Toluene Acetic Acid Research Articles

Power-efficient mass transfer of a novel pulsating multi-packed bed liquid - liquid extractor

This paper presents the development and performance evaluation of a new pulsating packed bed contactor designed for optimized diffusion-controlled liquid-liquid operations. Targeting applications like aromatics separation in petroleum, phenol removal from wastewater, and heat-sensitive material extraction (e.g., antibiotics), the contactor offers substantial advantages over traditional mechanical systems – notably, lower power consumption for equivalent production rates. Using the widely studied extraction of acetic acid from toluene-acetic acid by water as a model system, this work comprehensively investigates the factors impacting mass transfer within the pulsating contactor. Key variables explored include physical properties of the feed solution, oscillation frequency and amplitude, initial concentration of solute, flow rates, bed height, packing diameter, and bed spacing. Results reveal a significant enhancement in mass transfer with increasing frequency, amplitude, initial concentration, continuous phase flow rate, and dispersed phase flow rate. Interestingly, while increasing bed height initially improves mass transfer up to a specific point, further height increase exhibits a diminishing return. Packing sphere diameter shows minimal impact, while bed spacing has a negligible effect. A novel dimensionless equation effectively correlates the pulsating multi-packed bed data for broader applicability. To assess economic viability, the study also measures the mechanical power consumption under various operating conditions. Finally, diverse potential applications across pharmaceuticals, chemicals, biochemicals, petroleum, and nuclear fuel reprocessing are highlighted, showcasing the broad utility of this innovative mass transfer technology.

Vibration in Microchannel Causes Greater Enhancement of Mass Transfer in Toluene–Acetic Acid–Water System

Vibration in Microchannel Causes Greater Enhancement of Mass Transfer in Toluene–Acetic Acid–Water System

Investigation of the impact of synthesized hydrophobic magnetite nanoparticles on mass transfer and hydrodynamics of stagnant and stirred liquid–liquid extraction systems

The impact of modified magnetite nanoparticles (MMNPs) on hydrodynamics and mass transfer in liquid–liquid extraction process was assessed using a ternary chemical system of toluene-acetic acid–water. The organic phase which contained toluene and acetic acid was dispersed through water, and the mass transfer of acetic acid between two phases was investigated. The hydrophobic modified magnetite nanoparticles (MMNPs) prepared through an optimized in-situ method were added to the dispersed phase at different concentrations (0.001−0.005 wt%). Two separate conditions were provided in the experiments, i.e. stagnant and stirred continuous phase. The latter case was provided by a rotor at two different speeds of 330 and 450 rpm. The effects of nozzle size and acetic acid concentration were also considered. The results showed that the as-prepared MMNPs decreased the terminal velocity and increased the liquid hold-up of the drops. Under the stagnant condition, an enhancement of 103.1% in overall dispersed-phase mass transfer coefficient was achieved at the optimum concentration of 0.001 wt% of MMNPs, whereas under stirred condition, the extraction fraction enhancement was not appreciable.

Rapid validated thin-layer chromatography–densitometry for the simultaneous determination of three co-formulated drugs used for common cold treatment

A rapid validated thin-layer chromatography (TLC)—densitometric method has been developed for the simultaneous determination of 3 co-formulated drugs used for common cold and cough treatment. The studied drugs are paracetamol, pseudoephedrine, and chlorpheniramine maleate. The separation was achieved using silica gel 60 F254 plates and the developing system of methanol — toluene-acetic acid (44:16:1, v/v). Densitometry scanning was performed at 254 nm. The method was validated as per the International Conference on Harmonization (ICH) guidelines and was successfully applied for the analysis of pharmaceutical preparation containing the cited ternary mixture without interference from excipients. There is no previously published TLC—densitometric method for the determination of the previously mentioned ternary mixture. The suggested method is rapid and of low cost, so it can be used for quality control analysis.

