Gas hydrates inhibition via combined biomolecules and synergistic materials at wide process conditions

The motive of this research to present a systematic study in context of implementation of gas hydrate inhibitors that are obtained via naturally occurring amino acids (L-Alanine, Glycine, L-Histidine, L-Phenylalanine and L-Asparagine). These materials are tested for methane (CH4) hydrate inhibition purposes from both thermodynamically and kinetically perspectives at wide process conditions. In this presented work, all studied amino acids have been tested at both 1 wt % as low dosage inhibitors as well as at higher concentrations up to 5 wt %. Furthermore, Polyethylene-oxide (PEO) and Vinyl Caprolactum (VCap) were used at 1 wt % in studied aqueous solutions as synergetic compounds to enhance the inhibition performance for CH4 hydrate inhibition. Gas hydrate experiments were carried out by using rocking cell apparatus, from which pressure, temperature equilibrium data were obtained at recorded time and these data were translated into inhibitor performance evaluation from both thermodynamics and kinetic inhibition perspectives. This study includes the discussions of the effect of solubility limitation of studied amino acids, the effect of inhibitor concentration effect on the thermodynamic shift of the hydrate equilibrium curve, the role of side chain in amino acids in kinetic hydrate inhibition, the hydrophobic interactions of alkyl chain in water for synergistic point of view. The results showed that the suitability of amino acids combined with synergistic materials for high kinetic inhibition performance, which provided an additional time shift up to 35 h in hydrate formation at moderate process conditions up to 55 bars, specifically when L-Alanine was used.This work was made possible by NPRP grant # 6-330-2-140 and GSRA # 2-1-0603-14012 from the Qatar National Research Fund (a member of Qatar Foundation). The statements made herein are solely the responsibility of the authors.Scopu

On the viscosity of two 1-butyl-1-methylpyrrolidinium ionic liquids: Effect of the temperature and pressure

A new calibration procedure was used and four new temperatureprobes have been placed on afalling-body viscometer to improve its accuracy. The new configuration and calibrationprocedure allow measuring viscosities with an uncertainty of 3.5% at pressures up to 150 MPa.This device was employed to measure viscosities as a function of temperature and pressure fortwo ionic liquids (ILs): 1-butyl-1-methylpyrrolidiniumtris(pentafluoroethyl)trifluorophosphateand 1-butyl-1-methylpyrrolidinium trifluoromethanesulfonate.Besides, we have measured the flow curves at pressures up to 75 MPa and shear rates up to1000 s-1in a Couette rheometer. Dynamic viscosities were correlated as function of temperature and pressure with four differentequations with average absolute deviation lower than 1%. The pressure-viscosity and temperature-viscosity derived properties were analyzed and compared with those of other ionic liquids. Furthermore, experimental data were used to check the application of the thermodynamic scaling approach as well as the hard-sphere scheme. Both models represent the viscosity values with average relative deviations lower than 2%

Impact of opioid-free analgesia on pain severity and patient satisfaction after discharge from surgery: multispecialty, prospective cohort study in 25 countries

Background: Balancing opioid stewardship and the need for adequate analgesia following discharge after surgery is challenging. This study aimed to compare the outcomes for patients discharged with opioid versus opioid-free analgesia after common surgical procedures.Methods: This international, multicentre, prospective cohort study collected data from patients undergoing common acute and elective general surgical, urological, gynaecological, and orthopaedic procedures. The primary outcomes were patient-reported time in severe pain measured on a numerical analogue scale from 0 to 100% and patient-reported satisfaction with pain relief during the first week following discharge. Data were collected by in-hospital chart review and patient telephone interview 1 week after discharge.Results: The study recruited 4273 patients from 144 centres in 25 countries; 1311 patients (30.7%) were prescribed opioid analgesia at discharge. Patients reported being in severe pain for 10 (i.q.r. 1-30)% of the first week after discharge and rated satisfaction with analgesia as 90 (i.q.r. 80-100) of 100. After adjustment for confounders, opioid analgesia on discharge was independently associated with increased pain severity (risk ratio 1.52, 95% c.i. 1.31 to 1.76; P < 0.001) and re-presentation to healthcare providers owing to side-effects of medication (OR 2.38, 95% c.i. 1.36 to 4.17; P = 0.004), but not with satisfaction with analgesia (beta coefficient 0.92, 95% c.i. -1.52 to 3.36; P = 0.468) compared with opioid-free analgesia. Although opioid prescribing varied greatly between high-income and low- and middle-income countries, patient-reported outcomes did not.Conclusion: Opioid analgesia prescription on surgical discharge is associated with a higher risk of re-presentation owing to side-effects of medication and increased patient-reported pain, but not with changes in patient-reported satisfaction. Opioid-free discharge analgesia should be adopted routinely

Insights into Tris-(2-Hydroxylethyl)methylammonium Methylsulfate Aqueous Solutions

We report herein a combined experimental–computational study on tris-(2-hydroxylethyl)methylammonium methylsulfate in water solutions, as a representative ionic liquid of the aqueous-solution behavior of hydroxylammonium-based ionic liquids. Relevant thermophysical properties were measured as a function of mixture composition and temperature. Classical molecular dynamics simulations were performed to infer microscopic structural features. The reported results for ionic liquid in water-rich solutions show that it behaves as isolated non-interacting ions solvated by water molecules, through well-defined solvation shells, exerting a disrupting effect on the water hydrogen bonding network. Nevertheless, as ionic liquid concentration increase, interionic association increases, even for diluted water solutions, evolving from the typical behavior of strong electrolytes in solution toward large interacting structures. For ionic-liquid-rich mixtures, water exerts a minor disrupting effect on the fluid’s structuring because it occupies regions around each ion (developing water–ion hydrogen bonds) but without significantly weakening anion–cation interactions.* Ministerio de Ciencia e Innovación. Grant Number: CTQ2010-15871 * NPRP. Grant Number: NPRP-09-739-2-284Wiley Online librar

