Inhibition of acid corrosion of steel using cetylpyridinium chloride

The cationic surfactant cetylpyridinium chloride (CPC) showed high inhibition efficiency for the corrosion of low carbon steel in 1 M H₂SO₄. Electrochemical measurements were dedicated to test the performance of CPC at different concentrations and temperatures. CPC has a significant inhibiting effect on the corrosion of steel and protection efficiencies up to 97% were measured. The inhibitor shifted the corrosion potential in the cathodic direction. It was found that adsorption is consistent with the Bockris–Swinkels isotherm in the studied temperature range (30–60 °C). The negative values of the free energy of adsorption and the decrease in apparent activation energy in the presence of the inhibitor suggest chemisorption of the CPC molecule on the steel surface.     

Combustion of Mechanically Activated Heterogeneous Systems

A mathematical model for the combustion of preliminary activated heterogeneous systems is proposed which includes equations describing heat conduction, chemical kinetics, and the dynamics of the excess energy accumulated in condensed reagents at the stage of preliminary mechanical treatment. The excess energy decreases as a result of structure normalization and chemical transformation, whose activation energy, in turn, depends on the excess energy in the condensed reagents. The case of stationary combustion is analyzed in detail. The effect of mechanical activation on the velocity of the synthesis wave and its structure is analyzed by numerical modeling. The main conclusions are compared with available experimental data.__________Translated from Fizika Goreniya i Vzryva, Vol. 41, No. 3, pp. 90–97, May–June, 2005.     

Corrosion inhibition of iron in 1 M HCl by some gemini surfactants in the series of alkanediyl-α,ω-bis-(dimethyl tetradecyl ammonium bromide)

Three new gemini surfactants in the series of alkanediyl-α,ω-bis-(dimethylalkyl ammonium bromide) were synthesised and tested as corrosion inhibitors of iron in hydrochloric acid medium using gravimetric, electrochemical polarisation and electrochemical impedance spectroscopy (EIS) measurements. Results obtained show that the surfactants studied are good cathodic inhibitors and act on the cathodic hydrogen reaction without modifying its mechanism. EIS results show that the changes in the impedance parameters (R_T and C_dl) with concentration of surfactants studied is indicative of the adsorption of molecules of surfactant leading to the formation of a protective layer on the surface of iron. The effect of the temperature on the iron corrosion in both 1 M HCl and 1 M HCl with addition of various concentrations of 1,2-ethane bis-(dimethyl tetradecyl ammonium bromide) in the range of temperature 20–60 °C was studied. The associated apparent activation corrosion energy has been determined.     

Solution properties of mixed surfactant system sodium dodecyl sulfate and alkyl polyoxyethylene ether system

The effect of oxyethylene groups in a nonionic surfactant on the solution properties of anionicnonionic systems is described; these systems are sodium dodecyl sulfate (SDS)—hexadecyl polyoxyethylene ethers (C₁₆POE_n, where n=10, 20, 30 and 40). The degree of ionic dissociation of the mixed micelles decreases with increasing numbers of oxyethylene groups in the nonionic surfactant. As polyoxyethylene chain lengths increase, the electrical conductivities of the mixed surfactant solutions decrease, in spite of the decrease in activation energy for conduction. The radius of the mixed micelle with the electric double layer is larger for a nonionic surfactant having a shorter polyoxyethylene chain length than for one having a long polyoxyethylene chain. This may be attributed to the fact that the mixed micelle is formed more easily by a nonionic surfactant with a shorter polyoxyethylene chain length than by one with a longer chain.     

Manufacture of Granulated Chitosan

Conditions for dry-wet spinning of spherical chitosan granules 0.5–2.0 mm in diameter into a two-layer spinning bath consisting of immiscible liquids are proposed, where an organic liquid, decane in particular, is the upper layer of the bath while a solution of ammonium hydroxide is the lower layer. The possibility of obtaining chitosan microgranules from 2 to 30 µm in diameter by emulsification of a solution of chitosan in decane or a solution of an anion-active surfactant — sodium dodecyl sulfate — is demonstrated. The effect of the molecular weight and concentration of the solutions on the granule-forming power of chitosan is established. A 6% solution of chitosan with a molecular weight of 200 kD is recommended for further studies.__________Translated from Khimicheskie Volokna, No. 5, pp. 26–29, January–February, 2005.     

