Surface Coatings and Treatments for Controlled Hydrate Formation: A Mini Review

LA/P/0008/2020Gas hydrates (GHs) are known to pose serious flow assurance challenges for the oil and gas industry. Neverthless, over the last few decades, gas hydrates-based technology has been explored for various energy- and environmentally related applications. For both applications, a controlled formation of GHs is desired. Management of hydrate formation by allowing them to form within the pipelines in a controlled form over their complete mitigation is preferred. Moreover, environmental, benign, non-chemical methods to accelerate the rate of hydrate formation are in demand. This review focused on the progress made in the last decade on the use of various surface coatings and treatments to control the hydrate formation at atmospheric pressure and in realistic conditions of high pressure. It can be inferred that both surface chemistry (hydrophobicity/hydrophilicity) and surface morphology play a significant role in deciding the hydrate adhesion on a given surface.publishersversionpublishe

Diarylethene-Based Ionic Liquids: Synthesis and Photo-Driven Solution Properties

Funding text The authors acknowledge Fundação para a Ciência e Tecnologia through the PhD grant SFRH/BD/81693/2011 (M. R. C. Soromenho). This work was supported by the Associate Laboratory for Green Chemistry-LAQV (Portugal) (UIDB/50006/2020, UIDP/50006/2020, and LA/P/0008/2020) and by the Instituto de Investigação do Medicamento (iMed.ULisboa) (UIDB/04138/2020, and UIDP/04138/2020) which are financed by national funds from FCT/MCTES. The NMR spectrometers are part of the National NMR Network (PTNMR) are partially supported by Infrastructure Project Nº 022161 (co-financed by FEDER through COMPETE 2020, POCI and PORL and FCT through PIDDAC).In this work, the design and synthesis of a series of photochromic gemini diarylethene-based ionic liquids (GDILs) with different cationic motifs is reported. Several synthetic pathways were optimized for the formation of cationic GDILs with chloride as the counterion. The different cationic motifs were achieved through the N-alkylation of the photochromic organic core unit with different tertiary amines, including different aromatic amines such as imidazole derivatives and pyridinium, and other non-aromatic amines. These novel salts present surprising water solubility with unexplored photochromic features that broaden their known applications. The covalent attachment of the different side groups dictates their water solubility and differences upon photocyclization. The physicochemical properties of GDILs in aqueous and in imidazolium-based ionic liquid (IL) solutions were investigated. Upon irradiation with ultraviolet (UV) light, we have observed changes in the physico-chemical properties of distinct solutions containing these GDILs, at very low concentrations. More specifically, in aqueous solution, the overall conductivity increased with the time of UV photoirradiation. In contrast, in IL solution, these photoinducible changes are dependent on the type of ionic liquid used. These compounds can improve non-ionic and ionic liquids’ solutions since we can change their properties, such as conductivity, viscosity or ionicity, only by UV photoirradiation. The electronic and conformational changes associated with these innovative stimuli GDILs may open new opportunities for their use as photoswitchable materials.publishersversionpublishe

Probing the effect of amino acid-based ionic liquids on the CO2 (sI) and THF (sII) hydrate formation

Funding Information: The authors would like to thank Fundação para a Ciência e Tecnologia, FCT/MCTES (Portugal), for financial support through project PTDC/EQU-EQU/32050/2017. This work was partially supported by the Associate Laboratory for Green Chemistry—LAQV, which is financed by national funds from FCT/MCTES (UIDB/50006/2020 and UIDP/50006/2020 and LA/P/0008/2020). Publisher Copyright: © 2023 The Author(s)In the present work, four acetyl glycinate-based ionic liquids (ILs) with distinct cations, namely 1-alkyl-3-methylimidazolium acetyl glycinate [C2mim][AcGly], ammonium acetyl glycinate [NH4][AcGly], N-(2-hydroxyethyl)-N,N,N-trimethyl ammonium N-acetylglycinate [N111(2OH)][AcGly] ≈ [Ch][AcGly], and N-Butyl-N,N-dimethyl-N-(2-hydroxyethyl) ammonium N-acetylglycinate [N411(2OH)][AcGly] ≈ [C4Ch][AcGly], were synthesized and tested for their effect on the formation of CO2 hydrates at elevated pressures and tetrahydrofuran (THF) hydrate formation at atmospheric pressure. The phase behaviour of the CO2 hydrates, sI type, was studied in the presence of the selected ILs using the isochoric pressure search method. The ILs shifted the phase boundary towards lower temperatures indicating a thermodynamic inhibition characteristic. The constant cooling method was used to determine the onset nucleation temperature of CO2 hydrates in the presence and absence of additives. The isothermal method was used to determine the induction time of CO2 hydrates in the presence of additives. The pressure drops in both experiments indicate the hydrate growth in the absence/presence of additives. Later, the THF hydrate crystal growth experiments at atmospheric pressure were carried out to understand the effect of additives on the sII-type hydrate growth. The crystal morphology also points out the mode of action of the tested additives on hydrate formation and growth. The extensive testing using the same additives at identical concentrations revealed the importance of the method and conditions, which become crucial in the absence of a standard screening procedure for kinetic hydrate additives.publishersversionpublishe

