Ionic Strength NaCl Research Articles

Evaluation of Stability constant of Binary complex of Tannic Acid with Fe(II) in Aqueous Solution: Potentiometric Study

In this study, the protonation equilibria of the tannic acid was determined and used for determining the stability constants of the binary complexes formed with iron (II) ions in the aqueous medium under the experimental conditions by potentiometric method using Irving and Rossotti equation, where Stability constant was 3.205 for Fe(II)–tannic acid complex, while Fe(II) was formed complexes with tannic acid of various stoichiometries, which in the 1:1 molar ratio at pH = 11.24. Furthermore, the ionic strength and the influence of temperature on the stability of the complexes is investigated, where stability constant in presence 0.1 M NaCl (ionic strength) of binary iron-Tan complex equal 3.254, and at different temperatures were log K1= 3.156 at 298.15 K, log K1 = 3.205 at 310.15 K, and log K1 = 3.256 at 313.15 K.

The Impact of Dissolved Salts on the Erosion of Physically Purified Compacted Bentonite

Compressed bentonite is an appropriate cushion material for getting rid of spent nuclear waste below the surface storage. The contact of compressed bentonite with water, its immersion in water and subsequently its swelling into the neighboring gaps are the principal processes for the development of colloid fines. In this study, to examine the impact of ionic strength on the erosion of compacted bentonite, only the ionic power values of the water contacting the bentonite were changed by keeping the flow rates constant. Sodium chloride was used to change the ionic power of the water contacting the bentonite throughout the experiment. Turbidity meter (TM) was used to determine the amount of eroded particles. The dissolution of bentonite fragments is critical not only due to their physical stability but also due to the radioactive isotopes they contain. An experimentation methodology is introduced. The implemented flow rates were 0.06 ml/min and 0.22 ml/min, and the selected waters were distilled water and 0.05 M NaCl ionic strength water. The dry densities of the compressed bentonite samples used were 1.67 g/cm3, 1.72 g/cm3, 1.72 g/cm3 and 1.72 g/cm3. With distilled water, the total erosion value measured at the end of the 24th day using a flow rate of 0.06 ml/min was 1002.7 mg, whereas the final erosion value measured at the end of the 24th day using water containing 0.05 M NaCl salt was 31.13 mg. In the case of distilled water, the total erosion value measured at the end of the 24th day using a flow rate of 0.22 ml/min was 1774.85 mg, while the total erosion value measured at the end of the 24th day using water containing 0.05 M NaCl salt was 73.6 mg. This demonstrates that the influence of the ionic strongness of the water on erosion is too important to be neglected.

Influence of pH and ionic strength on the physicochemical and structural properties of soybean β-conglycinin subunits in aqueous dispersions

Understanding the impact of pH and ionic strength on the physicochemical and structural properties of soy proteins at subunit level is essential for design and fabrication of many plant-based foods. In this study, soybean β-conglycinin and its subunit fractions αα′ and β were dispersed in solutions with different pH values (3.7, 7.6, and 9.0) at low (5 mM NaCl) and high (400 mM NaCl) ionic strengths, respectively. The solubility, rheology, particle size, zeta potential, microstructure, secondary structure, and tertiary structure of the different dispersions were analyzed using a range of analytical methods. The β-conglycinin, αα′- and β-subunits aggregated near the isoelectric point (pH 3.7). Increasing the ionic strength led to the assembly of more homogeneous units. An increase in ionic strength at pH 7.6 and pH 9.0 led to electrostatic screening, which promoted dissociation of the aggregates. The β-subunit showed a greater sensitivity to pH and ionic strength than the αα′-subunits. Based on the evidence from a range of analytical methods, the highly hydrophilic extension region of the αα′-subunits played an important role in determining the stability of the β-conglycinin dispersions under different environmental conditions. Moreover, the N-linked glycans appeared to impact the conformation and aggregation state of the β-conglycinin.

