The Cloud Point Behaviors and the Liquid–Liquid Equilibrium of L31—Inorganic Sodium Salt Aqueous Two-Phase Systems

The cloud point (CP) of triblock-copolymer L31 aqueous solution was determined with salting-out salts (Na₂SO₄/Na₂CO₃/NaF/NaCl/NaBr). The results show that all these salts can decrease the CP of L31 aqueous solution and form aqueous two-phase system (ATPS). With increasing concentrations of Na₂SO₄ and Na₂CO₃, an obvious phase inversion could be observed and phase inversion points were found. This was mainly due to the change in density, the salt-rich phase shifted from the top phase to the bottom phase. Meanwhile, the liquid-liquid equilibrium (LLE) data for L31-Na₂SO₄/Na₂CO₃/NaF/NaCl/NaBr ATPSs were measured at 288.15 K. The salt ability to decrease the CP and to induce the phase separation is as follows: Na₂SO₄?>?Na₂CO₃, NaF?>?NaCl?>?NaBr. Finally, the order of anions that reduced the CP and caused phase separation was obtained as follows: SO₄^2? >CO₃^2?, F^??>?Cl^??>?Br^?.     

High-temperature equilibria and critical phenomena in the Na2CO3-NaCl-H2O and Na2CO3-Na2WO4-H2O systems

Phase equilibria in the Na₂CO₃-NaCl-H₂O and Na₂CO₃-Na₂WO₄-H₂O ternary systems formed by type 1 salts (NaCl, Na₂WO₄) and a type 2 salt (Na₂CO₃) were experimentally studied at temperatures from 425 to 500°C and pressures from 30 to 160 MPa with the contents of type 1 salts from 10 to 30 wt %. Transition from supercritical homogeneous fluid equilibria of the Na₂CO₃-H₂O system to heterogeneous equilibria of the title ternary systems was studied in the presence or absence of liquid phase immiscibility in the type 1 subsystems.     

A study of non-isothermal kinetics of limestone decomposition in air (O2/N2) and oxy-fuel (O2/CO2) atmospheres

The non-isothermal experiments of limestone decomposition at multi-heating rates in O₂/N₂ and O₂/CO₂ atmospheres were studied using thermogravimetry. The limestone decomposition kinetic model function, kinetic parameters of apparent activation energy (E), and pre-exponential factor (A) were evaluated by Bagchi and Malek method. The results shown that in 20 % O₂/80 % N₂ atmosphere, the limestone decomposed slowly following the contracting sphere volume model controlled by boundary reaction (spherical symmetry) in two stages, and the E increased by about 50 kJ mol^?1 in the second decomposition stage. But in 20 % O₂/80 % CO₂ atmosphere, the presence of high-concentration CO₂ significantly inhibited the limestone decomposition, and made the decomposition process occur at high temperature with a rapid rate; the decomposition kinetics was divided into three stages, the first stage was an accelerated decomposition process following the Mampel Power law model with the exponential law equation, the second stage followed the nth order chemical reaction model as an α–t deceleration process, and the third stage belonged to the random nucleation and nuclei growth model with the Avrami–Erofeev equation. And with the heating rate increasing, the reaction order n showed a slight rise tendency. The E was about 1,245 kJ mol^?1 in 20 % O₂/80 % CO₂ atmosphere, but was only about 175 kJ mol^?1 in 20 % O₂/80 % N₂ atmosphere. The E and A increased markedly in the O₂/CO₂ atmosphere.     

Corrosion inhibition and adsorption behavior of imidazoline salt on N80 carbon steel in CO2-saturated solutions and its synergism with thiourea

The inhibition and adsorption behavior of 2-undecyl-1-sodium ethanoate-imidazoline salt (2M2) and thiourea (TU) on N80 mild steel in CO₂-saturated 3 wt.% NaCl solutions was studied at 25?°C, pH 4, and 1 bar CO₂ partial pressure using electrochemical methods. It was found that inhibition efficiency (η%) increased with increase in 2M2 concentration but decreased with increase in TU concentration with optimum η% value at 20 mg l^?1 TU. The data suggest that the compounds functioned via a mixed-inhibitor mechanism. The inhibition process is attributed to the formation of an adsorbed film of 2M2 and TU via the inhibitors polycentric adsorption sites on the metal surface which protects the metal against corrosion. A synergistic effect was observed between TU and 2M2. Potential of unpolarizability, E _u, was observed in the presence of 100 mg l^?1 TU which was shifted positively in the presence of 2M2–100 mg l^–1 TU blends, which suggests that the presence of 2M2 stabilized the adsorption of TU molecules on the surface of the metal. The adsorption characteristics of 2M2 were approximated by Langmuir adsorption isotherm.     

