Physical Stability and the Droplet Distribution of Rice Oil–in–Water Emulsion

The objective of the current study was to evaluate long-term stability of emulsions with rice oil by assessing their physical properties. For this purpose, six emulsions were prepared, their stability was examined empirically, and the most correctly formulated emulsion composition was determined using a computer simulation. Variable parameters (oil and thickener content) were indicated with optimization software based on Kleeman's method. Synthesized emulsions were studied by numerous techniques involving determination of particle size and distribution of emulsion, optical microscopy, viscosity, and novelty analysis—Turbiscan test.

The emulsion containing 50 g of oil and 1.2 g of thickener had the highest stability. Empirically determined parameters proved to be consistent with the results obtained using the computer software. The computer simulation showed that the most stable emulsion should contain from 35.93 to 50 g of oil and 0.94 to 1.19 g of thickener. The computer software based on Kleeman's method proved to be useful for fast optimization of the composition and providing parameters of stable emulsion systems. Forming emulsions based on rice oil is a chance to introduce a new, interesting representative of functional food as well as a cosmetic product.     

Dilational Rheological Properties of Non-Ionic Surfactants at the Water–Decane Interface: Effect of Unsaturated Hydrophobic Group

The interfacial tensions and dilational properties of adsorbed films of two non-ionic surfactants with different hydrophobic groups, polyoxy-ethylene sorbitan stearate (Tween 60) and polyoxy-ethylene sorbitan monooleate (Tween 80), at the water–decane interface have been investigated by the drop-shape analysis method. The effects of dilational frequency and bulk concentration on the interfacial properties were expounded. The influence of low temperature on the interfacial tensions and dilational properties have also been researched. The experiment results show that the interfacial activity of Tween 80 is rather large compared with Tween 60. The minimum area per molecule at the water–decane interface (A_min) value of Tween 80 is little large than that of Tween 60, which is due to the steric effect of unsaturated double bond in Tween 80 molecule. The dilational data show that the ethylene oxide groups of non-ionic surfactant form a stable sub-layer, which results in the increase of modulus and the decrease of phase angle for both Tween 60 and Tween 80 than those of common ionic surfactants. Moreover, the unsaturated hydrophobic group of Tween 80 is much flexible, which is easily crosslinked and entangled. Therefore, dilational modulus of Tween 80 is higher and phase angle is lower than that of Tween 60. Low temperature decreases the flexibility of unsaturated hydrophobic group and lessens the influence on the interaction of saturated hydrophobic group. Saturated surfactant molecules of Tween 60 almost lose temperature response.     

Thermodynamics of Adsorption in a Cellulose–Water System

Russian Journal of Physical Chemistry A - The sorption properties of native cellulose and the state of water adsorbed by its fibers are studied by measuring 1H NMR relaxation. A scheme of the...     

Dilational Rheological Properties of P-(n-alkyl)-benzyl Polyoxyethylene Ether Carboxybetaine at Water–Decane Interface

The dilational rheological behaviors of absorbed films of p-(n-alkyl)-benzyl polyoxyethylene ether carboxybetaine C_xBE₂CB (x = 8, 10, 12) at the water–decane interface have been investigated by the drop-shape analysis method. The influences of time, oscillation frequency, and bulk concentration on dilational modulus and phase angle have been expounded. The experimental results show that the phase angle of C_xBE₂CB (x = 10, 12) decreases with the increase of time, the slope of the log ? ? log ω curve and phase angle of C_xBE₂CB (x = 10, 12) decrease in a wide concentration range. These phenomena become more and more apparent with the increase of hydrocarbon chain length and it cannot be attributed to the diffusion-exchange process between the bulk and the interface. It is reasonable to consider that ethylene oxide groups are flexible and can be compressed and expanded, just like a spring. Therefore, the compression and expansion of the ethylene oxide groups in the interfacial layer and the exchange between interface and sublayer play a more important role for C_xBE₂CB (x = 10, 12) adsorption film. The dependence of dilational modulus on interfacial pressure can support our provided mechanism strongly.     

