Cloud Point Extraction Process Research Articles

Investigation of europium(III) uptake from highly sulphate solution via cloud point extraction by mono-Schiff base combined with Triton X-100

ABSTRACT Owing to its unique physico-chemical properties, europium is one of the most precious and sought-after rare earth elements in the field of high technology. The major economic and commercial importance of such an element, combined with the pollution risks associated with its intensive use, require the development of efficient and eco-compatible recovery and recycling processes. This study focuses on the recovery of europium from highly saline sulphate media (0.5 mol/L) using an environmentally friendly two-phase aqueous extraction technique (known as cloud point extraction (CPE)), using 2((phenylimino)methyl)phenol mono-Schiff base (HPIMP) as the extractant and Triton X-100 as the non-ionic surfactant. The influence of key experimental parameters such as pH, extractant concentration, surfactant concentration and separation temperature on the europium extraction process was systematically studied and optimized. Under optimum experimental conditions, a quasi-quantitative extraction with a minimal volume fraction of surfactant-rich phase (φs = 0.025), and concentration factor of (CF = 38) was achieved at pH 9.8, in one stage. The analysis of the extraction data revealed that the CPE of europium(III) takes place by a cation exchange-solvation mechanism. The stoichiometry of the complex extracted into the surfactant-rich phase was ascertained to have a composition of 1:2 [Eu:HPIMP] with the slope analysis method. A higher extraction constant was obtained for CPE compared with conventional solvent extraction, confirming the feasibility and usefulness of CPE for Eu(III) recovery. On the other hand, this new HPIMP/Triton X-100 chelating system showed superior extractability for Eu(III) in the CPE process relative to other systems reported previously.

Simultaneously HPLC Analysis of B1, B9 and B12 Vitamins at Trace Levels via Cloud Point Extraction

An enrichment and determination method based on liquid chromatographically analysis and cloud point extraction (CPE) has been developed for trace levels of B vitamins (B1, B9 and B12) in the proposed study. Vitamin molecules were drawn into the non-ionic surfactant phase of Polyethylene Glycol (PEG-6000) in the presence of pH 9.0 medium. The surfactant-rich phase separated by centrifugation and then dissolved with 700 µL of ethanol. The obtained ethanol phase was filtered by 0.45-micron filter prior to the HPLC analysis. All parameters affecting the CPE method such as pH, buffer volume, incubation time, surfactant and electrolyte concentration, solvent for the surfactant-rich phase and its amount have been individually studied and optimized step by step. After the optimization of all parameters of the CPE process, the detection limits of the developed method for B1, B9 and B12 vitamins were calculated as 1.42 ng mL-1, 7.14 ng mL-1 and 14.28 ng mL-1 , respectively. The linear working ranges for three vitamin molecules was obtained in the range of 5.0-500.0 ng mL-1. After CPE procedure, determination of vitamin molecules was carried out by using HPLC system with diode array detector(DAD) at 244 nm for vitamin B1, 285 nm for vitamin B9, and 361 nm for vitamin B12, respectively

Green removal of low and high levels of Cu(II) and Cr(III) cations from concentrated saline chloride medium achieved by a mixture of N,N′-bis(salicylidene)-thiocarbohydrazide-TritonX-100 micellar system via cloud point extraction process

Abstract In this work, we performed the cloud point extraction with low and high concentrations of Cu(II) and Cr(III), two particularly toxic metallic pollutants, that have been shown to have adverse effects on human health and the environment. Removal of the metal ions was achieved in the presence of Triton X-100 as a non-ionic surfactant and N,N′-bis(salicylidene)-thiocarbohydrazide as a chelating ligand in concentrated chloride medium. The behavior of the Schiff base was initially investigated in homogeneous DMSO-water and micellar Triton X-100-water media. The obtained values of the acid constants show that the extractant is more acidic in micellar media than in pure aqueous medium. The recorded cloud point temperatures of Triton X-100 are significantly impacted by the sodium chloride concentration, the surfactant concentration, and the Schiff base ligand. Under the optimised experimental conditions, a quantitative extraction of Cu(II) and a maximum extraction rate of 74 % of Cr(III) were obtained. The reduction of the metal concentration from 10−3 mol L−1 to 10−6 mol L−1 resulted in a reduction of the temperature by 10 °C and a reduction of the contact time from 10 h to 3 h.

