunoassay performed in a microbead-based microfluidic device after being extracted and purified from a serum sample through an aqueous biphasic system (ABS). Given their well-established status as ABS components for successful bioseparations, ionic liquids (ILs) and polymers were used in combination with buffered salts. Using both IL-based and polymer-based ABS, it was demonstrated that it is possible to detect PSA in non-physiological environments. It was concluded that the ABS that performed better in extracting the PSA from serum were those composed of tetrabutylammonium chloride ([N4444]Cl) and tetrabutylphosphonium bromide ([P4444]Br), both combined with phosphate buffer, and constituted by polyethylene glycol with a molecular weight of 1000 g/mol (PEG1000) with citrate buffer. In comparison with the assay with PSA prepared in phosphate-buffered saline (PBS) or human serum in which no ABS-mediated extraction was applied, assays attained lower limits of detection after IL-based ABS-mediated extraction. These results reinforce the potential of this method in future point-of-care (PoC) measurements.

Performance evaluation of phosphonium based deep eutectic solvents coated cerium oxide nanoparticles for CO2 capture

The critical challenge being faced by our current modern society on a global scale is to reduce the surging effects of climate change and global warming, being caused by anthropogenic emissions of CO2 in the environment. Present study reports the surface driven adsorption potential of deep eutectic solvents (DESs) surface functionalized cerium oxide nanoparticles (CeNPs) for low pressure CO2 separation. The phosphonium based DESs were prepared using tetra butyl phosphoniumbromide as hydrogen bond acceptor (HBA) and 6 acids as hydrogen bond donors (HBDs). The as-developed DESs were characterized and employed for the surface functionalization of CeNPs with their subsequent utilization in adsorption-based CO2 adsorption. The synthesis of as-prepared DESs was confirmed through FTIR measurements and absence of precipitates, revealed through visual observations. It was found that DES6 surface functionalized CeNPs demonstrated 27% higher adsorption performance for CO2 capturing. On the contrary, DES3 coated CeNPs exhibited the least adsorption progress for CO2 separation. The higher adsorption performance associated with DES6 coated CeNPs was due to enhanced surface affinity with CO2 molecules that must have facilitated the mass transport characteristics and resulted an enhancement in CO2 adsorption performance. Carboxylic groups could have generated an electric field inside the pores to attract more polarizable adsorbates including CO2, are responsible for the relatively high values of CO2 adsorption. The quadruple movement of the CO2 molecules with the electron-deficient and pluralizable nature led to the enhancement of the interactive forces between the CO2 molecules and the CeNPs decorated with the carboxylic group hydrogen bond donor rich DES. The current findings may disclose the new research horizons and theoretical guidance for reduction in the environmental effects associated with uncontrolled CO2 emission via employing DES surface coated potential CeNPs.

Density Functional Theory Study of the Molecular Interaction between Selective Phenolic Compounds and Glycerol-Based Deep Eutectic Solvents

In this work, the global scalar properties, including the highest occupied orbital energy (HOMO), lowest unoccupied orbital energy (LUMO), global softness (S), hardness (η), electronegativity (χ), and electrophilicity index (ω) of the different salts of choline chloride [CHCL], tetra butyl ammonium bromide [TBAB], tetra methyl ammonium chloride [TMAC], tetra butyl phosphonium bromide [TBPB], tetra butyl ammonium chloride [TBAC] with glycerol [GLY], and these different combinations of deep eutectic solvents (DESs) with cardanol, were predicted using density functional theory in Gaussian 03 software (DFT theory). Furthermore, the sigma profile and sigma potential of all the studied DESs, technical cashew nut shell liquid (Tech.CNSL), natural cashew nut shell liquid (Natural.CNSL), and their phenolic compounds such as anacardic acid, cardanol, cardol, and 2-methyl cardol were generated using COSMO-RS model in COSMOThermX software in order to understand the molecular behavior of different salt combinations with glycerol for the removal of phenolic compounds from their mixtures in CNSL without affecting the individual compound structural configuration at the molecular level. Finally, the best DES was screened for the removal of selective phenolic compounds of cardanol from CNSL via the DES-based extraction process.