Liquid–Liquid Equilibrium Data, Density, Viscosity, and Interfacial Tension of Ternary System (Toluene–Acetic Acid–Water) at 298.15 K: Experiment and Correlation

Liquid–liquid equilibrium (LLE) data, density, viscosity, and interfacial tension for the ternary system of toluene–acetic acid–water were measured at 298.15 K and 101.7 kPa. The Othmer–Tobias and the Hand correlations were used to check the reliability of the experimental tie-lines. Moreover, the distribution coefficient and the separation factor were explored. It was found from the experimental results that a maximum separation factor value happens at an acetic acid mass fraction of 0.02 in the organic phase. Density, viscosity, and interfacial tension were correlated using the appropriate correlations such that the predicted results have excellent agreement with the experimental data. The experimental data in this work and the literature were correlated using both the nonrandom two-liquid (NRTL) and the universal quasi chemical (UNIQUAC) activity coefficient models at various temperatures (288.2, 298.15, 303.15, and 313.15 K). The experimental results were used to obtain binary interaction parameters in these models. The root-mean-square deviation (RMSD) values for both models were less than 3.58%, and the model predictions show acceptable agreement with the measured data particularly at the plait point.

Experimental studies on the effect of ultrasonic waves on single drop liquid–liquid extraction

The influence of ultrasonic waves on hydrodynamics and mass transfer of circulating drops in liquid–liquid extraction process was studied. The recommended chemical systems of toluene–acetic acid–water with mass transfer resistance mainly in the organic phase, and cumene–isobutyric acid–water in the aqueous phase were used. An extraction column, equipped with an ultrasonic emitter of 35.40kHz real frequency and 0.37mW/cm2 intensity, was employed. The ultrasound properties were measured using the hydrophone standard method. Drops terminal velocity was comparable with the Grace model. In mass transfer study, significant enhancement was revealed in overall mass transfer coefficient for different drop sizes and for the both mass transfer directions by using ultrasonic waves. The average and maximum enhancements were, respectively, 20.8 and 31.7% for toluene–acetic acid–water, and 40.3 and 55.1% for cumene–isobutyric acid–water. Small drops exhibited a higher enhancement percentage. Regarding the mass transfer direction, the system of cumene–isobutyric acid–water with continuous to dispersed phase direction, was benefited more as the consequence of creating effective agitation in continuous phase than in dispersed phase.

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.

Two-dimensional thin-layer chromatography fingerprint profiles of ten Cirsium species by chemometric processing

Ten methanolic extracts of selected Cirsium species were analyzed using two-dimensional thin-layer chromatography (2D-TLC) system with octadecyl reversed-phase (RP-18) chromatographic plate as the stationary phase and two eluents: nonaqueous, consisting of 2-butanone‒toluene‒acetic acid (4.5:5:0.5, v/v) used in the first direction of developing, and aqueous, consisting of methanol—water—formic acid (4:5:1, v/v) used in the second direction. The Naturstoff reagent was used for the derivatization of some phenolic compounds. Five selected standards were analyzed under the same chromatographic conditions, and their retention factor values were used for the confirmation of their presence on selected Cirsium chromatograms. Photographs of ten chromatograms were treated using the ImageJ program. 2D-TLC analysis was also performed to obtain the fingerprint chromatographic profiles of the studied methanolic extracts. The experimental data were objected to principal component analysis (PCA), and the PC2 vs. PC3 grap...

Hydrodynamics and mass transfer characteristics of circulating single drops with effect of different size nanoparticles

The effect of three different size silica nanoparticles, ranged within 11–14, 20–30 and 60–70 nm, on the hydrodynamic and mass transfer of circulating drops in liquid–liquid extraction was investigated. Chemical system of toluene–acetic acid–water was used; toluene in nanofluid drop phase. Six concentrations of each nanoparticle, within 0.0005–0.005 wt%, were examined. Mass transfer direction was from nanofluid drops to aqueous continuous phase. Viscosity of nanofluids increases slightly with the size and concentration of the nanoparticles whereas the system interfacial tension remains almost constant. Terminal velocity values were comparable with those predicted by Grace and Vignes equations. The average and maximum mass transfer enhancements of 51.8 and 78.7% were achieved, respectively, with nanofluid drops. The smallest size nanoparticle at nearly the mid concentration of 0.003 wt% provides the highest enhancement. Nanoconvention caused by Brownian motion is the main plausible cause of this behavior. It was demonstrated that enhancement factor of diffusivity coefficient can be reproduced by a quadratic equation of drops’ Reynlods number, and the Newman equation based on effective diffusivity can predict the mass transfer coefficient satisfactorily.

