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  • 1.
    Bhattacharyya, Shubhankar
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Shah, Faiz Ullah
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Thermal stability of choline based amino acid ionic liquids2018In: Journal of Molecular Liquids, ISSN 0167-7322, E-ISSN 1873-3166, Vol. 266, p. 597-602Article in journal (Refereed)
    Abstract [en]

    Thermal stability of different choline based amino acid ionic liquids were studied. Both short term as well as long term thermal studies were carried out. Long term thermal studies of all ILs were carried out by isothermal TGA and short term thermal studies were measured by temperature ramped TGA. Isothermal TGA were studied at two different temperatures 100 °C and 150 °C for 500 min. Whereas, short term thermal stability represents as T2%, T5% and T10% which are the temperature at which 2%, 5% and 10% mass loss of ILs were observed. The effect of alkyl side chain on the cation, etherification of the cation as well structural variation of anion on the thermal stability of choline based ILs were investigated. It was observed that thermal characteristics of ILs towards temperature ramped TGA were different compared to isothermal TGA.

  • 2.
    Filippov, Andrei
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering. Kazan State Medical University, Kazan, Russia.
    Antzutkin, Oleg
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering. Department of Physics, Warwick University, Coventry, UK.
    Shah, Faiz Ullah
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Reactivity of CO2 with aqueous choline-based ionic liquids probed by solid-state NMR spectroscopy2019In: Journal of Molecular Liquids, ISSN 0167-7322, E-ISSN 1873-3166, Vol. 286, article id 110918Article in journal (Refereed)
    Abstract [en]

    CO2 absorption in a series of choline-based ionic liquids is investigated using solid-state 13C and 15N MAS NMR spectroscopy. Natural abundance and 13C enriched CO2 gas was purged through 50 wt% aqueous solutions of alkyldimethyl(2-hydroxyethyl)ammonium threonine, [N1,1,n,2OH][Threo], (alkyl = butyl, pentyl and hexyl) and pentyldimethyl(2-hydroxyethyl)ammonium taurine [N1,1,5,2OH][Tau]. The process of CO2 absorption results in precipitation of a solid sediment, which stays in equilibrium with the liquid phase. Upon degassing of the sample, the sediment is dissolved back into the IL-aqueous phase. Solid state 13C and 15N MAS NMR data suggest that the solid sediment is composed of neutral threonine (or taurine) in the zwitterionic forms and the liquid phase contained the products of reactions between the ionic liquids and CO2 molecules. A plausible mechanism for formation of the solid sediments and the reaction products in liquid phases is suggested.

  • 3.
    Filippov, Andrei
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering. Institute of Physics, Kazan Federal University, Russia.
    Bhattacharyya, Shubhankar
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Shah, Faiz Ullah
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    CO2 absorption and ion mobility in aqueous choline-based ionic liquids2019In: Journal of Molecular Liquids, ISSN 0167-7322, E-ISSN 1873-3166, Vol. 276, p. 748-752Article in journal (Refereed)
    Abstract [en]

    CO2 absorption and ion mobility are investigated in a series of 50/50 wt% aqueous solutions of choline-based ionic liquids with different cations and anions: [N1,1,4,2OH][Threo], [N1,1,5,2OH][Threo], [N1,1,6,2OH][Threo], [N1,1,5,2OH][β-ala] and [N1,1,5,2OH][Tau]. The process of CO2 absorption was completed in an hour reaching maximum of absorption capacity 0.07–0.10 wt% to ionic liquid (by 0.4–0.6 molar ratios). A rapid CO2 absorption is observed by the formation of solid product as a result of reaction between CO2 molecule and the ionic liquid. Diffusion coefficients of the cation and anion in the mixture are comparable while the diffusivity of water molecules is found to be quite different from the ions. In the process of CO2 absorption, an increase in the diffusivity of ions is observed due to the precipitation of solid products and depletion of ions contents in the liquid phase of the system. 13C NMR measurements of diffusivity of CO2 enriched with 13C isotope showed that a part of the absorbed CO2 remained in the liquid phase being physically and chemically bound to ions. The ionic liquid is re-cycled by evaporating water and releasing CO2 molecules using vacuum and temperature.

