Sulfate Aqueous Two-phase System Research Articles

Efficient Separation of Re (VII) and Mo (VI) by Extraction Using E-1006–Ammonium Sulfate Aqueous Two-Phase System

Aqueous two-phase extraction (APTE) stands out as an environmentally friendly technique for the separation of metal ions. The separation of Re (VII) and Mo (VI) in an aqueous solution was investigated using a novel aqueous two-phase system (ATPS) consisting of isodecanol polyoxyethylene ether (E-1006), ammonium sulfate, and water. A phase diagram of this system was developed, and the effects of pH, temperature, extraction time, the concentrations of E-1006 and (NH4)2SO4, and metal ions on the separation of Re (VII) and Mo (VI) were examined. The results show that at pH 7.0, Mo (VI) had almost transformed into the (NH4)2SO4-rich phase, while Re (VI) was extracted into the E-1006-rich phase. The increase in temperature induces a transition of Mo (VI) to the salt-rich phase, which is unfavorable for the extraction of Re (VII). The increase in the concentrations of E-1006 and (NH4)2SO4 has a positive effect on the separation of rhenium and molybdenum. Overall, the ATPS consisting of 200 g/L of E-1006, 200 g/L of (NH4)2SO4, and water yields an extraction efficiency of 97.2% for Re and a high separation factor of 2700 for Re (VII) and Mo (VI) from a mixture of 0.1 g/L of Re (VII) and 5 g/L of Mo (VI) at pH 7.0 and 323.15 K. Separation studies of the simulated leaching solution show that the extraction efficiency for Re (VI) is 99.1% and the separation factor of Re (VII) and Mo (VI) is 5100.

Solubility of Naphthalene in the Top Phase of Polyethylene Glycol and Ammonium Sulfate Aqueous Two-Phase Systems

Solubility of Naphthalene in the Top Phase of Polyethylene Glycol and Ammonium Sulfate Aqueous Two-Phase Systems

Simultaneous separation and preliminary purification of anthocyanins from Rosa pimpinellifolia L. fruits by microwave assisted aqueous two-phase extraction

Rosa pimpinellifolia L. fruits (RPF) have great industrial potential due to the high presence of anthocyanins. In this work, microwave-assisted aqueous two-phase extraction (MA-ATPE) was applied to simultaneous extraction and purification of anthocyanins from RPF with ethanol/ammonium sulfate aqueous two-phase system (ATPS). MA-ATPE process was optimized by single-factor experiments and response surface methodology. The optimal anthocyanin yields were achieved in conditions of 0% HCl (w:w), 26.85% ethanol (w:w), 19.15% ammonium sulfate (w:w), liquid to solid ratio 40, 17.29 min, 60 °C and 400 W. Predicted anthocyanin yield of MA-ATPE at optimum conditions were determined as 1373.04 mg cyanidin 3-glucoside equivalent/g dry RPF. The purity of anthocyanin rich extract obtained by MA-ATPE was 1.65-fold greater than microwave assisted extraction using 80% ethanol (MAE). The compositional characterization of anthocyanins were carried out with HPLC-QTOF-MS. MA-ATPE had no obvious changes on anthocyanin composition when compared to MAE. Results indicated that the MA-ATPE could be a promising method for the extraction and preliminary purification of anthocyanins from different plant materials.

Recovery of lactose and proteins from cheese whey with poly(ethylene)glycol/sulfate aqueous two-phase systems

Cheese whey is an environmental problem as an effluent, but also a source of valuable raw materials, namely proteins and lactose. In this work, Aqueous Two-Phase Systems (ATPS) were studied for the recovery of lactose, BSA, β-lactoglobulin and α-lactalbumin, key components of cheese whey. ATPS formed by PEG (molecular weights: 200–8000 g.mol−1) with sodium or ammonium sulfate were investigated. Partitioning of the selected solutes was experimentally addressed in different ATPS and pH values. Partition behavior showed that ATPS formed by PEG1500/ammonium sulfate is able to separate lactose from proteins, while PEG300/sodium sulfate ATPS may be used for protein fractionation. These separation strategies were then tested with simulated and real cheese whey. Under optimized conditions, PEG 1500/ammonium sulfate ATPS allows efficient recovery of > 95% proteins (precipitate) and 80% of lactose (bottom phase), as confirmed for both simulated and real cheese whey. The results found indicate that the proposed polymer/salt ATPS can be used to design scalable and cost-effective separation strategies to apply in cheese whey and other related wastes.