Sensitive Cloud Point Extraction Method for the Determination of Isoxsuprine Hydrochloride in Pharmaceutical forms using Spectrophotometry

A simple and highly sensitive cloud point extraction process was suggested for preconcentration of micrograms amount of isoxsuprine hydrochloride (ISX) in pure and pharmaceutical samples. After diazotization coupling of ISX with diazotized sulfadimidine in alkaline medium, the azo-dye product quantitatively extracted into the Triton X-114 rich phase, dissolved in ethanol and determined spectrophotometrically at 490 nm. The suggested reaction was studied with and without extraction and simple comparison between the batch and CPE methods was achieved. Analytical variables including concentrations of reagent, Triton X-114 and base, incubated temperature, and time were carefully studied. Under the selected optimum conditions, the linearity ranges of calibration curves were 1-9 and 0.5-8 µg/mL with detection limits of 0.26 and 0.09 µg/mL of ISX for batch and CPE methods respectively. A relative standard deviation (RSD %) best than 1.98 and 2.67 % with the percentage recoveries range 100.14 and 99.63 % were obtained for both methods respectively. The proposed methods were successfully used in routine analysis of ISX in pharmaceutical forms with high accuracy and reproducibility.

Cloud point extraction assisted spectrophotometric quantification of trace boron impurity in uranium-based nuclear fuels

The separation of boron in nuclear fuels by cloud point extraction (CPE) has been a challenge due to high acidity of digested sample solutions. High acidity hampers the coacervation of micelles. As a result, the cloud point temperature increases and thus could cause the inevitable loss of boron as volatile species. Herein we have proposed a novel CPE-assisted colorimetric method for the quantification of traces of boron (B) in uranium-based fuels. A 1:1 mixture of 2-ethyl hexane-1,3-diol (EHD) and curcumin dispersed in Triton X-114 surfactant was used in the proposed CPE process. We had investigated several compounds to act as micelle surface modifiers. Among them, only bromine water (Br2) was found not only to lower the cloud point temperature (CPT, from 80 °C to 42 ± 2 °C) but also resulted in the quantitative recovery of boron (≥95%). The CPE of boron from uranium matrix in a 2.0 mol L−1 HCl medium was suitable for direct chemical quality assurance of routine uranium-based fuels. The molar extinction coefficient of the boron-EHD-curcumin complex was found to be 4.75 × 105 L mol−1 cm−1 (λmax at 458 nm) in N,N-dimethyl formamide medium. The linear dynamic range and detection limit of the proposed analytical procedure were calculated to be 10–150 ng mL−1 and 0.8 ng mL−1 respectively. The proposed analytical methodology was validated by analysis of three in-house working reference materials of uranium. Determination of traces of boron in two uranium dioxide and two metallic uranium samples were found to demonstrate the applicability of the method. The relative standard deviation of the proposed method was found to be of 3–5%.

Simple Cloud Point Extraction-Spectrophotometric for the Determination for Lead (II) Using-3-Anilino-1-Phenylimino-Thiourea

After complexing with 3-anilino-1-phenylimino-thiourea (R.), the cloud-point extraction (CPE) process was used to enrich lead (II), which was then analyzed using uv–visible spectrometry using Triton X-114 as a suitable non-ionic surfactant. pH, concentration for (R) and volume Triton X-114(0.6ml), equilibration temperature 50C and duration, and lastly centrifugation (rate and time)4,000 rpm,20 min have all been enhanced as experimental variables that impact the CPE process. Pre-concentration of sample in a 5 mL solution contains 2.5 percent (v/v) starting with the influence of pH at (4.2). The detection (LOD) of (0.018) μg.mL-1 of lead (+2) and the limit of quantification (LOQ) of (0.08) μg.mL-1 were achieved using Triton X-114 with 1×10-3 mol.L-1 of (R.). A linear calibration curve with a precision of relative standard deviation (R.S.D, n =7,0.3 μg. mL-1 Pb (II)) were obtained within the range (0.06 -3.0) μg.mL-1. Keywords: Pb+2; Triton( X—114) ,Clo’ud point extra’ction(C.P.E); 3-anilino-1-phenylimino-thiourea;

