The authors have declared that no competing interests exist.
The present study aims to shed light directly towards the extraction of (IV) cerium ions using "liquid surfactant membrane" technology, "LSM" developed in the presence of synergistic cationic and nonionic materials. The effect of various factors such as Ce (IV) transport, synergistic surfactants, curing ratio, stir speed, temperature, and mixing time between the carrier and the cerium ion on the extraction rate was studied by LSM taking into account surfactant agents. The positive effect of benzethonium chloride "Hy-1622" on the extraction of cerium ion was demonstrated by LSMs technique. Experiments confirmed the efficiency of Hy-1622 chloride synergistically with Span 80/85 to extract cerium ions with LSMs technology for emulsions in the oil phase is critical as it determines the stability, viscosity and mass transfer resistance of the resulting emulsion. Besides, Hy-1622 chloride was found as a new cationic surfactant that appeared in FTIR characterization and surfactant was found to speed up the permeability process and accelerate the extraction rate due to electrostatic interaction with the carrier.
The increased discharge of various metals into the environment by different industries is a threat to the environment. Thus, recovering it from wastewater is an important topic of research in wastewater treatment. Lanthanides are among the most toxic minerals. Cerium is one of the rare chemical elements that many daily industries depend on, such as color televisions, fluorescent lamps, glasses and energy-saving lamps, and its salts can be used to stimulate the metabolism process
2-DEHEHP, B (GR grade, Merck), Benzene (BDH), 1,2-dichloroethane (ClCH2CH2Cl) (ɛ=10.50), D=17.34, dichloromethane (5% v/v) (all from Merck) Ce(IV) (GR grade. Merck), different metal ions such as Mg(II), Ca(II) and K (I) 1x10-3 M in 3 M HNO3 (GR grade. Merck), sodium hydroxide, and sodium nitrate (BDH) were used without purification. 1,2-dichloroethane, dichloromethane, and Benzethonium chloride Wt= 448.1 g/mol (all from Merck) with the highest purity were used as liquid membranes. All aqueous solutions were prepared using doubled distilled water (DDW),
To prepare a stable emulsion membrane, the droplet size should be very small, in the range of 2.8-4 μm. This can be accomplished by image capture through high energy density into a W / O (dispersed / continuous) phase emulsion during emulsification. For the small liquid surfactant membrane system, high-speed agitators are used with stirring speeds of 4.000 rpm in the emulsion prepare. During emulsification, an internal aqueous phase containing a sodium nitrate as stripping agent is introduced. such as the extraction method with an extractant in the membrane phase, the selected sodium nitrate as stripping agent should be also thermodynamically appropriate for the stripping process and display, a fast reaction with aH+[NO3]-2 -2DEHEHP, B complex. However, due to the very large interfacial area of internal droplets as long as, even the sodium nitrate as stripping procedure, with very low reaction kinetics can be utilize in an LSM system. From
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Volume | 50 Cm |
Carrier 2(DEHEHP) | 1x10-3M |
Diluent (dichloromethane) | 5% v/v |
Non-anionic surfactant | |
Span 80 | 100 g/L |
Span 85 | 130 g/L |
Xylene | 50% |
Kow = KD = X0/Xw |
|
Cationic surfactant | |
(Hy-1622) | solubility of 160 g/L in water |
De-ionized water | 85 ml |
Volume | 15 ml |
Ce(IV) | 25 ml |
pH | 1-2.5 |
Buffer{NaNO3 HNO3} | 1X10-3 mol/L |
Volume | 15 ml |
Acidity | 3M of Ce(NO3)2 |
Feed composition | Ce(IV) with different metals such as Potassium, Magnesium &Calcium |
Concentration | 5x10-4 mol/L 1x10-3 mol/L |
Stirring speed | 2000-4000 rpm |
*For emulsion preparation of aqueous solution used deionized water
*Concentration of surfactant in organic phase=1.60x10-2M.