Distinct Pharmacological Properties of Gaseous CO and CO-Releasing Molecule in Human Platelets

Carbon monoxide (CO)—gaseous or released by CO-RMs—both possess antiplatelet properties; however, it remains uncertain whether the mechanisms involved are the same. Here, we characterise the involvement of soluble guanylate cyclase (sGC) in the effects of CO—delivered by gaseous CO–saturated buffer (CO_G) and generated by CORM-A1—on platelet aggregation and energy metabolism, as well as on vasodilatation in aorta, using light transmission aggregometry, Seahorse XFe technique, and wire myography, respectively. ODQ completely prevented the inhibitory effect of CO_G on platelet aggregation, but did not modify antiplatelet effect of CORM-A1. In turn, CO_G did not affect, whereas CORM-A1 substantially inhibited energy metabolism in platelets. Even though activation of sGC by BAY 41-2272 or BAY 58-2667 inhibited significantly platelet aggregation, their effects on energy metabolism in platelets were absent or weak and could not contribute to antiplatelet effects of sGC activation. In contrast, vasodilatation of murine aortic rings, induced either by CO_G or CORM-A1, was dependent on sGC. We conclude that the source (CO_G vs. CORM-A1) and kinetics (rapid vs. slow) of CO delivery represent key determinants of the mechanism of antiplatelet action of CO, involving either impairment of energy metabolism or activation of sGG.     

Effect of cysteine on the kinetics of electroless nickel deposition

Cysteine is found to accelerate electroless nickel (EN) deposition and hydrogen evolution simultaneously. Changes in the activation energy of the EN reaction and the electrochemical behaviour of the EN bath due to the presence of cysteine were studied. The composition of the deposit formed was determined by XPS. The results show that the activation energy of the EN reaction is decreased when cysteine is added to the bath, and also that cysteine only influences the anodic process and has no direct effect on the cathodic process. The high resolution XPS spectra show that cysteine is adsorbed in the surface layer, and S^2– in the inner layer of the deposit. It is deduced that cysteine may participate in the formation of a reactive intermediate and facilitate the oxidation of H₂PO ₂ ^– , which results in the acceleration of EN plating.     

Dehydrochlorination characteristics of waste PVC wires by thermal decomposition

In this work, the dehydrochlorination characteristics of waste PVC wires in ASR have been studied by static quartz tube reactor under various reaction temperatures. The effect of CaO additive has been investigated to eliminate HCl obtained from thermal decomposition of waste PVC wires. Also to obtain the overall activation energy of dehydrochlorination reaction of waste PVC wires, the dynamic thermogravimetric analysis (TGA) curve and its derivative were analyzed. From this work, it was found that Friedman method gave the activation energies of 89.1–166.8 kJ/mol, while Ozawa method gave the activation energies of 94.2–118.6 kJ/mol and the activation energy increased as increasing of conversion. The formation of gaseous products significantly was suppressed and the amount of HCl was obviously reduced by addition of CaO.     

Magnetic Activation of Water in Alkali Treatment of Polyester Fibre Materials

The effect of magnetic activation of the water used for preparation of process solutions and the rate of alkaline hydrolysis of poly(ethylene terephthalate) was determined. It was found that the degree of the effect and current strength in the electromagnet coil at which the maximum magnetic field effect is attained are a function of the initial activity of the alkaline bath. Magnetic activation of water has the greatest effect in the case of alkaline treatment of polyester fabrics in the presence of Katamine AB and the smallest effect in alkaline treatment in a bath containing sodium hydroxide alone.__________Translated from Khimicheskie Volokna, No. 2, pp. 13–15, March–April, 2005.     

Influence of clay addition on the properties of olive oil in water emulsions

The behaviour of olive oil-in-water emulsions (O/W) was studied in the presence of smectite particles. The distribution of these particles in the emulsions and the effect of their interaction with the surfactant on the stability of the emulsions were investigated. Whereas the variation of surfactant and/or clay content did not seem to affect the nature of the emulsion, it had a significant influence on emulsion stability. This observation led to two main assumptions on the distribution of clay particles within the emulsion, either exclusively in the continuous phase, or also at the oil-water interface.In the absence of clay, the variation of surfactant concentration (from 0 to 17% (w/w)) allowed to distinguish 3 domains. In the first concentration domain (0–4.2%) emulsions stability increased with the content of surfactant. Within the second domain (4.2–8.5% (w/w)), a slight decrease in stability was observed due to flocculation by depletion. For surfactant concentrations equal or higher than 8.5% (3rd domain), emulsion stability increased sharply, probably due to the development of interactions between surfactant molecules as they came closer to their gelling concentration. The effect of clay addition to the aqueous phase (up to 10% (w/w)) on the physicochemical properties of the studied emulsions was assessed from stability, drop size, interfacial tension, rheological and acido-basic analyses. A model based on the location of clay particles either in the bulk or at the interface could be proposed, in which clay particles would interact with surfactant molecules in the bulk phase, and form a mechanical barrier around the oil droplets, thus increasing emulsion stability.     

