Addition Of Neutral Salts Research Articles

Thermal gelation and digestion properties of hen egg white: Study on the effect of neutral and alkaline salts addition

In this study, the thermal gelation and digestion properties of hen egg white (hen EW) proteins with different salts were investigated. Results show that the addition of neutral salt - sodium chloride (NaCl) decreased the gel hardness/resilience, increased gel lightness, aggregated particle size and digestibility of hen EW proteins significantly. In contrast, alkaline salts – phosphate and carbonate addition increased the gel resilience and strain tolerance as well as reduced the aggregated particle size and gel lightness of hen EW proteins due to the increase of solution pH and negative charge. Correlation analysis shows that the digestibility of hen EW gels was affected by gel viscoelasticity, molecule forces and texture. In conclusion, thermal gelation properties of hen EW proteins could be modulated by salts with different pH/ionic strength, and thus affected the protein digestion and peptide released.

Efficient Conversion of Glucose into Fructose via Extraction-Assisted Isomerization Catalyzed by Endogenous Polyamine Spermine in the Aqueous Phase.

In the present study, natural polyamine spermine is demonstrated as a potential basic catalyst for glucose-to-fructose isomerization. For instance, spermine achieves a decent fructose yield (30% wt) and selectivity (74%) during the single-step aqueous phase isomerization under the modest operating conditions (100 °C for 15 min). In addition to the expected reaction byproduct monosugar mannose, spermine also assists in the synthesis of rare and important monosugar, that is, psicose up to 4% wt. Psicose is a zero calorie rare sugar, exhibits a low caloric value, and possesses anti-adipogenic property. A comparative study involving other polyamines concluded that the presence of 20 amines tends to exhibit the most significant impact in improving the target product yield by releasing a higher number of OH– ions, which are responsible for isomerization through the formation of an enediol anion. An attempt was made to further improve the fructose yield through the addition of neutral salts, but it promoted a meager achievement. In an alternate study, a selective extraction strategy was followed for the isolation of fructose from the reaction mixture. The employed aryl monoboronic acid remarkably improved the net fructose concentration, that is, fructose productivity up to 75% wt (cumulative) and 70% selectivity within three consecutive extractions and isomerization cycles, which is comparatively three times shorter than that reported in the literature. Notably, spermine itself provided the essential and necessary basic environment for selective fructose extraction and glucose isomerization, ruling out the use of any external reagents and thus establishing itself as a versatile material suitable for a typical isomerization reaction in an upscaled reactor.

Efficiency of Ionic Liquids-Based Aqueous Two-phase Electrophoresis for Partition of Cytochrome c.

Cytochrome c is a small water-soluble protein that is abundantly found in the mitochondrial intermembrane space of microorganism, plants and mammalians. Ionic liquids (ILs)-based aqueous two-phase electrophoresis system (ATPES) was introduced in this study to investigate the partition efficiency of cytochrome c to facilitate subsequent development of two-phase electrophoresis for the separation of cytochrome c from microbial fermentation. The 1-Hexyl-3-methylimidazolium bromide, (C6mim)Br and potassium citrate salt were selected as the phase-forming components. Effects of phase composition; position of electrodes; pH and addition of neutral salt on the partition efficiency of cytochrome c in the ATPES were evaluated. Highest partition coefficient (K = 179.12 ± 0.82) and yield of cytochrome c in top phase (YT = 99.63% ± 0.00) were recorded with IL/salt ATPES composed of 30% (w/w) (C6mim)Br and 20% (w/w) potassium citrate salt of pH7 and 3.0% (w/w) NaCl addition with anode at the bottom phase and cathode at the top phase. The SDS-PAGE profile revealed that cytochrome c with a molecular weight of 12kDa was preferably partitioned to the IL-rich top phase. Present findings suggested that the single-step ATPES is a potential separation approach for the recovery of cytochrome c from microbial fermentation. Graphical Abstract.

Extraction of natural astaxanthin from Haematococcus pluvialis using liquid biphasic flotation system

This work aimed to study the application of liquid biphasic flotation (LBF) for the efficient and rapid recovery of astaxanthin from H. pluvialis microalgae. The performance of LBF for the extraction of astaxanthin was studied comprehensively under different operating conditions, including types and concentrations of food-grade alcohol and salt, volume ratio, addition of neutral salt, flotation period, and mass of dried H. pluvialis biomass powder. The maximum recovery, extraction efficiency and partition coefficient of astaxanthin obtained from the optimum LBF system were 95.11 ± 1.35%, 99.84 ± 0.05% and 385.16 ± 3.87, respectively. A scaled-up LBF system was also performed, demonstrating the feasibility of extracting natural astaxanthin from microalgae at a larger scale. This exploration of LBF system opens a promising avenue to the extraction of astaxanthin at lower cost and shorter processing time.