Extraction and purification of ε-poly-l-lysine from fermentation broth using an ethanol/ammonium sulfate aqueous two-phase system combined with ultrafiltration.

ε-Poly-l-lysine (ε-PL) serves as a natural food preservative and is manufactured mainly by extraction from microbial fermentation broth using ion-exchange chromatography. In order to develop an alternative purification strategy, an environmentally friendly alcohol/salt aqueous two-phase system (ATPS) was explored in this study for ε-PL extraction. A study of the separation of ε-PL in different alcohol/salt systems showed that ethanol/ammonium sulfate ATPS exhibited the highest ε-PL partition coefficient and recovery ratio. Based on the phase diagram, the effect of phase composition on partition, and the removal of pigment and protein, an ATPS that was composed of 20% (w/w) ethanol and 20% (w/w) ammonium sulfate, with a feedstock at pH 9.5, was developed to extract ε-PL from the fermentation broth. This achieved an ε-PL recovery ratio of 96.15% with an ε-PL purity of 40.23% after triplicate extractions. Subsequently, desalting by ultrafiltration led to a final ε-PL product of 92.39% purity and 87.72% recovery. The ethanol/ammonium sulfate ATPS provides a new possibility for ε-PL purification.

Extraction of Lutein from Okra Leaves by Ethanol-Ammonium Sulfate Aqueous Two-Phase System

In this study,an aqueous two-phase system composed of ethanol and ammonium sulfate was selected to extract lutein from freeze-dried okra leaf powder. On the basis of single factor test,the response surface of ethanol mass fraction,ammonium sulfate mass fraction and crude extract mass fraction were optimized with three factors and three levels. The results showed that the optimized extraction process conditions were 6% of crude extract,14.5% of ethanol and 27.5% of ammonium sulfate. The yield was 1.99 mg/g under this condition.The kinetic study of the crude extract of lutein from ultrasonic assisted extraction showed that the extraction conforms to the second order kinetic equation. The lutein extracted by this method was compared by VC,and the IC50 value of lutein on ABTS free radical and DPPH free radical were 0.2841 and 0.7633 mg/mL,respectively,which had certain antioxidant activity.

Purification of (S)-3-cyano-5-methylhexanoic acid from bioconversion broth using an acetone/ammonium sulfate aqueous two-phase system

Abstract (S)-3-Cyano-5-methylhexanoic acid ((S)-CMHA) is the key chiral intermediate of pregabalin. In this paper, an aqueous two-phase system (ATPS) was developed to extract (S)-CMHA from nitrilase-catalyzed bioconversion broth. Inorganic salts and hydrophilic solvents were screened to form ATPS, among which an acetone/ammonium sulfate ATPS was investigated in detail, including phase diagram, effect of phase composition and stability of (S)-CMHA. The maximum product recovery of 99.15% was obtained by an optimized ATPS system composed of 15% (w/w) ammonium sulfate and 35% (w/w) acetone with the removal of 99% cells and 86.27% proteins. The total (S)-CMHA yield reached 92.11% after back-extraction. The recycling use of ammonium sulfate was investigated, and 93.10% of salt in the salt-rich phase was recovered with the addition of methanol. The results demonstrated the efficiency of the two-step extraction process for separation of (S)-CMHA.