Synthesis and Determination of Acid Dissociation Constants of Bis-Acyl Thiourea Derivatives

N,N'-((dodecane-1,12-diylbis(azanediyl))bis(carbonothioyl))bis(4-nitrobenzamide) 5 and N,N'-((dodecane-1,12-diylbis(azanediyl))bis(carbonothioyl))bis(3-nitrobenzamide) 6 as bis acyl thiourea derivatives were synthesized and their molecular structures were characterized using 1H NMR, 13C NMR, COSY, DEPT, HMQC, FT-IR, and HRMS techniques. The acid dissociation constants (pKa) of the bis-acyl thiourea derivatives 5, 6 were determined potentiometrically and spectrophotometrically. The pKa values of products 5, 6 were determined in 50% (v/v) dimethyl sulfoxide–water hydro-organic solvent in the presence of 0.1 molL1 ionic strength of NaCl and in the acidic medium at 25±0.1 °C, and two pKa values were calculated for each compound with the HYPERQUAD computer program using the data obtained from the potentiometric titrations performed. In addition, three pKa values for each compound were determined in the calculations using the HypSpec program from the data obtained from the spectrophotometric titrations performed under the conditions where the potentiometric titrations were performed. For compounds 5 and 6, spectrophotometrically, pKa1 was 3.56±0.08 and 3.87±0.01, respectively, pKa2 was 7.11±0.08 and 7.05±0.01, respectively, and pKa3 was 12.30±0.08 and 11.82±0.02, respectively. It can be said that pKa1, pKa2, and pKa3 values may belong to enol, enthiol, and NH, respectively. Moreover, for compounds 5 and 6, potentiometrically, pKa2 was 7.06±0.13 and 6.94±0.11, respectively, and pKa3 was 12.11±0.06 and 11.17±0.06, respectively, and it can be said that pKa2 and pKa3 values may belong to enthiol and NH, respectively. It is seen that the pKa values determined spectrophotometrically and potentiometrically are compatible with each other.

Development of stable organogels using egg yolk granules-chitosan complex: Structure, rheology, and stability

Organogels have emerged as potential alternatives to trans and saturated fats. We developed semi-solid stable organogels using egg yolk granules-chitosan complex (EYGs-CS). We investigated the impacts of pH and NaCl ionic strength on the structural, rheological, and stability characteristics of the organogels. We found that stable organogels formed under acidic pHs (≤ 5.0) and high ionic strengths (≥ 0.2 M), displaying small droplet sizes, excellent elasticity behavior, poor oil migration, and high stability. The efficient adsorption of EYGs-CS at the oil surfaces formed stable droplets with compact walls. A colloidal 3D-network was formed within the aqueous phase, resulting in elastic and firm organogels. The droplets under acidic conditions showed higher surface charges, which blocked their coalescence through the electrostatic repulsion. The electrostatic shielding at high ionic strengths caused high steric repulsion, resulting in higher stability. This work provides insight into the replacement of harmful fats with healthier alternatives.

Experimental measurements and numerical simulations of the transport and retention of nanocrystal CdSe/ZnS quantum dots in saturated porous media: Effects of electrolytes, organic ligand, and natural organic matter

This study explores the transport and retention of CdSe/ZnS quantum dot (QD) nanoparticles in water-saturated sand columns as a function of electrolytes (Na+ and Ca2+), ionic strength, organic ligand citrate, and Suwannee River natural organic matter (SRNOM). Numerical simulations were carried out to understand the mechanisms that govern the transport and interactions of QDs in porous media and to assess how environmental parameters impact these mechanisms. An increase in the ionic strength of NaCl and CaCl2 increased QDs retention in porous media. The reduction of the electrostatic interactions screened by dissolved electrolyte ions and the increase of divalent bridging effect are the causes for this enhanced retention behavior. Citrate or SRNOM enhanced QDs transport in NaCl and CaCl2 systems by either increasing the repulsion energy barrier or inducing the steric interactions between QDs and the quartz sand collectors. A non-exponential decay characterized the retention profiles of QDs along the distance to the inlet. The modeling results indicated the four models containing the attachment, detachment, and straining terms – Model 1: M1-attachment, Model 2: M2-attachment and detachment, Model 3: M3-straining, and Model 4: M4-attachment, detachment, and straining – closely simulated the observed breakthrough curves (BTCs) but inadequately described the retention profiles.