Design Equilibrium Parameters for Recovery of Chromium(III) from Concentrated Saline Sulfate Media via Room-Temperature Cloud-Point Extraction Process Using a Mixture of Multidentate Schiff Base Ligand/Tergitol 15-S-7 as a Novel Biodegradable Extracting System

Design Equilibrium Parameters for Recovery of Chromium(III) from Concentrated Saline Sulfate Media via Room-Temperature Cloud-Point Extraction Process Using a Mixture of Multidentate Schiff Base Ligand/Tergitol 15-S-7 as a Novel Biodegradable Extracting System

Developing a cloud point extraction process for lipopeptide recovery from cell-free broth of Bacillus sp. GY19

ABSTRACT Biosurfactants can be potentially used in food, cosmetics, pharmaceuticals, and environmental remediation because of their biodegradability and low toxicity. However, it is very challenging to recover biosurfactants from fermented broth as they are temperature-sensitive and present at dilute concentrations. This study aims to develop an alternative process that uses cloud point extraction (CPE) to recover lipopeptides biosurfactant from cell-free broth of Bacillus sp. GY19. The nonionic surfactant, Triton X-100, was selected as the aqueous-based solvent for CPE. Under the optimal conditions lipopeptides concentration in Triton X-100 was 23,000 mg/L, which is 14.8-folds higher than that in cell-free broth. Lipopeptides and Triton X-100 exerted a positive synergistic effect in reducing the critical micelle concentration of mixed micelles with a β value of −1.9. This could be considered a co-benefit of using CPE for biosurfactant recovery. Two techniques for back extraction of lipopeptides after the CPE process were proposed. Silica gel 60 selectively adsorbed Triton X-100 with 44% removal, while maintaining lipopeptides recovery at 86%. Cold acetone precipitation could remove 99% of Triton X-100 by precipitating lipopeptides. However, a 1%(w/v) SDS solution had to be used to re-solubilize the dehydrated lipopeptide

Preconcentration and spectrophotometric determination of Fe(III) by cloud point extraction using Zincon as complexing agent

A cloud point extraction (CPE) process was described for the separation and spectrophotometric analysis of Fe(III) in different water samples and blood as chelating agent. The complexation reaction between Fe(III) and Zincon was elaborated at pH 5.0 using acetate buffer and the complex was quantitatively recovered in a mixed micelle system composed of cethyltri methyl ammonium bromide (CTAB) and Triton X-114. This reaction was carried out at room temperature in the presence of 0.05 mol L-1 Na2SO4 as salting-out electrolyte. The linearity was up to 1000 µg L-1. The preconcentration factor was 50. The precision (as relative standard deviation) and the limit of detection were 2.5% and 3.1 µg L-1, respectively. The proposed procedure was used for the spectrophotometric detection of Fe(III) in water and blood samples and the data were statistically comparable to those achieved using ICP-OES technique.

Tandem micellar catalysis and cloud point extraction process for C-S coupling reaction in water

A tandem process of micellar catalysis and cloud point extraction (CPE) is developed for copper-catalyzed Ullmann C-S coupling reactions in water. The functional nonionic surfactant, amine terminated polyether M2070, affords nano-micelle environment in the aqueous system; the latter splits to two phases above the cloud point temperature (CPT). The nature of the micellar catalysis in M2070 aqueous was investigated by DLS, EDS, XPS, IR, TEM and 1H NMR. M2070 was verified to provide nano-space for encapsulation and aggregation of the substrates. More importantly, the metallic micelle formed by M2070 chelating copper was identified. It is noteworthy that excellent productivity in pre-micellar catalysis of C-S coupling reactions was obtained with good tolerance of substrate. Finally, the water-micelle system was separated into two phases above the CPT thus to achieve the product separation. Furthermore, the M2070/water system can be recycled and reused.

