Manuel Vicente

Rheology of clarified fruit juices. I: Peach juices

Abstract In this work, the rheological behaviour of clarified and depectinated peach juice is studied. Peach juices free of pectin and pulp behave as Newtonian fluids. The effect of temperature and concentration on the viscosity of these juices is examined. The temperature effect was studied at 10 different temperatures between 5 and 60°C. Finally, an equation describing the combined effect of temperature and concentration on the viscosity is given.

Treatment of bleaching waters in the paper industry by hydrogen peroxide and ultraviolet radiation

Abstract This study examines the use of hydrogen peroxide in combination with ultraviolet radiation in the treatment of wastewaters from the chlorination and alkaline extraction stages of paper pulp bleaching. The kinetic constants corresponding to the elimination of color from these effluents have been determined as well as their variation with the pH of the medium.

Rheological properties of clarified pear juice concentrates

Abstract The rheological behaviour of clarified and depectinized pear juice is reported. Pear juices free of pectin and pulp behave as Newtonian liquids. The effect of temperature and concentration on the viscosity of these juices is examined. Juices of different concentration were obtained by diluting 71° Brix juice. The effect of temperature was studied on ten different temperatures between 5 and 60°C. Finally, an expression for the combined effect of temperature and concentration on the viscosity is given.

Influence of lamp position on the performance of the annular photoreactor

Abstract The spherical light model was used to evaluate, for an annular photoreactor, the radiation intensity profiles of the inner wall and the flow rate of ra

Ozonization of bleaching waters of the paper industry

This study examines the ozonization of a kraft bleach plant effluent proceeding from the bleaching stages for kraft pulp decolorization. An outline for the reaction is proposed in which the oxidizable compounds of the effluent are grouped into three classes: colored compounds that react quickly with the ozone, colored compounds that react slowly with the ozone and uncolored compounds. In addition the constants for the second order reaction rate at 20°C and the stoichiometric coefficient were determined.

Influence of lamp position on available radiation flux in an annular photoreactor

Abstract The radiation flow rate at the inlet to an annular photoreactor has been evaluated analytically, its value compared with the radiation absorption rate (calculated using the perfectly mixed assumption), and a study made of the influence of radial and axial displacements of the lamp from the photoreactors centre on the ratio, radiation absorption rate to radiation flow rate. The light spherical model has been used without taking into account other light phenomena, such as reflection, refraction or scattering. The results show a slight increase in the radiation absorption rate when the lamp is radially displaced.

Temperature influence on norbornadiene photoisomerization sensitized with acetophehone

One of the best photochemical storage systems of solar energy is the interconversion between norbornadiene and quadricyclane. A kinetic study of norbornadiene photoisornerizalion sensitized with acetophenone, using ethanol as the solvent is presented. For the temperature range studied (25–55 °C), photoisomerization leads to quadricyclane, and no byproducts of the reaction were detected. Results show that a temperature increase leads to a slight decrease in the reaction rate.