Influence of magnetic field on extraction of model proteins in polyethylene glycol/magnesium sulfate aqueous two-phase system

Separation of molecules in aqueous two-phase systems (ATPS) depends on many factors, e.g. salt concentration, pH, polyethylene glycol (PEG) concentration and molecular weight. The aim of the study was to analyze partition of model proteins (lysozyme, bovine serum albumin and hemoglobin) depending on the magnetic field action and the factors mentioned above in PEG/MgSO4 ATPS. Partition of these proteins studied always depended on PEG molecular weight, while salt concentration influenced only BSA and HGB separation. Two of the proteins tested, i.e. lysozyme and BSA showed high affinity to the PEG-rich-phase. The magnetic field significantly forced distribution of BSA and lysozyme to the phase rich in MgSO4. Hemoglobin, which presented a tendency to accumulation in salt phase was not affected by the magnetic field. Thus, the influence of the magnetic field on protein partition in ATPS is a consequence of the properties of separated molecules, and rearranges of water dipoles and hydrogen bonds reshape.

Separation and Enrichment of Lectin from Zihua Snap-Bean (Phaseolus vulgaris) Seeds by PEG 600-Ammonium Sulfate Aqueous Two-Phase System.

A fast and efficient method based on a polyethylene glycol (PEG) 600/(NH4)2SO4 aqueous two-phase system for extracting lectin from Zihua snap-bean (Phaseolus vulgaris) seeds was established. According to a Box–Behnken design (BBD), involving four factors at three levels each subjected to analysis of variance (ANOVA) and response surface analysis, the protein recovery and the purification factor of lectin in the top phase were used as the response values of the variance analysis to acquire the multivariate quadratic regression model. SDS–PAGE electrophoresis and the hemagglutination test were used to detect the distribution of lectin in the aqueous two-phase system (ATPS). The obtained data indicated that lectin was preferentially partitioned into the PEG-rich phase, and the ATPS, composed of 15% (NH4)2SO4 (w/w), 18% PEG 600 (w/w), 0.4 g/5 g NaCl and 1 mL crude extract, showed good selectivity for lectin when the pH value was 7.5. Under the optimal conditions, most of the lectin was assigned to the top phase in the ATPS, and the hemagglutination activity of the purified lectin in the top phase was 3.08 times that of the crude extract. Consequently, the PEG 600/(NH4)2SO4 aqueous two-phase system was an effective method for separating and enriching lectin directly from the crude extract of Zihua snap-bean seeds.

Separation of polysaccharides from Spirulina platensis by HSCCC with ethanol-ammonium sulfate ATPS and their antioxidant activities

Three separation methods for water-soluble polysaccharides from Spirulina platensis (PSP) were compared, including sevage deproteinization and column chromatography, ethanol-ammonium sulfate aqueous two-phase system (ATPS) and column chromatography, and one-step high speed counter-current chromatography (HSCCC) with ethanol-ammonium sulfate ATPS. ATPS was confirmed as an efficient alternative method of protein removal for PSP purification. For the HSCCC with ethanol-ammonium sulfate ATPS, the stationary retention reached to 50.8% at the optimized rotation speed and flow rate. Moreover, the yield of PSP purified by one-step HSCCC rose nearly five times to 12.45mg/g(dry algae powder), it was higher than PSP yield by two-step column chromatography separation methods. PSP purified by HSCCC has the same purity as PSP obtained by traditional methods, which was proved by a single symmetrical peak of purified PSP with molecular weight of 12.33kDa through gel chromatography. Purified PSP was an α-acidic polysaccharide, composed of major glucose, slight rhamnose and mannose, which were detected within GC and FT-IR spectra. The antioxidation activity experiment showed that HSCCC-purified PSP had strong scavenging effects on hydroxyl free radical and DPPH free radical.

