Mass transfer of cadmium ions in a hollow-fiber module by pertraction

The facilitated transport of Cd(II) ions through a hollow-fiber-supported liquid membrane with bis-2-ethylhexyl phosphoric acid as carrier was studied. The mass transfer rate, expressed as permeability P, was measured as a function of mean aqueous solution velocity and carrier concentration. Characteristic ion permeabilities of 10-26×10-7m/s were measured at feed velocities between 1×10-2-19×10-2 m/s at stripping velocities between 0.22×10-2-7×10-2 m/s with constant feed flow. The measured permeabilities were compared to generally accepted mass transfer correlations. The predicted permeabilities adequately fit the experimental data, indicating that the rate limiting step in the transport of the ion was the diffusion through both aqueous films, feed and stripping, whereas the organic resistance of the membrane was negligible. Furthermore, the proposed model allowed the prediction of the permeability of cadmium for different experimental conditions, which is useful to perform experiments to reduce metal levels in water or other effluents.Fil: Marchese, Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich". Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich"; Argentina. Universidad Nacional de San Luis. Facultad de Ciencias Fisico Matematicas y Naturales. Departamento de Fisica. Laboratorio de Ciencias de Superficies y Medios Porosos; ArgentinaFil: Campderrós, Mercedes Edith. Universidad Nacional de San Luis. Facultad de Ciencias Fisico Matematicas y Naturales. Departamento de Fisica. Laboratorio de Ciencias de Superficies y Medios Porosos; Argentin

Effect of hydrophilicity on fouling of an emulsified oil wastewater with PVDF/PMMA membranes

Membranes with different degrees of hydrophilicity were prepared from PVDF and PMMA. The hydrophilicity was determined by using the contact angle technique. The distribution of pore radius was obtained from polydispersed solute permeation, scanning electron microscope (SEM) and hydraulic permeability. A higher hydrophilic character with the increase of PMMA in the casting solution and the appearance of larger macrovoids in the porous substructure were found without a substantial modification of the selective surface structure. However, a significant effect of compaction was evidenced due to the transmembrane pressure on membranes with high content of PMMA. An effluent from an engine factory was used to study the ultrafiltration performance of the prepared membranes. These assays show that membranes with a higher content of PMMA lead to a lower fouling.Fil: Ochoa, Nelio Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de San Luis. Facultad de Cs.fisico Matemáticas y Naturales. Laboratorio de Cs.de Superficies y Medios Porosos; ArgentinaFil: Masuelli, Martin Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de San Luis. Facultad de Cs.fisico Matemáticas y Naturales. Laboratorio de Cs.de Superficies y Medios Porosos; ArgentinaFil: Marchese, Jose. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de San Luis. Facultad de Cs.fisico Matemáticas y Naturales. Laboratorio de Cs.de Superficies y Medios Porosos; Argentin

Orange Juice Clarification by Microfiltration: Effect of Operational Variables on Membrane Fouling

Orange juice was clarified by cross-flow microfiltration by a PVDF/PMMA flat mem-brane synthesized in our laboratory. The effect oftransmembrane pressure (ǻp=0.4-1bar) and feedflow rate (v=0.77-1.25 m/s) on permeate flux atT=25ºC was studied. Permeate flux increases withincreasing feed velocity, while no significant increaseof permeate flux with pressure is observed (flux con-trolled by mass transfer). Resistances responsible forpermeate flux in the steady state conditions wereevaluated by applying the resistance-in-series model.Results indicate that the reversible gel layer resis-tance of the membrane was the dominant resistance(§ 70% of total membrane resistance) and it wasmainly caused by the adsorption and deposition ofsolutes on the membrane surface. The PVDF/PMMAmembrane showed high performance on both per-meate flux and clarified juice quality. The maximumpermeate flux at steady-state condition (J = 47L/m2h) was achieved at ǻp = 1 bar and v = 1.25 m/s.Total solids (TS) are completely removed from per-meate juice and the content of soluble solids, acidityand pH present in the feed and in the clarified per-meate are practically the same.Fil: Pagliero, Cecilia Liliana. Universidad Nacional de Río Cuarto. Facultad de Ingeniería; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Ochoa, Nelio Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich". Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich"; ArgentinaFil: Marchese, Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich". Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich"; Argentin

Orange Juice Clarification by Microfiltration: Effect of Operational Variables on Membrane Fouling