Cloud point extraction method for the sensitive determination of metoclopramide hydrochloride in pharmaceutical dosage forms

In this work, a simple and very sensitive cloud point extraction (CPE) process was developed for the determination of trace amount of metoclopramide hydrochloride (MTH) in pharmaceutical dosage forms. The method is based on the extraction of the azo-dye results from the coupling reaction of diazotized MTH with p-coumaric acid (p-CA) using nonionic surfactant (Triton X114). The extracted azo-dye in the surfactant rich phase was dissolved in ethanol and detected spectrophotometrically at λmax 480 nm. The reaction was studied using both batch and CPE methods (with and without extraction) and a simple comparison between the two methods was performed. The conditions that may be affected by the extraction process and the sensitivity of methods were carefully studied. Using optimal conditions, the linearity of calibration curves was in the range of 0.4-13 and 0.05-4µg/mL and limits of detection of 0.044 and 0.028 µg/mL of MTH for batch and CPE methods respectively. Average recoveries for samples were detected to be between 97-101 %for both methods, with the relative standard deviation (RSD %) best than 2.7 % and 4.5 % for both methods, respectively. The suggested methods were applied successfully for assay of MTH in commercial pharmaceutical tablets.

Adsorption onto MWCNTs Coupled with Cloud Point Extraction for Dye Removal from Aqueous Solutions: Optimization by Experimental Design.

The main aim of the study was to examine the feasibility and benefits of adsorption onto multi-walled carbon nanotubes (MWCNTs) coupled with cloud point extraction (CPE) for the removal of Rhodamine B (RB) from aqueous solutions. MWCNTs offer the particular features of the ideal adsorbents for the organic dyes such as hollow tubular structure and specific surface area. Nevertheless, they suffer from the drawbacks of low dispersion in the aqueous solutions and separation inconvenience from the media. Cloud point extraction, combined with the adsorption onto MWCNTs can be a promising method to overcome the problems. In the study, adsorption onto MWCNTs coupled with CPE was applied for RB removal from aqueous solutions. The process was optimized by the response surface modeling method. Moreover, the applicability of the proposed method in the real sample analyses was investigated. MWCNTs were used as adsorbent and Triton X-100 (TX-100) as the nonionic surfactant for CPE process. The experiments were carried out based on a Box-Behnken design (BBD) with the input variables of MWCNTs dosage (0.6-1.2 mg), solution pH (3-9), clouding time (20-40 min) and TX-100 concentration (10-20 v/v%) using 5 mg L-1 RB solutions. Regression analyses resulted in a statistically significant quadratic model (R2=0.9718, F=24.96, p<0.0001) by which the optimum levels of the variables were predicted as: MWCNTs dosage of 0.7 mg, pH=3, clouding time of 39.9 minutes and TX-100 concentration of 19.91% (v/v). The predicted conditions were experimentally validated by achieving an RB removal of 94.24%. Based on the results, the combination of the environmentally friendly technique of CPE with adsorption onto MWCNTs allows the efficient removal of RB from water samples and the method can be effectively optimized by the response surface modeling.

A novel, green environment-friendly cloud point extraction of polyphenols from pomegranate peels: a comparative assessment with ultrasound and microwave-assisted extraction

ABSTRACT Pomegranate peel is a potential source of polyphenols, antioxidants, pectin, organic acids. Cloud point extraction (CPE) process parameters were optimized for efficient separation of polyphenols. Maximum extraction was obtained at 1:70 solid: solvent ratio, 8% (v/v) Triton X-114 at 55°C, pH 4.5 with 14% NaCl for 30 minutes. Ultrasound assisted CPE showed maximum yield of total phenolic content (TPC; 96.28 mg GAE/g) and total flavonoids content (TFC; 12.27 mg QE/g) with 94.48% antioxidant activity (AA) to that of conventional, ultrasound and microwave-assisted CPE. These extractives can be labeled as green and may be used in food or dietary applications. Abbreviations: CPE: Cloud point extraction; AA: Antioxidant activity; TPC: Total polyphenol content; TFC: Total flavonoid content; CPT: Cloud point temperature; CMC: Critical micellar concentration; OVAT: One variable at a time; GAE: Gallic acid equivalent; QE: Quercetin equivalent; HLB: Hydrophilic lipophilic balance

