Dispersed Organic Phase Research Articles

Hydrophilic and hydrophobic deep eutectic solvent-based extraction to determine parathion in cereals by digital image colorimetry integrated with smartphones

To determine parathion in cereals, hydrophilic and hydrophobic deep eutectic solvents (DESs) were used by digital image colorimetry with smartphones. In the solid-liquid extraction part, hydrophilic DESs were used as extractants to extract parathion from cereals. In the liquid-liquid microextraction part, hydrophobic DESs dissociated into terpineol and tetrabutylammonium bromide in situ. The dissociated hydrophilic tetrabutylammonium ions reacted with parathion extracted in hydrophilic DESs under alkaline conditions to produce a yellow product, which was extracted and concentrated by dispersed organic phase terpinol. Digital image colorimetry integrated with the use of a smartphone was used for quantitative analysis. The limit of detection and quantification were 0.003 mg kg−1 and 0.01 mg kg−1, respectively. The recoveries for parathion were 94.8–106.2% with a relative standard deviation less than 3.6%. The proposed method was applied to analyze parathion in cereal samples: the method has the potential to be applied to pesticide residue analysis in food products.

In situ decomposition of deep eutectic solvent as a novel approach in liquid-liquid microextraction

In this study, a novel approach for effective liquid-liquid microextraction based on deep eutectic solvent (DES) decomposition was suggested for the first time. It was established that DESs synthesized from tetrabutylammonium bromide and long-chain alcohols decomposed in aqueous phase resulting in in situ dispersion of organic phase and extraction of hydrophobic analyte(s). It this process long-chain alcohol acted as an extraction solvent and tetrabutylammonium bromide acted as a dispersive agent and promoted mass transfer between aqueous and organic phases as a salting out agent. Phenomenon of DES decomposition was studied in detail and applied for separation and preconcentration in chemical analysis for the first time. The developed approach was applied for 17β-estradiol microextraction from transdermal gel samples as a proof-of-concept example. The results showed that the in situ dispersed organic phase obtained can provide efficient extraction of 17β-estradiol with good extraction recovery (95 ± 5%) and excellent reproducibility (6%). The reported approach proves to be fast, simple, and inexpensive.

Modified flow geometry for higher extraction performance with a liquid–liquid centrifugal contactor with Taylor vortices

ABSTRACT Extraction with multiple theoretical stages by a single contactor is possible when a liquid–liquid countercurrent centrifugal contactor with Taylor vortices (TVs) is used. A series of TVs inside the flow region between the coaxial inner rotor and static outer wall can sustain stable concentration gradients, thereby improving the extraction performance. In the TVs, an axial force driving the dispersed organic phase arises from the different specific weights of the organic and aqueous phases. In this study, the geometry of the flow region was modified using (1) different aspect ratios and (2) tapered and (3) eccentric geometries for better extraction performance. The flows were observed experimentally and simulated numerically using the volume-of-fluid method to understand the flow inside the TVs. Changing the geometry greatly affected the size of the TVs, the flow stability, and the emulsification behavior. In continuous-extraction experiments involving zinc ions with bis(2-ethylhexyl)phosphoric acid, the tapered geometry showed the highest number of theoretical stages because of its simultaneous vigorous agitation, stable TV arrangement, and phase separation.

Application of new chemical test reactions to study mass transfer from shrinking droplets and micromixing in the rotor-stator mixer

Abstract A pair of fast competitive reactions, neutralization and 2,2-dimetoxypropane (DMP) hydrolysis, has been applied do study mass transfer and micromixing in a T 50 Ultra-Turrax® - IKA rotor-stator device. In experiments the dispersed organic phase containing p-Toluenesulfonic acid (pTsOH) dissolved in diisopropyl ether, whereas the continuous phase was represented by the aqueous solution of sodium hydroxide, 2,2-dimetoxypropane (DMP) and ethanol. During mixing a fast mass transfer of a solute (pTsOH) from organic phase droplets, which were shrinking due to fast dissolution of the organic solvent, was followed by micromixing and chemical reactions in the continuous phase. Measured hydrolysis yields were applied to express effects of mixing on the course of chemical reactions. Modeling was based on application of models describing drop breakup, mass transfer in the liquid-liquid system and micromixing. Combined effects of mass transfer and drop breakage on drop population were expressed using the population balance equations. The model has been used to interpret experimental results, in particular to identify the efficiency of mixing.

