Impact of MOF-5 on pyrrolidinium-based poly(ionic liquid)/ionic liquid membranes for biogas upgrading

PostprintBearing in mind that Metal Organic Frameworks (MOFs) have remarkable CO2 adsorption selectivity and Mixed Matrix Membranes (MMMs) have been identified as potential solution for advancing the current state of the art of membrane separation technology, this work investigates the effect of combining a MOF, with high adsorption properties towards CO2 when compared to CH4 (MOF-5), with a blend of poly(ionic liquid)/ionic liquid (PIL/IL) for biogas upgrading. The blend system consisted of a pyrrolidinium-based PIL, poly([Pyr11][Tf2N]), and a free imidazolium-based IL, [C2mim][BETI]. The MOF-5 was incorporated at different loadings (10, 20, 30 wt%), and MMMs were prepared by solvent evaporation technique and characterized by diverse techniques (FTIR, SEM, TGA, puncture tests, water contact angle and single gas transport). The results showed that the free IL is miscible with the PIL, while MOF-5 particles were uniformly dispersed into the PIL/IL matrix. The formed PIL/IL/MOF-5 membranes revealed suitable thermal stability (Tonset up to 656 K) for biogas upgrading processes, but a loss of mechanical stability was found after the incorporation of MOF-5, and thus more rigid and fragile membranes were obtained. Besides, increasing MOF-5 content in the MMMs resulted in improved CO2 permeability. At 30 wt% of MOF-5 loading the CO2 permeability increased 133% when compared to that of the pristine PIL/IL membrane, while the ideal selectivity CO2/CH4 decreases. It was possible to demonstrate the relevance of studying different components within the polymeric matrix in order to assess not only thermal, mechanical and chemical properties, but also gas transport response.This work was supported by FCT (Fundação para Ciência e a Tecnologia) through the project PTDC/CTM-POL/2676/2014 and the Associate Laboratory for Green Chemistry - LAQV (UID/QUI/50006/2019). Ana R. Nabais and Luísa A. Neves are grateful to FCT/MCTES for their PhD grant (SFRH/BD/136963/2018) and FCT Investigador Contract (IF/00505/2014), respectively. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement no. 745734

Alkali Iodide Deep Eutectic Solvents as Alternative Electrolytes for Dye Sensitized Solar Cells

PTDC/QEQ- QFI/1971/2014 POCI- 01-0145-FEDER-016387Different alkali deep eutectic solvents (DES), such as LiI:nEG, NaI:nEG, and KI:nEG, have been tested as electrolytes for dye sensitized solar cells (DSSCs). These DSSCs were prepared using pure DES or, alternatively, DES combined with different amounts of iodine (I2). The most important parameters, such as open circuit voltage (VOC), short circuit current density (JSC), fill factor (FF), and the overall conversion efficiency (η), were evaluated. Some DES seem to be promising candidates for DSSC applications, since they present higher VOC (up to 140 mV), similar FF values but less current density values, when compared with a reference electrolyte in the same experimental conditions. Additionally, electrochemical impedance spectroscopy (EIS) has been performed to elucidate the charge transfer and transport processes that occur in DSSCs. The values of different resistance (Ω·cm2) phenomena and recombination/relaxation time (s) for each process have been calculated. The best-performance was obtained for DES-based electrolyte, KI:EG (containing 0.5 mol% I2) showing an efficiency of 2.3%. The efficiency of this DES-based electrolyte is comparable to other literature systems, but the device stability is higher (only after seven months the performance of the device drop to 60%).publishersversionpublishe

Preparation and characterization of films based on a natural P(3HB)/mcl-PHA blend obtained through the co-culture of Cupriavidus necator and Pseudomonas citronellolis in apple pulp waste

