Biodiesel Purification Using Polymeric Nanofiltration Composite Membranes Highly Resistant to Harsh Conditions

Biodiesel as alternative for conventional diesel fuel is mainly produced by the catalytic reaction of triglycerides with an alcohol. In this work, the purification of biodiesel was carried out with two lab-made solvent-resistant composite nanofiltration membranes of poly(vinylidene difluoride) (PVDF) as support and poly(dimethylsiloxane) as coating layer. Biodiesel was obtained from the esterification of partially refined soy oil with bioethanol (EtOH) and NaOH as catalyst. The best biodiesel purification performance was achieved with the PVDF-12SI membrane reaching high retention of glycerol, total glycerides, and soap. PVDF-SI membranes were found to have an excellent stability for biodiesel permeation, achieving a flux recovery ratio of EtOH as high as 0.94 after twenty cycles of use.Fil: Torres, Juan Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Toledo Arana, Javier Marcelo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; 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"; ArgentinaFil: Pagliero, Cecilia Liliana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; Argentin

Mass Transport through Nanostructured Membranes: Towards a Predictive Tool

This study proposes a new mechanism to understand the transport of solvents through nanostructured membranes from a fundamental point of view. The findings are used to develop readily applicable mathematical models to predict solvent fluxes and solute rejections through solvent resistant membranes used for nanofiltration. The new model was developed based on a pore-flow type of transport. New parameters found to be of fundamental importance were introduced to the equation, i.e., the affinity of the solute and the solvent for the membrane expressed as the hydrogen-bonding contribution of the solubility parameter for the solute, solvent and membrane. A graphical map was constructed to predict the solute rejection based on the hydrogen-bonding contribution of the solubility parameter. The model was evaluated with performance data from the literature. Both the solvent flux and the solute rejection calculated with the new approach were similar to values reported in the literature

Solvent Resistant Nanofiltration: From Membrane Manufacturing via Modeling and Simulation to Industrial Application (Solvent Resistente Nanofiltratie: van membraansynthese via modelering en simulatie tot industriële toepassing)

This dissertation focuses on the use of nanofiltration membranes as a separation tool inorganic solvents.The thesis starts from the material selection for membrane manufacturing. Nanoporouspolyphenylsulfone flat sheet and hollow fiber membranes were successfully prepared usingthe phase inversion method.The performance of polymeric membranes was studied in terms of the solvent flux and thesolute rejection. Several kinds of interactions are introduced when organic solvents are usedwith polymeric membranes and thus quantification of polymer-solvent interactions is critical.Pure solvent permeation studies were conducted to understand the mechanism of solventtransport through polymeric membranes. Different membrane materials (hydrophilic andhydrophobic) as well as different solvents (polar and non-polar) were used for the study.Polymeric membranes are prone to swelling effects, which leads to a reorganisation of themembrane structure, resulting in a new pore size distribution and a change of the degree ofhydrophilicity of the membrane surface. Hydrophobic membranes show a better solventresistance than hydrophilic membranes.The solvent flux appears to depend on three parameters: transport of momentum, sterichindrance effects and the affinity between the solvent and the membrane material. Newmodels for solvent transport were developed, which can be applied on experimental data ofboth hydrophilic and hydrophobic membranes, and for a broad range of organic solvents andsolvent mixtures.Solute transport in solvent resistant nanofiltration mainly occurs by convection. As ceramicmembranes show similar results as polymeric membranes, differences in membraneperformance cannot be attributed to swelling effects. Transport of dissolved components isalso found to be determined by three parameters: the nominal pore size, the degree ofsolvation of the solute, and the degree of pore wall solvation. A new methodology,incorporating a solvent effect for both the solute and the pore size is presented. Modelparameters, characteristic for specific membrane-solvent combinations, are determined andprovide excellent results for predictive modelling.A case-study on solvent recovery from an oleochemical industry and a pharmaceuticalproduction process via process simulation indicates that solvent resistant nanofiltration is atechnically feasible alternative for traditional separation processes. A membrane unit iscalculated to consume much less energy than a flash. Economic feasibility must however befurther investigated.status: publishe

Mass Transport through Nanostructured Membranes: Towards a Predictive Tool

This study proposes a new mechanism to understand the transport of solvents through nanostructured membranes from a fundamental point of view. The findings are used to develop readily applicable mathematical models to predict solvent fluxes and solute rejections through solvent resistant membranes used for nanofiltration. The new model was developed based on a pore-flow type of transport. New parameters found to be of fundamental importance were introduced to the equation, i.e., the affinity of the solute and the solvent for the membrane expressed as the hydrogen-bonding contribution of the solubility parameter for the solute, solvent and membrane. A graphical map was constructed to predict the solute rejection based on the hydrogen-bonding contribution of the solubility parameter. The model was evaluated with performance data from the literature. Both the solvent flux and the solute rejection calculated with the new approach were similar to values reported in the literature

Partitioning of Ciprofloxacin in aqueous two-phase system of poly(ethylene glycol) and sodium sulphate

status: publishe

Miscibility of polyimide blends: Physicochemical characterization of two high performance polyimide polymers

The intermolecular interactions and miscibility behavior of two polyimide blend systems, Extem/Matrimid and Extem/U-Varnish, in compositions of 100/0, 80/20, 50/50, 20/80, 0/100 have been evaluated. The polymer blend systems have been characterized by different analytical techniques such as optical microscopy, Differential Scanning Calorimetry (DSC), Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD) and rheological measurements. DSC results for the Extem/U-Varnish system showed the existence of a single glass transition temperature (Tg) in each composition, suggesting the miscibility of the blends, whereas DSC analysis of Extem/Matrimid system indicated immiscibility but compatibility between two polymers. In order to study the specific interactions between Extem and U-Varnish polymers, the Tgs of the polymer blends were estimated by theoretical equations and compared with experimental data. The empirical Tg values formed a concave curve as a function of composition and exhibited a positive deviation from the linearity, indicating the presence of specific interactions between Extem and U-Varnish polymer chains; this was confirmed by FTIR spectra. Interactions between studied polymer systems and four aprotic solvents including N-methyl-2-pyrrolidone (NMP), Dimethylacetamide (DMAc), Dimethylformamide (DMF) and Dimethyl sulfoxide (DMSO) were assessed on the basis of the difference between their solubility parameters. Among the selected solvents, DMAc showed the highest affinity with both blend systems. XRD patterns and rheological behavior of Extem/U-Varnish system revealed that the crystalline nature and viscosity of the blend polymers decreases as the ratio of Extem/U-Varnish increases. As an overall conclusion, Extem and U-Varnish were found to constitute a miscible pair at a molecular level over the entire composition range whereas Extem and Matrimid could not form a miscible blend