Synthesis of Cationic PEM Emulsion and Application in Waste Water Treatment

Cationic polymer as a kind of flocculant is widely applied in purification treatment of waste water. Because it has positive charge group, it is able to connect strongly the suspended matters, short cellulose and other microparticles. The research on synthesis of cationic polymer and application in treatment of waste water is very universal abroad. But domestic research on those is not general. The technology of synthesis of PEM is simple , and the production cost is low. It is easy to apply…     

Diffusion Model of Methane Hydrate Formation in “Dry Water”

Russian Journal of Physical Chemistry A - The kinetics of methane hydrate formation in “dry water” is studied using a diffusion model (the well-known modified shrinking core model). An...     

Direct Synthesis of Oxygenates from Water and Methane via Dielectric-barrier Discharge

In this investigation, a clean, atomic economic and direct synthesis of oxygenates (methanol, ethanol) form water and methane via dielectric-barrier discharge was developed at room temperature and under atmospheric pressure. The effect of discharge voltage on this process was studied. The results showed that the conversion of water can be as high as 7%, the selectivity of methanol and ethanol can be as high as 100%.     

Efficient Tosylation of Dihydroxybenzenes in a Two-Phase Water–Dichloromethane System

Theoretical and Experimental Chemistry - The effect of the structure of the catalyst and the type of base on the reaction rate and product yield of the tosylation of dihydroxybenzenes in a...     

The Effect of Temperature on Nucleation of Condensed Water Phase on the Surface of a β-AgI Crystal. 1. Structure

The Monte Carlo method has been employed to study the effect of temperature on the structure and the mechanism of retaining condensed water phase nuclei on the surface of the basal face of a silver iodide crystal. Comparative calculations of spatial correlation functions and computer images of vapors being condensed at 260 and 320 K have indicated an increased stability of monomolecular water-film spots with respect to thermal fluctuations. The disturbances of the regular “honeycomb” structure have a collective character and occur according to the “domino principle”; i.e., the rupture of a hydrogen bond between neighboring molecules releases enhanced libration motions of the latter, which, in turn, provoke the rupture of bonds with other neighbors. In accordance with this scenario, the distortion of the hexagonal structure of the film under the action of thermal fluctuations develops with the formation of growing spots of destruction. The thermal fluctuations significantly affect the orientational molecular order and the degree of clustering on the surface. The positions of molecules relative to the ions of the surface crystallographic layer of a substrate weakly depend on temperature.     

Mechanism and Modeling of Emulsion Polymerization: New Ideas and Concepts – 1. Particle Nucleation

Summary: New experimental data for nucleation in emulsion polymerization prove that the process is heterogeneous in nature so that water-borne oligomers precipitate at the surface of monomer drops. The particle morphology at the early stage of the process is strongly influenced by the initiator concentration. The hydrophilicity of the monomer is less important as methyl methacrylate, styrene, and 4-tert-butyl styrene show similar behaviour.     

Effect of Pressure on Clathrate Formation in a Water–Ethanol System

The water–ethanol (E) system was studied by differential thermal analysis (DTA) at atmospheric pressure and pressures up to 10 kbar. At atmospheric pressure, the system was shown to contain an incongruently melting hydrate of E · 2H₂O composition (t_decomp = -65.0°C). In addition, the system involves two metastable hydrates: E · 3H₂O (t_decomp = -69.0°C) and E · 4.75H₂O t_decomp = -74.5°C)}. The hydrate compositions were determined by Tamman's method for the corresponding temperature invariants. Studies at pressures below 10 kbar showed that E · 4.75H₂O metastable hydrate becomes stable at pressures above 0.25 kbar. At pressures from 1.0 to 7.3 kbar, this hydrate melts congruently, which allowed its composition to be determined more accurately. Presumably, this hydrate is of a semiclathrate nature (i.e., the ethanol molecule is involved in constructing the water framework) and has cubic structure I. In experiments at high pressures, E · 3H₂O was not found. Concerning E · 2H₂O hydrate, its peritectic melting was observed up to 5.0 kbar. Further extrapolation extends the incongruent melting curve to 7.5 kbar.     

