Lewis Cell Research Articles

Kinetics of Ozonation of Phenol and Substituted Phenols

In the treatment of wastewaters contaminated with phenol and substituted phenols, an intermediate chemical step of partial oxidation is often employed to facilitate the ensuing biodegradation process. Ozonation is a candidate technique for partial oxidation of phenolics. In this study, the kinetics of ozonation reactions of 20 substituted phenols is investigated using the renowned theory of mass transfer with chemical reaction. The stirred (Lewis) cell with a flat interface is used as a model contactor. It is found that the second-order rate constants for the reactions with the chosen phenolic compounds are in the 104–107 M–1 s–1 range. In particular, the rate constant for ozonation of phenol is 5.06 × 106 M–1 s–1. The liquid-side mass-transfer coefficient is estimated by using the chemical method, and its value (kL = 0.052 cm s–1) is in line with those typical of stirred-cell reactors. This work is useful for the design, operation, and scale-up of ozonation reactors used in wastewater treatment.

A study on the kinetics of extraction of Ti(IV) from sulphate medium by Cyanex 302

The kinetics of Ti(IV)-extraction by Cyanex 302 (H2A2) were investigated by measuring initial Ti(IV)-transfer flux, using a constant interfacial area stirring cell, operated at 3 Hz. The empirical flux equation, at 293 K, is: F = 10−4.40 [Ti(IV)] (1 + 233[H+])−1 [H2A2](o)0.5 (1 + 3.20[SO42−])−1 (F in kmol/m2 s and [ ] terms are in kmol/m3). The activation energy, Ea is measured to be (36–58) × 103 kJ/kmol depending on experimental conditions. The enthalpy change on activation, ΔS±, is always highly negative. Analysis of the flux equation has been done, at various concentration regions of H+ and SO42−, to elucidate the mechanism of extraction. The rate-determining chemical reaction step, irrespective of extraction condition, appears as: TiO2+ + A− → TiOA+. This step occurs in the bulk aqueous phase via an SN2 mechanism. The pseudo first order rate constant for the system is 7.5–55 times smaller than the maximum mass transfer coefficient attainable in a Lewis cell. This indicates that the process is chemically controlled or at least mixed controlled.

In Situ Monitoring and Kinetic Analysis of the Extraction of Nitric Acid by Tributyl Phosphate in N-Dodecane Using Raman Spectroscopy

ABSTRACTUnderstanding the fundamental rates of transfer and complex formation is crucial in maintaining optimal efficiency and effectivity in solvent extraction. Methodologies to analyze solvent extraction systems are lacking in that they are commonly performed off-line in subsequent experiments. Thus, a method to proficiently investigate solvent extraction systems in a Lewis cell using in situ Raman spectroscopy paired with chemometric modeling has been developed to allow for on-line analysis and monitoring. Forward and reverse interfacial transfer coefficients for the extraction of nitric acid by tributyl phosphate, a process crucial to used nuclear fuel reprocessing, were measured by spectroscopic monitoring of both phases simultaneously in a two-phase solvent extraction system. Concentration data was derived from the chemometric modeling using Raman spectra. The concentration data was fit to a nonlinear least squares regression model to allow for the calculation of the transfer coefficients in the system. The reverse interfacial transfer coefficient, kr, was determined along with the parameter 95% confidence intervals and 95% prediction intervals. The forward interfacial transfer coefficient, kf, was then back calculated from kr and the aqueous phase and organic phase equilibrium concentrations. The average calculated values of kr and kf were 2.56 (± 0.50) × 10−5 m s−1 and 4.75 (± 1.13) × 10−6 m s−1, respectively. The information obtained regarding solvent extraction parameters and transfer can be applied in the study of systems of higher complexity, involving complex formation and their transfer across a liquid:liquid interface.