Experimental validation of equilibrium based mathematical modelling of liquid‐liquid phase transfer catalysis

The reaction between two compounds which reside in immiscible phases can be accelerated using a phase transfer catalyst. The catalyst helps to transfer a species ion from one phase to the other phase, thus promoting its reaction. Several mechanisms have been proposed to describe phase transfer catalyzed reactions. In this work, we have carried out an experimental and theoretical study of phase transfer catalysis in batch mode. A mathematical model is developed which helps to predict the progress of the reaction under different operating conditions. Here the different species in the aqueous phase are assumed to be in equilibrium and these react with the species in the organic phase. The effect of diffusional resistance inside the dispersed organic phase is shown to be negligible. The two reaction systems studied are the phase transfer catalyzed (i) thioetherification and (ii) benzyl alcohol oxidation using sodium hypochlorite. Batch experiments were performed to determine the effect of catalyst loading, solvent dilution, and pH. The experimental results show that with an increase in catalyst loading, the phase transfer catalyzed reactions were accelerated. The use of a minimal amount of solvent results in a better performance. Benzyl alcohol oxidation is favoured under low pH conditions. The developed model is able to capture the performance of the system over a wide range of operating conditions accurately.

Influence of quadrupole magnetic field on mass transfer in an extraction column in the presence of MnFe2O4 nanoparticles

Recently, it has been observed that the use of magnetic nanoparticles and the magnetic field would result in heat and mass transfer intensification. But most of the investigations have been devoted to the enhancement of heat transfer. However, the investigations on the applicability of magnetic nanoparticles for mass transfer improvement are still in the developing stage. In the present study, the effect of MnFe2O4 nanoparticles on the mass transfer performance of a packed extraction column is evaluated in the presence of constant and alternating magnetic fields. The column is filled with Penta-Pak TM PS-500M1 structured packing; while four identical bar electromagnets made from zinc ferrite cores are used to generate the quadrupole magnetic field. The (toluene-acetic acid)-water system is employed. Spinel-type manganese ferrite nanoparticles are added to the organic dispersed phase (toluene+acetic acid) to intensify solute transfer. The quadrupole magnetic field is applied from 100 to 500G intensity and 100 to 500Hz frequency, accompanied with different nanoparticle concentrations from 0.001wt% to 0.005wt%. According to our observations, mass transfer performance increases remarkably in the presence of magnetic nanoparticles under the influence of magnetic field. Compared with no magnetic field, maximum improvements of 115% and 43% in overall mass transfer coefficient and extraction fraction are observed under alternating magnetic field with 300Hz frequency and 500G intensity for 0.003wt% nanoparticle concentration. That is, by using the magnetic nanoparticles and the magnetic field, one can considerably improve the performance of a liquid-liquid extraction system.

Assembled Block Copolymer Stabilized High Internal Phase Emulsion Hydrogels for Enhancing Oil Safety

Accidental spills and subsequent fires during oil storage and transportation periods cause serious damage to environments. Herein, we present a novel route to enhance oil safety by transforming oils into high internal phase emulsion (HIPE) hydrogels. These HIPE hydrogels are stabilized by solvent- or pH-driven assembled block copolymer (BCP), namely poly(4-vinylpyridine)-block-poly(ethylene glycol)-block-poly(4-vinylpyridine) (4VPm-EGn-4VPm). The assembled BCP shows high efficiency to stabilize HIPE hydrogels with a low concentration of 1.0 (w/v) % relative to the continuous aqueous phase. The volume fraction of the dispersed organic phase can be as high as 89% with a variety of oils, including toluene, xylene, blended vegetable oil, canola oil, gasoline, diesel, and engine oil. These smelly and flammable liquids were formed into HIPE hydrogels and thus their safety was enhanced. As the assembly is pH sensitive, oils trapped in the HIPE hydrogels can be released by simply tuning pH values of the continuou...