The phase diagrams of the CdCl2-NaCl-H2O system at 298 K

Solid-liquid equilibrium of ternary system Cd²⁺, Na⁺//Cl^?-H₂O at 298 K were studied by an isothermal solution saturation method. Experimental results indicate that there are three univariant curves AE, EF, and FB, two invariant points E, F, and three crystallization fields in the ternary system. The ternary system has one double salt Na₂CdCl₄ · 3H₂O. The crystallization zones of equilibrium solid phases are CdCl₂ · H₂O (AEG field), Na₂CdCl₄ · 3H₂O (EFM field), and NaCl (FBN field), respectively. The composition of the invariant point E is CdCl₂ · H₂O and Na₂CdCl₄ · 3H₂O of which content was 52.70 and 4.11%, respectively. The composition of the invariant point F is Na₂CdCl₄ · 3H₂O and NaCl of which content was 27.92 and 14.95%, respectively. The density of solution in the ternary system show regular changes along with the increased cadmium concentration. The results indicated that CdCl₂ · H₂O possessed the highest solubility among those three salts, which means a strong transfer of Cd ion and a high pollution risk of soil environment. And the solubility of NaCl would be restrained as the three salts existing together.     

Drawing Out the Structural Information About the First Hydration Layer of the Isolated Cl− Anion Through the FTIR-ATR Difference Spectra

The Fourier transform infrared-attenuated total reflectance (FTIR-ATR) difference spectra of aqueous MgSO₄, Na₂SO₄, NaCl and MgCl₂ solutions against pure water were obtained at various concentrations. The difference spectra of the solutions showed distinct positive bands and negative bands in the O–H stretching region, indicating the influences of salts on structures of hydrogen-bonds between water molecules. Furthermore the difference spectra of MgCl₂ solutions against NaCl solutions and those of MgSO₄ solutions against Na₂SO₄ solutions with the same concentrations of anions (Cl^? or SO ₄ ^2? , respectively) allowed extracting the structural difference of the first hydration layer between Mg²⁺ and Na⁺. Using SO ₄ ^2? as a reference ion, structural information of the first hydration layer of the Cl^? anion was obtained according to the difference spectra of MgCl₂ solutions against MgSO₄ solutions and those of NaCl solutions against Na₂SO₄ solutions containing the same concentrations of cations (Mg²⁺ or Na⁺, respectively). The positive peak at ~3,407 cm^?1 and negative peak at ~3,168 cm^?1 in these spectra indicated that adding Cl^? decreased the strongest hydrogen-bond component and increased the relatively weaker one.     

Semi-continuous Cultivation of Haematococcus pluvialis for Commercial Production

The objectives of the present study on the growth of Haematococcus pluvialis were to indicate the effects of a long-term semi-continuous cultivation, sterilization, carbon dioxide, and different culture media by using artesian well water. This investigation was an enterprise in order to commercialize the production economically. When the effect of CO₂ was investigated in basal culture medium, the influence of sterilization was also researched in Rudic’s culture medium in vertical panel-type photobioreactors for 31 days of semi-continuous cultivation. The maximum cell concentration of 10.55?×?10⁵ cells ml^?1, which corresponds to the growth rate of 0.271 day^?1 with the areal productivity of 3.531 g m^?2 day^?1, was found in non-sterilized RM medium on the 24th day of the third run of semi-continuous cultivation at a renewal rate of 50% in a vertical panel-type photobioreactor.     