*Concentration of cerium(IV) nitrate = 5x10-4M
*Concentration of NaNO3 as stripping agent=1x10-3 M.
The transport experiments utilized standardized concentric cells in which the aqueous phase (15 cm3) and receiving phase (25 cm3) were separated by an oily phase (50cm3). All experiments were carried out at 250C. The oily layer was stirred by a Teflon-coated magnetic bar at 200-400 rpm. Under better experimental conditions, the mixing process should be ideal to avoid the interfaces between the organic membrane and the two aqueous phases. The aqueous phase (AP) contained cerium (IV) nitrate (5x10-4M). The membrane phase (MP) contained the benzethonium chloride surfactant (1x10-3M) and the receiving phase (RP), consisted of sodium nitrate as a stripping agent (1x10-3 M). Through the implementation of the transport experiment, samples of aqueous phases jointly were analyzed for metal by atomic absorption spectroscopy (AAS) Model Thermo Scientific, USA), under optimal conditions λCe at 470-485 nm
Parameter | Span 80 | Span 85 | Benzathonium chloride(Hy-1622) |
M.Wt | 428.6 | 448.1 | |
Type | Non-ionic | 957.52 | Cationic |
Density | 0.986 g/ml | Non-ionic | 0.998 g/ml |
Viscosity | Viscous liquid | 0.94 g/ml | When shaken form viscous solution |
Sp.G | 0.986 | 200-300 mpa.s | 0.98 |
Solubility | Soluble in fatty oils | 0.956 | Soluble in H2O at 18o C |
Color | Yellow | Soluble in CHCl3 | White solid |
HLB | 4.3 | Light yellow | ---- |
Stability | Stable, incomplete with strong oxidizing agents | 1.8±1.1 | Stable but hygroscopic, ncompatible with strong oxidizing agents |
M.Wt = Molecular weight
Sp.G = Specific gravity
HLB = Hydrophilic-lipophilic balance
Emulsion stability plays an important role in the implementation of emulsion surfactant membrane ESM, it is decisively to culminate the desired level of stability. In this work, the optimum conditions for stable emulsion were determined practically. The stability study of the emulsion was carried out by manipulating different parameters like stripping rate, mixing stirring, treat ratio Vm/Vce , the effect of temperatures, and the effect of viscosity. The viscosities of the chemicals and mixtures were measured with a Vibro viscometer Brookfield RVDVE230 Medium-range viscometer), all viscosity measurements were done in thermostated conditions, at 45oC, except when the temperature influence was studied. Viscosity measurement systems used corresponding to the three apparatuses and the different conditions sets of rotation speed and spindle number. In each case, the dynamic viscosity/Absolute viscosity below 1. All results are shown in
Where ƹ% membrane breakage, Vi initial volume of the internal phase,Ve volume of the external phase.
Most of the types of surfactant added during emulsification adsorb to connect, between the membrane phase and the stripping phase. Therefore, an increase in the surfactant concentration in the membrane phase enhances the strength of the adsorption layer. When surfactant concentration increases due to a decrease in the interfacial tension between the membrane phase and the stripping phase
The new cationic surfactant, Hy-1622 and characterized in the solid-state by FT-IR, and in solution by1H-and13C-NMR spectroscopy. The value of (CMC) or critical micelle concentration was determined by UV-visible spectroscopy. Interaction of surfactant with cerium ion was studied by UV-visible spectroscopy. These surfactants were proved to be efficient in increasing the solubility of cerium molecules. To test the carrier efficiency of cationic surfactant against cerium-bond coordinate, a new complex interaction of recently reported cerium complex was tested with synthesized cationic surfactants by conductometric measurements
The cerium ion is transported from the aqueous phase or feed into the receiving phase via the oil membrane. The movement of charge cerium ion species through the DEHEHP, B (15%v/v) as the hydrophobic liquid membrane is achieved, by the presence of a cooperative factor collected by DEHEHP, B. After complexation of the carrier with Ce(IV) on the source outline phase of the membrane, the DEHEHP, B-Ce(IV) distribute, down its concentration gradient. On the receiving phase of the membrane, the metal ions species would be released into the receiving phase across the formation of a ternary complex from carrier/Ce (IV)/sodium nitrate). At this phase, the free carrier diffuses back via the liquid membrane. The data is the transport of cerium ion from the aqueous phase into the aqueous receiving phase via the bulk of the oil membrane phase
Where HR that the Di-(2-ethylhexyl) phosphoric acid extractant and the aq. and org. denotes aqueous and organic phase conditions respectively. At pH>2.0 the precipitate formation of Ce(OH)2 tends to diminished the efficiency, Ce(IV) aqueous concentration decreasing the Cerium extraction.