Effects of the Structure of Benzenesulfonate-Based Draw Solutes on the Forward Osmosis Process.

A series of phosphonium-based ionic liquids (ILs) based on benzenesulfonate derivatives (tetrabutylphosphonium benzenesulfonate ([TBP][BS]), tetrabutylphosphonium 4-methylbenzenesulfonate ([TBP][MBS]), tetrabutylphosphonium 2,4-dimethylbenzenesulfonate ([TBP][DMBS]), and tetrabutylphosphonium 2,4,6-trimethylbenzenesulfonate ([TBP][TMBS])) were synthesized via anion exchange with tetrabutylphosphonium bromide ([TBP][Br]). Then, we characterized the ILs and investigated their suitability as draw solutes for forward osmosis (FO), focusing on their thermoresponsive properties, conductivities, and osmotic pressures. We found that aqueous [TBP][BS] was not thermoresponsive, but 20 wt% aqueous [TBP][MBS], [TBP][DMBS], and [TBP][TMBS] had lower critical solution temperatures (LCSTs) of approximately 41, 25, and 21 °C, respectively, enabling their easy recovery using waste heat. Based on these findings, 20 wt% aqueous [TBP][DMBS] was tested for its FO performance, and the water and reverse solute fluxes were found to be approximately 9.29 LMH and 1.37 gMH, respectively, in the active layer facing the draw solution (AL-DS) mode and 4.64 LMH and 0.37 gMH, respectively, in the active layer facing the feed solution (AL-FS) mode. Thus, these tetrabutylphosphonium benzenesulfonate-based LCST-type ILs are suitable for drawing solutes for FO process.

(Digital Presentation) Phosphonium Salts As Potential Guest Substances for Ionic Semiclathrate Hydrates

Semiclathrate hydrates (SCHs) are ionic crystalline compounds consisting of an organic guest cation in several cages formed by hydrogen bonding of water1. SCHs have recently been considered for application to air conditioning systems and refrigeration systems since desirable equilibrium temperatures and the considerable decomposition enthalpies are observed in the solid-liquid equillibria2. Ionic guest substances of SCHs include quaternary onium compounds such as tetrabutylammonium2 and tetrabutylphosphonium based salts3. We report here the preparation and thermodynamic properties of SCHs based on quaternary phosphonium bromides containing an unsaturated carbon-carbon double bond, as shown in Fig. 1, in comparison with the conventional saturated phosphonium salt, such as tetrabutylphosphonium bromide (P4444-Br).The unsaturated phosphonium bromides (P444(1All)-Br and P444(2All)-Br) were synthesized by quaternarization reaction of tributylphosphine with alkenyl bromides in a nitrogen atmosphere. The aqueous solutions were prepared from 5 to 50 w/w %. After thorough stirring, the aqueous solutions were cooled in a freezer to form SCHs. The SCHs were immersed into a thermostatic bath at 268 K for at least 1 day. The temperature in the thermostatic bath was raised from 268 K at a rate of 0.1 K/step (1 step: more than 5 h). The equilibrium temperatures were defined as the temperature at which SCHs were completely dissolved. The ionic crystal structure was analyzed by a powder X-ray diffraction (PXRD) technique, the dissociation enthalpy was measured by a micro differential scanning calorimeter (μDSC).Fig. 2 depicts the solid-liquid phase equilibrium diagram representing the phase equilibrium temperatures of SCHs. The equilibrium temperature of P444(1All)-Br SCH was higher than P4444-Br SCH. These results might be due to the steric effect of alkenyl group. As shown in Fig. 3, the ionic crystal structure of both P444(1All)-Br and P444(All)-Br SCHs were orthorhombic. The dissociation enthalpy of P444(1All)-Br SCHs and P444(2All)-Br SCHs were 188 J/g and 199 J/g, respectively. The unsaturated phosphonium bromides would be regarded as potential guest substances used for latent heat storage materials in air conditioning systems.References M. Oshima, et al, J. Chem. Thermodynamics, 90, 277 (2015).H. Oyama, et al, Fluid Phase Equilibria, 234, 131 (2005).J. Shimada, et al, Chem. Eng. Sci., 236, 116514 (2021). Figure 1

