Browsing by Author "David, Oana"
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Item Catalytic nickel and nickel-copper alloy hollow-fiber membranes for the remediation of organic pollutants by electrocatalysis(2018) Allioux, Francois Marie; David, Oana; Merenda, Andrea; Maina, James W.; Benavides, Miren Etxeberria; Tanaka, Alfredo Pacheco; Dumée, Ludovic F.; TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOSElectrocatalytic membrane reactors are becoming a viable solution for the treatment of wastewater contaminated with persistent organic pollutants and compounds. The development of suitable membrane elements made of abundant and stable electrocatalytic materials remains a challenge to enable durable and large-scale operation. In this study, novel nickel (Ni) and nickel-copper (NiCu) alloy hollow-fiber (HF) membranes were synthesized for the first time and used for the electrocatalytic degradation of small organic molecule pollutants from model wastewater effluents. The novel porous metal HFs were characterized and tested for their capacity to degrade salicylic acid (SA) molecules by electrochemical oxidation. The degradation of SA was monitored in situ and over time using an ultraviolet-visible (UV/vis) quartz cell. The HF membranes were found to be highly stable and reusable while the kinetics of SA electro-oxidation were 9 to 20 times greater than with pure platinum wire electrodes. The high performance of the HF materials was attributed to the interconnected pore structure combined with the natural surface reactivity and excellent electron transport properties of the Ni metal and bare NiCu alloy.Item Fabrication of Defect-Free P84® Polyimide Hollow Fiber for Gas Separation: Pathway to Formation of Optimized Structure: Pathway to formation of optimized structure(2019-12) Etxeberria-Benavides, Miren; Karvan, Oguz; Kapteijn, Freek; Gascon, Jorge; David, Oana; Tecnalia Research & Innovation; TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOSThe elimination of the additional defect healing post-treatment step in asymmetric hollow fiber manufacturing would result in a significant reduction in membrane production cost. However, obtaining integrally skinned polymeric asymmetric hollow fiber membranes with an ultrathin and defect-free selective layer is quite challenging. In this study, P84® asymmetric hollow fiber membranes with a highly thin (~56 nm) defect-free skin were successfully fabricated by fine tuning the dope composition and spinning parameters using volatile additive (tetrahydrofuran, THF) as key parameters. An extensive experimental and theoretical study of the influence of volatile THF addition on the solubility parameter of the N-methylpyrrolidone/THF solvent mixture was performed. Although THF itself is not a solvent for P84®, in a mixture with a good solvent for the polymer, like N-Methyl-2-pyrrolidone (NMP), it can be dissolved at high THF concentrations (NMP/THF ratio > 0.52). The as-spun fibers had a reproducible ideal CO2/N2 selectivity of 40, and a CO2 permeance of 23 GPU at 35 °C. The fiber production can be scaled-up with retention of the selectivity.Item Green Preparation of Thin Films of Polybenzimidazole on Flat and Hollow Fiber Supports: Application to Hydrogen Separation(2021-02-05) Sánchez-Laínez, Javier; Etxeberria-Benavides, Miren; David, Oana; Téllez, Carlos; Coronas, Joaquín; TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOSThis work shows the preparation of thin films, with thickness from 70 nm to 1 μm, of meta-polybenzimidazole (m-PBI) on polyimide P84 supports. Ethanolic solutions of m-PBI were used to coat flat and hollow fiber supports of asymmetric P84 with m-PBI in a process where the coating and drying was performed at room temperature. A solution of NaOH in EtOH allowed the dissolution of the m-PBI powder, providing the perfect coating solution to build thin films of m-PBI without damaging the polymeric support. It also meant a green alternative, avoiding the use of toxic solvents, such as dimethylacetamide. The resulting membranes have been tested for the separation of H2 mixtures at high temperature at different setups to allow checking their reproducibility. With 100 nm thickness the membranes showed their best gas separation performance. For flat membranes at 180 °C and 3 bar feed pressure a H2 