The co-culture of Cupriavidus necator DSM 428 and Pseudomonas citronellolis NRRL B-2504 was performed using apple pulp waste from the fruit processing industry as the sole carbon source to produce poly(3-hydroxybutyrate), P(3HB) and medium-chain length PHA, mcl-PHA, respectively. The polymers accumulated by both strains were extracted from the co-culture’s biomass, resulting in a natural blend that was composed of around 48 wt% P(3HB) and 52 wt% mcl-PHA, with an average molecular weight of 4.3 105 Da and a polydispersity index of 2.2. Two melting temperatures (Tm) were observed for the blend, 52 and 174 C, which correspond to the Tm of the mcl-PHA and P(3HB), respectively. P(3HB)/mcl-PHA blend films prepared by the solvent evaporation method had permeabilities to oxygen and carbon dioxide of 2.6 and 32 Barrer, respectively. The films were flexible and easily deformed, as demonstrated by their tensile strength at break of 1.47 0.07 MPa, with a deformation of 338 19% until breaking, associated with a Young modulus of 5.42 1.02 MPa. This study demonstrates for the first time the feasibility of using the co-culture of C. necator and P. citronellolis strains to obtain a natural blend of P(3HB)/mcl-PHA that can be processed into films suitable for applications ranging from commodity packaging products to high-value biomaterialsinfo:eu-repo/semantics/publishedVersio

Poly(ionic liquid)-based engineered mixed matrix membranes for CO2/H2 separation

Unformatted preprintPoly(ionic liquid)s (PIL) have emerged as a class of versatile polyelectrolites, that can be used to prepare new materials able to achieve superior performances compared to conventional polymers. The combination of PILs with ionic liquids (ILs) may serve as a suitable matrix for the preparation of membranes for gas separation. In this work, mixed matrix membranes (MMMs) combining a pyrrolidinium-based PIL, an IL and three highly CO2-selective metal organic frameworks (MOFs) were prepared. The different MOFs (MIL-53, Cu3(BTC)2 and ZIF-8) were used as fillers, aiming to maximize the membranes performance towards the purification of syngas. The influence of different MOFs and loadings (0, 10, 20 and 30 wt.%) on the thermal and mechanical stabilities of the membranes and their performance in terms of CO2 permeability and CO2/H2 ideal selectivity was assessed. The compatibility between the materials was confirmed by SEM-EDS and FTIR spectroscopy. The prepared MMMs revealed to be thermally stable within the temperature range of the syngas stream, with a loss of mechanical stability upon the MOF incorporation. The increasing MOF content in the MMMs, resulted in an improvement of both CO2 permeability and CO2/H2 ideal selectivity. Among the three MOFs studied, membranes based on ZIF-8 showed the highest permeabilities (up to 97.2 barrer), while membranes based on MIL-53 showed the highest improvement in selectivity (up to 13.3). Remarkably, all permeation results surpass the upper bound limit for the CO2/H2 separation, showing the membranes potential for the desired gas separation.This work was partially supported by R&D Units UID/Multi/04551/2013 (Green-it), UID/QUI/00100/2013 (CQE), and the Associated Laboratory Research Unit for Green Chemistry, Technologies and Clean Processes, LAQV which is financed by national funds from FCT/MCTES(UID/QUI/50006/2013) and co-financed by the ERDF under the PT2020 Partnership Agreement (POCI-01-0145-FEDER-007265). Ana R. Nabais, Luísa A. Neves and Liliana C. Tomé acknowledge FCT/MCTES for financial support through project PTDC/CTM-POL/2676/2014, FCT Investigator Contract IF/00505/2014 and Post-doctoral research grant SFRH/BDP/101793/2014, respectively. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 745734

Multidrug-Resistant Bacteria in Diabetic Foot Infections: Experience from a Portuguese Tertiary Centre