New non-toxic biocompatible dianionic ionic liquids that enhance the solubility of oral drugs from BCS class II

The authors thank Fundação para a Ciência e Tecnologia, FCT/ MCTES (Portugal) for financial support through an Investigator contract (IF/00621/2015 – P.M. Reis), and through projects IF/00621/2015 and CryoDES (PTDC/EQU-EQU/29851/2017). This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme, under grant agreement No ERC-2016-CoG 725034. This work was also partially supported by the Associate Laboratory for Green Chemistry - LAQV which is financed by national funds from FCT/MCTES (UIDB/50006/2020 and UIDP/50006/2020) The NMR spectrometers are part of The National NMR Facility, supported by FCT/MCTES (RECI/BBB-BQB/0230/2012). The authors are grateful for important discussions with PhD Wagner Silva about two-dimensional NOESY 1H-1H experiments.New dianionic ionic liquids (ILs) based on carboxylic anions and ammonium cations were prepared and characterized. They were used as excipients to increase the solubility of two model oral drugs of BCS class II, ibuprofen and piroxicam. With only 0.2 mol% (≈100 mM) of [N4 1 1 2OH]2[C4H4O4], the solubility increases over 40-fold and 2-fold for ibuprofen, when compared with the parent drug for water and phosphate buffer solution (PBS) 0.01M pH=7.4, respectively. With only 0.02 mol% of [N4 1 1 2OH]2[C4H4O4] it is possible to achieve a water solubility of ≈600 mg/L, in only 5 min at 37°C, corresponding to one dose of ibuprofen that an adult can take. Piroxicam also showed an increase of 20-fold and 1.5-fold for water and PBS respectively, with [N4 1 1 2OH]2[C4H4O4] and [N4 1 1 2OH]2[C5H6O4]. The lipophilicity (logP) of both drugs decreased in the presence of these compounds. The cytotoxicity profile of several of these ILs was determined, and all except [N4 1 1 2OH]2[C3H2O4] have an IC50 higher than 100 mM for fibroblasts L929 cells.publishersversionpublishe

Unveiling the Temperature Influence on the Sorptive Behaviour of ZIF-8 Composite Materials Impregnated with [Cn MIM][B(CN)4 ] Ionic Liquids

LA/P/0008/2020 PTDC/CTM-CTM/ 30326/2017Composite sorbent materials (IL@MOF) with a metal-organic framework (MOF) ZIF-8 and [B(CN)4 ]−-based ionic liquids (ILs) were produced for the first time. Characterization results indicate the successful IL impregnation and conservation of the ZIF-8 crystalline structure and morphology. The data collected from the nitrogen (N2 ) physisorption at 77 K suggest that these IL@ZIF-8 materials are nonporous as their textural properties, such as BET specific surface area and total pore volume, are negligible. However, CO2, CH4, and N2 adsorption/desorption measurements in the IL@ZIF-8 composites at 303 and 273 K contradict the N2 data at 77 K, given that the obtained isotherms are Type I, typical of (micro)porous materials. Their gas adsorption capacity and ultramicroporous volume are in the same order of magnitude as the pristine microporous ZIF-8. The case study [C6 MIM][B(CN)4 ] IL revealed a high affinity to both CO2 and CH4 . This compromised the selectivity performance of its respective composite when compared with pristine ZIF-8. This work highlights the importance of accurate experimental gas adsorption/desorption equilibrium measurements to characterize the adsorption uptake and the porous nature of adsorbent materials.publishersversionpublishe

