Une méthode mécanique pour mesurer la pression de vapeur d'équilibre de l'eau dans un milieu complexe

Abstract

Sorption from the vapor phase is an important factor controlling the transport of volatile organic compounds (VOCs) in the vadose zone. Therefore, an accurate description of sorption behavior is essential to predict the ultimate fate of contaminants. Several measurement techniques are available in the case of water, however, when dealing with VOCs, the determination of sorption characteristics generally relies on gas chromatography. To avoid some drawbacks associated with this technology, we propose a new method to determine the sorption isotherm of any liquid compounds adsorbed in a soil. This method is based on standard and costless transducers (gas pressure, temperature) leading to a simple and transportable experimental device. A numerical estimation underlines the good accuracy and this technique is validated on two examples. Eventually, this method is applied to determine the sorption isotherm of three liquid compounds (water, heptane and trichloroethylene) in a clayey soil.

A New Experimental Method to Determine the Sorption Isotherm of a Liquid in a Porous Medium

“…The experimental device, called "activity-meter", is schematized in Figure 1. This device and the associated method are protected by a patent applied for by the French National Industrial Property Institute (09 05293) (15), commercial apparatus are supplied by TMI Orion SA, Montpellier, France.…”

Highlighting of a local non-equilibrium thermodynamics during the transfer of trichlorethylene (TCE) in the superficial layers of arid soils

“…It was initially developed to measure water activity and has been called "activity-meter". This device and the associated method were validated in our previous works (Ouoba et al, 2014b;Ouoba et al, 2010a) and have been patented in Europe and United States (Bénet et al, 2012) The sample (a) is placed against a pressure transducer (b) (Druck, PMP4030AB) and a temperature thermocouple (c) (type K). This records the total pressure of the gas, P g , and its temperature, T, throughout the test.…”

Une méthode mécanique pour déterminer la porosité totale d'un sol

“…Toutefois, pour accroître la précision sur la mesure, quatre à six incréments de volume sont réalisés et la résolution du système se fait en utilisant une méthode de minimisation de Levenberg-Marquadt (Matlab). Cette méthode avait déjà été validée dans nos précédentes publications pour le cas de l'eau en utilisant deux approches [8,9]. Six essais expérimentaux ont été réalisés sur le matériau continu et la Figure 4 présente les résultats du volume mort, obtenus pour les six essais.…”

“…1 is called activitymeter and is relatively simple in design and easy to handle. Recent works on saturated salt solutions [8] and several liquid compounds [9] have contributed to validate the proposed method. The experimental results on the total porosity of 5 samples analyzed give an idea about the accuracy of the method to obtain results with good agreement.…”