Carbon dioxide and nitrogen adsorption on porous copolymers of divinylbenzene and acrylic acid

Porous copolymers of divinylbenzene (DVB) and acrylic acid (AA) having DVB:AA ratios of 6:4, 8:2 and 9:1 were prepared following a distillation-precipitation method, using toluene as the porogenic agent. The materials thus obtained, which showed specific surface area in the range of 380–600 m² g^?1 and pore volume in the range of 0.14–0.18 cm³ g^?1, were investigated as possible adsorbents for CO₂ capture from the flue gas of coal-fired power stations. For that purpose, the isosteric heat of adsorption (and CO₂ adsorption capacity) was analysed from N₂ and CO₂ adsorption equilibrium isotherms obtained over a temperature range. For CO₂, q _st resulted to be in the range of 27–31 kJ mol^?1 (the highest value corresponding to the 6:4 sample), while for N₂ a value of q _st ≈ 12 kJ mol^?1 was obtained. Equilibrium adsorption capacity for CO₂ (at ambient temperature and pressure) showed the value of about 1.35 mmol g^?1. These results are discussed in the broader context of corresponding literature data for CO₂ capture using protonic zeolites.     

Integrated Process Production and Extraction of the Fibrinolytic Protease from Bacillus sp. UFPEDA 485

Fibrinolytic proteases are enzymes that degrade fibrin; these enzymes are a promising alternative for thrombolytic therapy, and microorganisms produce them. The aim of this study was to evaluate the optimum conditions for the integrated production and purification of fibrinolytic protease from Bacillus sp. UFPEDA 485. Extractive fermentation was carried out in a culture medium containing soybean flour and by adding polyethylene glycol (PEG) and Na₂SO₄ according to a 2³ experimental design. In all assays, the enzyme preferentially partitioned to the bottom phase (K?<?1), with an optimum activity of 835 U ml^?1 in the bottom phase (salt-rich phase). The best conditions for extractive fermentation were obtained with 18 % PEG 8000 and 13 % Na₂SO₄. Characterization showed that it is a metalloprotease, as a strong inhibition—residual activity of 3.13 %—occurred in the presence of ethylenediaminetetraacetic acid. It was also observed that enzymatic activity was stimulated in the presence of ions: CaCl₂ (440 %), MgCl₂ (440 %), FeSO₄ (268 %), and KCl (268 %). The obtained results indicate that the use of a low-cost substrate and the integration of fermentation with an aqueous two-phase system extraction may be an interesting alternative for the production of fibrinolytic protease.     

Micelle-Catalyzed Interaction Between [Ni(II)-Gly-Gly]+ and Ninhydrin

The effect of cationic micelles of cetyltrimethyl ammonium bromide (CTAB) on the observed pseudo-first-order rate constant for the interaction of nickel dipeptide complex [Ni(II)-Gly-Gly]⁺ with ninhydrin has been studied spectrophotometrically. At constant temperature and pH, increase in the [CTAB] from 0.0 to 60.0 × 10^?3 mol dm^?3 caused nearly three-fold increase of the rate constant. The micellar catalysis is explained in terms of the pseudophase model. From the observed kinetic data, binding constants of micelle–[Ni(II)-Gly-Gly]⁺ (K _S), and micelle–ninhydrin (K _N) are evaluated, respectively, to be 5.3 mol^?1 dm³ and 84.0 mol^?1 dm³. The role of added inorganic (NaCl, NaBr, Na₂SO₄) and organic salts (NaBenz, NaSal) on the reaction rate has also been examined.     

Study of scandium and thorium sorption from uranium leach liquors

Scandium and thorium sorption from simulated uranium leach liquors by phosphorous containing ion exchange resins was studied. Increase of thorium concentration resulted in a decrease of scandium sorption by 26–65%. Tulsion CH 93 resin was chosen for Sc separation from uranium leach liquors. It was shown that 180 g L^?1 Na₂CO₃ allowed for elution 94.1% of Sc and 98.9% of Th in dynamic conditions. Using (NH₄)₂SO₄ (50 g L^?1) + ACBM (180 g L^?1) mixture for primary Sc/Th separation at the resin/eluent ratio of 1:5 resulted in thorium desorption degree as high as 66–69%, whereas scandium loss did not exceed 10%.     