A new bubbling extraction tower: Toward liquid–liquid solvent extraction at large aqueous‐to‐oil phase ratios

Enrichment and recovery of valuable components in industrial waste waters by traditional liquid–liquid solvent extraction is not economic due to extremely low concentrations of those targets. Large‐phase‐ratio extraction exhibits potential advantages for recovery of small quantities of target components from large volume of aqueous solutions. A novel bubbling extraction tower is proposed toward performing solvent extraction at large aqueous‐to‐oil phase ratios in this work. Organic extractants were covered onto surface of gas bubbles to form a layer of organic liquid membrane and the dispersed organic phase in tower could be small enough. The target components are extracted from aqueous feed solution onto the surface of the bubbles, and the enrichment ratios could be extremely high. We develop a feasible methodology to calculate tower height and operation phase ratios of the bubbling extraction tower, which is essential for future industrial scale‐up. Experimental results in pilot test are highly consistent with calculations. © 2015 American Institute of Chemical Engineers AIChE J, 61: 3889–3897, 2015

Removal of tributyl phosphate from aqueous stream in a pilot scale combined air-lift mixer-settler unit: Process intensification studies

This work reports the removal of tributyl phosphate (TBP) from aqueous stream using organic solvent in an industrial scale combined air-lift mixer-settler unit (CAL-MSU) having 10 stages. The solute i.e., TBP is transferred from aqueous continuous (0.3M HNO3 saturated with TBP) to organic dispersed phase i.e., normal paraffin hydrocarbon (NPH). Effect of phase flow ratios on steady state, number of stages as well as mass transfer coefficient on TBP removal and mass transfer coefficient, is observed. The maximum TBP extraction efficiency of about 96% (201ppm to 8ppm) and maximum overall volumetric mass transfer coefficient of 13.3×10−5s−1 was observed at continuous phase flowrate 36 LPH and dispersed phase flowrate 24 LPH. For optimized operating parameters, the energy input per unit volume for 10-stage CAL-MSU and similar configuration 10-stage pump-mix mixer-settler are found to be 37.0kJ/m3 and 77.7kJ/m3, respectively.

Liquid–liquid extraction intensification with magnetite nanofluid single drops under oscillating magnetic field

The influence of an oscillating magnetic field was investigated in mass transfer from magnetite nanofluid single drops in liquid–liquid extraction process. The chemical system of toluene–acetic acid–water was used, while hydrophobic magnetite nanoparticles were present in the organic dispersed phase. The magnetic field intensity was within the range of 0.36–1.45T, accompanied with different nanofluid concentrations within 0.001–0.005wt%. Compared with no magnetic field, an average enhancement of about 65% and a maximum of 121% (for the smallest used drops) were achieved. This essential matter can be attributed to the induced nanoparticles micro-convection inside the drops.

Effect of curing conditions on the properties of multivesiculated polyester particle dispersions

Multivesiculated polyester particles were synthesized from a double emulsion system comprising water and a solution of unsaturated polyester in styrene. A suspension of solid micro-particles containing multiple water-filled vesicles is obtained after curing (i.e., crosslinking) the dispersed organic phase. These have several applications, like opacifying agents in paint formulations. The effects of curing time and temperature on relevant properties of the final product (particle size distribution, dry film opacity, dispersion viscosity, and stability) were investigated. Results showed that more than 1 h was necessary when curing at room temperature, in order to avoid coalescence and loss of opacity upon drying. On the other hand, well-individualized particles were obtained within a few minutes when curing above 60°C, and the internal alveolar structure was preserved after drying. Furthermore, high curing temperatures enhanced not only the final dry film opacity, but also originated less viscous and more stable particle dispersions. POLYM. ENG. SCI., 54:396–403, 2014. © 2013 Society of Plastics Engineers

Correlation between the polymerization kinetics and the chemical structure of poly(urethane–urea) nanocapsule membrane obtained by interfacial step polymerization in miniemulsion

Kinetics of the interfacial step polymerization in direct miniemulsion between 1,6-hexanediol and isophorone diisocyanate, at different temperatures and with different organic solvents as dispersed phase was investigated. Despite the complexity of the reaction system due to the specific experimental conditions, the profiles of consumption of the isocyanate groups and diisocyanate monomer, and the chemical structure of the being formed polymer membrane, were concurrently determined by gas chromatography, FTIR spectroscopy, 13C NMR and MALDI-TOF mass spectrometry. The results were connected with the key-steps of the membrane formation by interfacial polymerization, pointing out the prevailing influence of the organic dispersed phase on the hydrophilic monomer diffusion and the swelling rate of the polymeric membrane.