  • 4.
    Filippov, Andrei
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering. Institute of Physics, Kazan Federal University.
    Gnezdilov, Oleg I.
    Institute of Physics, Kazan Federal University.
    Antzutkin, Oleg
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering. Department of Physics, Warwick University, Coventry.
    Static magnetic field alters properties of confined alkylammonium nitrate ionic liquids2018In: Journal of Molecular Liquids, ISSN 0167-7322, E-ISSN 1873-3166, Vol. 268, p. 49-54Article in journal (Refereed)
    Abstract [en]

    Ethylammonium nitrate (EAN) and propylammonium nitrate (PAN) ionic liquids confined between polar glass plates and exposed to a strong magnetic field of 9.4 T demonstrate gradually slowing diffusivity, a process that can be reversed by removing the sample from the magnetic field. The process can be described well by the Avrami equation, which is typical for autocatalytic (particularly, nucleation controlled) processes. The transition can be stopped by freezing the sample. Cooling and heating investigations showed differences in the freezing and melting behavior of the sample depending on whether it had been exposed to the magnetic field. After exposure to the magnetic field, the sample demonstrated decrease in the 1H NMR signal of residual water. 1H NMR spectroscopy with presaturation demonstrates that the most probable mechanism of the decrease of the bulk water signal is adsorption of water on polar surfaces of glass plates. Generally, our findings confirm our previous suggestion that alteration of the dynamic properties of confined alkylammonium nitrate ionic liquids exposed to a magnetic field is related to the alteration of real physical-chemical phases

  • 5.
    Filippov, Andrei
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering. Kazan State Medical University, Kazan, Russia.
    Gnezdilov, Oleg I.
    Kazan Federal University, Kazan, Russia. Zavoisky Physical-Technical Institute, FRC Kazan Scientific Center, Russian Academy of Sciences, Kazan, Russia.
    Luchkin, Alexander G.
    Kazan Federal University, Kazan, Russia.
    Antzutkin, Oleg
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Self-diffusion of ethylammonium nitrate ionic liquid confined between modified polar glasses2019In: Journal of Molecular Liquids, ISSN 0167-7322, E-ISSN 1873-3166, Vol. 284, p. 366-371Article in journal (Refereed)
    Abstract [en]

    Ethylammonium nitrate (EAN) ionic liquid confined between flat polar glass platesdemonstrates variable diffusivity that is sensitive to an external static magnetic field. Outside the magnetic field, diffusivity between the plates is higher than that in the bulk. However, after placing the system in a strong static magnetic field, the diffusivity gradually decreased. These processes occur during transformations between phases formed in EAN subjected to micrometer-size restrictions outside and within the magnetic field (Filippov et al., JMolLiq. [2018] 268, 49). In this study, we used samples of two types: (i) with roughened surface formed by treatment of the glass plates with aqueous solutions of hydrofluoric acid and (ii) with vacuum deposited TiO2 layers with a thickness of ca. 1 μm at glass-plate edges. Neither the surface modification of the glass plates, nor the TiO2 layers controlled thickness of EAN confined between glass-plates significantly changed the above-described effects, which have been observed in studies using untreated glass plates. Therefore, the range of systems with detected phase transformations in EAN and accompanying effects, such as accelerated diffusivity and change in diffusivity under the influence of a static magnetic field, was expanded to the systems with roughened surfaces and the systems with TiO2 layers controlled inter-plates distances. Results of experiments with roughened surfaces additionally suggested that the phase transformation of confined EAN in the external magnetic field is isotropic in nature rather than a phase transition from “layered to bulk” structures.

  • 6.
    Filippov, Andrei
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering. Kazan State Medical University, Kazan, Russian Federation.
    Kurakin, S.
    Institute of Physics, Kazan Federal University, Kazan, Russian Federation.
    Gnezdilov, O.I.
    Institute of Physics, Kazan Federal University, Kazan, Russian Federation.
    Antzutkin, Oleg
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering. Department of Physics, Warwick University, Coventry, United Kingdom.
    Effect of magnetic field on diffusion of ethylammonium nitrate: water mixtures confined between polar glass plates2018In: Journal of Molecular Liquids, ISSN 0167-7322, E-ISSN 1873-3166, Vol. 4, p. 45-51Article in journal (Refereed)
    Abstract [en]

    We used 1H NMR diffusometry to study mixtures of ethylammonium nitrate (EAN) with water (3.1–12.4 mol% of added H2O) confined between polar glass plates and exposed to a static magnetic field of 9.4 T. The presence of such restrictions reverses the concentration dependence of the diffusivities of the EA (ethylammonium) cation and water typical for the bulk system. The presence of water weakens the effects of a static magnetic field on diffusion of the EA cation as well as on proton exchange of –NH3 groups. Surprisingly, the amplitude of the echo signal of water protons decreases during exposure to the magnetic field and finally disappears, a phenomenon that depends on the concentration of water in the system. Based on experimental data, we suggest that water in the system is present in two states with different dynamic properties. One type of water formed in confinement possesses NMR relaxation time typical for liquids; its diffusivity can be measured by 1H NMR. The second type of water is formed upon exposure of the sample of the first type to the magnetic field and eventually includes all the water in the system. This type of water possesses “solid-like” NMR relaxation features that makes it “invisible” to the NMR diffusometry technique. We suggest that this second type of water is adsorbed onto the glass plates. Correspondingly, EAN exists in two liquid phases: the first one contains an EAN-water mixture, while the second one contains neat EAN, and forms on the microscopic scale range under the influence of a static magnetic field.