THERMODYNAMIC BASED AQUEOUS SOLVATION AND DISSOCIATION OF BENZOIC ACID

In article, we have reported a thermodynamic based study of aqueous solvation of benzoic acid (C6H5COOH) at 288 to 318 Kelvin temperature. At this temperature range the dissociation constant (Ka) of benzoic acid into aqueous solvent has been determined by applying of titration method against standard basic solution of NaOH at different ionic strength of NaCl. Although, in observation, the value of Ka is being inversely proportional in respect of temperature in between 289 K to 303 K, and at higher temperature in between 303 K to 314 K, it being directly proportional. This reports that, there are no regular correlation in between temperature and Ka of that acid. Graphically, the plot has shown the value of Ka of benzoic acid is being 4.176 at 298 K temperature. In finding of precious results for benzoic acid solvation and its dissociation into water the applying Vant Hoff equation with Gibbs free energy change relationship (∆G = ∆H - T∆S) for reaction (endothermic or exothermic) process at standard condition of thermodynamic parameters as in terms of enthalpy (H) and entropy (S). Where, the thermodynamic parameters value (in kJ.mol-1) are being as ∆G = 12.507, ∆H = 3.823 and ∆S = -29.14, but, at 298 K it is show that, the acid dissociation into aqueous is an endothermic process and non-spontaneous.

Self-assembled zein hydrolysate glycosylation with dextran for encapsulation and delivery of curcumin

Curcumin has been widely used to promote human health and nutrition due to its high antioxidant capacity. However, its low solubility and bioaccessbility limit its practical application. In this study, we used glycosylated zein hydrolysate to encapsulate hydrophobic curcumin to improve its bioaccessbility and stability at extreme processing conditions. Glycosylated zein hydrolysate exhibited good amphiphilicity and self-assembly properties. The nanoparticles, made up of glycosylated zein hydrolysate encapsulated curcumin, had a number-average particle size of 117 nm, polydispersity coefficient (PDI) value of 0.16 and high apparent loading efficiency value of 81%. Under the observation of TEM and AFM, the nanoparticles were spherical, stable and uniform in particle size distribution, and dispersed well in the solution after dilution. Steady-state fluorescence spectroscopy showed that there is a strong affinity between curcumin and glycosylated zein hydrolysate with Ka value of 3.17 × 105 M−1. The bioaccessbility of nanoparticles was 86%, increasing the bioaccessbility of curcumin by 9 times. The covalently bound dextran formd the protective layer on the outside of the nanoparticles, which could effectively resist the destruction of gastric enzymes, significantly increase the retention rate in the gastric digestion stage and achieve release in the intestinal tract. In addition, the stability of nanoparticles in various environment with different ionic strengths NaCl (∼600 mM)/Ca2+ (∼50 mM) and temperature (∼90 °C) were significantly enhanced.

Vortex assisted magnetic ionic liquid based dispersive liquid–liquid microextraction approach for determination of metribuzin in some plant samples with UV–Vis spectrophotometer

A vortex assisted magnetic ionic liquid based dispersive liquid–liquid microextraction (VA-MIL-DLLME) approach was proposed using a tetrachloromanganate-based magnetic ionic liquid (MIL, as extraction solvent) for the determination and extraction of metribuzin in some plant samples by UV–Vis spectrophotometer. The MIL was prepared from a mixture of trihexyl(tetradecyl)phosphonium chloride [P6,6,6,14+][Cl−] and manganese(II) chloride tetrahydrate (MnCl2·4H2O) in chloroform. Important factors for the VA-MIL-DLLME approach were optimized in detailed. The optimum conditions were: 8.0 of pH, 80 mg of the [P6,6,6,14+]2[MnCl42−] (extraction solvent), 250 μL of ethanol (as dispersing solvent), 3 min of vortex time and 1.5 mL of 30 % NaCl (w/v) (ionic strength). Calibration graph was linear in the range of 35–800 μg L−1 with correlation of determination 0.995. The limit of detection, limit of quantification and enrichment factor were found to be 10.6 μg L−1, 35 μg L−1 and 247, respectively. The VA-MIL-DLLME approach was applied for extraction and determination of metribuzin in the samples. The relative standard deviations (RSD) in the samples were less than 2.8 %. Moreover, the recoveries were obtained in the range of 91 ± 2–102 ± 3 %.