In recent years, the emergence of antibiotic resistant pathogens made increasingly difficult to establish appropriate empiric antimicrobial therapy protocols for acute diabetic foot infection (DFI) treatment. Early recognition of the population at-risk for multidrug-resistant (MDR) bacterial infection is of paramount importance in order to decrease large-spectrum antibiotic overuse. This study used retrospective cohort study in a multidisciplinary tertiary diabetic foot unit. Patients with severe DFI were included and divided according to their infection resistance profile (susceptible vs MDR bacteria). Data regarding their comorbidities and length of hospital stay were collected. The primary endpoint was to determine the risk factors for MDR infections and to evaluate if these were associated with an increased length of stay (LOS). A total of 112 microbial isolates were included. Predominance of Gram-positive bacteria was observed and 22.3% of isolated bacteria were MDR. Previous hospitalisation was associated with a higher likelihood of MDR infection. MDR bacterial infection was also associated with an increased LOS (P = .0296). Our study showed a high incidence of MDR bacteria in patients with a DFI, especially in those who had a recent hospitalisation. MDR infections were associated with a prolonged LOS and represent a global public health issue for which emergent measures are needed.info:eu-repo/semantics/publishedVersio

Influence of anion structure on thermal, mechanical and CO2 solubility properties of uv-cross-linked poly(Ethylene glycol) diacrylate iongels

PTDC/CTM-POL/2676/2014 UID/QUI/50006/2019 grant 471837 SFRH/BD/136963/2018 IF/00505/2014Iongel-based CO2 separation membranes were prepared by fast (< 1 min) UV-initiated polymerization of poly(ethylene glycol) diacrylate (PEGDA) in the presence of different ionic liquids (ILs) with the [C2mim]+ cation and anions such as [TFSI]−, [FSI]−, [C(CN)3]− and [B(CN)4]−. The four ILs were completely miscible with the non-ionic PEGDA network. Transparent and freestanding iongels containing between 60 and 90 %wt of IL were obtained and characterized by diverse techniques (FTIR, TGA, DSC, DMTA, SEM, CO2 solubility and pure gas permeability). The thermal and mechanical stability of the iongels, as well as CO2 solubility, were found to be strictly dependent on the IL content and the anion’s nature. The TGA results indicated that the iongels mostly follow the thermal profile of the respective neat ILs. The DMTA analysis revealed that the iongels based on fluorinated anions have higher storage modulus than those of cyano-functionalized anions. Conversely, the PEGDA–C(CN)3 iongels presented the highest CO2 solubility values ranging from 72 to 80 mmol/g. Single CO2 permeabilities of 583 ± 29 Barrer and ideal CO2/N2 selectivities of 66 ± 3 were obtained with the PEGDA–70 C(CN)3 iongel membrane. This work demonstrates that the combination of PEGDA with high contents of the best performing ILs is a promising and simple strategy, opening up new possibilities in the design of high-performance iongel membranes for CO2 separation.publishersversionpublishe

Impact of Ionic Liquid Structure and Loading on Gas Sorption and Permeation for ZIF-8-Based Composites and Mixed Matrix Membranes

Carbon dioxide (CO2) capture has become of great importance for industrial processes due to the adverse environmental effects of gas emissions. Mixed matrix membranes (MMMs) have been studied as an alternative to traditional technologies, especially due to their potential to overcome the practical limitations of conventional polymeric and inorganic membranes. In this work, the effect of using different ionic liquids (ILs) with the stable metal–organic framework (MOF) ZIF-8 was evaluated. Several IL@ZIF-8 composites and IL@ZIF-8 MMMs were prepared to improve the selective CO2 sorption and permeation over other gases such as methane (CH4) and nitrogen (N2). Different ILs and two distinct loadings were prepared to study not only the effect of IL concentration, but also the impact of the IL structure and affinity towards a specific gas mixture separation. Single gas sorption studies showed an improvement in CO2/CH4 and CO2/N2 selectivities, compared with the ones for the pristine ZIF-8, increasing with IL loading. In addition, the prepared IL@ZIF-8 MMMs showed improved CO2 selective behavior and mechanical strength with respect to ZIF-8 MMMs, with a strong dependence on the intrinsic IL CO2 selectivity. Therefore, the selection of high affinity ILs can lead to the improvement of CO2 selective separation for IL@ZIF-8 MMMsinfo:eu-repo/semantics/publishedVersio