Review on the Use of Ionic Liquids (ILs) as Alternative Fluids for CO2 Capture and Natural Gas Sweetening

The capture of CO2 from flue gases derived from fossil-fueled power plants and the absorption of CO2/H2S for natural gas sweetening purposes are two relevant industrial problems closely related to very important environmental, economical, and technological problems that need to be solved. Amine-based technologies are widely used in the industry for these purposes, but they lead to several problems that have led many researchers to pose new alternatives. Ionic liquids (ILs) have emerged in the last few years as promising new acid gas absorbents, and thus, this remarkable interest, in both industry and academia, has led to a large collection of experimental and theoretical studies in which the most important aspects of the absorption process are analyzed. In this review, we show the most relevant conclusions obtained from the analysis of the literature, analyzing the state-of-the-art results, trying to infer the viability of ILs as an alternative to the available amine-based absorption processes, and showing the possible future directions of research. ? 2010 American Chemical Society.Scopu

The impact of charges in force field parameterization for molecular dynamics simulations of deep eutectic solvents

The nanoscopic characteristics and macroscopic physicochemical properties of choline chloride:levulinic acid (1:2 mole ratio) deep eutectic solvent are analyzed from molecular dynamics simulations. Considering the ionic character of some of the involved molecules, the influence of several charge schemes in the applied force field parameterization was studied. Assessed charge schemes include atomic charges obtained from wavefunctions (Mulliken, NPA, L?wdin, Mayer), electrostatic potentials (ChelpG, MK), spectroscopic data (APT) and partitioning of the electronic densities (Hirshfeld, VDD, AIM). Molecular dynamics simulations were carried out using these ten charge schemes with the remaining force field parameters being constant. The reported results show the remarkable role of the used charges in the results from molecular dynamics simulations, with large differences both in the predicted macroscopic properties. This work shows the need of using suitable charge models for developing reliable and accurate molecular dynamics simulations of deep eutectic solvent structuring. Charges from electrostatic potentials along to cluster approach should be the most adequate option for developing force field parameterization in deep eutectic solvents.Ministerio de Economia y Competitividad (Spain, project CTQ2013-40476-R) and Junta de Castilla y Leon (Spain, project BU324U14). Gregorio Garcia acknowledges the funding by Junta de Castilla y Leon, cofunded by European Social Fund, for a postdoctoral contract.Scopu

Viscous origin of ionic liquids at the molecular level: A quantum chemical insight

The viscosity of selected families of ionic liquids has been assessed at the molecular level as a function of the intermolecular interactions using Density Functional Theory together with Atoms-in-a-Molecule and Natural Bond Orbitals approaches. Large ion clusters were studied, with the energetics and topology of interactions being related with experimental viscosity data to infer nanoscopic mechanisms controlling the viscous behavior. The reported results exhibit important information on the molecular basis controlling viscosity, which would allow advancing in the development of low-viscous ionic liquids, through a judicious selection of ion pairs considering their interactions and molecular structure.Junta de Castilla y Leon, cofunding by European Social FundScopu

Effectiveness of pyrrolidinium based ionic liquids in flow assurance: Preventing hydrates formation in offshore sub-sea pipelines

[No abstract available]Scopu

Nanoscopic characterization of type II porous liquid and its use for CO2 absorption from molecular simulation

The properties of cage(33:133) macrocycle in perchloropropene (PCP) as model for type II porous liquids were studied using molecular simulation tools. Likewise, the behaviour of CO2 in these porous liquid phases were studied to analyse the nanoscopic mechanism for carbon capture purposes. Quantum chemistry calculations using Density Functional Theory were carried out to characterize the intermolecular forces between cage, solvent and CO2 molecules. Molecular dynamics simulations of liquid phases at different cage concentration provides information on the structuring, aggregation, solvation and dynamic properties of these porous liquids. The reported results led to a full characterization of the features controlling type II porous liquids properties as well as the behaviour of carbon dioxide in them, thus providing the required information for the proper design of porous liquids and their use for carbon capturing operations. The nanoscopic structure of the studied fluids showed that it is possible to solubilize suitable amounts of the cages in the solvents to develop a network of pores in the liquid to capture CO2 in an efficient way

Theoretical study on the solvation of C60 fullerene by ionic liquids

The solvation of C60 fullerene by 24 different ionic liquids belonging to the imidazolium, piperazinium, and cholinium families was analyzed from a nanoscopic viewpoint using classic molecular dynamics simulations and Density Functional Theory (DFT) methods. Charge transfer between the ions and fullerene were computed by DFT. Force field parametrization used in molecular dynamics simulations was corrected to reproduce DFT ion-C60 interaction mechanism. Structural, dynamic, and energetic factors were analyzed to infer the role of the studied ions on the behavior of fullerenes in ionic liquids. The intermolecular ion-C60 interaction energy controls the behavior of these fluids, leading to prevailing roles by interaction mechanism through the ? system of C60 nanoparticle, both for anions and cations.Junta de Castilla y Leon, cofunded by European Social Fund.Scopu