Gibbs Free Energy Change (∆G) in Aqueous Dissociation of Benzoic Acid at Temperature ‘K’: A Thermodynamic Study

In article, we have reported a thermodynamic based study of the Gibbs free energy change (∆G) in aqueous dissociation of benzoic acid at Kelvin temperature range in between of 288 K to 318 K. Thermodynamically, at this Kelvin temperatures range the dissociation constant (Ka) of benzoic acid into aqueous solutions have been determined by applying of titration method against standard basic solution of NaOH at different concentrations or ionic strength of NaCl. In observation, the value of Ka is being inversely proportional with respect to temperature in between 289 K to 303 K, and at higher temperature in between 303 K to 314 K, it being directly proportional. This is reported that, there are no regular correlation in between temperature and Ka of that acid. In graph, the plot has shown the value of Ka of benzoic acid is being 4.176 at 298 K temperature. Thus, in finding of precious results for benzoic acid dissociation into water an applying the Gibbs free energy change relationship (∆G = ∆H - T∆S) for endothermic or exothermic reaction process at standard condition of thermodynamic parameters. These parameters value (in kJ.mol-1) are being as ∆G = 12.507, ∆H = 3.823 and ∆S = -29.14. And, at 298 K, it is show that the acid dissociation into aqueous solvent is an endothermic and non-spontaneous process with ordered entropy (∆S).

Impact of water activity on the radial growth of fungi in a dairy environment

Filamentous fungi are used in the dairy industry as adjunct cultures in fermented products, but can also lead to food spoilage, waste and economic losses. The control of filamentous fungi with abiotic factors contributes to longer food shelf life and prevention of fungal spoilage. One of the main abiotic factors for controlling fungal growth in foods is water activity (aw). This study aimed to evaluate radial growth as a function of aw for sixteen fungal adjuncts and/or spoilers isolated from dairy products or a dairy environment. Glycerol (a non-ionic compound) and sodium chloride (NaCl, an ionic compound) were used to adjust the aw of culture media. This study showed significant diversity in the responses of the tested fungal strains as a function of medium aw. The growth response of Penicillium bialowiezense and Sporendonema casei was binary, with no clear decrease of growth rate until the growth limit, when the aw was reduced. For the strains of Bisifusarium domesticum, Mucor circinelloides and Penicillium camemberti, a decrease of aw had the same impact on radial growth rate regardless of the aw belonging to their growth range. For the strains of Aspergillus flavus, Cladosporium herbarum, Geotrichum candidum, Mucor lanceolatus, Penicillium expansum, Penicillium fuscoglaucum, Penicillium nalgiovense, Paecilomyces niveus, Penicillium roqueforti, Penicillium solitum and Scopulariopsis asperula, the impact of a decrease in aw was more pronounced at high aw than at low aw. A mathematical model was suggested to describe this impact on the radial growth rate. For all tested species, radial growth was more sensitive to NaCl than glycerol. The ionic strength of NaCl mainly explains the difference in the effects of the two solutes.

Understanding the Adsorptive Removal of Bromophenol Blue Dye Based Graphene Oxide Nanoparticles as Adsorbent

ABSTRACT This study shows two sizes of graphene oxide nanoparticles (GO – 450 nm and GO – 200 nm) which are introduced as adsorbents to remove Bromophenol blue dye. The GO – 450 nm was made by oxidation-reduction reaction, followed by tip sonication to obtain GO – 200 nm. The microscopic and spectroscopic properties were realised using scanning electron microscopy and FTIR spectroscopy, respectively. The batch adsorption was used to evaluate the removal of BPB onto both sizes of adsorbents. The amount of BPB that was successfully removed depending on the pH, the adsorbent dose, the contact time, the initial dye concentration, and the reaction temperature. The optimal conditions for the removal of BPB were at pH = 2, applying a dose of 160 mg/ml and for a contact time of 40 minutes. Moreover, the experimental data agree well with the Langmuir isotherm in both cases, and the maximum adsorption capacities of removal of BPB dye were found to be 28.57 mg/g and 40 mg/g for GO – 450 nm and GO – 200 nm, respectively. The percent removal of BPB dye was enhanced in the presence of NaCl ionic strength. The thermodynamic parameters like ∆G, ∆H and ∆S were elucidated.