Formulation of approximate generalised experimental data based model in a liquid–liquid extraction using zinc oxide nanomaterial

Summary The present phenomenon, i.e. enhancement of mass transfer coefficient in liquid–liquid extraction operation is a complex one and it cannot be reasoned out by any logic based model, so it is find out by experimental data based model. The present investigation is focused on the behaviour of nanofluid in the liquid–liquid extraction process. The chemical system of toluene–acetic acid–water was used, and nanofluids containing 0.1%, 0.2% and 0.3% (V/V) of zinc oxide nanoparticles of size 48.79 nm synthesised by chemical precipitation method. Maximum enhancements in the rate of mass transfer of were achieved using about 0.3 wt% zinc oxide based nanofluids; however, a decreasing variation was observed at higher concentrations. The effect of nonionic surfactants Rokanol K7 (500 ppm) on mass transfer of the liquid–liquid extraction process was also investigated and it was observed that the mass transfer coefficient increases rapidly with surfactants under a varying speed of agitation but deteriorates at high concentration. The formulation of approximate generalised experimental data based model has been developed followed by interpretation and the quantitative analysis of the model. For the aim of modelling, the experimental results obtained from liquid–liquid extraction were validated with mathematical modelling for calculation of reliability of model.

The Effect of Size and Concentration of Nanoparticles on the Mass Transfer Coefficients in Irregular Packed Liquid–Liquid Extraction Columns

This investigation explored the effects of nanofluids on mass transfer enhancement using an irregularly packed liquid–liquid extraction column and the chemical systems of water–acetic acid–toluene. SiO2 nanoparticles with sizes of 10, 30, or 80 nm are dispersed in toluene–acetic acid to produce nanofluids with different volume fractions of 0, 0.01, 0.05, and 0.1 vol.%. The effects of nanoparticle size and concentration on dispersed phase mass transfer coefficient were discussed based on the experimental data. This is for the first time that the effect of nanoparticle size is studied in liquid–liquid extraction systems. It was found that the mass transfer enhancement was more significant in nanofluids with smaller particles. It was also observed that mass transfer coefficient is larger in nanofluids compared to that in dispersed phase without nanoparticles, with a peak enhancement at a nanoparticle volume fraction of 0.05 vol.% for 10-nm particles and 0.01 vol.% for 30- and 80-nm particles. The maximum mass transfer coefficient enhancement was approximately 42% at 0.05% concentration of nanoparticles using smaller particles (10 nm). Finally, a novel correlation for prediction of effective diffusivity in the presence of nanoparticles has been proposed, which is a function of nanoparticle size and its concentration. The main advantage of this approach is that the principal effect of these two parameters is considered in correlation without which the experimental data could not be fitted with an acceptable accuracy.

Mass transfer characteristics of liquid–liquid flow in small diameter conduits

Experiments are conducted to investigate mass transfer characteristics during flow of two immiscible liquids through glass capillaries of internal diameter 2mm and 6mm. Water and toluene–acetic acid mixture are introduced in the test passage by a T mixer and the overall mass transfer co-efficient for acetic acid (10% by volume) diffusing from the organic to the aqueous phase is estimated for the slug, annular, dispersed and inverted dispersed flow patterns. Experiments are conducted for three flow orientations namely horizontal, vertical up and vertical downflow. The data are analysed by considering the prevailing flow pattern and correlating measured values of mass transfer co-efficient (kova) and solute transferred per unit pressure gradient with input parameters. It is seen that (kova) and solute transferred per unit pressure gradient is highest in case of slug flow as compared to other flow patterns. Further, (kova) is a function of both tube diameter and flow orientation, being higher in the smaller tube diameter and in downflow orientation of both the capillaries. The relationship between (kova) and energy dissipation factor is observed to be a function of phase velocity and flow pattern. Based on the experiments, the study proposes that an efficient co-current tubular contactor should be trumpet shaped with short horizontal sections connecting long vertical up and downflow sections.