Acoustic determination of thermophysical properties and critical parameters for R404A and critical line of x CO2+(1− x) R404A

The thermophysical properties and critical parameters for the alternative refrigerant R404A (52 wt % of 1,1,1- trifluoroethane (R143a) + 44 wt % of pentafluoroethane (R125) + 4 wt % of 1,1,1,2-tetrafluoroethane (R134a)) were investigated using two different acoustic techniques. The critical behavior of the system xCO2 + (1 - x)R404A was also investigated. Experimental data of speed of sound in liquid R404A from 258 K to 338 K and pressures up to 65 MPa were measured using a pulse-echo method. Derived thermodynamic properties are calculated, combining our experimental data with density and isobaric heat capacity values published by other authors. Measurements of the critical temperature Tc and pressure pc on (R404A) and mixtures of xCO2 + (1 - x)R404A were performed using another simple ultrasonic time-delay technique. The binary critical line was determined over the whole composition range showing that this system deviates only slightly from ideality since the critical line is a continuous line. The Peng-Robinson equation of state with conventional mixing and combining rules was used to correlate the binary experimental data.info:eu-repo/semantics/publishedVersio

Multifunctional magnetoelectric sensing and bending actuator response of polymer-based hybrid materials with magnetic ionic liquids

With the evolution of the digital society, the demand for miniaturized multifunctional devices has been increasing, particularly for sensors and actuators. These technological translators allow successful interaction between the physical and digital worlds. In particular, the development of smart materials with magnetoelectric (ME) properties, capable of wirelessly generating electrical signals in response to external magnetic fields, represents a suitable approach for the development of magnetic field sensors and actuators due to their ME coupling, flexibility, robustness and easy fabrication, compatible with additive manufacturing technologies. This work demonstrates the suitability of magnetoelectric (ME) responsive materials based on the magnetic ionic liquid (MIL) 1-butyl-3-methylimidazolium tetrachloroferrate ([Bmim][FeCl4]) and the polymer poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE) for magnetic sensing and actuation device development. The developed sensor works in the AC magnetic field and has frequency-dependent sensitivity. The materials show voltage responses in the mV range, suitable for the development of magnetic field sensors with a highest sensitivity (s) of 76 mV·Oe−1. The high ME response (maximum ME voltage coefficient of 15 V·cm−1·Oe−1) and magnetic bending actuation (2.1 mm) capability are explained by the magnetoionic (MI) interaction and the morphology of the composites.This work was supported by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding UID/FIS/04650/2020, UID/QUI/00686/2020, LA/P/0008/2020, UIDB/50006/2020 and UIDP/50006/2020. The authors are grateful for funds through FCT under the projects 2022.05932.PTDC, PTDC/BTM-MAT/28237/2017 and PTDC/EMD-EMD/28159/2017 and grant SFRH/BD/145345/2019 (L.C.F). D.M.C. and P.M. thank FCT—Fundação para a Ciência e Tecnologia for the contract under the Stimulus of Scientific Employment, Individual Support 2020.02915.CEECIND and CEECIND/03975/2017, respectively. This study forms part of the Advanced Materials programme and was supported by MCIN with funding from European Union NextGenerationEU (PRTR-C17.I1) and by the Basque Government under the IKUR program. Funding from the Basque Government Industry Departments under the ELKARTEK program is also acknowledged. Technical and human support provided by IZO-SGI, SGIker (UPV/EHU, MICINN, GV/EJ, ERDF and ESF) is gratefully acknowledged

Acoustic determination of thermophysical properties and critical parameters for R410A and critical line of x CO2+(1− x) R410A