Salting‐out extraction of sinomenine from Sinomenium acutum by an alcohol/salt aqueous two‐phase system using ionic liquids as additives

AbstractBACKGROUNDThe aqueous two‐phase extraction (ATPE) based on organic solvent and inorganic salt was considered a promising method in the extraction, enrichment, and purification field. Ionic liquids (ILs) used as additives to the aqueous two‐phase system (ATPS) can improve the extraction yield.RESULTSIn this study, seven ILs were added to the ethanol/ammonium sulfate ATPS and used for the salting‐out extraction (SOE) of sinomenine from Sinomenium acutum. The IL [C2OHmim]FeCl4 was screened as the optimal additive, then the influencing factors IL amount, ethanol concentration, salt concentration, and temperature were investigated. The maximum extraction efficiency of 96.4% was obtained under the following conditions: 23.06 wt% ethanol concentration, 27.28 wt% (NH4)2SO4 concentration, 4.0 wt% [C2OHmim]FeCl4 and 40°C temperature. Moreover, the components in the SOE system can be recycled after extraction.CONCLUSIONThus, this ATPS had lower cost and higher extraction ability, and it is feasible to scale up using a small amount of ILs. This system can also be used in the extraction of some other important active compounds from natural plant resources. © 2017 Society of Chemical Industry

Partitioning of pyrimidine single stranded oligonucleotide using polyethylene glycol – sodium sulfate aqueous two-phase systems; experimental and modeling

In this work partitioning of TAMRA (Tetramethyl-6-Carboxyrhodamine) - oligonucleotide in systems containing 18% (w/w) polyethylene glycol (PEG 600, PEG 1000, PEG 1500 and PEG 4000) and 15% (w/w) sodium sulfate (designated as 18/15) was investigated. To find the optimum condition, effective parameters on biomolecule partitioning including polymer molecular weight, pH, temperature and addition of a second salt were studied. The results showed that as pH increases and molecular weight of polymer decreases, the affinity of TAMRA oligonucleotide to accumulate in the top PEG-rich phase increases. In order to find the temperature effects, partitioning of TAMRA oligonucleotide was studied at two different temperatures 20 and 30 °C). At this range, no significant change was observed. Meanwhile, it is found that addition of 0.5% (w/w) of KH2PO4 as the second salt reversed the partitioning behavior of the oligonucleotide. A similar trend with smaller gradients was observed when KH2PO4 was substituted by KCl; whereas, substitution by MgSO4 increased the affinity of the oligonucleotide to partition to top phase. The best results achieved using PEG 600 at pH = 6. In this case, almost 100% of TAMRA oligonucleotide was recovered in the upper phase. Finally, the partitioning of the biomolecule was correlated using a model based on UNIFAC-FV group contribution. The results showed that the model can correlate the partitioning of the oligonucleotide with an acceptable accuracy.

The effect of temperature on polyethylene glycol (4000 or 8000)–(sodium or ammonium) sulfate Aqueous Two Phase Systems

PEG (4000 or 8000)-(Ammonium or Sodium) Sulfate Aqueous Two-Phase Systems were characterized at 278.15, 293.15 and 308.15 K. Two physical properties (density and refractive index) were used to obtain the compositions of the ends of the tie-lines. The binodal curve was constructed from these end points. A comparison with some available data at close temperatures allowed for assessing different experimental techniques. Data correlation for the experimental binodal curves and tie-lines was carried out using Merchuk and Guan’s equations. The effect of temperature, polymer molecular weight and nature of the cation of the salt on the phase diagram were assessed using these models. It has been found that the heterogeneous region increases with temperature, polymer molecular weight, or the hydration shell (salting-out) of the cations. PEG 8000 and sodium sulfate formed the largest heterogeneous region, thus needing the smallest amount of phase-forming components for phase splitting.

Purification of a fibrinolytic protease from Mucor subtilissimus UCP 1262 by aqueous two-phase systems (PEG/sulfate).