Role of diversified constituents of organic phase during the liquid surfactant membrane formulation Feed phase at pH =2.5 has a very strong effect on the concentration of acidic dissociated (H+ + A−) as (2-ethylhexyl) phosphoric acid in H+,[NO3]-2.In a typical experiment, 15 ml of the required metal ion (5.0 ×10-4 M) was placed in the titration cell, thermostated at 250C, and the conductance of the solution was measured. Then, a known amount of a concentrated DEHEHP, B solution (1×10-3M) using a calibrated micropipette. The conductance of the solution was measured after each addition. The ligand solution (L) was added continually until the required (L: M) ratio was achieved. The formation constants, Kf, and the molar conductance (ɅM), of the resulting 1:1 complexes between 2DEHEHP, B and the Ce (IV) cation used, in different mixtures and at different from 10-250C, were calculated by fitting the observed molar conductance, Λobs, at varying DEHEHP B/[Ce4+] mole ratios to express the Λobs as a function of the free and complexes Ce(IV) ions.
This may be due to the size of the Ce4+(r = 1.05 A˚) ion and, therefore, it can connect a fit condition for the DEHEHP, B (r=2.8A˚) cavity. Another data, we preliminarily investigated on competitive transmission, of cerium ion among some various metal cations and affected of surfactants also.
Interfering ions | Surfactant | Results |
Span 80 only | The concentration of surfactant Span 80 of Ce(IV) by analysis of different parameters showed that the nonionic surfactant does not affect K (I), Mg (II), Ca(II) while Ce(IV) slightly extraction effectiveness at pH 2.5 | |
K (I) | 0% | |
Mg (II) | 0% | |
Ca (II) | 0% | |
Ce (IV) | 34% | |
Span 85 only | The concentration of surfactant Span 85 of Ce (IV) by analysis of different parameters showed that the nonionic surfactant does not affect K (I),Mg (II), Ca (II) 1% while Ce (IV) increasing extraction effectiveness at pH 2.5 | |
K (I) | 0% | |
Mg (II) | 0% | |
Ca (II) | 1% | |
Ce (IV) | 56% | |
Hy-1622 only | The concentration of surfactant Hy-1622 of Ce(IV) by analysis of different parameters showed that the cationic surfactant effect on K (I), Mg (II), Ca (II) while Ce(IV) increasing extraction effectiveness at pH 2.5 | |
K (I) | 2% | |
Mg (II) | 10.50% | |
Ca (II) | 25% | |
Ce (IV) | 82% |
Interfering ions dissolving in HNO3 (3M).