  • 7.
    Gusain, Rashi
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering. Chemical Science Division, CSIR-Indian Institute of Petroleum, Dehradun.
    Panda, Somenath
    Department of Chemistry, Indian Institute of Technology Madras, Chennai.
    Bakshi, Paramjeet Singh
    Chemical Science Division, CSIR-Indian Institute of Petroleum, Dehradun.
    Gardas, Ramesh L.
    Department of Chemistry, Indian Institute of Technology Madras, Chennai.
    Khatri, Om Prakash
    Chemical Science Division, CSIR-Indian Institute of Petroleum, Dehradun.
    Thermophysical properties of trioctylalkylammonium bis(salicylato)borate ionic liquids: Effect of alkyl chain length2018In: Journal of Molecular Liquids, ISSN 0167-7322, E-ISSN 1873-3166, Vol. 269, p. 540-546Article in journal (Refereed)
    Abstract [en]

    Thermophysical properties of halogen-free ionic liquids are gaining significant attention for industrial applications. In this context, trioctylalkylammonium bis(salicylato)borate (N888n-BScB) ionic liquids having variable alkyl chain length (n = 4, 8, 12, 16) are synthesized to explore the effect of chain length and temperature on their physicochemical properties. The density (ρ), refractive index (nD), and speed of sound (u) are measured in the temperature range of 293.15 to 333.15 K. The tetraoctylammonium-BScB is found to be highly dense ionic liquid, and it was attributed to the closer packing of symmetric structure of tetraoctylammonium cation. Furthermore, derived thermodynamic properties such as isentropic compressibility (βs), coefficient of thermal expansion (α), standard entropy (S°), intermolecular free length (Lf) and lattice energy (UPOT) are calculated for the N888n-BScB ionic liquids using the experimental data and shown the effect of variable chain length. This study provides a comprehensive insight on the thermophysical properties of halogen-free ionic liquids.

  • 8.
    Liu, Yanrong
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science. CAS Key Laboratory of Green Process and Engineering, Beijing Key Laboratory of Ionic Liquids Clean Process, State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, PR China.
    Nie, Yi
    CAS Key Laboratory of Green Process and Engineering, Beijing Key Laboratory of Ionic Liquids Clean Process, State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, PR China.
    Pan, Fengjiao
    CAS Key Laboratory of Green Process and Engineering, Beijing Key Laboratory of Ionic Liquids Clean Process, State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, PR China.
    Zhou, Le
    CAS Key Laboratory of Green Process and Engineering, Beijing Key Laboratory of Ionic Liquids Clean Process, State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, PR China.
    Ji, Xiaoyan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Kang, Zhaoqing
    CAS Key Laboratory of Green Process and Engineering, Beijing Key Laboratory of Ionic Liquids Clean Process, State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, PR China.
    Zhang, Suojiang
    CAS Key Laboratory of Green Process and Engineering, Beijing Key Laboratory of Ionic Liquids Clean Process, State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, PR China.
    Study on ionic liquid/cellulose/coagulator phase diagram and its application in green spinning process2019In: Journal of Molecular Liquids, ISSN 0167-7322, E-ISSN 1873-3166, Vol. 289, article id 111127Article in journal (Refereed)
    Abstract [en]

    In this work, the cellulose phase separation behavior was investigated by using ionic liquids (ILs) as novel solvents to acquire a green process for cellulose fiber spinning. The cloud point titration method combined with the turbidity correlation equation was used to obtain the ternary diagram of IL/cellulose/coagulator throughout the whole compositional range. The effects of the type of ILs, the cellulose materials, the kind of coagulators and the regeneration temperatures for cellulose fiber manufacturing process on the phase separation behavior were studied systematically. It was found that the linearized cloud point (LCP) curve correlation fits to experimental data well and can be used to quantify the optimized coagulator, and among the studied cases, the system of [EMIM]DEP, cotton pulp and water with the regeneration temperature at 298.15 K is the best. Meanwhile, COSMO-RS was used to predict the interaction between solvent, cellulose and coagulator, and the comparison with the LCP correlation shows good agreement. The crystal structure of the regenerated cotton pulp was determined with XRD, and the result evidences that the crystal structure of the regenerated cellulose transforms from cellulose I to cellulose II. The crystallinity decreases from 96.0% (raw cotton pulp) to 85.6% after 24 h dissolution in [EMIM]DEP at 363.15 K, and it has a slight deviation from 24 h to 72 h, which illustrates that the spinning process can run continuously at 363.15 K when using [EMIM]DEP as the solvent.