permeance of 48.5 GPU was obtained, with respective H2/CO2 and H2/N2 selectivities of 33.3 and 55.8. Besides, the hollow fibers under a feed pressure of 6 bar and tested at the same temperature showed near 90 GPU of H2 with a H2/CO2 selectivity of 13.5 in the one-fiber module and over 39 GPU of H2 with a H2/CO2 selectivity of 20.2 in the five-fiber module. Finally, the stability of the membranes was proved for 22 days at 180 °C.Item High performance mixed matrix membranes (MMMs) composed of ZIF-94 filler and 6FDA-DAM polymer(2018-03-15) Etxeberria-Benavides, Miren; David, Oana; Johnson, Timothy; Łozińska, Magdalena M.; Orsi, Angelica; Wright, Paul A.; Mastel, Stefan; Hillenbrand, Rainer; Kapteijn, Freek; Gascon, Jorge; Tecnalia Research & Innovation; TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOSCarbon capture and storage (CCS) using membranes for the separation of CO2 holds great promise for the reduction of atmospheric CO2 emissions from fuel combustion and industrial processes. Among the different process outlines, post-combustion CO2 capture could be easily implemented in existing power plants. However, for this technology to become viable, new membrane materials have to be developed. In this article we present the development of high performance mixed matrix membranes (MMMs) composed of ZIF-94 filler and 6FDADAM polymer matrix. The CO2/N2 separation performance was evaluated by mixed gas tests (15CO2:85N2) at 25 °C and 1–4 bar transmembrane pressure difference. The CO2 membrane permeability was increased by the addition of the ZIF-94 particles, maintaining a constant CO2/N2 selectivity of ~22. The largest increase in CO2 permeability of ~ 200% was observed for 40 wt% ZIF-94 loading, reaching the highest permeability (2310 Barrer) at similar selectivity among 6FDA-DAM MMMs reported in literature. For the first time, the ZIF-94 metal organic framework crystals with particle size smaller than 500 nm were synthesized using nonhazardous solvent (tetrahydrofuran and methanol) instead of dimethylformamide (DMF) in a scalable process. Membranes were characterized by three non-invasive image techniques, i.e. SEM, AFM and nanoscale infrared imaging by scattering-type scanning near-field optical microscopy (s-SNOM). The combination of these techniques demonstrates a very good dispersion and interaction of the filler in the polymer layer, even at very high loadings.Item Hollow fiber membranes of PCL and PCL/graphene as scaffolds with potential to develop in vitro blood– brain barrier models(2020-08) Mantecón-Oria, Marián; Diban, Nazely; Berciano, Maria T.; Rivero, Maria J.; David, Oana; Lafarga, Miguel; Tapia, Olga; Urtiaga, Ane; TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOSThere is a huge interest in developing novel hollow fiber (HF) membranes able to modulate neural differentiation to produce in vitro blood–brain barrier (BBB) models for biomedical and pharmaceutical research, due to the low cell-inductive properties of the polymer HFs used in current BBB models. In this work, poly(ε-caprolactone) (PCL) and composite PCL/graphene (PCL/G) HF membranes were prepared by phase inversion and were characterized in terms of mechanical, electrical, morphological, chemical, and mass transport properties. The presence of graphene in PCL/G membranes enlarged the pore size and the water flux and presented significantly higher electrical conductivity than PCL HFs. A biocompatibility assay showed that PCL/G HFs significantly increased C6 cells adhesion and differentiation towards astrocytes, which may be attributed to their higher electrical conductivity in comparison to PCL HFs. On the other hand, PCL/G membranes produced a cytotoxic effect on the endothelial cell line HUVEC presumably related with a higher production of intracellular reactive oxygen species induced by the nanomaterial in this particular cell line. These results prove the potential of PCL HF membranes to grow endothelial cells and PCL/G HF membranes to differentiate astrocytes, the two characteristic cell types that could develop in vitro BBB models in future 3D co-culture systems.Item PBI mixed matrix hollow fiber membrane: Influence of ZIF-8 filler over H2/CO2 separation performance at high temperature and pressure: Influence of ZIF-8 filler over H2/CO2 separation performance at high temperature