The optimal conditions parameter indicate a stable emulsion is emulsification speed: 2000-4000 rpm,
emulsification time at 3 min, agitation speed: 300 rpm, internal phase concentration (NaNO3):1x10-3M carrier concentration (DEHEHP, B): 22% (w/w), Hy-1622 surfactant concentration and 3% Span 80/85 (w/w), volume, the ratio between the membrane phase and internal phase 1:3 and the volume ratio between the emulsion phase and the external phase as 1:1, 1, 2-dichloroethane as diluent. The chemical structure of the Hy-1622 surfactants was confirmed using FT-IR spectra characterization and biological activity of colloidal cerium. Besides, the cationic surfactant showed a high recurrence estimated in a period of comparative is to transport the ultimate amount of waste during the treatment process. The calculated diagram of prevalence, on a species of Ce(IV) enhances, these observations in
(
Experiments were performed under the optimal conditions as mentioned previously with a carrier concentration. In a benzethonium chloride as an LSM system, a surfactant added as an emulsifier in the liquid membrane phase affects not only the stability of the liquid membrane but affect the swelling of the emulsion and the rate of cerium ion extraction. Initiatory experiments were proceeding, using benzethonium chloride (Hy-1622) and Span, 80/85 (3:1) as a cationic surfactant. Data indicated that Hy-1622 gives higher breakage values while Span 80/85 due to lower break-up of the emulsion. Thus Span 80/85(3:1) was chosen as a nonionic surfactant in this study
The volume fraction of the stripping phase and the viscosity of the oily phase determine the viscosity of the W/O emulsion. The viscosity of the oily phase is proportional to the stability of emulsions. Subsequently, utilizing highly viscous oil as a membrane phase can supply more stable emulsions. However, it has been found that the increased viscosity of the membrane safely decreases the diffusivity for anisotropic fluids. Thus, this medication reduces a solute diffusivity, and consecutive lowering in the extraction rate has been specified, as a movable, in the ELM process.
Interfacial tensions in separate ions by using cationic/anionic surfactant mixtures in one aqueous phase-, without and with NaNO3 added were determined by the spinning drop method at 25oc. The relation between interfacial tension and the concentration cationic/anionic surfactant mixtures determined by the density and viscosity is shown in
T=25oC | Kgm-1 ρ | (mpa)ƞ | span80ⱴ | Kgm-1 ρ | (mpa)ƞ | span85ⱴ | Kgm-1 ρ | (mpa)ƞ | Hy-1622ⱴ |
0 | 983.2 | 0.371 | 3.77x10-4 | 989.3 | 0.381 | 3.85x10-4 | 992.3 | 0.384 | 3.86x10-4 |
0.2 | 951.7 | 0.611 | 6.427x10-4 | 962.7 | 0.712 | 7.49x10-4 | 989.7 | 0.742 | 7.49x10-4 |
0.4 | 923.5 | 0.763 | 8.26x10-4 | 953.8 | 0.873 | 9.12x10-4 | 978.8 | 0.893 | 9.12x10-4 |
0.6 | 848.6 | 0.814 | 9.59x10-4 | 924.3 | 0.921 | 9.72x10-4 | 967.4 | 0.941 | 9.72x10-4 |
0.8 | 823.44 | 0.81 | 9.83x10-4 | 843.5 | 0.92 | 1.09x10-3 | 895.3 | 0.93 | 1.03x10-3 |
1 | 796.5 | 0.774 | 9.71x10-4 | 805.7 | 0.835 | 1.03x10-3 | 822.4 | 0.845 | 1.02x10-3 |
1.2 | 664.11 | 0.736 | 1.1x10-3 | 728.3 | 0.827 | 1.1x10-3 | 798.3 | 0.833 | 1.04x10-3 |