Heat Transfer Complicated by Phase Transitions in a Moving Layer

A mathematical model of heat transfer that is complicated by phase transitions in a moving layer is proposed. An analytical solution is obtained using fractional differential-integral calculus. An expression for the temperature in the front as a function of the phase-transition boundary velocity is derived, from which an expression for the front velocity is found. The theoretical expression of the front velocity fits experimental data. A method for estimating the activation energy is proposed.__________Translated from Teoreticheskie Osnovy Khimicheskoi Tekhnologii, Vol. 39, No. 3, 2005, pp. 243–250.Original Russian Text Copyright © 2005 by Kholpanov, Zakiev, Pomogailo.     

Concentrated emulsion polymerization of methyl methacrylate/butyl acrylate initiated by a redox system

Stable concentrated emulsions of methyl methacrylate/butyl acrylate were prepared with sodium dodecyl sulfate and cetyl alcohol as the compound surfactant and poly(vinyl alcohol) as the major reinforcer of the liquid film. With a redox system based on benzoyl peroxide/N,N′‐dimethyl phenylamine introduced into the concentrated emulsions, polymer particles with different shapes and sizes were obtained by initiation of the polymerization at low temperatures. We investigated the kinetic behaviors of concentrated emulsion polymerization and drew linear regression diagrams of its time–conversion curves in a constant rate phase (conversions ranged from 20 to 70%), and the experimental results show that the variation of the concentrations of the compound surfactant and initiator, the categories of reinforcers of the liquid film, the temperatures, and so on were responsible for the polymerization stability and the polymerization rate. Finally, the kinetics equation and activation energy of the initiator were obtained. The particle size and distribution of particle diameters of latex particles were determined by photon correlation spectroscopy. The determination results reveal that concentrations of the compound surfactant, polymerization temperatures, and so on affected the shape and size of the polymer particles greatly. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1695–1701, 2005     

Molecular Insight into the Possible Mechanism of Drag Reduction of Surfactant Aqueous Solution in Pipe Flow

The phenomenon of drag reduction (known as the “Toms effect”) has many industrial and engineering applications, but a definitive molecular-level theory has not yet been constructed. This is due both to the multiscale nature of complex fluids and to the difficulty of directly observing self-assembled structures in nonequilibrium states. On the basis of a large-scale coarse-grained molecular simulation that we conducted, we propose a possible mechanism of turbulence suppression in surfactant aqueous solution. We demonstrate that maintaining sufficiently large micellar structures and a homogeneous radial distribution of surfactant molecules is necessary to obtain the drag-reduction effect. This is the first molecular-simulation evidence that a micellar structure is responsible for drag reduction in pipe flow, and should help in understanding the mechanisms underlying drag reduction by surfactant molecules under nonequilibrium conditions.     

New Insights into the Role of Insulin and Hypothalamic-Pituitary-Adrenal (HPA) Axis in the Metabolic Syndrome

Recent data suggests that (pre)diabetes onset is preceded by a period of hyperinsulinemia. Consumption of the “modern” Western diet, over-nutrition, genetic background, decreased hepatic insulin clearance, and fetal/metabolic programming may increase insulin secretion, thereby causing chronic hyperinsulinemia. Hyperinsulinemia is an important etiological factor in the development of metabolic syndrome, type 2 diabetes, cardiovascular disease, polycystic ovarian syndrome, and Alzheimer’s disease. Recent data suggests that the onset of prediabetes and diabetes are preceded by a variable period of hyperinsulinemia. Emerging data suggest that chromic hyperinsulinemia is also a driving force for increased activation of the hypothalamic-adrenal-pituitary (HPA) axis in subjects with the metabolic syndrome, leading to a state of “functional hypercortisolism”. This “functional hypercortisolism” by antagonizing insulin actions may prevent hypoglycemia. It also disturbs energy balance by shifting energy fluxes away from muscles toward abdominal fat stores. Synergistic effects of hyperinsulinemia and “functional hypercortisolism” promote abdominal visceral obesity and insulin resistance which are core pathophysiological components of the metabolic syndrome. It is hypothesized that hyperinsulinemia-induced increased activation of the HPA axis plays an important etiological role in the development of the metabolic syndrome and its consequences. Numerous studies have demonstrated reversibility of hyperinsulinemia with lifestyle, surgical, and pharmaceutical-based therapies. Longitudinal studies should be performed to investigate whether strategies that reduce hyperinsulinemia at an early stage are successfully in preventing increased activation of the HPA axis and the metabolic syndrome.     