Oxidative degradation of Orange G by peroxomonosulfate in presence of biosynthesized copper nanoparticles—A kinetic study

The present study reports the highly stable dispersednanosized copper particles (CuNPs) was prepared by the biosynthesis process. The reduction of copper salts by Azadirachta indica (neem) leaf broth is a new and green approach, in which biomolecules present in leaf broth is act as reducing and stabilizing agent in aqueous medium. The effect of reaction temperature on the size of dispersed CuNPs was studied. The morphology of CuNPs was investigated by Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM) analysis. Fourier Transform Infrared Spectroscopy (FTIR) studies reveal the presence of bioactive functional groups such as phenolic, amines and an aromatic ring are responsible for capping and stabilizing of nanoparticles (NPs). Further, the catalytic activity of synthesized NPs was measured on the degradation of Orange G (OG) in presence of peroxomonosulfate (PMS) spectrophotometrically. The results indicates that biosynthesized CuNPs at different temperature have different degradation efficiency at different average size 48.01 >50.57 >68.54 >73.54 nm respectively. The effect of different experimental condition as well as addition of neutral salts on the rate of degradation was also studied.

Salt-Promoted Glucose Aqueous Isomerization Catalyzed by Heterogeneous Organic Base

Effective isomerization of glucose to fructose is a crucial step for 5-hydroxymethylfurfural production from lignocellulose. The present study investigated polystyrene-supported organic bases with varied structural properties for aqueous isomerization of glucose. The results indicate that the heterogeneous organic bases can achieve approximately 30% fructose yields at 120–140 °C. As heterogeneous catalysts, they are generally less efficient than homogeneous organic bases and can lose catalytic activity during recycling likely from thermal-induced byproducts. However, the addition of neutral salt made the heterogeneous organic bases as efficient as homogeneous organic bases, achieving approximately 41% maximum fructose yields at 80–100 °C; and improved the reusability allowing the heterogeneous organic bases to be reused for at least four times without significant loss of catalytic activity.

Extraction of lipase from Rhizopus microsporus fermentation culture by aqueous two-phase partitioning

The purification of a desired protein from the complex mixture of biomolecules in a fermentation broth is one of the main challenges in industrial-scale biotechnological processes. For partial purification of industrial enzymes, one possible approach is to use aqueous two-phase extraction (APTE) as a primary downstream processing step. In the present study, the feasibility of utilizing ATPE for the purification of lipase from Rhizopus microsporus fermentation culture was investigated. The effects of the phase composition and salt type, molecular weight of the polyethylene glycol (PEG), pH of the system, sample loading and addition of neutral salts on lipase partitioning were investigated at 24 °C. In most of the examined aqueous two-phase systems (ATPSs), lipase showed affinity to the top phase. Optimum conditions for lipase purification were obtained in 20% PEG 2000/12% (NH4)2SO4, with 5% Na2CO3 addition at pH = 8 for 30% crude load. For the optimized ATPS, the recovery yield and purification factor in the top phase were determined to be 92.3% and 19.8, respectively.

1-Hexyl-3-Methylimidazolium Chloride-Potassium Carbonate Aqueous Two Phase System: Equilibrium Characteristics and BSA Partitioning Behavior

The partitioning behavior of the model protein (bovine serum albumin) was investigated in ionic liquid (1-hexyl-3-methylimidazolium chloride) -salt (potassium carbonate) based aqueous two phase system (ATPS). The phase diagram with binodal curve and tie lines for the selected ATPS was developed at different temperatures and analyzed through effective excluded volume (EEV) and Othmer-Tobias and Bancroft equations, respectively. The influence of various process parameters like the ionic liquid and salt concentration, system temperature, tie line length, phase volume ratio, and neutral salt addition on partition coefficient/extraction efficiency of BSA protein was evaluated.