Mechanism of Extractive Separation of Light Cycle Oil Using a Deep Eutectic Solvent Composed of Tetrabutylphosphonium Bromide and Levulinic Acid

To achieve maximum usage and economically upgrade light cycle oil, it is necessary to separate light cycle oil components into nonaromatic and aromatic fractions. A deep eutectic solvent composed of tetrabutylphosphonium bromide and levulinic acid exhibited excellent extraction performance in separating light cycle oil components. In this work, the mechanisms of deep eutectic solvent formation and light cycle oil separation are investigated using characterization analysis and molecular dynamics simulations. Both Fourier-transform infrared spectra and molecular dynamics simulation results indicate that the main driving force for deep eutectic solvent formation is hydrogen-bonding interactions between the Br– anion of tetrabutylphosphonium bromide and the carboxyl group (−COOH) of levulinic acid. On the other hand, while the TBP+ cation of tetrabutylphosphonium bromide and the carbonyl group (−C═O) of levulinic acid are less likely to contribute to deep eutectic solvent formation, they are more likely to interact with the aromatic ring of tetralin via CH−π and π–π interactions, respectively. The results suggest that each functional group of tetrabutylphosphonium bromide and levulinic acid plays an essential role either in deep eutectic solvent formation or in aromatic compound extraction, which provides insights into the mechanism of extractive separation of light cycle oil components using deep eutectic solvents.

Tuning the density of Brønsted acid sites on mesoporous ZSM-5 zeolite for enhancing light olefins selectivity in the catalytic cracking of n-octane

A molecular template (tetrapropylammonium hydroxide, TPAOH) and a phosphorus-containing template (tetrabutylphosphonium hydroxide, TBPOH or tetrabutylphosphonium bromide, TBPBr) were used as dual templates to prepare the mesoporous ZSM-5 zeolites. The physicochemical properties of the as-prepared ZSM-5 catalysts were characterized by means of XRD, N2 adsorption, NH3-TPD, FT-IR spectra of adsorbed pyridine, 27Al MAS NMR, etc., and their performances for the catalytic cracking of the n-octane to light olefins were investigated. The results indicated that the acidity of ZSM-5, especially the concentration of strong Brønsted acid sites (SBAS) can be finely modulated by tuning the molar ratio of TPA+/TBP+. The charge-compensation effect of TBP+ and the phosphorus species played critical roles in regulating the SBAS concentrations of ZSM-5. Consequently, the as-prepared ZSM-5 catalysts with suitable strong Brønsted acid sites density was favorable for enhancing the selectivity to light olefins. At the temperature of 600 °C, the selectivity of propene and light olefins over MFI-9/2.5 catalyst were achieved 34.7% and 70.4%, which were higher than those over conventional ZSM-5 by 2.4% and 5.1%, respectively. Selectivity to C2=∼C4= light olefins was found to be decreased with increasing the concentration of strong Brønsted acid sites due to the reduction of SBAS which inhibited the hydrogen transfer reaction. This work will provide insights and new platforms for the design of high-efficiency zeolite catalysts for important industrial reactions.

Green synthesis of benzaldehydes by the selective oxidation o benzyl alcohols using hexacyanoferrate (III) and bromate under phase transfer catalysis

The selective oxidation of benzyl alcohols and substituted benzyl alcohols was carried out in greener solvents like ethyl acetate and toluene by hexacyanoferrate (III) and bromate ions under phase transfer catalysis. Various phase transfer catalysts like tetrabutylphosphonium bromide, tetrabutylammonium bromide, tetrabutylammonium hydrogen sulphate, cetyltrimethylammonium bromide and tricaprylmethylmmonium chloride were used. A pinch of sodium tungstate dihydrate is added as a co-catalyst when bromate is used an oxidant and hexacyanoferrate (III) is used in presence of mineral acids. The products obtained were precipitated as their 2,4- dinitrophenylhydrazone, purified, weighed and the yield was found to be > 90 %. The products were recrystallized in ethanol and analyzed by melting point and by various spectral techniques. It was proved that corresponding benzaldehydes were formed and there was no further oxidation to corresponding acids. All the catalysts were found effective in bringing out the reaction but based on yield and ease of reaction, the order of reactivity is tricaprylmethylammonium chloride > tetrabutylphosphonium bromide > tetrabutylammonium bromide > tetrabutylammonium hydrogen sulphate > cetyltrimethylammonium bromide. The selective oxidation of benzyl alcohols is very difficult to proceed in organic solvents without the aid of a phase transfer catalyst. Yield of products is found to be slightly more in ethyl acetate than that in toluene due to difference in polarity.