Visible Light Detection of Dopamine Enhanced by Cloud Point Extraction

Background: Monitoring of DA, in the presence of other chemical analogues such as epinephrine, norepinephrine, serotonin, ascorbic acid, uric acid, catechol, phenethylamine, tyramine, and tyrosine, is crucial in the diagnosis and mechanistic understanding of human neuropathology. Therefore, the determination of DA at trace levels has become a very important analytical task, as part of health safety and forensic analysis. Introduction: A cloud point extraction (CPE) process was developed for the isolation and detection of dopamine in food, urine, and pharmaceutical samples. Methods: In this procedure, dopamine was derivatized with o-phthalaldehyde (OPA) and sodium sulphite in aqueous solution. The isoindole derivative was synthesized by the reaction of OPA and sodium sulphite with the amino group of dopamine and the resulted isoindole derivatives were extracted by cloud point extraction. After extraction process, the concentration of enriched analyte was measured by UV-VIS spectrophotometry. The parameters affecting the CPE such as concentration of surfactant and electrolyte, equilibration temperature and time and pH of sample solution were investigated. Results: After optimization of the CPE conditions, the linear range of 8-80 µM (without extraction 100- 1000 µM) was established for dopamine with detection limit at 2.6 µM. Conclusion: The developed extraction procedure was applied to the quantification of dopamine in chocolate, urine, and pharmaceutical samples. The study ensures a promising strategy for the detection of dopamine in the presence of biological constituents, e.g. ascorbic acid, uric acid, and serotonin.

Cloud point extraction combined with HPLC–MS for the determination of nimesulide in biological samples

A high performance liquid chromatography (HPLC) method with mass spectrometry (MS) detection coupled previously cloud point preconcentration was developed for the determination of nimesulide in synthetic urine. Non-ionic surfactants Triton X-100 and Triton X-114 were used for cloud point extraction (CPE) of nimesulide. Various influencing parameters on the CPE process, such as pH, the concentration of non-ionic surfactant, equilibration temperature, incubation time and centrifugation parameters were studied and optimized. The developed method was validated; the linear range was in the range 67–5000 ng mL−1, the detection (3σ) and quantification (10σ) limits were 20 ng mL−1 and 67 ng mL−1, respectively. The intra-day and inter-day precisions were less than 14%, the average recovery factors were in the range 95–117%. The suggested CPE–HPLC–MS method was simple and sensitive and could be an effective tool for the determination of nimesulide in biological samples.

Prediction of the cloud point of polyethoxylated surfactants and their mixtures by the thermodynamic model of Flory-Huggins-Rupert

The cloud point curves of polyethoxylated surfactants are established experimentally. These experimental data are preliminary to the development of the cloud point extraction process, which appears as an interesting alternative to the usual solvent extraction unit operation. Starting from the thermodynamic model developed by Flory and Huggins for phase separation of polymer aqueous solutions, this paper aims at the prediction of cloud point curves. In this work, Rupert’s approach is extended to commercial nonionic surfactants, mixtures of homologous species, namely a few alkylphenol and alcohol ethoxylates. The limit of such an approach is clearly demonstrated, provided that a fitting parameter is finally required for a successful model application to pilot-plant manufactured surfactants, like C8ΦEn (n = 7.5, 10, 12), C9ΦEn (n = 8, 10, 12), C12E4, C12E6 and commercial Tergitol 15-S-7 (linear C12-C14 secondary alcohol with an average of 7 ethylene oxide units).GRAPHICAL ABSTRACT

Selective cloud point extraction of uranium from thorium and lanthanides using Cyanex 301 as extractant

