En este trabajo, se presenta un modelo de infiltraci.n, redistribuci.n y transporte de solutos vol.tiles no pasivos en la zona no saturada, que incorpora la dependencia con la concentraci.n de la ...densidad, la viscosidad, la tensi.n superficial, el coeficiente de difusi.n molecular en fase l.quida y los coeficientes de partici.n gas-l.quido y s.lido-l.quido. Adicionalmente, se considera la reducci.n del coeficiente de partici.n gas-l.quido debido a presiones capilares elevadas. El modelo se contrast. con datos experimentales y simulaciones recogidas de la bibliograf.a sobre infiltraci.n de mezclas butanol-agua en arena. La simulaci.n de eventos de contaminaci.n con metanol a corto plazo muestra que hay un efecto importante de la concentraci.n sobre la volatilizaci.n de soluto. El modelo predice tambi.n la eventual formaci.n de un m.ximo de concentraci.n en el caso de presiones capilares elevadas. Los resultados obtenidos simulando la redistribuci.n del soluto a corto y mediano plazo muestran que pueden haber diferencias significativas entre las simulaciones que consideran las dependencias de las propiedades f.sicas con la concentraci.n y las que las ignoran, diferencias que tienden a disiparse a largo plazo.
In this work, a model for non-passive volatile solute migration in the unsaturated zone has been developed. The model incorporates the dependence of the following physical properties on the solute concentration: density, viscosity, surface tension, molecular diffusion coefficient in the liquid phase, and gas-liquid and solidliquid partition coefficients. A correction for the gas-liquid partition coefficient due to the capillary pressure is also included. Results from the proposed model for migration of butanol-water mixtures in sand are in agreement with experimental data taken from literature. Simulation of short-term methanol pollution events shows that solute concentration affects significantly the solute volatilization. In case of high capillary pressures the actual model predicts the eventual formation of a peak of maximum concentration. Results obtained from simulations of shortterm and medium-term pollution events show significant differences compared with those ignoring the dependence of physical properties on the solute concentration. These differences tend to diminish in long term simulations.
The study conducted on effect of leaf extract of Ruellia tuberosa L. on the physiological status of floral buds of mango cv. Dusehri Aman (syn. dushehari) revealed that the buds treated with leaf ...extract of Ruellia tuberosa L. (methanol extract diluted @ 12 g fresh leaf/l water) applied at the time of flower bud differentiation in October showed reduced amount of total phenols and abscisic acid and also the activity of indole acetic acid oxidase and increased amount of indole-3-acetic acid and poly phenol oxidase enzyme activity over control buds. However, the content of gibberellic acid did not differ much in both types of buds.
The production of methyl esters from Jatropha curcas oil using hexane as co-solvent and NaOH as catalyst was systematically optimized in terms of four process variables---co-solvent to methanol ...volumetric ratio, methanol to oil molar ratio, amount of catalyst with respect to the amount of oil, and reaction temperature. With meeting the legislated minimum methyl ester purity of 96.5% as criteria, the optimum co-solvent to methanol volumetric ratio was found to be 2:5. The optimum methanol to oil molar ratio was found to be a range covering the 8:1 molar ratio, but considering process economics, the 8:1 ratio was taken as the best ratio. The optimum amount of catalyst as mass percentage of oil mass was found to be 1%. When carried out near the boiling points of both hexane and methanol, attainment of the legislated minimum methyl ester purity of can be achieved in only about seven minutes of reaction.