1.4 | 584.32 | 0.685 | 1.17x10-3 | 687.4 | 0.769 | 1.11x10-3 | 756.3 | 0.775 | 1.02x10-3 |
T=35oC | Kgm-1 ρ | (mpa)ƞ | pan80ⱴ | Kgm-1 ρ | (mpa)ƞ | span85ⱴ | Kgm-1 ρ | (mpa)ƞ | Hy-1622ⱴ |
0 | 962.7 | 0.337 | 3.5x10-4 | 974.5 | 0.345 | 3.5x10-4 | 985.3 | 0.361 | 3.66x10-4 |
0.2 | 935.2 | 0.578 | 6.18x10-4 | 953.2 | 0.705 | 7.39x10-4 | 974.2 | 0.687 | 7.05x10-4 |
0.4 | 911.2 | 0.685 | 7.5x10-4 | 936.4 | 0.796 | 8.50x10-4 | 956.7 | 0.756 | 7.90x10-4 |
0.6 | 830.2 | 0.712 | 8.5x10-4 | 915.3 | 0.897 | 9.80x10-4 | 945.2 | 0.866 | 9.2x10-4 |
0.8 | 814.6 | 0.789 | 9.68x10-4 | 820.3 | 0.842 | 1.02x10-3 | 886.7 | 0.897 | 1.01x10-3 |
1 | 768.2 | 0.712 | 9.26x10-4 | 789.3 | 0.802 | 1x10-3 | 812.3 | 0.911 | 1.12x10-3 |
1.2 | 637.4 | 0.653 | 1.02x10-3 | 712.3 | 0.798 | 1.1x10-3 | 787.6 | 0.82 | 1.04x10-3 |
1.4 | 547.6 | 0.579 | 1.05x10-3 | 624.9 | 0.687 | 1.09x10-3 | 723.5 | 0.66 | 9.1x10-4 |
T=40oC | Kgm-1 ρ | (mpa)ƞ | span80ⱴ | Kgm-1 ρ | (mpa)ƞ | span85ⱴ | Kgm-1 ρ | (mpa)ƞ | Hy-1622ⱴ |
0 | 956.3 | 0.321 | 3.35x10-4 | 969.3 | 0.356 | 3.67x10-4 | 978.3 | 0.375 | 3.8x10-4 |
0.2 | 947.6 | 0.6 | 6.33x10-4 | 943.7 | 0.7 | 7.41x10-4 | 962.6 | 0.712 | 7.39x10-4 |
0.4 | 914.5 | 0.723 | 7.9x10-4 | 936.8 | 0.842 | 8.9x10-4 | 954.3 | 0.865 | 9.06x10-4 |
0.6 | 814.6 | 0.802 | 9.9x10-4 | 919.3 | 0.902 | 9.81x10-4 | 936.2 | 0.922 | 9.84x10-4 |
0.8 | 818.4 | 0.809 | 1.01x10-3 | 823.7 | 0.911 | 1.10x10-3 | 874 | 0.928 | 1.06x10-3 |
4870451141730001 | 754.5 | 0.764 | 1.12x10-3 | 798.7 | 0.815 | 1.12x10-3 | 811.7 | 0.836 | 1.02x10-3 |
1.2 | 632.3 | 0.712 | 1.1x10-3 | 718.6 | 0.808 | 1.1x10-3 | 769.2 | 0.82 | 1.06x10-3 |
1.4 | 567.12 | 0.549 | 9.68x10-4 | 656.4 | 0.685 | 1.04x10-3 | 736.3 | 0.747 | 1.01x10-3 |
T=45oC | Kgm-1 ρ | (mpa)ƞ | span80ⱴ | Kgm-1 ρ | (mpa)ƞ | span85ⱴ | Kgm-1 ρ | (mpa)ƞ | Hy-1622ⱴ |
0 | 944.8 | 0.318 | 3.36x10-4 | 960.5 | 0.325 | 3.38x10-4 | 964.3 | 0.344 | 3.56x10-4 |
0.2 | 921.1 | 0.525 | 5.69x10-4 | 933.2 | 0.698 | 7.47x10-4 | 945.2 | 0.654 | 6.92x10-4 |
0.4 | 908.8 | 0.647 | 7.21x10-4 | 906.4 | 0.596 | 6.5x10-4 | 935.6 | 0.712 | 7.6x10-4 |
0.6 | 824.3 | 0.7 | 8.49x10-4 | 875.3 | 0.799 | 9.1x10-4 | 923.5 | 0.832 | 9.01x10-4 |
0.8 | 808.9 | 0.772 | 9.54x10-4 | 811.3 | 0.833 | 1.02x10-3 | 838.7 | 0.847 | 1.0x10-3 |
1 | 742.6 | 0.674 | 9.07x10-4 | 765.3 | 0.759 | 9.91x10-4 | 800.3 | 0.902 | 1.12x10-3 |
1.2 | 624.8 | 0.622 | 9.96x10-4 | 702.3 | 0.778 | 1.10x10-3 | 747.5 | 0.803 | 1.0x10-3 |
1.4 | 523.8 | 0.509 | 9.7x10-4 | 612.3 | 0.668 | 1.09x10-3 | 698.5 | 0.647 | 9.2x10-4 |
Where ⱴ = (ƞ / ρ) ⱴ= kinematic viscosity, ƞ=dynamic viscosity/Absolute viscosity ρ=density
The treat ratio, defined as the volume ratio of the emulsion phase (Vm) to the aqueous external solution (VCe), an important key in determining the efficiency of ELM. Through experiments were to study the effect of treat ratio on the extraction of cerium ion species. It's not changeable random, because it is necessary to pledge that the HNO3 concentration that's existent in the internal phase is high enough to react with the external phase which is the cerium nitrate solution. The flow rate ratio of the dispersed phase to the continuous phase was varied from (Vm: VCe =1:2) to (Vm:VCe = 1:50) by confirmation, the flow rate of the dispersed phase as 25 ml/min and changing the flow rate of the continuous phase, which is the external phase, from 25 to 100 ml/min. The influence of the treat ratio of Vm into VCe(IV) is shown in