Extraction kinetics of uranium(VI) and thorium(IV) with di(1-methyl-heptyl)methyl phosphonate from nitric acid medium using a Lewis cell

The extraction kinetics of uranium(VI) and thorium(IV) with di(1-methyl-heptyl)methyl phosphonate (DMHMP) dissolved in kerosene were investigated from HNO3 media. Experiments were performed in a constant interfacial area stirred Lewis cell. The results with the influence of stirring speed, specific interfacial area, and temperature indicated that the extraction process was governed by diffusion in the bulk phase or by chemical reaction at the liquid-liquid interface at the stirring speed below or above 140 rpm, respectively. The activation energies for the reactions were calculated as 28.5 kJ·mol−1 and 26.8 kJ·mol−1 for U(VI) and Th(IV), respectively. Meanwhile, the obtained thermodynamic parameters (ΔH, ΔS and ΔG) revealed that the extraction of both U(VI) and Th(IV) was an endothermic and non-spontaneous process and the structure of the extracted species was more ordered than that of the extractant itself. Furthermore, the influences of initial concentrations of HNO3, DMHMP and metal ions on the extraction rates were also examined. Based on the reaction orders with respect to the reactants, the rate equations and the extraction mechanism for U(VI) and Th(IV) were also presented.

Kinetics and mechanism study of lithium extraction from alkaline solution by HFTA and TOPO and stripping process using Lewis cell technique

The kinetics of forward extraction of lithium from alkaline solution is investigated using a Lewis cell. Different parameters such as lithium concentration, HFTA concentration, TOPO concentration, pH value of aqueous phase, type of anion ion, as well as temperature are studied separately to examine their effect on lithium extraction rate, and an initial rate equation is deduced based on the experiment results. By changing the agitation speed and interfacial area of the Lewis cell, controlling mechanism of the extraction process is determined. Experimental results suggest that lithium extraction is controlled by chemical reaction at the interface rather than in the bulk phase. Further data analysis demonstrates that the lithium extraction is first order with respect to lithium ion concentration, HFTA concentration, and TOPO concentration. Different types of anion ions in aqueous phase show almost no effect on lithium extraction rate according to the experiments. Rate equation of lithium extraction by HFTA and TOPO is proposed as RLi,0 = 10−4.33±0.1 [Li+][HFTA][TOPO]. The rate-determining step of lithium extraction is the formation of final complex at the interface and the deduced extraction mechanism justified the experiments results well. For stripping process, effect of lithium concentration in organic, hydrogen ion concentration stirring speed and interfacial area on stripping rate are investigated. Analysis of the experimental data reveal that lithium stripping from organic phase is mainly controlled by chemical reaction and the reaction takes place at the interface rather than phase bulk. Linear regression of the plot of log[HCl] and log[Li+]org versus logRLi,st reveals that the reaction orders with respect to HCl and lithium in organic are both 1, namely the stripping process is first order with HCl and lithium concentration in organic. Rate equation of lithium stripping from organic phase by HCl is proposed as RLi,st = 10−4.0±0.1 [Li+]org[HCl].

Solvent extraction kinetics of Ag(I) with methyl ketonic p-tert-octylcalix[4]arene in the modified Lewis cell technique

The solvent extraction kinetics of Ag(I) with methyl ketonic p-tert-octylcalix[4]arene as a hydrophobic extractant have been studied using a modified Lewis cell system. The effects of different parameters affecting the extraction efficiency such as the stirring speed, the temperature, and the Ag concentration were all investigated. The initial Ag(I) extraction efficiency was found to rapidly increase on increasing the stirring speed in the Lewis cell to 170 rpm after which a plateau in the efficiency occurred. That is, Ag(I) extraction was influenced by diffusion up to 170 rpm, with the diffusion contribution being minimized over 170 rpm. Thus, for the cell configuration employed, 170 rpm represents the crossover point between diffusion and chemical reaction control at the liquid–liquid interface. The results are thus in accord with the efficiency of Ag(I) extraction by methyl ketonic p-tert-octylcalix[4]arene being governed by a mixed regime (diffusion and chemical reaction) for the liquid–liquid extraction system investigated. Furthermore, study of the thermodynamic parameters indicated that the adsorption process was spontaneous and exothermic in nature. Overall, using a modified Lewis cell system it has been possible to identify the factors influencing the efficiency of extraction under different conditions for the above liquid–liquid extraction system.