A fibrinolytic protease from M. subtilissimus UCP 1262 was recovered and partially purified by polyethylene glycol (PEG)/sodium sulfate aqueous two-phase systems (ATPS). The simultaneous influence of PEG molar mass, PEG concentration and sulfate concentration on the enzyme recovery was first investigated using a 2(3) full factorial design, and the Response Surface Methodology used to identify the optimum conditions for enzyme extraction by ATPS. Once the best PEG molar mass for the process had been selected (6000g/mol), a two-factor central composite rotary design was applied to better evaluate the effects of the other two independent variables. The fibrinolytic enzyme was shown to preferentially partition to the bottom phase with a partition coefficient (K) ranging from 0.2 to 0.7. The best results in terms of enzyme purification were obtained with the system formed by 30.0% (w/w) PEG 6000g/mol and 13.2% (w/w) sodium sulfate, which ensured a purification factor of 10.0, K of 0.2 and activity yield of 102.0%. SDS-PAGE and fibrin zymography showed that the purified protease has a molecular mass of 97kDa and an apparent isoelectric point of 5.4. When submitted to assays with different substrates and inhibitors, it showed selectivity for succinyl-l-ala-ala-pro-l-phenylalanine-p-nitroanilide and was almost completely inhibited by phenylmethylsulfonyl fluoride, behaving as a chymotrypsin-like protease. At the optimum temperature of 37°C, the enzyme residual activity was 94 and 68% of the initial one after 120 and 150min of incubation, respectively. This study demonstrated that M. subtilissimus protease has potent fibrinolytic activity compared with similar enzymes produced by solid-state fermentation, therefore it may be used as an agent for the prevention and therapy of thrombosis. Furthermore, it appears to have the advantages of low cost production and simple purification.

Effect of sodium chloride on solute–solvent interactions in aqueous polyethylene glycol–sodium sulfate two-phase systems

Partition behavior of eight small organic compounds and six proteins was examined in poly(ethylene glycol)-8000–sodium sulfate aqueous two-phase systems containing 0.215M NaCl and 0.5M osmolyte (sorbitol, sucrose, TMAO) and poly(ethylene glycol)-10000–sodium sulfate–0.215M NaCl system, all in 0.01M sodium phosphate buffer, pH 6.8. The differences between the solvent properties of the coexisting phases (solvent dipolarity/polarizability, hydrogen bond donor acidity, and hydrogen bond acceptor basicity) were characterized with solvatochromic dyes using the solvatochromic comparison method. Differences between the electrostatic properties of the phases were determined by analysis of partitioning of sodium salts of dinitrophenylated (DNP-) amino acids with aliphatic alkyl side-chain. The partition coefficients of all compounds examined (including proteins) were described in terms of solute–solvent interactions. The results obtained in the study show that solute–solvent interactions of nonionic organic compounds and proteins in polyethylene glycol–sodium sulfate aqueous two-phase system change in the presence of NaCl additive.

Analysis of partitioning of organic compounds and proteins in aqueous polyethylene glycol-sodium sulfate aqueous two-phase systems in terms of solute–solvent interactions

Partition behavior of nine small organic compounds and six proteins was examined in poly(ethylene glycol)-8000-sodium sulfate aqueous two-phase systems containing 0.5M osmolyte (sorbitol, sucrose, trehalose, TMAO) and poly(ethylene glycol)-10000-sodium sulfate system, all in 0.01M sodium phosphate buffer, pH 6.8. The differences between the solvent properties of the coexisting phases (solvent dipolarity/polarizability, hydrogen bond donor acidity, and hydrogen bond acceptor basicity) were characterized with solvatochromic dyes using the solvatochromic comparison method. Differences between the electrostatic properties of the phases were determined by analysis of partitioning of sodium salts of dinitrophenylated (DNP-) amino acids with aliphatic alkyl side-chain. It was found out that the partition coefficient of all compounds examined (including proteins) may be described in terms of solute–solvent interactions. The results obtained in the study show that solute–solvent interactions of nonionic organic compounds and proteins in polyethylene glycol-sodium sulfate aqueous two-phase system differ from those in polyethylene glycol-dextran system.