Studies on aggregation of AOT and NaDEHP via the energy transfer between AO and RB molecules

The aggregation behaviours of sodium bis(2-ethylhexyl)sulfosuccinate (AOT) and sodium bis(2-ethylhexyl)phosphate (NaDEHP) solutions are studied via the energy transfer of acridine orange (AO) and rhodamine B(RB) molecules. The approximate apparent energy transfer efficiency (ϕ_a) of the dye molecules reaches its maximum value when the concentrations of AOT and NaDEHP are far lower than their cmc. This might be caused by the formation of surfactant–dye mixtures. The anionic surfactants (SDS, AS, AOT and NaDHEP), cationic surfactant (CTAB) and nonionic surfactant (Triton-X-100) are chosen to investigate the effect of the structure of surfactant on the ϕ_a between AO and RB molecules. The results indicate that the effective energy transfer may occur in the anionic surfactant systems and it is not obvious in the nonionic and cationic surfactant systems.     

Effect of halide ions on electroless nickel plating

The effect of halide ions (F^–, Cl^–, Br, I^–) on nickel deposition in acidic electroless nickel plating baths is investigated. Halide ions were found to have a significant effect on the nickel deposition and the results could not fully be explained using mixed-potential theory. A correlation between the stability constants of halide ions with palladium (ii) ions and the plating rate is proposed to explain the observations. Various parameters, such as the activation energy, deposit microstructure and phosphorus contents of the plating bath in the presence of various halide ions, were also studied.     

High capacity supercapacitors based on modified activated carbon aerogel

Carbon aerogel derived from a modified resorcinol–formaldehyde (RF) method without supercritical drying step was activated under CO₂ flow and further modified with a surfactant sodium oleate solution. Carbon aerogel, activated carbon aerogel (ACA) and modified activated carbon aerogel (MACA) were characterized by Brunaver, Emmett and Teller(BET) surface measurement, constant-current charge–discharge and cyclic voltammetry(CV). It was found that the specific surface area of the ACA was twice that without activation. At relatively low discharge rates the specific capacitance and energy delivered from the capacitor were improved greatly by the activation of carbon aerogel. To apply the ACA at high discharge rate, a surface modification was introduced. After the surface modification the wettability of the organic electrolyte based on non-polar organic solvent (i.e. propylene carbonate) to the ACA was improved greatly and, as a result, the internal resistance of the capacitor decreased and the specific capacitance and energy delivered increased at all the test discharge rates. The effects from the modification become more marked at higher discharge rates, i.e. at 48mAcm^–2, the energy delivered increased by ca. 70%, which indicates the MACA more suitable as electrode material in electric double-layer capacitors (EDLCs) for high current applications.     

Fireproof Water Glass Composite Based on Mechanically Activated Alumina

The effect of the silica modulus of water glass, functional additives, and mechanical activation of the filler on the composition of a fireproof composite is described. At temperatures up to 700°C one can decrease thermal diffusivity by the formation of a heat-insulating layer frothed by water vapor dehydrated from water glass. Within the high-temperature range heat-insulating properties are improved by the synthesis of nepheline in the reaction between sodium silicate and alumina. Mechanical activation of alumina improves this effect. Introduction of carbamide and boric acid additives improves the fireproof properties of the gaseous medium.__________Translated from Steklo i Keramika, No. 2, pp. 28 – 30, February, 2005.     

Modeling of copper(II) oxide dissolution in sulfuric acid solutions in the presence of ammonia and complexones

The effect of ammonia and complexones on the kinetics of copper(II) oxide dissolution in aqueous solutions of sulfuric acid is studied. It is found that addition of complexones and ammonia to acidic media decreases the dissolution rate. Modeling of the dissolution kinetics shows that the inhibiting effect of complexing agents is caused by a decrease in the concentration of surface intermediate compounds, which are transferred into the solution.Translated from Teoreticheskie Osnovy Khimicheskoi Tekhnologii, Vol. 39, No. 2, 2005, pp. 220–228.Original Russian Text Copyright © 2005 by Plakhotnaya, Gorichev, Batrakov, Izotov, Kutepov.Deceased.     

Adsorption equilibria between dye and surfactant in single and binary systems onto geological materials

Adsorption characteristics of cationic dyes and surfactants onto clay and sandstone from a single component system were studied using toluidine blue (TB) and cetyl trimethylammonium bromide (CTAB). Equilibrium data of TB and CTAB in the single solute systems fit well to the Langmuir and the Freundlich adsorption isotherms. Competitive adsorption was observed between dye and surfactant cations. The effect of sodium chloride on dye and surfactant adsorption was studied in TB–NaCl and CTAB–NaCl binary systems. Equilibrium adsorption for binary systems was analyzed by using the extended Langmuir and the extended Freundlich models. Adsorption results for the TB–CTAB system onto both adsorbents were also well described by the Sheindorf–Rebuhn–Sheintuch (SRS) model for multi-component systems. Free energy changes for adsorption systems were calculated using thermodynamic equilibrium constants evaluated from selectivity coefficients of the binary systems. The site distribution functions estimated using Freundlich model parameters gave valuable information about the ratio of the adsorption sites on adsorbent surface having different affinity for competing cations.