1,720,975 research outputs found
Influence of particle size distribution and wettability on the displacement of LNAPL in saturated sandy soils
Get PDFImmiscible displacement processes are of key importance in remediation actions of light nonaqueous phase liquid (LNAPL) contaminated soil and groundwater. LNAPLs remain trapped in soil pores after a spill or flushing process due to the interplay of viscous, gravity, and capillary forces. In this research immiscible displacement tests were conducted in homogenous and heterogeneous sand samples. Also, the influence of fine content, mineralogy, and wettability was evaluated by testing mixtures of coarse sand with silt, zeolite, bentonite, and hydrophobic sand. Obtained results highlight the importance of pore-scale heterogeneities on the resulting displacement pattern in macroscopically homogeneous samples, and show the preferential accumulation of LNAPLs at the interfaces between different materials in heterogeneous samples. Fine particle content shows no important consequences on residual saturation but significantly changes relative permeability. In addition, the presence of hydrophobic particles also modifies hydraulic conductivity and residual LNAPL saturation. Finally, relative permeability models were fitted to experimental data in order to estimate relative permeability of tested samples.Fil: Francisca, Franco Matias. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; ArgentinaFil: Montoro, Marcos Alexis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; Argentin
Measuring the dielectric properties of soil–organic mixtures using coaxial impedance dielectric reflectometry
Get PDFContamination of soils with non-aqueous phase liquids (NAPLs) is frequently produced by accidental spills and storage tanks or pipes leakage. The main goals dealing with soil and groundwater contamination include determining the extension of the affected zone, monitoring the contaminant plume and quantifying the pollution degree. The objective of this work is to evaluate the potential of dielectric permittivity measurements to detect the presence of NAPLs in sands. Tested samples were fine, medium, coarse and silty sand with different volumetric contents of water and paraffin oil. The dielectric permittivity was measured by means of a Coaxial Impedance Dielectric Reflectometry method in specimens with either known fluid content or at different stages during immiscible displacement tests. A simplified method was developed to quantify the amount of oil from dielectric permittivity measurements and effective mixture media models. Obtained results showed that groundwater contamination with NAPL and the monitoring of immiscible fluid displacement in saturated porous media can be clearly identified from dielectric measurements. Finally, very accurate results can be obtained when computing the contamination degree with the proposed method in comparison with the real volumetric content of NAPL (r2>90%).Fil: Francisca, Franco Matias. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Montoro, Marcos Alexis. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentin
Digital image analysis of distribution of immiscible fluids in natural porous media
Get PDFThis article proposes a method of digital image analysis to monitor immiscible flow in soil samples. Four different natural soil samples were studied: coarse, medium, fine, and silty sand. Paraffin oil and a sodium fluorescein solution were used as the displaced and displacing phase, respectively. Immiscible flow tests were performed in a Plexiglas cell and monitored by means of digital image analysis and direct volumetric measurement. The images were processed to obtain gray levels at different stages during the tests. Saturation of paraffin oil was then computed from the gray level and a linear regression equation was developed for each soil tested. The proposed method enabled valuable information to be obtained of the processes that take place at the face of the samples during liquid displacement and in the middle of the samples at the end of the tests. This procedure was very effective for analyzing different flow patterns, isolating areas with trapped paraffin oil, and to determining the ganglia size distribution at different stages of the immiscible flow tests. The results indicated that particle size and microstructure heterogeneities determine the flow pattern features observed during the immiscible displacement of paraffin oil by water.Fil: Montoro, Marcos Alexis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Estudios Avanzados en Ingeniería y Tecnología. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Estudios Avanzados en Ingeniería y Tecnología; ArgentinaFil: Francisca, Franco Matias. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Estudios Avanzados en Ingeniería y Tecnología. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Estudios Avanzados en Ingeniería y Tecnología; Argentin
Effect of ion type and concentration on rheological properties of natural sodium bentonite dispersions at low shear rates
No full textUnderstanding the behavior of bentonite dispersions is of remarkable importance in many industrial and engineering applications. Dispersion behavior depends on interparticle interactions. These mechanisms are influenced by the volumetric content of solid particles, ionic concentration in suspending fluid, ion valence, and pH. In this research, natural sodium bentonite dispersions were analyzed. Tests were performed in dispersions prepared with different volumes of particles in solutions of sodium chloride, calcium chloride, and magnesium sulphate with different concentrations. The rheology of dispersions was analyzed by fitting three rheological models, namely the power law, Bingham plastic, and Herschel-Bulkley models. Changes in shear stress and model parameters with ionic strength were analyzed. The observed behavior was interpreted in terms of particle-particle association and was later confirmed by computing the Derjaguin, Landau, Verwey and Oberbeek (DLVO) interparticle interaction energy. Finally, electroviscous effects were analyzed by computing the importance of the electroviscous parameter considering Einstein's equation and the Dougherty-Krieger equation. The electroviscous parameter was found to decrease with the increase in ionic concentration. The influence of ion type had a negligible effect on the electroviscous parameter.Fil: Montoro, Marcos Alexis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Estudios Avanzados en Ingeniería y Tecnología. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Estudios Avanzados en Ingeniería y Tecnología; ArgentinaFil: Francisca, Franco Matias. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Estudios Avanzados en Ingeniería y Tecnología. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Estudios Avanzados en Ingeniería y Tecnología; Argentin