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.

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.

Mass Transfer from Nanofluid Single Drops in Liquid–Liquid Extraction Process

This investigation is focused on the behavior of nanofluid single drops in the liquid–liquid extraction process. The chemical system of toluene–acetic acid–water was used, and the drops were organic nanofluids containing magnetite or alumina nanoparticles. Synthesized nanoparticles were modified with fatty acids for hydrophobicity and ease of dispersion in the organic phase and were then characterized using different methods. Maximum enhancements in the rate of mass transfer of 157% and 121% were achieved using about 0.002 wt % magnetite and alumina nanoparticles, respectively; however, a decreasing variation was observed at higher concentrations. The microconvection and particle aggregation due to the interpenetration layers can provide this kind of variation. For the aim of modeling, the determined enhancement factors were correlated with an empirical expression that can be used, together with the Newman equation, for the prediction of the overall mass-transfer coefficient.

Immunoaffinity column clean-up and thin layer chromatography for determination of ochratoxin A in green coffee

An immunoaffinity clean-up-based method for determining ochratoxin A (OTA) in green coffee aiming at one-dimensional thin layer chromatography (TLC) analysis was established. OTA was extracted with a mixture of methanol and aqueous sodium hydrogen carbonate solution, purified through an immunoaffinity column, separated on normal or reversed-phase (RP) TLC plates and detected and quantified by visual and densitometric analysis. The linear equation of the standard calibration curve by densitometric analysis gave R2 > 0.999 (0.04–84 ng). The mean recovery (R) of OTA from spiked samples (1.8–109 µg kg−1) by densitometric and visual analyses were 98.4 and 103.8%, respectively. The relative standard deviations (RSD) for densitometric and visual analysis varied from 1.1 to 24.9% and from 0.0 to 18.8%, respectively. The RSD for naturally contaminated samples by densitometry (three levels of contamination, n = 3) varied from 11.1 to 18.1%. The correlation (R2) between high-performance liquid chromatography (HPLC) and densitometry, and between visual and densitometric analysis for spiked samples were > 0.99. The limit of detection (LOD) of the method was 0.5 µg kg−1 for normal TLC. Toluene-ethyl acetate-88% formic acid (6:3:1 v/v/v) and acetonitrile-methanol-water-glacial acetic acid (35:35:29:10 v/v/v/v) were regarded as the suitable TLC solvents for eluting both standards and samples on normal and RP TLC plates, respectively. Toluene-acetic acid (99:1 v/v) was chosen as the spotting solvent among several others for giving the best sensitivity and resolution of OTA on TLC plates as well as the best recovery of OTA from standard and sample extract residues. Preliminary studies were carried out to investigate the reuse of the immunoaffinity column and the interference of caffeine in the OTA recovery.

Stability indicating HPTLC determination of piroxicam

A rapid and sensitive HPTLC method was developed and validated for the estimation of Piroxicam (PM). Spectrodensitometric scanning-integration was performed at an absorbance wavelength of 360 nm. To justify the suitability, accuracy and precision of the proposed method, recovery studies were performed at three concentration levels. One of the degradation products of PM is 2-aminopyridine (2AP). It becomes imperative to separate this compound as it is a precursor during synthesis of the drug. A TLC aluminium plate precoated with silica gel 60F-254 was used as the stationary phase. The solvent system toluene–acetic acid (8:2 v/v) gave a dense and compact spot of PM with a Rf value of 0.58±0.01 which was well separated from 2AP (Rf 0.23±0.01). The polynomial regression data for the calibration plots exhibited good linear relationship (coefficient of correlation r=0.9982) over a concentration range of 400–800 ng. Statistical analysis proves that the proposed method is accurate and reproducible. The method is stability indicating and being economical can be employed for the routine analysis in bulk drug as well as pharmaceutical formulations.