A new highly stable methane hydrate from the synergic mixture of common promoters: Experimental and modeling surveys

One of the main issues in flow assurance in offshore operations, specially at high pressure conditions as in deep pipelines is the formation of hydrates in the corners of pipelines that causes notable problems like pipe blockage followed by an explosion. Hydrate or gas hydrate is a bright solution for gas storage and transportation. Tetrabutylphosphonium bromide (TBPB) and tetrabutylammonium bromide (TBAB) are salts capable of tackling the thermodynamic and kinetic limitations of hydrate formation/dissociation conditions. In the present work, the effect of TBAB, TBPB and TBAB + TBPB mixture on CH4 hydrate dissociation condition was studied. All experiments were performed by pursuing a constant-volume pressure search technique with the step heating approach to study the effects of additive mixtures with different compositions. A mass fraction of 5%, 10% TBAB/TBPB was used. The experiments were conducted at 280–290.05 K and 1–5.5 MPa. In all the conducted experiments, the mixture had a promoting effect. After generating the accurate data of TBAB-TBPB-CH4 hydrate in water system, a thermodynamic prediction model was developed to investigate efficient hydrate-based applications. The hydrate phase was predicted on the basis of Chen and Guo's approach. Soave−Redlich−Kwong equation of state was applied to predict the required methane properties in the gas phase. The TBAB-TBPB activity coefficient and water activity in the electrolyte phase were obtained through the Bromley equations. The results of the proposed thermodynamic model showed that there is a satisfactory accordance between the experimental phase equilibrium data and the predicted data with an acceptable AARD % of 0.95%.

Enzymatic Activity and Its Relationship with Organic Matter Characterization and Ecotoxicity to Aliivibrio fischeri of Soil Samples Exposed to Tetrabutylphosphonium Bromide.

This study aimed to determine the impact of tetrabutylphosphonium bromide [TBP][Br] on the soil environment through an experiment on loamy sand samples. The tested salt was added to soil samples at doses of 0 (control), 1, 10, 100, and 1000 mg kg−1 dry matter (DM). During the experiment, the activity of selected enzymes involved in carbon, phosphorus, and nitrogen cycles, characteristics of organic matter with Fourier-transform infrared (FT-IR) spectroscopy, and toxicity of soil samples in relation to Aliivibrio fischeri were determined at weekly intervals. The results showed that low doses of [TBP][Br] (1 and 10 mg kg−1 DM) did not have much influence on the analyzed parameters. However, the addition of higher doses of the salt into the soil samples (100 and 1000 mg kg−1 DM) resulted in a decrease in the activity of enzymes participating in the carbon and phosphorus cycle and affected the activation of those enzymes involved in the nitrogen cycle. This may be due to changes in aerobic conditions and in the qualitative and quantitative composition of soil microorganisms. It was also observed that the hydrophobicity of soil organic matter was increased. Moreover, the findings suggested that the soil samples containing the highest dose of [TBP][Br] (1000 mg kg−1 DM) can be characterized as acute environmental hazard based on their toxicity to Aliivibrio fischeri bacteria. The increased hydrophobicity and ecotoxicity of the soil samples exposed to the tested salt were also positively correlated with the activity of dehydrogenases, proteases, and nitrate reductase. Observed changes may indicate a disturbance of the soil ecochemical state caused by the presence of [TBP][Br].