Behavior of Natural Fine Soil Particle Dispersions in Nonaqueous-Phase Liquids
No full textUnderstanding and quantifying particle-fluid interaction (PFI) is of fundamental importance for such geoenvironmental issues as polluted soil behavior, transport of organic contaminants in porous media, and the behavior of slurries in contact with nonaqueous-phase liquids (NAPLs). NAPLs have a very low dielectric permittivity in comparison with water, and therefore significant changes in soil properties can be expected as a consequence of PFI. This study evaluates interactions between soil particles and NAPLs using the rheology measurement of loess silt, zeolite, and bentonite particle concentrated dispersions. The dispersing liquids were kerosene, two paraffin oils with different viscosities, and deionized water (DIW) as a reference liquid. The results show the influence of the volumetric content of particles on the undrained shear strength of dispersions. The effects of suspending fluid viscosity and the magnitude of PFI were analyzed in a novel way by comparing the volume of particles for which the dispersion presents an undrained shear stress of 1 Pa determined for two different fluids. These results highlight the importance of PFI in the macroscopic properties of soils, hydraulic conductivity, and liquid limit.Fil: Francisca, Franco Matias. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Estudios Avanzados en Ingeniería y Tecnología. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Estudios Avanzados en Ingeniería y Tecnología; ArgentinaFil: Montoro, Marcos Alexis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Estudios Avanzados en Ingeniería y Tecnología. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Estudios Avanzados en Ingeniería y Tecnología; Argentin
Macroscopic properties of soils controlled by the diffuse double layer around particles
Get PDFPhysic and chemical properties ofliquids and particle-fluid interaction (PFI) mechanisms control relevant soil properties. Chemical properties of pore fluids affect mainly the structure and hydraulic conductivity of fine soils with high specific surface. In this work, the hydraulic conductivity of three different soils (sand, silt and a bentonite-sand mixture) was measured using fluids with different chemical properties: deionized water, kerosene, 1N Sodium chloride solution and a solution with 20% of ethylic alcohol. The hydraulic conductivity was determined by following the falling head test procedure and using three different rigid-wall permeameters. Resultsshow that the hydraulic conductivity of coarse granular soils does not depend on fluid chemistry since PFI have negligible effect on soil behavior. In this case, the dry density of soils and viscosity of fluids determine the ob- served behavior. On the other hand, the hydraulic conductivity of fine soils (silts and bentonite-sand mixtures) shows a dispersion of five orders of magnitude when tested at the same dry density but with different perme- ating fluids.Fil: Francisca, Franco Matias. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Estudios Avanzados en Ingeniería y Tecnología. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Estudios Avanzados en Ingeniería y Tecnología; ArgentinaFil: Montoro, Marcos Alexis. Universidad Nacional de Córdoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Nieva, Pablo M.. Universidad Nacional de Córdoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentin
Soil Permeability Controlled by Particle–Fluid Interaction
No full textIn this paper, Atterberg limits and hydraulic conductivity tests are performed in sand samples mixed with different amounts of silt, zeolite and bentonite. The testing liquids consist of kerosene, two paraffin oils with different viscosities, distilled water and 1, 10 and 1,000 mol/m3 calcium chloride solutions. Experimental results show that soils completely lost their plasticity when are in contact with light nonaqueous phase liquids, and that the liquid limit depends on the dynamic viscosity of the fluid surrounding the particles. Also, tested soils show different hydraulic conductivity with water before and after Ca2? ions are introduced in the permeating fluid, in agreement with the change in the formation Gibbs free energy and diffuse double layer theory. Finally, the influence of viscosity ratio, specific surface of particles, soil fabric and PFI on hydraulic conductivity is discussed and related to the effective particle diameter and soil void ratio.Fil: Montoro, Marcos Alexis. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de Construcciones Civiles; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Francisca, Franco Matias. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de Construcciones Civiles; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentin
Importancia de la Vinculación Tecnológica en las carreras de ciencias aplicadas
