Diego Gómez-Díaz

Rheology of aqueous solutions of food additives: Effect of concentration, temperature and blending

Rheological properties of carboxymethyl cellulose and alginate sodium salts had been studied. The molecular weight of these polymers were calculated using Huggins and Kramer equations and intrinsic viscosity was determined for the polymers. The apparent viscosity and the influence of shear rate on different polymers concentration in aqueous solutions was measured. The effect of temperature on rheological behaviour was also studied. Blends of two aqueous solutions of these polymers were studied and a high deviation from the ideal behaviour was found.

Effect of Temperature on the Viscosity of Honey

Influence of temperature on the viscosity of honeys was analysed in the present work. The viscosity value decreased with the increase of temperature. The effect caused by temperature in the range studied was more important in the low range of temperature, whereas at high temperature, the viscosity showed less variation. Water activity and glass transition temperature was determined to relate these characteristics. Four experimental viscosity models were checked using the experimental data to correlate the influence of temperature upon honey viscosity.

Intrinsic Viscosity and Flow Behaviour of Arabic Gum Aqueous Solutions

The intrinsic viscosity and flow behaviour of aqueous solutions of different concentrations of Arabic gum were studied. The molecular weight of this polymer was calculated using the value of the intrinsic viscosity, employing both Huggins and Kramer and Mark-Houwink equations. The value of the apparent viscosity and the influence of the shear rate on the rheological behaviour of different polymer concentrations in aqueous solution were determined. The effect of temperature over the flow behaviour was also studied. The Ostwald model has been employed to fit the experimental data and model parameters have been obtained.

Physicochemical characterization of Galician Honeys

The characterization of the north-west Spanish honeys was carried out on the basis of different parameters: density, viscosity, refractive index, glass transition temperature, pH, electrical conductivity, ash, sugars, and water activity. The influence of certain characteristics and honey composition (based on water content) on different physico-chemical properties was analysed.

Density, speed of sound, refractive index and derivatives properties of the binary mixture n-hexane + n-heptane (or n-octane or n-nonane), T = 288.15 – 313.15 K

This article reports experimental values of refractive index nD , density ρ, speed of sound u, isentropic compressibility κs, excess molar volume of mixing V E, deviations of refractive index δnD and isentropic compressibility δκs of the binary mixture n-hexane + n-alkane from T = (288.15 to 323.15) K and atmospheric condition. The corresponding excess derived property was computed from the experimental data. Parameters of analytical expressions which represent the composition dependences of the derived property are reported. Values of physical properties were compared with the results obtained by different prediction methods.

Physicochemical characterization of chitosan derivatives

The present work analyses different chitosan synthesized derivatives from the point of view of their chemical structure (Fourier transform infrared spectroscopy, deacetylation degree, elemental analysis and average molecular weight) as well as different physicochemical properties such as density, kinematic and dynamic viscosity, intrinsic viscosity and surface tension. The characterization of different solutions of these solutes has a high importance due to the large potential uses of these compounds. Chitosan has low solubility in water, and for this reason, the present work has synthesized soluble chitosan derivatives. Important differences between original chitosan and synthesized derivatives have been found in different properties.The present work analyses different chitosan synthesized derivatives from the point of view of their chemical structure (Fourier transform infrared spectroscopy, deacetylation degree, elemental analysis and average molecular weight) as well as different physicochemical properties such as density, kinematic and dynamic viscosity, intrinsic viscosity and surface tension. The characterization of different solutions of these solutes has a high importance due to the large potential uses of these compounds. Chitosan has low solubility in water, and for this reason, the present work has synthesized soluble chitosan derivatives. Important differences between original chitosan and synthesized derivatives have been found in different properties.

Hydrodynamic and absorption studies of carbon dioxide absorption in aqueous amide solutions using a bubble column contactor

The present work analyses the carbon dioxide absorption process in aqueous n-alkylpyrrolidones solutions, from the point of view of hydrodynamic studies as well as mass transfer, using a bubble column contactor. An analysis of the influence of solute concentration and gas flow-rate is complemented by the study of the effect caused by the alkyl group on the hydrodynamics and mass transfer. The presence of this kind of substance produces a decrease in mass transfer rate, but on the basis of interfacial area and mass transfer coefficient values, ethyl-2-pyrrolidine (EP) shows suitable characteristics to replace methyl-2-pyrrolidine (MP) in gas separation processes due to its lower safety problems.

Viscosity and Percolative Phenomena in AOT based Microemulsions

Abstract Present work includes experimental studies related to the viscosimetric behaviour of microemulsions that consist of three compounds: isooctane (organic phase), water (aqueous phase) and Aerosol OT (surfactant). The effect of the microemulsion composition, based on the ω parameter value, and the effect caused by the temperature have been analysed in this work. In relation to the influence of temperature and the use of microemulsions in different processes, one important characteristic of this kind of systems (the percolation phenomenon) must be taken into account in the discussion of the experimental results.

Chemical Reaction Effect upon Gas–Liquid Interfacial Area in a Bubble Column Reactor

Abstract This work analyses the influence of different experimental conditions over important hydrodynamic parameters of a bubble column reactor, such as bubble size distribution, gas hold-up and the gas–liquid interfacial area. The influence of gas flow-rate (18–40 L h–1) and reagent concentration (0–0.5 mol L–1) in the liquid phase upon these hydrodynamic parameters have been studied. The influence of experiment time must also be taken into account due to non-steady-state regime. Under these considerations, the chemical absorption rate changes throughout time, and it produces important changes upon the global absorption process, due to modifications in the gas–liquid interfacial area. The presence of a fast reaction in the liquid bulk has the highest influence upon interfacial area.

Thermophysical properties of the ternary mixture ethanol + n-hexane + n-octane in function of the temperature

This article presents the analysis of the following physical properties such as refractive indices, excess molar volumes, sound velocity and the temperature dependence of the ternary system ethanol + n-hexane + n-octane in the temperature range 288.15–323.15 K at atmospheric pressure. The derived properties are calculated from data obtained experimentally and fitted to Cibulka equation.