Kinetic study for ionic liquid catalyzed green O-methylation of cresols using dimethyl carbonate

In this work, we have systematically studied the kinetics and mechanism of ionic liquid catalyzed solvent less liquid-phase O-methylation of p-cresol with dimethyl carbonate (DMC). The effect of various parameters such as mass transfer resistance, catalyst loading, mole ratio, initial CO2 pressure, and temperature was studied. The reaction was found to be pseudo zero order with respect to p-cresol and first order with respect to DMC. o- and m-Cresols were also used. The values of apparent activation energy for o-, m-, and p-cresol are found as 32.5, 34.0, and 32.5 kcal/mol, respectively. Our study also suggests that type of cation and anion affects the catalytic acitivity of ionic liquids. Ionic liquid, tetra butyl phosphonium bromide, offers excellent activity, selectivity, reusability, recyclability and stability.

Insight into the mechanism of tuned extractive desulfurization by aqueous tetrabutylphosphonium bromide

Molecular dynamics simulations with the combination of FT-IR and 1H NMR spectra were carried out to study the mechanism of tuned extractive desulfurization by aqueous tetrabutylphosphonium bromide (TBPB). The intermolecular interaction and microstructure of TBPB with water and the sulfur compound dibenzothiophene (DBT) were investigated. Both the spectra and MD simulation results indicated that TBPB with a small amount of water has strong CH–π interaction between TBP+ cation and dibenzothiophene (DBT) and hydrogen bonding between Br− anion and DBT, which are the driving forces for extraction of DBT into aqueous TBPB phase in fuel desulfurization. Further addition of water into aqueous TBPB phase causes the solvation of cation and anion, which weakens the interactions of TBPB with DBT and hence facilitates DBT aggregation and TBPB recovery. The results provide an insight into the mechanism of water tuned extraction and regeneration process in fuel desulfurization.

Amorphous Alloy Architectures in Pore Walls: Mesoporous Amorphous NiCoB Alloy Spheres with Controlled Compositions via a Chemical Reduction

Amorphous bimetallic borides are an emerging class of catalytic nanomaterial that has demonstrated excellent catalytic performance due to its glass-like structure, abundant unsaturated active sites, and synergistic electronic effects. However, the creation of mesoporous Earth-abundant bimetallic metal borides with tunable metal proportion remains a challenge. Herein, we develop a sophisticated and controllable dual-reducing agent strategy to synthesize the mesoporous nickel-cobalt boron (NiCoB) amorphous alloy spheres (AASs) with adjustable compositions by using a soft template-directed assembly approach. The selective use of tetrabutylphosphonium bromide (Bu4PBr) is beneficial to generate well-defined mesopores because it both moderates the reduction rate by decreasing the reducibility of M2+ species and prevents the generation of soap bubbles. Our meso-Ni10.0Co74.5B15.5 AASs generate the highest catalytic performance for the hydrolytic dehydrogenation of ammonia borane (AB). Its high performance is attributed to the combination of optimal synergistic effects between Ni, Co, and B as well as the high surface area and the good mass transport efficiency due to the open mesopores. This work describes a systematic approach for the design and synthesis of mesoporous bimetallic borides as efficient catalysts.

Biomagnification of ionizable organic compounds in rainbow trout Oncorhynchus mykiss