Get PDFEn los últimos años el perfil de las instituciones académicas y científicas se ha ido modificando a nivel internacional hacia un perfil de instituciones emprendedoras, reconociendo de esta forma el valor agregado que pueden aportar los conocimientos científicos al desarrollo de innovación y tecnología. La vinculación representa una posibilidad única en donde las unidades académicas generan interrelaciones sinérgicas con el medio socio–productivo y cultural. La Facultad de Ciencias Exactas, Físicas y Naturales (FCEFyN) de la Universidad Nacional de Córdoba (UNC)se distingue por su extensa trayectoria en actividades de vinculación. En este trabajo se realiza una revisión y síntesis de las diferentes estrategias de vinculación que ha llevado adelante la FCEFyN –UNC en el periodo 2008 –2018, analizando la evolución de las mismas y su impacto institucional con diferentes indicadores. Finalmente se analizan nuevos modos de vinculación que se pueden implementar en los próximos años para maximizar los beneficios de la relación academia –industria –sociedad.During last years, the focus of traditional universities is changing worldwide, from academic and research institutions towards entrepreneur institutions. These changes recognize the value of pure scientific knowledge applied to innovation and development initiatives. Services to industry represent a unique possibility for Schools to generate synergistic interrelations with the socio-productive and cultural environment. On this matter, the Engineering and Natural Sciences College (FCEFyN, for its acronym in Spanish) of the Universidad Nacional de Córdoba (UNC, for its acronym in Spanish) is distinguished by its extensive trajectory in services to industry and knowledge transference. This article presents a review and synthesis of the different transfer strategies that the FCEFyN - UNC has carried out in the 2008-2018 period, analyzing their evolution and their institutional impact observing the evolution of different indicators. Finally, we analyze the new ways of transference that can be implemented on the forthcoming years for maximizing the benefits of the academy - industry - society relationship.Fil: Montoro, Marcos Alexis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Estudios Avanzados en Ingeniería y Tecnología. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Estudios Avanzados en Ingeniería y Tecnología; ArgentinaFil: Glatstein, Daniel Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Estudios Avanzados en Ingeniería y Tecnología. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Estudios Avanzados en Ingeniería y Tecnología; ArgentinaFil: Bosch, Luis Antonio. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; Argentin
Detection of hydrocarbon spills by means of a coaxial impedance dielectric sensor
Get PDFLeakages from storage tanks or pipes frequently produce pollution of soils and groundwater reservoirs by hydrocarbons. Common practices for monitoring and characterising site contamination involve soil drilling, sampling and chemical analysis, complemented with geophysical surveys. This study evaluates the presence of paraffin oil inside soil pores bymeans of dielectric permittivity measurements, using a coaxial impedance device in laboratory-scale models. The real dielectric permittivity of unsaturated sand is measured before, during and after a contamination process. Monitoring small variations in real dielectric permittivity allows detection of the partial replacement of air (= 1) by paraffin oil (≈ 2) in soil pores. These variations in soil dielectric properties enable pollution levels to be assessed, knowing in advance the real permittivity of the soil at the initial stage and measuring the influence of oil and water content on the real permittivity. The technique proposed can also be used for monitoring the lateral extension of a contaminant plume and can be successfully applied at the laboratory scale for oil leakage detection by periodically monitoring changes in the soil dielectric permittivity.Fil: Francisca, Franco Matias. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Estudios Avanzados en Ingeniería y Tecnología. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Estudios Avanzados en Ingeniería y Tecnología; ArgentinaFil: Montoro, Marcos Alexis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Estudios Avanzados en Ingeniería y Tecnología. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Estudios Avanzados en Ingeniería y Tecnología; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; ArgentinaFil: Mozejko, Clara Alexandra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Estudios Avanzados en Ingeniería y Tecnología. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Estudios Avanzados en Ingeniería y Tecnología; Argentin
Discussion of "Fines classification based on sensitivity to pore-fluid chemistry" by Junbong Jang and J. Carlos Santamarina
No full textAtterberg limits of fine soils are strongly influenced by particlefluid interaction phenomena, fluid chemistry, particle mineralogy, and testing procedure (Koumoto and Houlsby 2001). The original paper proposed a very interesting approach for soil classification considering particle-fluid interactions. The discussers consider that the additional data required for the evaluation of the impact of the fluid chemistry on liquid limits can be considered of great importance for several actual and new geotechnical and geoenvironmental engineering problems, including soil microstructure, and mineral-contaminant interactions during mass transport. The authors proposed classifying fine soils by determining their liquid limits using three different fluids: distilled water, kerosene and brine (1-M NaCl solution) with the purpose of determining the electrical and dielectric susceptibility of soil particles with regard to the formation of double layers around particles. From the different liquid limits the proposed methodology includes the evaluation of the electrical sensitivity as complementary data to the traditional description of soil plasticity.Fil: Montoro, Marcos Alexis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Estudios Avanzados En Ingeniería y Tecnología. Universidad Nacional de Córdoba. Facultad de Ciencias exactas Físicas y Naturales. Instituto de Estudios Avanzados En Ingeniería y Tecnología; Argentina; Argentina. Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de Córdoba; ArgentinaFil: Francisca, Franco Matias. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Estudios Avanzados En Ingeniería y Tecnología. Universidad Nacional de Córdoba. Facultad de Ciencias exactas Físicas y Naturales. Instituto de Estudios Avanzados En Ingeniería y Tecnología; Argentina. Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de Córdoba; Argentin
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