Biosorption of toxic acidic dye–Acid Blue 25, by aquatic plants

The adsorption of Acid Blue 25 (AB25) ions by aquatic plants, Potamogeton pusillus and Ceratophylum demersum from aqueous solutions was studied. The adsorption was studied as a function of solution pH (2–11), contact time (0–60 min), biomasses dosage (0.1–2.5 g/L), initial dye concentration (30–100 mg AB25 /L), biosorbents particle size (53–500 μm), addition of neutral salts (20–100 mg KNO3/L and 20–100 mg KH2PO4/L), and salinity (0.5–40 g NaCl/L). The results of equilibrium adsorption were successfully described through Freundlich and Temkin isotherm for both of the biosorbents. Maximum adsorption capacity of 183.46 and 129.68 mg/g were observed for P. pusillus and C. demersum, respectively. Different kinetic models including pseudo-first order, pseudo-second order, and intra-particle diffusion were examined, and the pseudo-second order was shown to be the best model to fit the adsorption kinetics data. Thermodynamic parameters demonstrated that adsorption of AB25 ions was spontaneous and endothermic at a temperature range of 10–40°C. FTIR analysis confirmed the responsibility of several functional groups on the surface of the biosorbents for the adsorption of AB25 in this process.

Comparative Study of Alkaline, Saline, and Mixed Saline–Alkaline Stresses with Regard to Their Effects on Growth, Nutrient Accumulation, and Root Morphology of Lotus tenuis

Both saline and alkaline conditions frequently coexist in nature; however, little is known about the effects of alkaline and salt–alkaline stresses on plants. We performed pot experiments with four treatments, control without salt addition and three stress conditions—neutral, alkaline, and mixed salt–alkaline—to determine their effects on growth, nutrient accumulation and root architecture in the glycophytic species Lotus tenuis. Neutral and alkaline salts produced a similar detrimental effect on L. tenuis growth, whereas the effect of their combination was synergistic. Neutral salt addition, alone or mixed with NaHCO3, led to significant leaf Na+ build up and reduced K+ concentration. In contrast, in plants treated with NaHCO3 only, Na+ levels and the Na+/K+ ratio remained relatively unchanged. Proline accumulation was not affected by the high pH in the absence of NaCl, but it was raised by the neutral salt and mixed treatments. The total root length was reduced by the addition of NaCl alone, whereas it was not affected by alkalinity, regardless of the presence of NaCl. The topological trend showed that alkalinity alone or mixed with NaCl turned the root more herringbone compared with control roots, whereas no significant change in this index was observed in the treatment with the neutral salt only. The pattern of morphological changes in L. tenuis root architecture after the alkaline treatment (in the absence of NaCl) was similar to that found in the mixed salt–alkaline treatment and different from that observed in neutral salt. A unique root morphological response to the mixed salt–alkaline stress was the reduction in the ratio between xylem vessels and root cross-sectional areas.

Differential partitioning of β-galactosidase and β-glucosidase using aqueous two phase extraction

Aqueous two phase extraction (ATPE) is used for the first time for simultaneous separation and purification of β-galactosidase and β-glucosidase from barley (Hordeum vulgare). The influence of various process parameters such as polymer molecular weight and its concentration, salt type and its concentration, system pH, tie line length, phase volume ratio and neutral salt addition on separation and purification of these two enzymes was evaluated. The β-galactosidase and β-glucosidase were selectively partitioned to top and bottom phases, respectively. Suitable conditions for purification were found in aqueous two phase system, having 14% (w/w) polyethylene glycol 1500/13% (w/w) ammonium sulphate, at tie line length of 19.65% (w/w). Single stage of ATPE resulted in an activity recovery of 98.26% with purification of 2.1 fold of β-galactosidase and an activity recovery of 92.58% with purification of 3.3 fold of β-glucosidase. Second stage of ATPE with respective new phases increased the purification of β-galactosidase and β-glucosidase to 2.4 and 4.1 fold, respectively. During ATPE, conditions which enabled a balance between yield and purification of both the enzymes were selected. Further ultrafiltration in diafiltration mode increased the purification of enzymes (β-galactosidase 6.8 fold and β-glucosidase 7.7 fold) besides the removal of the phase components.

Direct purification of Burkholderia Pseudomallei lipase from fermentation broth using aqueous two-phase systems

An aqueous two-phase purification process was employed for the recovery of Burkholderia pseudomallei lipase from fermentation broth. The partition behavior of B. pseudomallei lipase was investigated with various parameters such as phase composition, tie-line length (TLL), volume ratio (VR), sample loading, system pH, and addition of neutral salts. Optimum conditions for the purification of lipase were obtained in polyethylene glycol (PEG) 6000-potassium phosphate system using TLL of 42.2% (w/w), with VR of 2.70, and 1% (w/w) NaCl addition at pH 7 for 20% (w/w) crude load. Based on this system, the purification factor of lipase was enhanced to 12.42 fold, with a high yield of 93%. Hence, the simplicity and effectiveness of aqueous two-phase systems (ATPS) in the purification of lipase were proven in this study.