Phase Separation Behavior and System Properties of Aqueous Two-Phase Systems with Polyethylene Glycol and Different Salts: Experiment and Correlation

The phase separation behaviors of PEG1000/sodium citrate, PEG4000/sodium citrate, PEG1000/ammonium sulfate, and PEG4000/ammonium sulfate aqueous two-phase systems were investigated, respectively. There are two distinct situations for the phase separation rate in the investigated aqueous two-phase systems: one state is top-continuous phase with slow phase separation rate and strong bottom-continuous phase with fast phase separation rate and weak volume ratio dependence. The system properties such as density, viscosity, and interfacial tension between top and bottom phases which have effects on the phase separation rate of aqueous two-phase systems were measured. The property parameter differences between the two phases increased with increasing tie line length and then improved the phase separation rate. Moreover, a modified correlation equation including the phase separation rate, tie line length, and physical properties of the four aqueous two-phase systems has been proposed and successfully tested in the bottom-continuous phase, whose coefficients were estimated through regression analysis. The predicted results of PEG1000/sodium citrate aqueous two-phase systems were verified through the stationary phase retention in the cross-axis countercurrent chromatography.

Enhancement of a Novel Extracellular Uricase Production by Media Optimization and Partial Purification by Aqueous Three-Phase System

Uricase (urate: oxygen oxidoreductase, EC 1.7.3.3), an enzyme belonging to the class of oxidoreductases, catalyzes the enzymatic oxidation of uric acid to allantoin and finds a wide variety of application as therapeutic and clinical reagent. In this study, uricase production ability of the bacterial strains isolated from deep litter poultry soil is investigated. The strain with maximum extracellular uricase production capability was identified as Xanthomonas fuscans subsp. aurantifolii based on 16S rRNA sequencing. Effect of various carbon and nitrogen sources on uricase productivity was investigated. The uricase production for this strain was optimized using statistically based experimental designs and resulted in uricase activity of 306 U/L, which is 2 times higher than initial uricase activity. Two-step purification, such as ammonium sulfate precipitation and aqueous two-phase system, was carried out and a twofold increase in yield and specific activity was observed.

Partitioning of Propionic Acid in Polyethylene Glycol/ Different Salts of Sulfate Aqueous Two-Phase Systems

The extraction of propionic acid has been studied by liquid–liquid extraction with poly ethylene glycol /different salts of sulfate aqueous two-phase system (ATPS). In this study, a multilevel factorial design was applied to evaluate the effects of four independent variables (PEG molecular weight, type of salt, salt concentration, and temperature) on propionic acid extraction yield. The statistical significance of each factor was evaluated by an analysis of variance. The results indicated that the type and concentration of salt were the major contributing factors to propionic acid extraction. The PEG4000/ MnSO4 system was suitable for the extraction of propionic acid from dilute water.

Aqueous two-phase system: An alternative process for recovery of succinic acid from fermentation broth

Aqueous two-phase system was studied for the extraction of succinic acid (SA) produced by Actinobacillus succinogenes from the fermentation broth. Various hydrophilic solvents and inorganic salts were used to form the aqueous two-phase system for SA extraction, among which an acetone/ammonium sulfate aqueous two-phase system was investigated in detail, including examination of the phase diagram, effects of phase composition and pH on partitions, removal of cells and proteins from the fermentation broth, and recovery of ammonium sulfate. Under optimized conditions, with the fermentation broth pH value of 2 and aqueous two-phase system composed of 35% (w/w) acetone and 15% (w/w) ammonium sulfate, the recovery of SA from the fermentation broth was 94.4% with the removal of 93.6%, 98.1%, and 78.5% glucose, cells, and proteins, respectively. The total SA yield was 77.3% and the purity of SA was 98.7%. With the addition of methanol, 95.9% of ammonium sulfate in the salt-rich phase could be recovered, which indicated less waste discharge in SA extraction using the aqueous two-phase system.