The thermophysical properties and critical parameters for the alternative refrigerant R410A (a near azeotropic refrigerant mixture containing difluoromethane (R32) and pentafluoroethane (R125) (50 wt % of each)) were investigated using two different acoustic techniques. The critical behavior of the system xCO2 + (1 - x)R410A was also investigated. Experimental data of speed of sound in liquid R410A from (253 to 338) K and pressures up to 65 MPa were measured using a pulse-echo method. Derived thermodynamic properties were calculated, combining our experimental data with density and isobaric heat capacity values published by other authors. Measurements of the critical temperature Tc and pressure pc on (R410A) and mixtures of xCO2 + (1 - x)R410A were performed using another simple ultrasonic time-delay technique. The binary critical line was determined over the whole composition range, showing that this system deviates only slightly from ideality since the critical line is a continuous line. The Peng-Robinson equation of state with conventional mixing and combining rules was used to correlate the binary experimental data.info:eu-repo/semantics/publishedVersio

Electrochemical applications of electrolytes based on ionic liquids

The potential utility of room temperature ionic liquids as electrolytes in current electrochemical applications has been explored. Hence, the electrochemical behavior of [Ni(tmc)]Br2 complex at a glassy carbon electrode in the absence or in the presence of unsaturated halides in the ionic liquids, 1-ethyl-3- methylimidazolium ethylsulfate, [C2mim][C2SO4] and N,N,Ntrimethyl- N-(2-hydroxyethyl) ammonium bis(trifluoromethylsulfonyl)imide, [N1 1 1 2(OH)][NTf2], has been examined by cyclic voltammetry. It was observed that [Ni(tmc)]2+ complex is reduced in a reversible one-electron step and the electrogenerated [Ni(tmc)]+ complex catalytically reduces the carbon-halogen bond of unsaturated halides. The potencial use of natural ionic conducting polymer matrixes was also investigated. Samples of natural macromolecules-based electrolytes with the ionic liquid 1-ethyl- 3-methylimidazolium ethylsulfate, [C2mim][C2SO4], were prepared and characterized. The preliminary studies carried out with electrochromic devices (ECDs) incorporating optimized compositions have confirmed that these materials may perform as satisfactory multifunctional component layers in the field of ECD-based devices.Fundação para a Ciência e a Tecnologia (FCT

Biocompatible ammonium-based ionic liquids/ZIF-8 composites for CO2/CH4 and CO2/N2 separations

The authors thank Fundação para a Ciência e Tecnologia, FCT/ MCTES (Portugal), for financial support through PhD grant SFRH/BD/ 139627/2018 (T. J. F.), FCT Investigator contract (IF/00621/2015 – P. M. R). Additionally, the work was also partially supported by the Associate Laboratory for Green Chemistry, LAQV, which is funded by national funds from FCT/MCTES (LA/P/0008/2020).The development of sorbent materials with high carbon dioxide (CO2) selectivity is of vital importance to minimize the impact of global warming by separating and capturing this major greenhouse gas. In this work, for the first time five ammonium-based ionic liquids (ILs) were impregnated into the metal-organic framework (MOF) ZIF-8 for gas sorption applications. Characterization results showed that the produced IL@ZIF-8 composites are thermally stable and of microporous nature. IL impregnation was successfully accomplished and did not affect the crystalline structure of ZIF-8. Sorption-desorption equilibrium isotherms of different gases, including CO2, methane (CH4) and nitrogen (N2) were measured at 303 K for the pristine MOF and the composites. Given the careful choice of the ILs, the anion and cation effects were studied in terms of their impact on the sorption capacity and selectivity performance of each composite. Acetate-based composites showed high CO2 selectivity when compared to ZIF-8; specifically, the composite [N2 1 1 4][Ac]@ZIF-8 showed 51% increase, at 1 bar and for flue gas conditions. Because of the good CO2/N2 selectivity of the acetate-based composites, sorption-desorption equilibrium isotherms of the above-mentioned gases were also measured at 323 K, along with ZIF-8. Ideal selectivities were thus calculated to study the temperature impact on the selectivity performance of the materials. It can be observed that the higher the temperature, the less selective the materials are. Nevertheless, at 323 K and when compared to ZIF-8, the composite [N2 1 1 4][Ac]@ZIF-8 showed 56% increase, at 1 bar and for flue gas conditions. Finally, the isosteric heats of adsorption of ZIF-8 and the acetate-based ILs were calculated revealing that all gases are physisorbed by the three materials.publishersversionpublishe