Effect of neutral salts and methylglyoxal on the cis-trans equilibrium of n-methylacetamide. A 13-carbon nuclear magnetic resonance study

Cis-trans isomers of N-methylacetamide were observed by using 13C nuclear magnetic resonance spectroscopy. The addition of neutral salts altered the isomer ratio favoring the cis form. The salt-induced cis isomerization is reversible and depends on salt concentration. Methylglyoxal added to N-methylacetamide formed a stable cis isomer. It is proposed that concentrated salts and methylglyoxal, by binding to the peptide bond, affect the properties of proteins.

Selective partition of plasmid DNA and RNA in aqueous two-phase systems by the addition of neutral salt

The selective partition of plasmid DNA (pDNA) and RNA in polyethylene glycol (PEG) and di-potassium hydrogen phosphate aqueous two-phase systems (ATPSs) by addition of NaCl salt was studied with pure pDNA and RNA solutions. The pDNA is increasingly excluded from top phases upon the addition of 0.5% and 3% (w/w) NaCl. With 3% (w/w) NaCl, the logarithmic partition coefficient of RNA was 1.2 and as a result, the RNA concentration in the top phase was 3.3-fold higher than that in the bottom phase. It is demonstrated that 47%, 13.7% and 7.5% (w/v) of PEG were required to achieve identical precipitation effects with PEG 300, 1450 and 6000, respectively. The precipitation efficiency of 6.3% (w/v) PEG 300 corresponds to that of 1% (w/v) PEG 6000. The excluded volume effects in the top phase were probably responsible for the selective exclusion of different nucleic acids species. The results obtained in this study contribute to the basic knowledge of partition of macromolecules in ATPSs in terms of excluded volume theory.

Kinetics of Carbon Dioxide Absorption into Aqueous Potassium Carbonate and Piperazine

The absorption rate of CO2 was measured in a wetted-wall column in 0.45−3.6 m piperazine (PZ) and 0.0−3.1 m potassium carbonate (K2CO3) at 25−110 °C. A rigorous kinetic model was used to model the data and interpret diffusivities and rate constants. The rate approaches second-order behavior with PZ and is highly dependent on other strong bases. In 1 M PZ, the overall rate constant is 102 000 s-1, 20 times higher than in monoethanolamine. The activation energy is 35 kJ/mol, similar to other amine−CO2 reactions. Rate constants for contributions of carbonate, PZ carbamate, and water to the rate were determined according to base catalysis theory. The addition of neutral salts to aqueous PZ increases the apparent rate constant. In 2.7 M NaCl/0.6 M PZ, the overall rate constant is increased by a factor of 7. Ionic strength effects were accounted for within the rigorous model of K+/PZ mixtures. The absorption rate in concentrated K+/PZ mixtures is up to 3 times faster than in 30 wt % monoethanolamine. At low temperatures and low CO2 loadings, a pseudo-first-order approximation adequately represents the absorption rate. At high loadings, the reaction approaches instantaneous behavior but is still influenced by reaction kinetics. Under industrial conditions, gas film resistance may account for >80% of the total mass transfer resistance at low loadings.

Effect of reactive anionic agent on dyeing of cellulosic fibers with a Berberine colorant—part 2: anionic agent treatment and antimicrobial activity of a Berberine dyeing

A reactive anionic agent containing dichloro- s-triazinyl reactive group was synthesized and applied to the cotton fabric. Berberine as a natural cationic colorant showed considerable substantivity towards anionic agent modified fabric. This Berberine can be also employed in antimicrobial finishes as a natural agent due to its characteristic of cationic quaternary ammonium salt. It was found that the adsorption of Berberine onto cotton fabric pretreated with the anionic agent was greatly increased when compared to that of untreated counterpart. The addition of neutral salts was greatly effective to increase the exhaustion–fixation efficiencies (%EF) of the anionic agent onto the cotton fabric. In terms of antimicrobial activity of Berberine dyeing, the dyed sample with Berberine showed very effective antimicrobial functions showing about 99.5% of bacterial reduction against Staphylococcus aureus.

Observation of a combined dilution and salting effect in buffers under conditions of high dilution and high ionic strength

The pH value of buffer solutions is crucially dependent on the relative concentrations of all species in solution. The addition of water or neutral salt can have a significant effect on the pH of a buffer solution. This study examines the magnitude of the "dilution effect" and the "salt effect" for several commonly used inorganic and biological buffers. Novel data are obtained for the change in pH observed upon dilution or addition of neutral salt to these buffers which add to, complement and extend existing literature values. The validity of considering the dilution and salt effects as a combined ionic strength effect is also considered as well as the ability of the pH measuring device to perform valid measurements in these extreme conditions.