BackgroundThe assessment of persistence, bioaccumulation and toxicity (PBT) is part of the regulation process of ionic organic compounds (IOCs) and a major challenge, as a commonly acknowledged approach for the estimation of the bioaccumulation potential of IOCs is still missing. The goal of the present study was, therefore, to experimentally determine the bioaccumulation of fully ionized compounds and to identify screening parameters that can indicate high bioaccumulation potential of IOCs. Three feeding studies with rainbow trout (Oncorhynchus mykiss) were carried out according to OECD TG 305. Separation of liver, gastrointestinal tract (GIT) and carcass allowed to further elucidate the tissue distribution of the individual test substances. The chemicals chosen had characteristics that made them suspect for high bioaccumulation, and included two cations (tetrabutylphosphonium bromide (TBP), trimethyloctadecyl ammonium chloride (TMOA)) and four anions (benzotriazole, tecloftalam, pentachlorophenol (PCP), MEE-phosphonate). Data on the dietary biomagnification of IOCs (strong acids) were also collected from published literature.ResultsThe highest distribution factors were found for the GIT, followed by liver. However, none of the tested IOCs showed a distinct biomagnification potential, as kinetic biomagnification factors (BMFk) ranged between 0.001 and 0.05 g/g (median 0.009 g/g). Cations showed lower assimilation efficiency (α) than anions, except for tecloftalam. In contrast, anions showed a considerably faster depuration rate (half-life less than 0.5 days) compared to cations (half-life of around 5 days). Sixteen potential screening parameters for BMF were calculated with a chemical property estimation tool (ACD/i-Lab) and correlated with the BMF data from this study and from literature. The number of hydrogen bond donors (nHBD) showed the highest correlation to measured BMF, but the prediction is only based on two values (one or two nHBD), while the other descriptors were insignificantly correlated.ConclusionThe suspected dietary bioaccumulation potential of the six IOCs could not be confirmed in the feeding studies with rainbow trout. The more than twenty screening parameters showed no particularly high correlation neither with the test results nor with the BMF values collected from literature. The results corroborate earlier findings that ionization lowers the tendency of a chemical for dietary bioaccumulation, compared to non-ionized chemicals. In addition to the lipophobicity of ionic molecule moieties, fast depuration seems to be a major reason for the observed low dietary bioaccumulation of ionic compounds, in particular anions. Fast depuration may happen due to rapid metabolism of charged compounds, and future studies should test this hypothesis.

Vapor Pressure Assessment of Sulfolane-Based Eutectic Solvents: Experimental, PC-SAFT, and Molecular Dynamics.

Since their discovery, deep eutectic solvents (DES) have been explored in multiple applications. However, the complete physicochemical characterization is still nonexistent for many of the proposed and used DES. In particular, vapor pressure, which is a crucial property for the application of DES as solvents, is very rarely available. In this work, the measurement of the total and partial pressures of two sulfolane-based DES, tetrabutylammonium bromide:sulfolane and tetrabutylphosphonium bromide:sulfolane, in several proportions, from 40 to 100 °C and atmospheric pressure, was performed using headspace gas chromatography mass spectrometry, HS-GC-MS. A large decrease on the total pressure was recorded which, together with the finding that total pressures showed negative deviations from Raoult's law, is indicative of the favorable, strong interactions between the two components within the DES. Additionally, the study of vapor pressure change with DES molar composition was carried out, and surprisingly, the existence of inflection points in the pressure curve was observed. Experimental results were modeled using the PC-SAFT equation of state, and in addition, MD simulations were performed to provide a molecular understanding of the pressure data. Considering the different results and insights obtained from the used strategies, it can be concluded that both DES systems have especially strong interactions between salt and sulfolane, at high sulfolane content, due to the different structural rearrangement of the liquid state.

Performance of p-Toluenesulfonic Acid-Based Deep Eutectic Solvent in Denitrogenation: Computational Screening and Experimental Validation.

Deep eutectic solvents (DESs) are green solvents developed as an alternative to conventional organic solvents and ionic liquids to extract nitrogen compounds from fuel oil. DESs based on p-toluenesulfonic acid (PTSA) are a new solvent class still under investigation for extraction/separation. This study investigated a new DES formed from a combination of tetrabutylphosphonium bromide (TBPBr) and PTSA at a 1:1 molar ratio. Two sets of ternary liquid–liquid equilibrium experiments were performed with different feed concentrations of nitrogen compounds ranging up to 20 mol% in gasoline and diesel model fuel oils. More than 99% of quinoline was extracted from heptane and pentadecane using the DES, leaving the minutest amount of the contaminant. Selectivity was up to 11,000 for the heptane system and up to 24,000 for the pentadecane system at room temperature. The raffinate phase’s proton nuclear magnetic resonance (1H-NMR) spectroscopy and GC analysis identified a significantly small amount of quinoline. The selectivity toward quinoline was significantly high at low solute concentrations. The root-mean-square deviation between experimental data and the non-random two-liquid (NRTL) model was 1.12% and 0.31% with heptane and pentadecane, respectively. The results showed that the TBPBr/PTSADES is considerably efficient in eliminating nitrogen compounds from fuel oil.