A novel constant interfacial area cell for determining the extraction kinetics of Er(III) from chloride medium

Abstract A novel constant interfacial area cell (NCIAC), by spatially separating the agitation from liquid flow circulation of organic and aqueous two phases, was suggested to obtain detailed kinetic data for Er(III) extraction from chloride medium by 2-ethyl-hexyl-phosphonic acid mono-(2-ethylhexyl) ester (EHEHPA). Different from the traditional Lewis cell and the constant interfacial area cell with laminar flow, the concentrations of Er(III) in organic and aqueous two phases were uniform, and the stability of the interfacial area between the two phases could be controlled effectively. Therefore, the special requirements for the design of agitators in the traditional Lewis cell and the constant interfacial area cell for minimizing the influence of diffusion resistance could be avoided. Experimental results indicated that the extraction kinetics was mainly affected by the aqueous flow rate, interfacial area between organic and aqueous two phases, and the aqueous pH values. An extraction kinetic equation was suggested based on the experimental data.

Extraction kinetics of lithium from salt lake brine by N,N-bis(2-ethylhexyl) acetamide using Lewis Cell

Lithium, as the green energy, its application and exploitation attract much attention. The lithium extraction kinetics with N,N-bis(2-ethylhexyl) acetamide(N523) in sulfonated kerosene has been investigated experimentally using Lewis Cell. The effects of diffusion resistance area, interfacial area, temperature and the concentration of reagents were studied. The results showed that the diffusion resistance mainly existed in aqueous phase, the extraction process was a diffusion-controlled kinetics process with an interfacial reaction and the extraction kinetic equation was obtained.

Extraction kinetics and mechanism of Zr and Hf by DIBK−TOPO system using Lewis Cell

ABSTRACTKinetics studies on the extraction of Zr and Hf using the mixture of diisobutyl ketone (DIBK) and trioctylphosphine oxide (TOPO) as extractant were performed in a Lewis Cell. The results showed that the extraction rate of Zr was governed by chemical reaction in the bulk phase. The extraction rate of Hf was controlled by chemical reaction and mass diffusion at the interface. It testified that the overall extraction reaction was an exothermic and non-spontaneous process, which occurred via an SN2 mechanism. Under the given conditions, the overall extraction rate equation and rate-limiting chemical reaction step of Zr and Hf were proposed.

Kinetics study and simulation of CO2 absorption into mixed aqueous solutions of methyldiethanolamine and hexylamine

This study investigated kinetics of CO2 absorption into mixed methyldiethanolamine (MDEA) and hexylamine (HA) solutions in a Lewis cell reactor. The experiments were conducted in the temperatures 298, 313 and 333 K with mass concentrations MDEA 37 wt.% + HA 3 wt.%, MDEA 35 wt.% + HA 5 wt.% and MDEA 33 wt.% + HA 7 wt.%. Our results showed that adding a small amount of hexylamine enhances the kinetics of CO2 absorption and that the kinetics of CO2 absorption with aqueous MDEA 37 wt.% + HA 3 wt.% is pseudo first order regime with reduced activation energy compared to that of MDEA 40 wt.%. The absorption/regeneration system was simulated using Aspen plus™ software for the treatment of gas streams from cement plant in a post-combustion process. The analysis of our results established that blended solvent MDEA 37 wt.% + HA 3 wt.% gives lower energy consumption than that of MDEA 40 wt.%.