Microfluidics-Based Low Salinity Wettability Alteration Study of Naphthenic-Acid-Adsorbed Calcite Surfaces

Microfluidics is relatively a new area in the oil and gas industry and has great potential to be used as an effective tool to address various outstanding research questions where microscale investigation is necessary. Low salinity brine flooding has been known to enhance oil recovery in carbonate reservoirs through a wettability alteration mechanism. Wettability alteration is a molecular-scale phenomenon that is often characterized at a mesoscale through contact angle experiments. By using microfluidic chips, the low salinity effects involving solid–fluid interactions could be directly visualized, and the wettability alteration could be verified at microscale. However, to replicate solid–fluid interactions involved in carbonate reservoirs, the internal wetting surfaces must be transformed to carbonate surfaces. In this study, first, wetting surfaces of straight-channel glass microfluidic chips were functionalized using a metal-chelating silane coupling agent, and then, the surfaces were coated with CaCO3 using a layer-by-layer (LbL) deposition process. The calcite-coated straight-channel glass microfluidic chips were then used to investigate the effects of brine salinity and the role of divalent ions in the wettability alteration of oil-wet calcite surfaces at both room temperature and high temperature (70 °C). Naphthenic acid was used as the surface-active component in a model oil to render calcite surfaces oil wet. Six single-electrolyte-based brines were used in this study: high salinity 5 M NaCl, seawater equivalent 0.656 M NaCl, and 4-times diluted seawater-equivalent low salinity brines─0.164 M ionic strength NaCl, Na2SO4, MgSO4, and MgCl2. The low salinity brines were found to induce significant wettability alteration on naphthenic-acid-adsorbed calcite surfaces at ambient temperature. Low salinity Na2SO4 resulted in the highest wettability alteration followed by low salinity NaCl solution. Insignificant wettability alteration was observed in 0.656 M NaCl compared to 0.164 M NaCl where the wettability alteration was significant, suggesting the extent of wettability alteration increases with reduction in brine salinity. Magnesium ions were found to be unfavorable for wettability alteration in the presence or absence of sulfate ions. Exposure to higher temperature resulted in no or insignificant further wettability alteration in most of the brines.

Formation of Natural Egg Yolk Granule Stabilized Pickering High Internal Phase Emulsions by Means of NaCl Ionic Strength and pH Change.

Pickering high internal phase emulsions (HIPEs) are gel-like concentrated emulsions that have the potential to be an alternative to partially hydrogenated oil (PHO). In this study, egg yolk granules (EYGs), natural complexes of protein and lipid isolated from egg yolk, were used as an emulsifier to prepare Pickering HIPEs. Gel-like HIPEs with an oil phase volume fraction of 85% and with an emulsifier concentration of only 0.5% could be prepared by using EYGs as an emulsifier. The EYGs were able to form stable HIPEs at NaCl ionic strengths over 0.2 M and at pH over 5.0 with NaCl ionic strength of 0.3 M. The EYGs, which could stabilize HIPEs, were easily to adsorb and cover the oil-water interface to form emulsion droplets with small particle size. In addition, interacting EYGs in the aqueous phase formed a continuous network structure, and the oil droplets packed closely, exhibiting high elasticity and shear thinning behavior. Furthermore, the formed HIPEs had suitable storage stability with no significant changes in appearance and microstructure after storage for 60 days. This work can transform traditional oils from liquid-like to solid-like by using EYGs to enrich food processing diversity and improve the storage stability of oils while reducing the intake of PHO and providing a healthier diet for consumers.

Synthesis and characterization of novel thermo- and salt-sensitive amphoteric terpolymers based on acrylamide derivatives

A novel linear amphoteric terpolymers based on neutral monomer — N-isopropylacrylamide (NIPAM), ani- onic monomer — 2-acrylamido-2-methyl-1-propanesulfonic acid sodium salt (AMPS), and cationic mono- mer — (3-acrylamidopropyl) trimethylammonium chloride (APTAC) were synthesized by free-radical polymerization in aqueous solution and characterized by methods of 1H NMR and FTIR spectroscopy, TGA, GPC, Dynamic light scattering (DLS) and zeta-potential. The thermal and salt sensitivity of amphoteric ternary polymers of various compositions, particularly, [NIPAM]:[AMPS]:[APTAC] = 90:2.5:7.5; 90:5:5; 90:7.5:2.5 mol.% were studied in aqueous and aqueous-salt solutions in the temperature range from 25 to 60 C and at the NaCl ionic strength  interval from 10–3 to 1M. It was found that due to hydrophobic/hydrophilic balance, the temperature dependent conformational and phase change of macromolecular chains becomes sensitive to salt addition and allows the fine-tuning of the phase transition. In aqueous and aqueous-salt solutions, the average hydrodynamic size of amphoteric terpolymers is varied from 8 to 300 nm exhibiting bimodal distribution at room temperature. The number average (Mn) and weight average (Mw) molecular weights, polydispersity index (PDI), and zeta-potentials of amphoteric terpolymers in aqueous solu- tions were determined