  • 9.
    Mu, Liwen
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements. The University of Akron, Akron, USA.
    Ma, Xiaofeng
    Nanjing Forestry University, Nanjing, PR China.
    Guo, Xiaojing
    Chinese Academy of Sciences, Shanghai, PR China.
    Chen, Minjiao
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Ji, Tuo
    The University of Akron, Akron, USA.
    Hua, Jing
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Zhu, Jiahua
    The University of Akron, Akron, USA.
    Shi, Yijun
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Structural strategies to design bio-ionic liquid: Tuning molecular interaction with lignin for enhanced lubrication2019In: Journal of Molecular Liquids, ISSN 0167-7322, E-ISSN 1873-3166, Vol. 280, p. 49-57Article in journal (Refereed)
    Abstract [en]

    Lignin strengthened ionic liquids (ILs) have shown high potential to be used as high performance green lubricants. Strengthened lignin-ILs molecular interaction is an effective approach to improve their lubrication properties. The molecular interactions of ILs’ cation and anion containing different functional groups with lignin and efficiency on the lubricating properties have rarely been studied yet. In this work, a series of novel green lubricants with dissolved lignin in [Choline][Amino Acid] ([CH][AA]), [Tetramethylammonium][Glycine] ([N 1111 ][Gly]) and [Tetrabutylammonium][Glycine] ([N 4444 ][Gly]) ILs have been synthesized and their tribological properties were systematically investigated. The longer alkyl chain in cation without reciprocal H-bond interaction between ILs’ cation and anion has the positive effect on the anti-wear properties. In addition, the less steric effect and more negative natural charges of amino acid anion synergistically contribute to the stronger H-bond interaction between lignin and choline base ILs, which enhances lubrication film strength and thus resulting in the better tribological property of ILs/lignin green lubricants. Specifically, the wear volume loss of the steel disc lubricated by [N 4444 ][Gly] with the addition of 15% lignin is only 12% of the one lubricated by pure [N 4444 ][Gly]. This work presents a method to tune molecular interaction between lignin and ILs via the structural design of ILs’ cation and anion, which are revealed as the key factor that bridges the individual components and improves overall lubricating properties. 

  • 10.
    Zhu, Wei
    et al.
    College of Chemical Engineering, State Key Laboratory of Materials-oriented Chemical Engineering, Nanjing Tech University, Nanjing, PR China.
    Zhang, Cheng
    College of Chemical Engineering, State Key Laboratory of Materials-oriented Chemical Engineering, Nanjing Tech University, Nanjing, PR China.
    Zhu, Yu-dan
    College of Chemical Engineering, State Key Laboratory of Materials-oriented Chemical Engineering, Nanjing Tech University, Nanjing, PR China.
    An, Rong
    Herbert Gleiter Institute of Nanoscience, Nanjing University of Science & Technology, Nanjing, China.
    Lu, Xiao-hua
    College of Chemical Engineering, State Key Laboratory of Materials-oriented Chemical Engineering, Nanjing Tech University, Nanjing, PR China.
    Shi, Yi-jun
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Jiang, Sheng-yu
    College of Chemical Engineering, State Key Laboratory of Materials-oriented Chemical Engineering, Nanjing Tech University, Nanjing, PR China.
    Molecular insights on the microstructures of nanoconfined glycerol and its aqueous solutions: The effects of interfacial properties, temperature, and glycerol concentration2019In: Journal of Molecular Liquids, ISSN 0167-7322, E-ISSN 1873-3166, Vol. 291, article id 111238Article in journal (Refereed)
    Abstract [en]

    In this work, we conducted molecular dynamics simulations to investigate the effects of rutile–liquid and graphene–liquid interfacial properties, glycerol concentrations (i.e., 10%, 40%, 70%, and 100% molar contents), and temperature (i.e., 180, 273, and 320 K) on the microstructures of nanoconfined glycerol and its aqueous solutions. Results indicated that the effect of interfacial properties on the spatial and orientation distributions of nanoconfined glycerol and water molecules was more prominent than that of temperature. In glycerol aqueous solutions, water and glycerol molecules localized into two distinct layers on the hydrophilic rutile surface but partially mixed with each other near the hydrophobic graphene surface, because water molecules near the hydrophobic surface exhibited more random orientations and formed more hydrogen bonds with glycerol molecules than those near the hydrophilic surface. Moreover, interface introduction and increased temperature drastically reduced the hydrogen bonding ability of water molecules in glycerol aqueous solutions. The addition of glycerol molecules can break hydrogen bonds between water molecules and inhibit water crystallization in glycerol aqueous solutions. Temperature and glycerol concentration exerted limited effects on the hydrogen bonding ability of water molecules on hydrophilic surfaces in glycerol aqueous solutions. Meanwhile, the presence of a hydrophilic surface can effectively decelerate hydrogen bond breakage induced by increasing temperature or by decreasing glycerol contents

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