Abstract A cloud point extraction (CPE) process using TX-114 as nonionic surfactant and bis(2,4,4-trimethylpentyl)dithiophosphinate (Cyanex 301) as extractant was successfully applied to extract UO22+ selectively and quantitatively in the presence of Th4+ and lanthanide ions. The thermodynamic parameters of the interaction between the related metal ions and the micelles were obtained by isothermal titration calorimetry (ITC), and the binding constant followed the order of UO22+ > Th4+ > La3+, consistent with the result of extraction selectivity. In the absence of NaCl, the stability constants β1 and β2 of the UO22+-Cyanex 301 complex in the micellar system were determined via UV–vis spectroscopic titration to be 6.3 × 103 and 2.0 × 105, respectively. In the presence of 0.10 mol L−1 NaCl, the stability constants β1 and β2 were measured to be 5.9 × 103 and 1.0 × 107, separately. It is believed that the combination of UO22+ and Cyanex 301 leads to the formation of a neutral complex, which enters the micelles and results in a high extraction efficiency.

Non-aqueous phase cold vapor generation and determination of trace cadmium by atomic fluorescence spectrometry

Cold vapor generation (CVG) of cadmium was firstly accomplished in non-aqueous media by using solid reductant of potassium borohydride (KBH4) as a derivation reagent. The mixture of surfactant Triton X-114 micelle and octanol was innovatively used as the non-aqueous media for the CVG and atomic fluorescence spectrometry (AFS) was used for the elemental determination. The analyte ions were firstly extracted into the non-aqueous media from the bulk aqueous phase of analyte/sample solution via a novelly established ultrasound-assisted rapidly synergistic cloud point extraction (UARS-CPE) process and then directly mixed with the solid redcutant KBH4 to generate volatile elemental state cadmium in a specially designed reactor, which was then rapidly transported to a commercial atomic fluorescence spectrometer for detection. Under the optimal conditions, the limit of detection (LOD) for cadmium was 0.004 μg L−1. Compared to conventional hydride generation (HG)-AFS, the efficiency of non-aqueous phase CVG and the analytical performance of the developed system was considerably improved.

Non-aqueous phase hydride generation and determination of trace bismuth by atomic fluorescence spectrometry

Hydride generation (HG) of bismuth was accomplished in non-aqueous media by using solid reductant of potassium borohydride (KBH4) as a derivation reagent. The riched micelle phase of surfactant Triton X-114 was used as the non-aqueous media for the chemical vapor generation (CVG), and atomic fluorescence spectrometry (AFS) was used for the elemental determination. The analyte ions were firstly extracted into the non-aqueous media from the bulk aqueous phase of analyte/sample solution via a rapid cloud point extraction (RCPE) process and then directly mixed with the solid reductant KBH4 to generate volatile bismuth hydride in a specially designed reactor, which was then rapidly transported to a commercial atomic fluorescence spectrometer for detection. Under the optimal conditions, the limit of detection (LOD) for bismuth was 0.08μg/L. Compared to conventional HG-AFS, the efficiency of non-aqueous phase HG accomplished using solid reductant and the analytical performance of the developed method was considerably improved.

Recovery of Ru(III) from hydrochloric acid by cloud point extraction with 2-Mercaptobenzothiazole-functionalized ionic liquid

An arisen and environment-friendly method of cloud point extraction (CPE) which involved Octylphenoxypolyethoxyethanol (TX-114) as surfactant and 2-Mercaptobenzothiazole-functionalized ionic liquid as extractant was carried out to separate Ru(III) from aqueous phase to bottom surfactant phase for the first time. A host of variable (e.g., the extractant concentration, hydrochloric acid concentration, nitric acid concentration, TX-114 mass fraction, TX-114 volume and sodium chloride concentration) were evaluated and optimized to investigate the extraction behavior. At optimized experimental conditions, the extraction percentage of Ru(III) was found to be 82%, together with the enrichment factor of 40. A special complexation extraction mechanism of Ru(III) in CPE process was studied systemically and confirmed via job method, UV–vis spectrum and FT-IR spectrum in detail. Taking together, the rational-designed functional ionic liquid as a novel extractant exhibited superior extractability for Ru(III) in CPE system.