Kinetic study on reactive extraction of clorprenaline enantiomers with a combined chiral selector

ABSTRACTThis paper reports on the kinetic study on reactive extraction of clorprenaline (CPNL) enantiomers with isobutyl (d)-tartrate (DT) and boric acid (BA) as combined chiral selector in a Lewis cell, where exists an interfacial reaction involving three species: BA, DT, and CPNL enantiomers. The important factors that influence the kinetics of reactive extraction are investigated. Through multiple linear regression analysis of the experimental data, the order with respect to BA, CPNL, and DT of the interfacial reaction is 0.6, 0.8, and 0.8, respectively, and the total order of reaction is about 2.2. The forward rate constants have been calculated to be 2.476 × 10–4 L1.53/(mol1.2 s) for (R)-CPNL and 1.349 × 10–4 L1.53/(mol1.2 s) for (S)-CPNL.

Targeted blockade of TGF-\u03b2 and IL-6/JAK2/STAT3 pathways inhibits lung cancer growth promoted by bone marrow-derived myofibroblasts

To investigate the role of TGF-β and IL-6 in myofibroblasts (MFs) — lung cancer cell interactions, lung cancer cells (Lewis and CTM-167 cell lines) were stimulated by IL-6, MF-conditioned medium (MF-CM) or MFs, with or without TGF-β signaling inhibitor — SB431542 and/or JAK2/STAT3 inhibitor — JSI-124. MFs were stimulated by TGF-β, cancer cell-CM or cancer cells, with or without SB431542 and JSI-124. Cell proliferation, the levels of cytokines, expression of mRNA and protein were determined. Mice bearing xenograft tumors were intraperitoneally treated with SB431542 or JSI-124 and monitored for up to 45 days. In co-culture systems, MFs secreted high levels of IL-6, while cancer cells produced high levels of TGF-β. Recombinant IL-6 and MF-CM activated STAT3 and upregulated TGF-β in cancer cells. In contrast, cancer cell-CM or TGF-β stimulated MFs to produce IL-6. Blockade of JAK2/STAT3 and TGF-β signaling by specific inhibitors significantly inhibited cell proliferation in vitro and tumor growth in vivo of lung cancer cells. Our study demontrated that the TGF-β and IL-6/JAK2/STAT3 signaling pathways form a positive feedback signaling loop that mediated the interactions between MFs and lung cancer cells. Targeted inhibiton of this signaling loop could be a new approach for lung cancer prevention and therapy.

Study of CO2 Absorption into Phase Change Solvents MAPA and DEEA

This work provides new data for carbon dioxide (CO2) absorption into phase change solvent systems consisting of an aqueous solution of 2-(diethylamino)ethanol (DEEA) and 3-(methylamino)propylamine (MAPA). The variables related to CO2 absorption are studied and a Lewis cell type apparatus is taken into use. The latter was first validated with experiments of CO2 absorption into aqueous methyl diethanolamine (MDEA) solutions. Experiments are carried out for the determination of apparent kinetic absorption constant and absorption rate of CO2 for aqueous DEEA/MAPA mixtures. The determined kinetic constants (0.008–0.007 mol·(m3·s)−1 for MAPA/DEEA between 308 and 318 K and 0.0184–0.0022 m3·(mol·s)−1 for MDEA between 296 and 318 K) are compared to the literature where available. The phenomena related to phase change solvent absorption are carefully studied. A relation between total CO2 loading and absorption rate is observed, and reasons behind the dependency and the phenomena are analyzed.

A kinetic study on solvent extraction of copper from sulfate solution with Cupromex-3302 using Lewis cell

The reactive extraction of Cu(II) from a sulfate aqueous solution using Cupromex-3302 as a new extractant was investigated using a Lewis cell to reveal the mechanism of extraction. Various affecting parameters such as stirring speed, temperature, interfacial area, extractant concentration, Cu(II) concentration and aqueous phase pH were studied. The rate of copper extraction was found to be directly proportional to the concentrations of Cu(II) and extractant and inversely proportional to the concentration of H+. The extraction rate of Cu(II) increased with an increase in specific interfacial area demonstrated that the rate determining step of Cu(II) extraction by Cupromex-3302 was reactive extraction at the interface. Also, extraction rate increased with increasing the temperature. The activation energy (E) was calculated to be 15.2kJ/mol. This value suggested that extraction of Cu(II) in this system is controlled by diffusion mechanism.