Orange juice was clarified by cross-flow microfiltration by a PVDF/PMMA flat mem-brane synthesized in our laboratory. The effect oftransmembrane pressure (ǻp=0.4-1bar) and feedflow rate (v=0.77-1.25 m/s) on permeate flux atT=25ºC was studied. Permeate flux increases withincreasing feed velocity, while no significant increaseof permeate flux with pressure is observed (flux con-trolled by mass transfer). Resistances responsible forpermeate flux in the steady state conditions wereevaluated by applying the resistance-in-series model.Results indicate that the reversible gel layer resis-tance of the membrane was the dominant resistance(§ 70% of total membrane resistance) and it wasmainly caused by the adsorption and deposition ofsolutes on the membrane surface. The PVDF/PMMAmembrane showed high performance on both per-meate flux and clarified juice quality. The maximumpermeate flux at steady-state condition (J = 47L/m2h) was achieved at ǻp = 1 bar and v = 1.25 m/s.Total solids (TS) are completely removed from per-meate juice and the content of soluble solids, acidityand pH present in the feed and in the clarified per-meate are practically the same.Fil: Pagliero, Cecilia Liliana. Universidad Nacional de Río Cuarto. Facultad de Ingeniería; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Ochoa, Nelio Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich". Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich"; ArgentinaFil: Marchese, Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich". Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich"; Argentin

Preparation and characterization of non-supported microfiltration membranes from aluminosilicates

In the present work non-supported microfiltration ceramic membranes have been made from different aluminosilicate paste formulations. The cast green dopes were sintered at temperatures between 1100 and 1400°C. The membrane characterisation was made by scanning electron microscopy (SEM), mercury porosimetry, gas and water permeabilities and microorganisms rejection. The results indicate that an appropriate election of the size of the particles in the paste and of the final sintering temperature allows to obtain membranes with different mechanical and structural properties, with mean pore sizes within the range from 0.1 to 1 μm, that make them suitable for microfiltration.Fil: Almandoz, M.C.. Universidad Nacional de San Luis. Facultad de Ciencias Fisico Matematicas y Naturales. Departamento de Fisica. Laboratorio de Ciencias de Superficies y Medios Porosos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis; ArgentinaFil: Marchese, Jose. Universidad de Valladolid; España. Universidad Nacional de San Luis. Facultad de Ciencias Fisico Matematicas y Naturales. Departamento de Fisica. Laboratorio de Ciencias de Superficies y Medios Porosos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis; ArgentinaFil: Prádanos, P.. Universidad de Valladolid; EspañaFil: Palacio, L.. Universidad de Valladolid; EspañaFil: Hernández, A.. Universidad de Valladolid; Españ

Deacidification and solvent recovery of soybean oil by nanofiltration membranes

Four tailor-made flat composite membranes of poly(vinylideneflouride) (PVDF) as a support and polydimethylsiloxane (PDMS) or cellulose acetate (CA) as coating layer, and a commercially available composite membrane (Solsep 030306) were used to remove hexane and free fatty acid (FFA) from crude soybean oil-hexane mixture. The effects of transmembrane pressure (Δp=10-20 bar), temperature (T=30-50ºC) and feed oil concentration (Cf=10-35 w/w %) on membrane selectivity and permeation flux were determined. The PVDF-12% siloxane composite nanofiltration membrane achieved the best results, being stable in commercial hexane and having promising permselectivity properties to separate soybean oil/hexane miscella. Improved separation performance was obtained at Cf = 25%, Δp = 20 bar, and T = 30°C, achieving a permeate flux of 20.3 Lm-2h-1, 80% oil retention, 58% FFA removal.Fil: Firman, Leticia Raquel. Universidad Nacional de Río Cuarto. Facultad de Ingeniería; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ochoa, Nelio Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto de Física Aplicada; ArgentinaFil: Marchese, Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto de Física Aplicada; ArgentinaFil: Pagliero, Cecilia Liliana. Universidad Nacional de Río Cuarto. Facultad de Ingeniería; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Preparation and characterization of polymeric microspheres for Cr(VI) extraction