Carbon stability and mobility of ball milled lignin- and cellulose-rich biochar colloids

Numerous studies have explored the transport mechanism of biochar colloids in porous medium. However, the effect of feedstock biopolymer compositions and pyrolytic temperature on carbon stability and mobility of biochar colloids is limited. This study prepared four ball milled biochar colloids pyrolyzed from lignin-rich pinewoods and cellulose-rich corn stalks under 300 °C and 500 °C (termed as PW300, PW500, CS300, CS500) and analyzed their differences in the chemical stability and transport behaviors. The results indicated that high contents of lignin in biomass and pyrolytic temperature could enhance the compact aromatic structures of biochar colloids characterized by the elemental composition, FTIR, 13C NMR and XRD analyses. Therefore, PW500 with the strongest chemical stabilities (least C loss of 13%), electronegativity (−44.9 mV vs. −41.6–28.3 mV) and smallest hydrodynamic diameter (608.7 nm vs. 622–997.2 nm) was obtained under ball milling. Moreover, both the critical coagulation concentrations (CCC) and the maximum relative effluent concentration (C/C0) with the NaCl ionic strength of 1 mM were demonstrated to be in the increase order of CS300 (76.1 mM, 70%) < PW300 (183.1 mM, 78%) < CS500 (363.9 mM, 89%) < PW500 (563.1 mM, 95%), which suggested stronger colloidal stability and mobility of PW biochar colloids than those of CS biochar colloids. In addition, the C/C0 for CS300, PW300 and CS500 were about 7.3%–36% lower than that for PW500 with the NaCl ionic strength increasing to 50 mM indicated the notable superiority in the mobility of PW500. These findings can provide new insights toward understanding the transformation and migration, and evaluating the environmental risk of biochar colloids.

Impact of sulfate on the solubility of Tc(IV) in acidic to hyperalkaline aqueous reducing systems

Abstract The solubility of 99Tc(IV) was investigated from undersaturation conditions in NaCl–Na2SO4 (0.3 M ≤ I ≤ 5.0 M), MgCl2–MgSO4 (I = 13.5 M) and CaCl2–CaSO4 (I = 13.5 M) systems with 0.001 M ≤ [SO4 2−]tot ≤ 1.0 M and 1 ≤ pH m ≤ 12 (with pH m = −log[H+], in molal units). Reducing conditions were set by either Sn(II) or Fe(0). Special efforts were dedicated to accurately characterize the correction factors A m required for the determination of pH m from the experimentally measured pH values in the mixed salt systems investigated, with pH m = pHexp + A m . The combination of (pe + pH m ) measurements with Pourbaix diagrams of Tc suggests that technetium is present in its +IV redox state. This hypothesis is confirmed by XANES, which unambiguously shows the predominance of Tc(IV) both in the aqueous and solid phases of selected solubility samples. XRD and SEM–EDS support the amorphous character of the solid phase controlling the solubility of Tc(IV). EXAFS data confirm the predominance of TcO2(am, hyd) at pH m &gt; 1.5, whereas the formation of a Tc(IV)–O–Cl solid phase is hinted at lower pHm values in concentrated NaCl–Na2SO4 systems with ≈5 M NaCl. Solubility data collected in sulfate-containing systems are generally in good agreement with previous solubility studies conducted in sulfate-free NaCl, MgCl2 and CaCl2 solutions of analogous ionic strength. Although the complexation of Tc(IV) with sulfate cannot be completely ruled out, these results strongly support that, if occurring, complexation must be weak and has no significant impact on the solubility of Tc(IV) in dilute up to highly saline media. Solubility upper-limits determined in this work can be used for source term estimations including the effect of sulfate in a variety of geochemical conditions relevant in the context of nuclear waste disposal.