To prepare emulsions of two liquids that are insoluble or dominate only slight reciprocal, solubility. Benzethonium chloride as emulsification is usually accomplished, by the application of mechanical energy. At first, the interface between the two liquid phases is distorted to such a dimension, that large droplets are established, and these large droplets are posteriorly separate, into a minimum. During emulsification, the interfacial area between two aqueous solutions increases. Liquids lead to minimizing this surface area; thus, the driving force is required for emulsification to proceed. This work described that increasing domestic, separation, of driving force in the breaking area, lead to the high circulation exhaustion through the mixer area is found to be the best effect. Method of drops reduced diameter. The purpose of stirring is to format, of stable and emulsion of homogeneous by breaking large liquid drops into smaller drops.
The transfer of cerium ion species into the emulsion is facilitated due to reducing in viscosity by rising temperatures. Then, the stability of the emulsion is reduced at increasing temperatures.
The effect of mixing time MT on the emulsion stability was tested. Experiments under optimal conditions used were corresponding, to those used formerly. The MT was different, from 0 to 35 min.
The removal of cerium ions (IV) species from aqueous nitrate solution was studied by ELM technique, in the presence of C64H124O26 with C60H108O8 as a non-ionic surfactant synergistic with the cationic benzethonium chloride, which plays a major role in stabilizing the emulsion. The present study showed that emulsions made with Span 80 / Span 85 (3: 1) in the absence of other than Hy-1622 chloride are very stable and show low extraction efficiency. The extraction efficiency increases with increasing the dose of Hy-1622 up to a certain concentration of surfactant and then decreasing due to the dominating effect of the surfactant on the mass rate transfer. The stability of the emulsion is increased by reducing the ratio of the emulsion O / W to the small oil droplets dispersed in the aqueous phase. The preferable, ratio was 1:1 by volume. Higher stirring speed is produced in a more stable emulsion. The optimal stirring speed was 4000 rpm for the emulsion system investigated. High temperatures are reduced, and the best emulsifying temperature was 250C according to the density and viscosity data of different surfactants at different temperatures. The stability of emulsion increased with stirring speed up to 18 min, behind which the stability, reduced with furthermore higher in stirring time led to the withdrawal of surfactant from the oil-water interface. The emulsion liquid membranes technique for extracting and recovering Ce (IV) in the presence of Hy-1622 as a cationic surfactant has the advantages of low cost, high efficiency, environmental protection, and increased potential in industries.