Study on kinetics of reactive extraction of propranolol enantiomers by multiple linear regression method

AbstractKinetic study on reactive extraction of propranolol (Pra) enantiomers with di‐cyclohexyl (D)‐tartrate (DT) and boric acid (BA) as combined chiral selector was performed in a modified Lewis cell. The effects of agitation speed, interfacial area, pH value of aqueous phase, as well as initial concentrations of DT, BA and Pra enantiomers on extraction rate were investigated. The experimental data were analyzed by multiple linear regression method to evaluate some important parameters. It was found that the interfacial reaction is 0.4, 0.8 and 0.8 order separately with respect to BA, Pra and DT, and the forward rate constants have been found to be 5.08 × 10−4 L/(mol s) for (R)‐Pra and 2.42 × 10−4 L/(mol s) for (S)‐Pra. An interfacial reaction mechanism was proposed to understand the rate equation. © 2017 Curtin University of Technology and John Wiley & Sons, Ltd.

Effects of simvastatin on the proliferation, invasion and radiosensitivity in Lewis lung cancer cell line

Objective: To investigate the effects of simvastatin on proliferation, invasion and radiosensitivity of mouse Lewis lung cancer cell line in vitro. Methods: The inhibitory effects of simvastatin on proliferation of Lewis lung cancer cells were detected by MTT assay. Matrigel invasion and migration assay was used to determine the invasion and motility ability of the Lewis cells. P38 activity was measured by p38 activity detection kit, and the expressions of p-p38, MKP-1, RhoA and MMP-2 were analyzed by Western blot. Lung cancer xenograft model was established in C57BL/6 mice. The mice were randomly divided into control group, simvastatin group, radiotherapy alone group and combined treatment group. The mice were killed 27 days after inoculation. The tumor mass, volume and lung metastatic nodules in the mice were compared. Results: The cell proliferation rates of 0 μmol/L, 10 μmol/L, 20 μmol/L and 30 μmol/L simvastatin groups were 100%, (87.0±9.0)%, (76.5±8.1)% and (67.0±7.3)%, respectively (P<0.05). Invasive cell numbers of the above groups were 298±30, 251±26, 207±20 and 132±19 per field, respectively (P<0.05). The intracellular p38 activities were 100%, (83.1±8.8)%, (70.2±8.2)% and (59.0±6.4)%, respectively. The relative expressions of p-p38 were 100%, (76.2±6.7)%, (56.4±5.4)% and (36.5±3.2)%, respectively. The expressions of RhoA were 100%, (80.1±5.3)%, (55.3±6.2)% and (38.6±4.8)%, respectively. The expressions of MMP-2 were 100%, (89.6±8.6)%, (51.9±4.7)% and (42.7±3.1)%, respectively, while the expressions of MKP-1 were 100%, (136.5±12.2)%, (168.8±15.3)% and (187.7±13.4)%, respectively (all P<0.05). Lung metastatic nodules and mass in the control, simvastatin, radiotherapy group and combined treatment groups were 6.24±1.09, 3.07±0.71 g, 5.09±1.16, 2.43±0.53 g, 3.12±0.68, 1.96±0.62 g and 2.65±0.38, 1.12±0.43 g, respectively (all P<0.05). The tumor inhibition rates were 39.0%, 48.1% and 26.5%, respectively, in the radiotherapy alone, combined treatment and simvastatin groups (all P<0.05). Conclusions: Simvastatin inhibits the proliferation of Lewis cell line by inhibiting the activity of p38 and expression of p-p38. Meanwhile, simvastatin reduces the invasion and motility of Lewis cell line through down-regulating the expression of RhoA and MMP-2. When combined with radiotherapy, simvastatin can inhibit tumor growth and metastasis, and improve the treatment efficacy of radiotherapy synergistically.