Formation of mono- and binuclear complexes of Nd3+ with d-gluconate ions in hyperalkaline solutions – Composition, equilibria and structure

The composition and stability constants (or formation constants) of complexes comprising of d-gluconate (Gluc–) and Nd3+ has been determined via potentiometry and Vis-spectrophotometry in aqueous solutions at 4.0 M (NaCl) ionic strength and in alkaline conditions. The chemical model derived from these measurements were complemented with freezing-point depression, Raman, ESI-MS and 1H/13C NMR measurements, some of these contributed to reveal structural features of the complexes formed. The presence of four variously protonated binuclear (Nd2Gluc4H–53–, Nd2Gluc4H–64–, Nd2Gluc6H–44–, Nd2Gluc6H–55–) and a mononuclear (NdGluc2H–54–) complexes were detected in highly alkaline media. The main coordination sites are the carboxylate and the alcoholate group attached to the C2 and C3 carbon atoms. The chemical picture obtained from our studies is of potential relevance in modeling some aspects of the aqueous chemistry of low or intermediate level radioactive waste (L/ILW) repositories.

Facile synthesis of novel nanocurcuminoids–sacha inchi oil using the phase inversion temperature method: Characterization and antioxidant activity

A nanocurcuminoids emulsion (NCE) was successfully synthesized via the phase inversion temperature (PIT) method combining magnetic stirring. Factors affecting the fabrication of this material, including emulsifier concentration, types of oils, temperature, and stirring time, were investigated. Results showed that the synthesized efficiency obtained 94.56 ± 3.78% at 11% of emulsifier concentration, 2% of sacha inchi oil with 5,000 rpm of shaking speed within 25 min of reaction time at 80°C. Besides, dynamic light scattering analysis presents that NCE gets 24.1 ± 2.9 nm of the average diameter, −10.4 ± 0.8 mV of zeta potential (ZP), and 0.173 ± 0.021 a.u of the polydispersity index (PDI) at the optimal condition. Moreover, the prepared NCE was stable at the ionic strength of NaCl 0.5 M and pH of 7 after 60 days of storage. In particular, the antioxidant activity of this NCE was slightly higher than that of free curcuminoids. Practical applications The mixture, including NCE 12%, maltose 58%, honey 12%, and water, was homogenized at a rate of 10,000 rpm in 15 min. Afterward, the system was condensed by a vacuum rotary evaporator (Yamato RE301 vacuum rotary evaporator) at 60°C in 30 min to obtain the Instant Beverage Jam. The obtained products showed a moderate sweetness and retained the characteristic taste of curcumin.

The determination of the thermodynamic constants of MgUO2(CO3)32- complex in NaClO4 and NaCl media by time-resolved luminescence spectroscopy, and applications in different geochemical contexts.

The formation constants and specific ion interaction coefficients of MgUO2(CO3)32- complex were determined in 0.1 to 1.0 mol kgw-1 NaCl and 0.10 to 2.21 mol kgw-1 NaClO4 media in the framework of the specific ion interaction theory (SIT), by time-resolved laser-induced luminescence spectroscopy. The upper limits of ionic strength were chosen in order to limit luminescence quenching effects generated by high concentrations of Cl- and ClO4- already observed during our earlier studies on CanUO2(CO3)3(4-2n)- complexes (Shang & Reiller, Dalton Trans., 49, 466; Shang et al., Dalton Trans., 49, 15443). The cumulative formation constant determined is , and the specific ion interaction coefficients are ε(MgUO2(CO3)32-, Na+) = 0.19 ± 0.11 kgw mol-1 in NaClO4 and ε(MgUO2(CO3)32-, Na+) = 0.09 ± 0.16 kgw mol-1 in NaCl. Two gratings of 300 and 1800 lines per mm were used to acquire MgUO2(CO3)32- luminescence spectra, where the high-resolution 1800 lines per mm grating detected slight spectral shifts for the principal luminescent bands relative to CanUO2(CO3)3(4-2n)-. The applications of the consistent set of thermodynamic constants and ε values for MnUO2(CO3)3(4-2n)- (M = Mg and Ca) were examined in different geochemical contexts, where Mg over Ca concentration ratio varies to help defining the relative importance of these species.