Thermodynamics of carbon dioxide and carbonic acid: (a) the standard enthalpies of solution of Na2CO3(s), NaHCO3(s), and CO2(g) in water at 298.15 K; (b) the standard enthalpies of formation,standard Gibbs energies of formation,and standard entropies of CO2(aq), HCO3−(aq), CO32−(aq), NaHCO3(s), Na2CO3(s), Na2CO3·H2O(s), and Na2CO3·10H2O(s)

Enthalpies of solution of CO₂(g), NaHCO₃(s), and Na₂CO₃(s) in excess NaOH solution were measured at 298.15 K by solution calorimetry. The results were reduced to standard-state processes through use of results from a preceding paper, and standard enthalpies of solution for CO₂(g), NaHCO₃(s), and Na₂CO₃(s) in water at 298.15 K were found to be: ?(4720 ± 40), (4474 ± 30), and ?(6371 ± 30) cal_th mol^?1 respectively. The results of equilibrium studies involving CO₂(g) (solubility and e.m.f. studies) were reviewed and assembled,together with entropies for related solids. Standard values of ΔH_f^o, ΔG_f^o, and S^o at 298.15 K were evaluated for CO₂(aq, non-ionized), HCO₃^?(aq), CO₃^2?(aq), NaHCO₃(s), Na₂CO₃(s), Na₂CO₃·H₂O(s), and Na₂CO₃·10H₂O(s).     

Facile fabrication of mesoporous manganese oxides as advanced electrode materials for supercapacitors

Mesoporous manganese oxides (MnO₂) were synthesized via a facile chemical deposition strategy. Three kinds of basic precipitants including sodium carbonate (Na₂CO₃), sodium bicarbonate (NaHCO₃), and sodium hydroxide (NaOH) were employed to adjust the microstructures and surface morphologies of MnO₂ materials. The obtained MnO₂ materials display different microstructures. Great differences are observed in their specific surface area and porosity properties. The microstructures and surface morphologies characteristics of MnO₂ materials largely determine their pseudocapacitive behavior for supercapacitors. The MnO₂ prepared with Na₂CO₃ precipitant exhibits the optimal microstructures and surface morphologies compared with the other two samples, contributing to their best electrochemical performances for supercapacitors when conducted either in the single electrode tests or in the capacitor measurements. The optimal MnO₂ electrode exhibits a high specific capacitance (173 F g^–1 at 0.25 A g^?1), high-rate capability (123 F g^?1 at 4 A g^?1), and excellent cyclic stability (no capacitance loss after 5,000 cycles at 1 A g^?1). The optimal activated carbon//MnO₂ hybrid capacitor exhibits a wide working voltage (1.8 V), high-power and high-energy densities (1,734 W kg^?1 and 20.9 Wh kg^?1), and excellent cycling behavior (93.8 % capacitance retention after 10,000 cycles at 1 A g^?1), indicating the promising applications of the easily fabricated mesoporous MnO₂ for supercapacitors.     

Uranium (VI) recovery from saline environment by a marine unicellular cyanobacterium, Synechococcus elongatus

Sequestration of uranium from simulated sea water and reverse osmosis concentrates by the marine cyanobacterium, Synechococcus elongatus was assessed. Short term experiments established removal of 90–98 % uranium by the strain from simulated sea water containing 13 nM uranyl carbonate at pH 7.8, resulting in a loading of 7–42 μg U g^?1 over a period of 1–5 days respectively. Long term experiments involving repeated exposure of Synechococcus biomass to fresh simulated sea water every third day, showed a loading of 2,960 μg U g^?1 in 4 weeks. Nearly 85–90 % of cell bound uranium could be desorbed using 0.1 N HCl. The organism could sequester uranium (13,306 μg U g^?1 in 24 h) from aqueous solutions supplemented with 0.6 M NaCl and 21 μM [UO₂(CO₃)₂]^2? at pH 7.8. The results demonstrate noteworthy potential of this organism for harnessing uranium from marine environments.     