The Kinetics of the Adsorption of Different Ester Type Polyols toward the Poly Ethylene Terephthalate Fiber

The adsorption kinetics of different ester types polyol toward polyethylene terephthalate (PET) fibers was studied and the solvent effect, the activation energy, adsorbing rate constant and amount of adsorption temperature and pH or addition of neutral salts were investigated in this paper. We found that the adsorption capacity of ester type polyols with double benzene rings (PTET400 and PTETE400) toward PET fibers is better than that of polyols with a single benzene ring (PT400 and PTE400). The adsorption for all polyols showed a two-step adsorption phenomenon. The first step is instant adsorption and the second step is diffusion adsorption. The diffusion adsorption is a first-order adsorption. The adsorption curves of diffusion adsorption for the same polyols under different LR (liquor ratio) of polyol aqueous solution toward PET fabrics were to cross in one point, when t=0. The adsorption rate (K) of polyols showed a linear relationship with the LR (liquor ratio) of solution. As for the absorption amounts, both amounts of instant and diffusion adsorption for all polyols showed a linear relationship with increase in temperature. The instant adsorption amount of the polyols with double benzene rings toward PET fibers is greater than that of polyols with a single benzene ring particularly under a lower pH. The addition of neutral salts had a positive effect on absorption. The order of adsorption activation energy for polyols toward PET fibers is PTE400 > PT400 > PTETE400 > PTET400.

Salt Addition Effects on Mesophase Structure and Optical Properties of Aqueous Hydroxypropyl Cellulose Solutions

The effects of addition of neutral salts on the cholesteric mesophase structure and optical properties of aqueous solutions of hydroxypropyl cellulose (HPC) were investigated by spectrophotometry and an NMR technique with D2O as solvent. In the measurements of selective light-reflection spectra, the wavelength of maximal reflectance and therefore the cholesteric helical pitch (P), too, varied systematically with a change in strength of a so-called “chaotropic” effect of the additive salts; i.e., their effectiveness in increasing P was pronounced in the order of Cl-<Br -<NO3-<I-<SCN- and Cs+<K+<Na+ <Ca2+<Li+≤Mg2+<Al3+, when compared in a series of salts with a common sort of cation or anion. An LCST-type of phase separation behavior of the HPC/water system was also affected by the coexistence of salt ions; the cloud point shifted either down or up in almost the same manner as that found in the salt-sort dependence of the cholesteric periodicity. In the deuteron NMR study, a frequency width of the quadrupolar splitting, detected as a measure of the molecular orientation development within the mesophase, was found to be less affected by the salt addition. It is suggested that the hydrophobic bond-disrupting or promoting activity of the salts added could regulate subtly a conformational state of the cellulosic polymer, to induce a marked change in cholesteric twisting power without disturbing the orientational ordering in each of the pseudonematic layers.

Partitioning behaviour of cephalexin and 7‐aminodeacetoxicephalosporanic acid in PEG/ammonium sulfate aqueous two‐phase systems

AbstractIn order to develop an aqueous two‐phase system (ATPS) for cephalexin synthesis with extractive bioconversion, the partitioning behaviour of cephalexin and 7‐aminodeacetoxicephalosporanic acid (7‐ADCA) in poly(ethylene glycol) (PEG)/salt ATPS were examined. Parameters such as PEG size, salt type and tie line length were investigated to find a primary extraction system. In PEG400/ammonium sulfate and PEG400/magnesium sulfate systems, the partition coefficient of cephalexin (KC) was larger than 1 while that of 7‐ADCA (KA) deviated about 1.5. Addition of neutral salts, surfactants and water‐miscible solvents were also investigated in the primary ATPS in order to improve the separation efficiency. KC greatly increased when neutral salts and surfactants were added to the PEG400/ammonium sulfate primary systems whereas KA was only slightly higher than that of the additive‐free ATPS. In an improved ATPS for extractive bioconversion, consisting of PEG400 (20% w/w), ammonium sulfate (17.5% w/w), methanol (5% w/w) and NaCl (3% w/w), a KC value of up to 15.2 was achieved; KA was 1.8; KP (partition coefficient of phenylglycine methyl ester) was 1.2 and the recovery yield of cephalexin was 94.2%. The results obtained from the extractive bioconversion of cephalexin in the improved ATPS showed that it is feasible to perform such an enzymatic process in an ATPS and the system offers the potential as a model for enzymatic synthesis of some water soluble products.© 2001 Society of Chemical Industry