Microspheres (MS) from different polymers were prepared using two routes. Route A: process of phase inversion with solutions of polysulfone (PSf) in dichloromethane (DCM) and polyvinylpyrrolidone (PVP) as additive. Different weight ratios of PSf-PVP were used in the MS preparation. Route B: MS were obtained by cross-linking in emulsion using a commercial silicone as raw material. The obtained MS were analysed according to their morphological-structural characteristics and in relation to their Cr(VI) extraction capacity using impregnated MS with Aliquat 336. The results obtained showed that MS prepared with PSf-PVP have both less specific surfaces and relative porosities when the proportion of PVP in the mixture is increased. Extraction tests of ion Cr(VI) indicated that synthesized MS have adequate structural characteristics and interesting adsorptive properties which give rise to impregnating selective extractants. Impregnated microspheres with Aliquat 336 prepared from 2:1 PSf-PVP ratio achieved the highest Cr(VI) extractive performance (92% of Cr extraction for contact time of 60 min) and the best breakthrough point in column tests (up to 10 h in the first cycle).Fil: Ochoa, Nelio Ariel. Universidad Nacional de San Luis. Facultad de Ciencias Fisico Matematicas y Naturales. Departamento de Fisica. Laboratorio de Ciencias de Superficies y Medios Porosos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis; ArgentinaFil: Illanes, Cristian Omar. Universidad Nacional de San Luis. Facultad de Ciencias Fisico Matematicas y Naturales. Departamento de Fisica. Laboratorio de Ciencias de Superficies y Medios Porosos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis; ArgentinaFil: Marchese, Jose. Universidad Nacional de San Luis. Facultad de Ciencias Fisico Matematicas y Naturales. Departamento de Fisica. Laboratorio de Ciencias de Superficies y Medios Porosos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis; ArgentinaFil: Basualto, C.. Universidad de Chile; ChileFil: Valenzuela, Fernando R.. Universidad de Chile; Chil

Morphology and structure of ABS membranes filled with two different activated carbons

Mixed matrix-composite membranes (MMCM) for gas separation are prepared and characterized in this work. Acrylonitrile-butadiene-styrene (ABS) copolymer was used for the continuum phase of the membrane filled with two different activated carbons (AC). The so-obtained membranes have been characterized by gas permeability, optical microscopy, electronic microscopy and atomic force microscopy. The membranes have different roughness on both their surfaces but are always recovered by the polymeric material. Better ABS-AC adhesion has been always reached giving high selectivity and permeability for CO2 / CH4. Such intimate contact can be attributed to the rubber properties of the butadiene-styrene chains in ABS. The morphological characteristics and the increase in both permeability and selectivity with the volume fraction of the filler are explained in terms of the properties of pure activated carbons.Fil: Marchese, Jose. Universidad Nacional de San Luis; Argentina. Universidad Nacional de San Luis. Facultad de Ciencias Fisico Matematicas y Naturales. Departamento de Fisica. Laboratorio de Ciencias de Superficies y Medios Porosos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis; ArgentinaFil: Anson, M.. Universidad Nacional de San Luis; Argentina. Universidad Nacional de San Luis. Facultad de Ciencias Fisico Matematicas y Naturales. Departamento de Fisica. Laboratorio de Ciencias de Superficies y Medios Porosos; ArgentinaFil: Ochoa, Nelio Ariel. Universidad Nacional de San Luis; Argentina. Universidad Nacional de San Luis. Facultad de Ciencias Fisico Matematicas y Naturales. Departamento de Fisica. Laboratorio de Ciencias de Superficies y Medios Porosos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis; ArgentinaFil: Prádanos, P.. Universidad de Valladolid; EspañaFil: Palacio, L.. Universidad de Valladolid; EspañaFil: Hernández, A.. Universidad de Valladolid; Españ

Phylogeny and phylogenetic classification of the antbirds, ovenbirds, woodcreepers, and allies (Aves: Passeriformes: Infraorder Furnariides)

The infraorder Furnariides is a diverse group of suboscine passerine birds comprising a substantial component of the Neotropical avifauna. The included species encompass a broad array of morphologies and behaviours, making them appealing for evolutionary studies, but the size of the group (ca. 600 species) has limited well-sampled higher-level phylogenetic studies. Using DNA sequence data from the nuclear RAG-1 and RAG-2 exons, we undertook a phylogenetic analysis of the Furnariides sampling 124 (more than 88%) of the genera. Basal relationships among family-level taxa differed depending on phylogenetic method, but all topologies had little nodal support, mirroring the results from earlier studies in which discerning relationships at the base of the radiation was also difficult. In contrast, branch support for family-rank taxa and for many relationships within those clades was generally high. Our results support the Melanopareidae and Grallariidae as distinct from the Rhinocryptidae and Formicariidae, respectively. Within the Furnariides our data contradict some recent phylogenetic hypotheses and suggest that further study is needed to resolve these discrepancies. Of the few genera represented by multiple species, several were not monophyletic, indicating that additional systematic work remains within furnariine families and must include dense taxon sampling. We use this study as a basis for proposing a new phylogenetic classification for the group and in the process erect new family-group names for clades having high branch support across methods. © 2009 The Willi Hennig Society