Adsorption behaviors of CO<Subscript>2</Subscript> and CH<Subscript>4</Subscript> on zeolites JSR and Na<Subscript>n</Subscript>JSR using the GCMC simulations

The adsorption behaviors of CO₂ and CH₄ on new siliceous zeolites JSR and Na_nJSR (n = 2, 8, 16) were simulated using the Grand Canonical Monte Carlo method. The adsorption isotherms of CO₂ became higher with an increase in the Na⁺ number at a low pressure range (<150 kPa), whereas the isotherms showed a crossover with increasing pressure and the adsorption amount became smaller at a high pressure range (>850 kPa). With an increase in Na⁺ number, the pore volume decreased as the pore space was occupied by increasing Na⁺ ions. Additionally, two energy peaks on the interaction energy curves implied that CO₂ was adsorbed on two active sites. On the other hand, the adsorption amount of CH₄ decreased with an increase in the Na⁺ number and only one energy peak was observed. Adsorption isotherms were well fitted with the Langmuir and Freundlich equations up to 1000 kPa and the adsorption affinity of CO₂ on Na₁₆JSR zeolite was highest. The adsorption capacities of CO₂ in the studied zeolites were up to 38 times higher than those of CH₄. Diffusion constants of CO₂ and CH₄ decreased with an increase in the adsorbed amount and Na⁺ number. Considering the adsorbed amount, adsorption selectivity and affinity, zeolites JSR with a low Na⁺ number (JSR and Na₂JSR) is a good candidate for a pressure swing adsorption in the separation of CO₂/CH₄ mixture whereas JSR zeolites with high Na⁺ ratios (Na₁₆JSR and Na₈JSR) may be a better selection for a vacuum swing adsorption.     

Separation of no-carrier-added 99mTcO4 − from 99Mo–99mTc equilibrium mixture by PEG based aqueous biphasic separation technique using sodium/potassium salts of citric and tartaric acid

Extraction and separation of no-carrier-added (nca) ^99mTcO₄ ^? from ⁹⁹Mo–^99mTc equilibrium mixture was carried out by environmentally benign polyethylene glycol based liquid–liquid aqueous biphasic systems (ABS) consisting various inorganic salts. Among the various inorganic salt trisodium citrate and potassium sodium tartrate showed the suitable salt rich phase for the best separation in this report. The concentration variation of salt rich phase, temperature and PEG phase also exhaustively studied in paper for the achievement of high separation factor. At 40 °C temperature in 50 % (w/v) PEG-4000-2M Na₃citrate showed the highest separation factor (S _Tc/Mo) 1.2 × 10⁷.     

Piper nigrum: Micropropagation, Antioxidative enzyme activities, and Chromatographic Fingerprint Analysis for Quality Control

A reliable in vitro regeneration system for the economical and medicinally important Piper nigrum L. has been established. Callus and shoot regeneration was encouraged from leaf portions on Murashige and Skoog (MS) medium augmented with varied concentrations of plant growth regulators. A higher callus production (90 %) was observed in explants incubated on MS medium incorporated with 1.0 mg?L^?1 6-benzyladenine (BA) along with 0.5 mg?L^?1 gibberellic acid after 4 weeks of culture. Moreover, a callogenic response of 85 % was also recorded for 1.0 mg?L^?1 BA in combination with 0.25 mg?L^?1 α-naphthalene acetic acid (NAA) and 0.25 mg?L^?1 2,4-dichlorophenoxyacetic acid or 0.5 mg?L^?1 indole butyric acid (IBA) along with 0.25 mg?L^?1 NAA and indole acetic acid. Subsequent sub-culturing of callus after 4 weeks of culture onto MS medium supplemented with 1.5 mg?L^?1 thiodiazoran or 1.5 mg?L^?1 IBA induced 100 % shoot response. Rooted plantlets were achieved on medium containing varied concentrations of auxins. The antioxidative enzyme activities [superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX)] revealed that significantly higher SOD was observed in regenerated plantlets than in other tissues. However, POD, CAT, and APX were higher in callus than in other tissues. A high-performance liquid chromatography (HPLC) fingerprint analysis protocol was established for quality control in different in vitro-regenerated tissues of P. nigrum L. During analysis, most of the common peaks represent the active principle “piperine.” The chemical contents, especially piperine, showed variation from callus culture to whole plantlet regeneration. Based on the deviation in chromatographic peaks, the in vitro-regenerated plantlets exhibit a nearly similar piperine profile to acclimated plantlets. The in vitro regeneration system and HPLC fingerprint analysis established here brought a novel approach to the quality control of in vitro plantlets, producing metabolites of interest with substantial applications for the conservation of germplasm.     