The Effect of Temperature on Nucleation of Condensed Water Phase on the Surface of a β-AgI Crystal. 2. Formation Work

In the condensation mechanism of heterogeneous ice formation, water crystallization occurs after a necessary amount of the liquid phase has accumulated on a substrate surface. In this way, the ice-forming activity of the surface is governed by its adsorption ability with respect to water vapor. The Monte Carlo canonical statistical ensemble method has been used to calculate the free energy, entropy, and work of nucleation of a disordered condensed water phase on the surface of crystalline silver iodide and to determine the surface tension. Comparative calculations have been performed at 260 and 320 K for the defect-free surface of a basal face of a crystal. The surface of a β-AgI crystal is completely covered with a monomolecular film even in unsaturated water vapors. The surface tension at the growing nucleus–substrate interface substantially increases due to the formation of the underlying film, and the growth of the nucleus becomes possible only in a supersaturated vapor. As the vapor density increases, the thickness of the condensed water layer grows, and, at negative Celsius temperatures, conditions are created for its crystallization. The underlying film with pronounced hydrophobic properties hinders nucleation, thereby decreasing the ice-forming activity of the surface in the condensation process. Under these conditions, the observed abnormally high ice-forming activity of silver-iodide aerosol particles may be explained by the presence of numerous crystal defects on the particle surface, with these defects representing channels that provide overcoming the hindering action of the film.     

Characterization and Evaluation of Electrolyte Influence on Canola Oil/Water Nano‐Emulsion

Emulsion stability is controlled by the physicochemical properties of the adsorbed layers formed on the surface of the droplets. Zeta potential and droplet size measured initially and during storage can estimate O/W emulsion stability. The aim of this study was to characterize and evaluate the effects of different hydrolyzable compounds employed in pharmaceutical and cosmetic preparations on the zeta potential and droplet size of canola O/W nano‐emulsions and, consequently, the emulsion stability. The samples containing additives demonstrated significant change in zeta potential, but in spite of that, no macroscopic instability was observed. Yet the droplet size values did not undergo significant change.     

Heterogeneous Reaction of Dimethyl Sulfide with Iodine Oxide in a Temperature Range of 291–365 K

Kinetics and Catalysis - A reaction of the iodine oxide (IO) radical with dimethyl sulfide (DMS) in a temperature range of 291–365 K was studied using atomic iodine resonance fluorescence. It...     

Methane—the Promising Career of a Humble Molecule

Methane, CH4, here represents natural gas (NG) of which it is the main constituent. Routes ofchemical utilisation of NG — as opposed to energy usage — are discussed. A main step is the conversion of NG to synthesis gas, a mixture of CO and H2. Simple molecules derived from synthesis gas, like methanol,can be further reacted to longer-chained hydrocarbons like propylene and other olefins and even to gasoline and diesel.     

Cryoscopic Studies of the Uranyl Sulfate–Water, Uranyl Nitrate–Water, and Uranyl Nitrate–Nitric Acid–Water Systems

Freezing point lowerings of aqueous solutions of uranyl sulfate in the concentration range m 0.40 mol-kg^–1 and the activity and osmotic coefficients, which were calculated using the Pitzer equations for 2:2 electrolytes, are presented. Crystallization temperatures are reported for 0 to 13 molar nitric acid and 10–150 g uranium per liter uranyl nitrate–nitric acid–water solutions.     

Influences of Electrolytes, Polymers and a Surfactant on Rheological Properties of Bentonite–Water Systems

Characteristic rheological properties, such as viscosity, shear stress, yield point, gel strength and thixotropy, of natural Ca- bentonite and Na-peptized bentonite were studied after adding LiCl, KCl, CaCl2, MgCl2·6H2O electrolytes; (NaPO3)n, polyvinyl pyrolidone (PVP) polymers and an anionic surfactant (linear alkyl benzene sulphonate, LABS). Changes in flow properties under the influence of various additives at different quantities were investigated in these slurries. The experimental results are discussed in terms of bentonite forms, types and concentrations of additives and influence of exchangeable cations. Bivalent and monovalent cations display entirely different rheological properties in two groups of muds. Furthermore, the difference in the degree of activity of PVP polymer on the viscosity of two mud systems depend on the clay mineral structure. The slurry prepared with Na-bentonite contains a minimum number of tactoids and a maximum number of sheet-bearing clay particles, which reduces the surface area of the clay minerals and increases viscosity by adding PVP polymer.