Emulsification liquid phase microextraction followed by on-line phase separation coupled to high performance liquid chromatography

An emulsification liquid phase microextraction followed by on-line phase separation coupled to high performance liquid chromatography (HPLC) is introduced based on a novel idea for the separation of dispersed organic phase from aqueous phase. In this method, the dispersed organic extraction phase was filtered using an in-line filter and it was separated from the water sample. The new approach is simple and, in addition to improving some limitations of the conventional emulsification liquid phase microextraction, eliminates the need for centrifugation in the phase separation step.To demonstrate the applicability of the method, it was applied for the extraction and determination of trace amounts of selected parabens as model analytes. In this procedure, 30μL of 1-octanol was injected slowly into 10mL of the aqueous sample inside the ultrasonic water bath. Then, the emulsion formed was passed through the in-line filter located in the loop of the HPLC valve and the organic extraction phase was separated and it was retained in the filter. By changing the position of the valve, the filter was located in the mobile phase pass and the retained organic phase was eluted and transferred to the separation column. The effects of some important parameters such as types of extraction solvent and its volume, ionic strength, and ultrasonication time on extraction efficiency were investigated and optimized. Under optimal conditions, preconcentration factors and limits of detection for the compounds studied were obtained in the ranges of 289–595 and 0.05–0.2μgL−1, respectively. Finally, the method was successfully applied to determine selected parabens in some water and cosmetic samples.

Mass Transfer from Single Drops and the Influence of Temperature

Temperature can alter the performance of conventional liquid–liquid extraction columns in which one phase is dispersed inside another phase. In this research, the influence of temperature on the extraction process was investigated using a toluene–acetic acid–water chemical system with dominant mass transfer resistance in the organic phase. Single drop experiments with a range of drop size within 2.49–3.77 mm and temperature within 15–40 °C were performed. Results demonstrate significant impact of temperature on the rate of mass transfer with an average enhancement of 93.6% in overall mass transfer coefficient while small drops are benefited more. Having lower contributions by drop size and terminal velocity, the extraction efficiency is the most effective term in this regard which itself is increased by increasing molecular diffusivity in the organic dispersed phase. For the aim of modeling, effective diffusivity was substituted for molecular diffusivity in Newman’s equation and consequently, a reliable empirical equation was derived for the enhancement factor of diffusivity as a function of dimensionless variables.

In-line cold column trapping of organic phase in dispersive liquid–liquid microextraction: Enrichment and determination of curcumin in human serum

A new temperature controlled cold column trapping (CCT) system was developed for in-line sequestration of organic phase in dispersive liquid–liquid microextraction (DLLME) method. In the developed CCT–DLLME method, the dispersed organic extraction phase is solidified and trapped in the CCT, packed with glass particles. Subsequently, the sequestered phase is washed out in an elevated temperature by using an appropriate solvent. The column temperature is controlled by a pair of thermal electric cooler (TEC) plates. The new device is simple and portable and can eliminate the need for centrifugation in the DLLME method for solvents with an appropriate melting point. Some important parameters such as types of extraction and disperser solvents and their volumes, minimum and maximum column temperatures and extraction time were optimized for the extraction of curcumin, as a model compound. Using 1-dodecanol as the organic solvent and acetone as the disperser, recoveries exceeding 90% and a relative standard deviation of 2.87% were obtained for 5 replicated analyses of curcumin by an HPLC method. The detection limit of curcumin (3σ) extracted by the CCT–DLLME system was 28μgL−1. The method was successfully applied to the determination of curcumin in some human serum samples.

Experimental Study on Dynamic Interfacial Tension with Mixture of SDS–PEG as Surfactants in a Coflowing Microfluidic Device

In this work, a coflowing microfluidic device was used to determine the influence of different mixed sodium dodecyl sulfate (SDS)-poly(ethylene glycol) (PEG) compound systems on dynamic interfacial tension and, by extension, corresponding emulsion droplet sizes. The aqueous solutions were used as the continuous phase in the microfluidic device, while octane was used as the organic dispersed phase. Combined SDS-PEG systems lower the interfacial tension more than either component can alone up to the critical aggregation concentration (CAC) of SDS. Octane droplet sizes produced in the microfluidic device using combined SDS-PEG systems were smaller than those produced using SDS alone, and a reduction in dynamic interfacial tension as determined by drop size followed a pattern similar to that observed in the static case (PEG4000 > PEG600 > PEG400 > PEG200 > PEG8000) with the exception of PEG8000. Finally, a previously formulated model relating interfacial tension to droplet size was used to estimate the dynamic interfacial tensions in the microfluidic device.