and pressure(2020-04-15) Etxeberria-Benavides, Miren; Johnson, Timothy; Cao, Shuai; Zornoza, Beatriz; Coronas, Joaquín; Sanchez-Lainez, Javier; Sabetghadam, Anahid; Liu, Xinlei; Andres-Garcia, Eduardo; Kapteijn, Freek; Gascon, Jorge; David, Oana; Tecnalia Research & Innovation; TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOSHigh performance and commercially attractive mixed-matrix membranes were developed for H2/CO2 separation via a scalable hollow fiber spinning process. Thin (~300 nm) and defect-free selective layers were successfully created with a uniform distribution of the nanosized (~60 nm) zeolitic-imidazole framework (ZIF-8) filler within the polymer (polybenzimidazole, PBI) matrix. These membranes were able to operate at high temperature (150 °C) and pressure (up to 30 bar) process conditions required in treatment of pre-combustion and syngas process gas streams. Compared with neat PBI hollow fibers, filler incorporation into the polymer matrix leads to a strong increase in H2 permeance from 65 GPU to 107 GPU at 150 °C and 7 bar, while the ideal H2/CO2 selectivity remained constant at 18. For mixed gas permeation, there is competition between H2 and CO2 transport inside ZIF-8 structure. Adsorption of CO2 in the nanocavities of the filler suppresses the transport of the faster permeating H2 and consequently decreases the H2 permeance with total feed pressure down to values equal to the pure PBI hollow fibers for the end pressure of 30 bar. Therefore, the improvement of fiber performance for gas separation with filler addition is compromised at high operating feed pressures, which emphasizes the importance of membrane evaluation under relevant process conditions.Item Pre-combustion gas separation by ZIF-8-polybenzimidazole mixed matrix membranes in the form of hollow fibres—long-term experimental study(2021-09-01) Perea-Cachero, Adelaida; Etxeberría-Benavides, Miren; David, Oana; Deacon, Adam; Johnson, Timothy; Malankowska, Magdalena; Téllez, Carlos; Coronas, Joaquín; Tecnalia Research & Innovation; TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOSPolybenzimidazole (PBI) is a promising and suitable membrane polymer for the separation of the H2/CO2 pre-combustion gas mixture due to its high performance in terms of chemical and thermal stability and intrinsic H2/CO2 selectivity. However, there is a lack of long-term separation studies with this polymer, particularly when it is conformed as hollow fibre membrane. This work reports the continuous measurement of the H2/CO2 separation properties of PBI hollow fibres, prepared as mixed matrix membranes with metal-organic framework (MOF) ZIF-8 as filler. To enhance the scope of the experimental approach, ZIF-8 was synthesized from the transformation of ZIF-L upon up-scaling the MOF synthesis into a 1 kg batch. The effects of membrane healing with poly(dimethylsiloxane), to avoid cracks and non-selective gaps, and operation conditions (use of sweep gas or not) were also examined at 200°C during approximately 51 days. In these conditions, for all the membrane samples studied, the H2 permeance was in the 22–47 GPU range corresponding to 22–32 H2/CO2 selectivity values. Finally, this work continues our previous report on this type of application (Etxeberria-Benavides et al. 2020 Sep. Purif. Technol.237, 116347 (doi:10.1016/j.seppur.2019.116347)) with important novelties dealing with the use of ZIF-8 for the mixed matrix membrane coming from a green methodology, the long-term gas separation testing for more than 50 days and the study on the membrane operation under more realistic conditions (e.g. without the use of sweep gas).Item Preparation of porous stainless steel hollow-fibers through multi-modal particle size sintering towards pore engineering(2017-09) Allioux, Francois Marie; David, Oana; Benavides, Miren Etxeberria; Kong, Lingxue; Tanaka, David Alfredo Pacheco; Dumée, Ludovic F.; TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOSThe sintering of metal powders is an efficient and versatile technique to fabricate porous metal elements such as filters, diffusers, and membranes. Neck formation between particles is, however, critical to tune the porosity and optimize mass transfer in order to minimize the densification process. In this work, macro-porous stainless steel (SS) hollow-fibers (HFs) were