Separation of 97Ru from niobium target using PEG based aqueous biphasic systems

Separation of no-carrier-added (NCA) ⁹⁷Ru from bulk niobium target has been carried out for the first time using green analytical technique, aqueous biphasic system. 50 % (w/v) polyethylene glycol (PEG)-4000, against 2 M solutions of various salts such as Na-citrate, Na-tartarate, Na-malonate, Na₂CO₃, NaHSO₃, Na₂SO₄, Na₂S₂O₃ K₂HPO₄, K₃PO₄, K₂CO₃ and 4 M KOH were employed at room temperature for the extraction of NCA ⁹⁷Ru from bulk niobium. Influence of molecular weight of PEG rich phase as well as pH of some salt rich phase (e.g., Na-tartarate) on the extraction behaviour of NCA ⁹⁷Ru into PEG rich phase was also observed. In the presence of sodium-tartarate salt solution, when volume of PEG-4000: Na-tartarate was 3:1, 91 % of NCA ⁹⁷Ru was extracted into the PEG rich phase without any contamination of niobium target. Dialysis of PEG rich phase containing NCA ⁹⁷Ru was carried out against deionised water to obtained pure NCA ⁹⁷Ru.     

Micellar Aggregation Behavior and Electrochemically Reversible Solubilization of a Redox-Active Nonionic Surfactant

For the purpose of studying the potential of a novel nonionic switchable surfactant, 11-ferrocenylundecyl polyoxyethylene ether (FPEG), applied to surfactant-enhanced remediation (SER), the surface properties and micelle solubilization behavior of FPEG were investigated with different inorganic salts. With the addition of inorganic salts (NaCl and CaCl₂), the critical micelle concentration (CMC) of FPEG dropped from 15 to 12 and 8 mg·L^?1, respectively, due to the salting-out effect on the alkyl chain. Thermodynamic parameters based on the CMCs indicated that micelle formation was an entropy-driven process. Dynamic light scattering measurements verified that these inorganic salts can decrease the hydrodynamic diameters (D _h) of the micelles. Solubilization experiments with three typical polycyclic aromatic hydrocarbons (PAHs) demonstrated that the system of FPEG with NaCl shows the highest solubilization ability, and the molar solubilization ratio and micelle–water partition coefficient (K _m ) values follow the order pyrene > phenanthrene > acenaphthene. After oxidation, PAHs can be released from the micelles through breaking up of the micelles, and the cumulative release efficiency of pyrene, phenanthrene and acenaphthene are 31.2, 42.8 and 44.6 %; the order of release efficiency is opposite to that of the reduced form for solubilization abilities. All the results suggest that the ferrocene-containing, redox-active surfactant FPEG has the potential to be recycled in SER technology through electrochemistry approaches.     

Activation and Stabilization of Olive Recombinant 13-Hydroperoxide Lyase Using Selected Additives

The stabilization of olive recombinant hydroperoxide lyases (rHPLs) was investigated using selected chemical additives. Two rHPLs were studied: HPL full-length and HPL with its chloroplast transit peptide deleted (matured HPL). Both olive rHPLs are relatively stable at 4 °C, and enzyme activity can be preserved (about 100% of the rHPL activities are maintained) during 5 weeks of storage at ?20 or at ?80 °C in the presence of glycerol (10%, v/v). Among the additives used in this study, glycine (2.5% w/v), NaCl (0.5 M), and Na₂SO₄ (0.25 M) provided the highest activation of HPL full-length activity, while the best matured HPL activity was obtained with Na₂SO₄ (0.25 M) and NaCl (1 M). Although the inactivation rate constants (k) showed that these additives inactivate both rHPLs, their use is still relevant as they strongly increase HPL activity. Results of C6-aldehyde production assays also showed that glycine, NaCl, and Na₂SO₄ are appropriate additives and that NaCl appears to be the best additive, at least for hexanal production.