Study on extraction kinetics of α -cyclopentylmandelic acid enantiomers with hydroxyethyl- β -cyclodextrin as chiral selector

Abstract In this work, the kinetic study on reactive extraction of α -cyclopentylmandelic acid ( α -CPMA) enantiomers was performed in a Lewis cell using hydroxyethyl- β -cyclodextrin (HE- β -CD) as chiral selector. The enantioselective complexation equilibrium between HE- β -CD and α -CPMA enantiomers was studied by phase solubility method. The important process parameters affecting the initial extraction rate were separately studied and the reaction rate equations were deduced. The optimal conditions for kinetic study were as follows: stirring speed of 75 r·min − 1 , interfacial area of 12.56 cm 2 , pH of 2.5, initial HE- β -CD concentration of 0.05 mol ·L − 1 , initial α -CPMA concentration of 5 mmol·L − 1 , and temperature of 278 K. The reaction has been found to be first order in α -CPMA and second order in HE- β -CD with the forward rate constants of 2.056 × 10 − 3 m 6 ·mol − 2 ·s − 1 and 1.459 × 10 − 3 m 6 ·mol − 2 ·s − 1 for ( S )- α -CPMA and ( R )- α -CPMA, respectively. The complexation equilibrium constants were evaluated as 61 L·mol − 1 and 117 L·mol − 1 for ( S )- α -CPMA and ( R )- α -CPMA, and the intrinsic enantioselectivity is estimated as 1.92.

Study on the Extraction Kinetics of Ketoconazole with Hydroxypropyl-β-Cyclodextrin as a Selector

This paper reports on the kinetics of extraction of ketoconazole enantiomers in a Lewis cell, which accompanies by an inclusion reaction. The mass transfer model of the extraction process is established based on the homogeneous reaction mechanism and two-film theory. Factors such as stirring speed, phase contact area, and ketoconazole concentration are separately investigated. The obtained data show the inclusion reaction is a fast reaction. The reactions have been found to be first order for ketoconazole enantiomers and second order for hydroxypropyl-β-cyclodextrin with forward rate constants of 1.716 × 10−3 m6/(mol2·s) for (−)-ketoconazole and 2.067 × 10−3 m6/(mol2·s) for (+)-ketoconazole.

Kinetics of extraction of Ti(IV) from SO42– medium by Cyanex 301 dissolved in kerosene containing 5% heptan-1-ol

ABSTRACTThe kinetics of Ti(IV) extraction by Cyanex 301 (HA) were investigated by measuring initial flux of Ti(IV) transfer (F, kmol/m2s), using a Lewis cell, operated at 3 Hz. The empirical flux equation at 298 K is found to be as follows: F (kmol/m2s) = 10–4.288 [Ti(IV)] (1 + 447 [H+])–1 [HA](o) (1 + 1.18[SO42–])–1. The activation energy, Ea, has been measured to be within 37–60 kJ/mol, depending on experimental parameters and temperature region. The ΔS± value is always highly negative. Analysis of the flux equation has been done, given various parametric conditions, to elucidate the mechanism of extraction. The rate-determining chemical reaction step, in most parametric conditions, appears to be as follows: TiO2+ + A– → TiOA+; and this step occurs via an SN2 mechanism as suggested by high negative ΔS± values. However, in certain cases, the extraction process appears as intermediate controlled as supported by Ea value of less than ~48 kJ/mol.

Incorporating spectroscopic on-line monitoring as a method of detection for a Lewis cell setup.

A Lewis cell was designed and constructed for investigating solvent extraction systems by spectrophotometrically monitoring both the organic and aqueous phases in real time. This new Lewis cell was tested and shown to perform well compared to other previously reported Lewis cell designs. The advantage of the new design is that the spectroscopic measurement allows determination of not only metal ion concentrations, but also information regarding chemical speciation - information not available with previous Lewis cell designs. For convenience, the new Lewis cell design was dubbed COSMOFLEX (COntinuous Spectroscopic MOnitoring of Forrest's Liquid-liquid EXtraction cell). After construction performance testing was done for establishing the ideal stir speed range, UV-Vis measured concentration and D value determination. Each one of these tests was satisfactorily passed.