fabricated by the extrusion and sintering of a dope comprised, for the first time, of a bimodal mixture of SS powders. The SS particles of different sizes and shapes were mixed to increase the neck formation between the particles and control the densification process of the structure during sintering. The sintered HFs from particles of two different sizes were shown to be more mechanically stable at lower sintering temperature due to the increased neck area of the small particles sintered to the large ones. In addition, the sintered HFs made from particles of 10 and 44 µm showed a smaller average pore size (<1 µm) as compared to the micron-size pores of sintered HFs made from particles of 10 µm only and those of 10 and 20 µm. The novel HFs could be used in a range of applications, from filtration modules to electrochemical membrane reactors.Item Proton-exchange membranes based on sulfonated poly(ether ether ketone)/polyaniline blends for all- and air-vanadium redox flow battery applications(2015) David, Oana; Percin, Korcan; Luo, Tao; Gendel, Youri; Wessling, Matthias; TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOSThin and mechanically stable proton-exchange membranes with high V(IV) barrier properties and good proton conductivity have been fabricated by polymer blending of sulfonated poly(ether ether ketone) with polyaniline. V(IV) diffusion coefficient of blended membranes in a wt. ratio of 80/20 was 2.6 and 6 times lower than for pure sulfonated poly(ether ether ketone) and Nafion 112 membrane, respectively. This behaviour is assumed to be caused by a densified polymer matrix given by acid/base interactions between the two polymers. Blended membranes in a wt. ratio of 80/20 had a good proton conductivity of 54.15mScm-1 and ion exchange capacity of 1.44mmolg-1. The membranes were also characterized in all-vanadium redox flow battery, where only slightly higher efficiencies were achieved than for pure polymer. Slow PANI degradation determines a decrease in membrane performance, reaching values close to the starting polymer (SPEEK-E600). Therefore, the application of blended membranes in the all-vanadium redox flow battery is not advantageous. However, the improved barrier properties are likely to be beneficial for their application in vanadium/air-redox flow battery in order to reduce oxygen crossover. In the latter, no V(V) ions can oxidize the blend polymer.Item Structural Contraction of Zeolitic Imidazolate Frameworks: Membrane Application on Porous Metallic Hollow Fibers for Gas Separation(2017-06-21) Cacho-Bailo, Fernando; Etxeberría-Benavides, Miren; David, Oana; Téllez, Carlos; Coronas, Joaquín; TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOSPositive thermal expansion coefficients (TECs) of 52 × 10-6 and 35 × 10-6 K-1 were experimentally calculated in the -116 to 250 °C range for the III-phases of zeolitic imidazolate frameworks (ZIF) ZIF-9(Co) and ZIF-7(Zn), respectively, by means of the unit cell dimensions and volume of the materials in the monoclinic crystal system calculated from the XRD patterns. The unit cell dimensions and volume showed a significant expansion phenomenon as the temperature increased, by as much as 5.5% for ZIF-9-III in the studied range. To exploit the advantages of such thermal behavior, a new approach to the fabrication of ZIF-9-III membranes on thin, flexible, and highly porous nickel hollow fiber (Ni HF) supports by a versatile and easy-controllable microfluidic setup is herein reported. These Ni HF supports result from the sintering of 25-μm Ni particles and display very positive mechanical properties and bending resistance. As compared to the traditional polymer-based HF membranes, the ZIF metal-supported membrane exhibited good durability and robustness throughout its operation in a wide temperature range and after heating and cooling cycles. These benefits derive from (1) the pore-plugging membrane configuration resulting from the high porosity of the support and (2) the similarity between the TECs of the ZIF and the metallic support, both positive, which enhances their mutual compatibility. An increase in the H2/CO2 separation selectivity at low temperatures (as high as 22.2 at -10 °C, along with 102 GPU permeance of H2) was achieved, in agreement with the structural variations observed in the ZIF material.