Analysis of a Single-Stage Mixer–Settler Performance

Abstract A new design of a single-stage mixer–settler is presented. The mixer, a vertical cylindrical vessel 5.5 cm in diameter and 18.0 cm long, is used for mixing the phases in its lower part. Complete solute transfer occurs in the mixer since coalescence of the dispersed phase droplets takes place on their way up via the mixer outlet to the settler. The settler, a vertical tower 3.4 cm in diameter and 40.0 cm long, serves only as a flash separator. The contactor has been tested by the toluene-acetic acid–water system in both directions of mass transfer. The contactor operates as an ideal stage when tested with the acid system. The hydrodynamics and the dynamic behavior of the contactor have been studied. A model approach has been adopted for the mixer. Agreement between the model output data and the experimental results was excellent.

Synthesis and electrochemical studies of new ferrocene-labelled dinuclear rhodium(II) complexes. Crystal structures of [Rh2(O2CMe)2{[(C6H4)PhP(C5H4)]Fe(C5H5)}2(HO2CMe)2] and [Rh2(O2CMe)2{[(C6H4)PhP(C5H4)]2Fe}(HO2CMe)]·CH2Cl2

The reaction of diphenylphosphinoferrocene and 1,1′-bis(diphenylphosphino)ferrocene with [Rh2(O2CMe)4(MeOH)2](1:1 and 1:2 molar ratio respectively) yields the monoadducts [Rh2(O2CMe)4{(Ph2PC5H4)Fe(C5H5)}]1 and [{Rh2(O2CMe)4(MeOH)}2{(Ph2PC5H4)2Fe}]2. By thermal treatment of 1 in refluxing toluene–acetic acid (10:3) the monometallated product [Rh2(O2CMe)3{[(C6H4)PhP(C5H4)]Fe(C5H5)}(HO2CMe)2]3 was obtained in practically quantitative yield. Compound 3 reacts with [Fe(C5H5)(C5H4PPh2)](1:1 molar ratio) giving the adduct [Rh2(O2CMe)3{[(C6H4)PhP(C5H4)]Fe(C5H5)}{(Ph2PC5H4)Fe(C5H5)}]4, which reacts thermally in toluene–acetic acid (10:3) yielding the doubly metallated product [Rh2(O2CMe)2{[(C6H4)PhP(C5H4)]Fe(C5H5)}2(HO2CMe)2]5 as a mixture of conformational isomers. An X-ray determination of 5 has been carried out: space group Pbca(orthorhombic), a= 18.065(3), b= 20.606(4), c= 26.242(5)A, Z= 8, and R= 0.038. The crystal structure shows that the two metallated phosphines are in a head-to-tail configuration. Thermal treatment of a mixture of [Rh2(O2CMe)4(MeOH)2] and [Fe(C5H4PPh2)2](1:1 molar ratio) in acetic acid yields the compound [Rh2(O2CMe)2{[(C6H4)PhP(C5H4)]2Fe}(HO2CMe)]·CH2Cl26 after purification and crystallization from a CH2Cl2–hexane–acetic acid mixture. An X-ray diffraction investigation showed that this compound crystallizes in space group P21/c(monoclinic) with a= 12.735(4), b= 16.811(5), c= 20.161(8)A, β= 95.17(4)°, Z= 4 and R= 0.089. The two PPh2 fragments of the ferrocene ligand act as bridging orthometallated ligands in a head-to-head configuration. Two well defined oxidation processes were detected by cyclic voltammetry for all the complexes in CH2Cl2 solution: the first one, in the range 0.6–0.7 V, is due to the couple Fe2+–Fe3+ while the second one, in the range 0.9–1.32 V, is due to the couple Rh24+–Rh25+.

Environmental Factors Affecting the Content of Usnic Acid in the Lichen Mycobiont of Ramalina siliquosa

Environmental Factors Affecting the Content of Usnic Acid in the Lichen Mycobiont of Ramalina siliquosa