Magnetic Behavior of Zn-Doped Fe3O4 Nanoparticles Estimated in Terms of Crystal Domain Size

A series of zinc (Zn) doped Fe3O4 nanoparticles with different Zn concentrations represented as ZnxFe3–xO4 (0 < x ≤ 1) were synthesized by the chemical coprecipitated technique mainly in the presence of sodium dodecyl benzene sulfonate (SDBS) as one of the surface modifiers. The prepared zinc-doped Fe3O4 nanoparticles were characterized by a vibrating sample magnetometer (VSM), wide-angle X-ray diffraction (WAXD), and transmission electron microscopy (TEM). The VSM measurements showed that magnetization vs applied magnetic field for zinc-doped particles showed an increasing curve with very small hysteresis and that the saturation magnetization (Ms) of ZnxFe3–xO4 reached a maximum 80.93 emu/g at x = 0.2. The experimental result exhibited that Zn0.2Fe2.8O4 nanoparticles coated with different surface modifiers give good dispersivity and outstanding stability in the organic dispersed phase compared with noncoated particles. The value of Ms decreased with further increase in x beyond 0.2. Such decreasing behav...

Mass Transfer Enhancement of Gas Absorption by Adding the Dispersed Organic Phases

Mass transfer enhancement of gas absorption by adding a dispersed organic phase has been studied in this work. Various dispersed organic phases (heptanol, octanol, isoamyl alcohol, heptane, octane, and isooctane) were tested respectively in the experiment. According to the theoretical model and experimental data, the overall volumetric mass transfer coefficient and enhancement factor were obtained under different dispersed organic phase volume fraction and stirring speed. The experimental results indicate that gas-liquid mass transfer is enhanced at different level by adding a dispersed organic phase. The best performance of enhancement were achieved with the dispersed organic phase volumetric fraction of 5% and under an intermediate stirring speed of 670 r·min −1. Among the organic phases tested in the experiment, alcohols show better performance, which gave 20% higher enhancement of overall volumetric mass transfer coefficient than adding alkanes.

Enhancement of Gas Physical Absorption in Gas-Liquid-Liquid System

The enhancement of physical absorption of CO2 in the presence of second liquid phase (dispersed organic phase) was investigated due to many important industrial applications. Gas-liquid interfacial area, volumetric mass transfer coefficient and amplification factor were calculated and discussed using penetration model. The experimental results indicated that addition of the dispersed organic phase to water leads to the increase of volumetric mass transfer coefficient by 46%, 34%, 20% for heptanol, toluene and heptane respectively. The performed in this paper shows that addition of the dispersed organic phase to water increases gas-liquid interfacial area and reduces bubble diameter. These two effects play an essential role in the rate of carbon dioxide absorption increase. The effect of enhancement could be quantified by an amplification factor.

Miniemulsion as efficient system for enzymatic synthesis of acid alkyl esters

The aim of this work is to devise an efficient enzymatic process for the production of linear alkyl esters in aqueous miniemulsion systems. The esterification reactions of linear alcohols and carboxylic acids were performed with three different enzymes, commercial Amano lipase PS from Pseudomonas cepacia, Lipase type VII from Candida rugosa, and lyophilized Fusarium solani pisi cutinase expressed in Saccharomyces cerevisiae SU50. The miniemulsion system shows a high potential for the synthesis of linear alkyl esters, for example, hexyl octanoate, which could be synthesized with an ester yield of 94% using Amano lipase PS. Even with hydrophilic alcohols as ethanol, ethyl decanoate could be obtained with a concentration of 0.45 M and a yield of 62% using F. s. pisi cutinase as catalyst. High esterification rates for ethyl- and hexyloleate in miniemulsion showed a significant shift in cutinase selectivity towards longer chain length carboxylic acids. The stepwise addition of the alcohol led to an increase of the esterification yield. Moreover, increasing the amount of dispersed organic phase, mainly consisting of the substrates, led to a significant increase of the final ester concentration (e.g., concentration of 1.4 M for ethyl decanoate for the esterification with Amano Lipase PS).