Faculty of Applied Sciences
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Item Influence of epoxy group in 2-pyrrolidonium ionic liquid interactions and thermo-physical properties with Ethanoic or Propanoic acid at various temperatures(ACS Publications, 2016) Vasanthakumar, Arumugam; Redhi, Gan G.; Gengan, Robert MoonsamyIn this present study, the interaction between a carboxylic acid and ionic liquids, in terms of their binary mixtures and corresponding thermo-physical properties, was investigated. Here, the novel ionic liquid (IL) [EPMpyr]+[Cl]− was synthesized, and it has been mixed with ethanoic or propanoic acids. The influence of the epoxy group in this ionic liquid was more strongly affected with the acids, and their physicochemical properties at varied temperatures are discussed in term of density (ρ), viscosity (η), speed of sound (u), and refractive index (n) measurements. The density (ρ), speed of sound (u), viscosity (η), and refractive index (n) of the IL, ethanoic acid, propanoic acid, and their corresponding binary mixtures {[([EPMpyr]+[Cl]− (1) + ethanoic or propanoic acid (2)} have been measured at T = (293.15–313.15) K and at P = 0.1 MPa. The theoretical thermodynamic properties of excess molar volumes (VmE), isentropic compressibility (ks), deviation in isentropic compressibility (Δks), and intermolecular free length (Lf) are calculated using experimental density and speed of sound data. The VmE and Δks values for both binary mixtures were found to be negative over the entire mole fraction range of composition at all the investigated temperatures. These results suggest the existence of specific interactions between components in the molecules. The experimental data could be helpful to understand the molecular interactions between the IL and carboxylic acid combinations. The experimental data were fitted to the Redlich–Kister polynomial equation.Item Influence of temperature on molecular interactions of imidazolium-based ionic liquids with acetophenone: thermodynamic properties and quantum chemical studies(Royal Society of Chemistry, 2016) Bahadur, Indra; Masilo, Kgomotso; Ebenso, Eno, E.; Redhi, Gan G.The physicochemical properties namely: densities (ρ), sound velocities (u), viscosities (η), and refractive indices (nD) of a series of alkyl imidazolium-based ionic liquids (ILs) with same cation and different anion and vice versa of ILs: 1-butyl-3-methylimidazolium tetrafluoroborate [BMIM]+[BF4]−, 1-butyl-3-methylimidazolium hexafluorophosphate [BMIM]+[PF6]−, 1-ethyl-3-methylimidazoium ethyl sulphate [EMIM]+[EtSO4]− and 1-ethyl-3-methylimidazolium tetrafluoroborate [EMIM]+[BF4]−, with acetophenone over the wide range of composition and at (293.15, 303.15, 313.15, 323.5 and 333.15) K under atmospheric pressure is reported in this study. The excess molar volumes, (VEm), deviation in isentropic compressibilities (Δκs), deviation in viscosities (Δη) and deviation in refractive indices (ΔnD) were derived from experimental results. The VEm, Δκs and ΔnD values for the mentioned systems are both negative and positive over the entire composition range while the Δη values are negative under the same experimental conditions. The derived properties were fitted to the Redlich–Kister polynomial equation to check the accuracy of experimental results. Furthermore, the inter-ionic interactions between the cations and anions of the ILs both in vacuo and in acetophenone (using continuum solvation) were confirmed using quantum chemical technique such as [Density Functional Theory (DFT)]. The quantum chemical results are in good agreement with the experimental results suggesting that there exist appreciable interactions between the ILs and acetophenone. The theoretical and measured data were interpreted in terms of intermolecular interfaces and structural effects between similar and dissimilar molecules upon mixing in order to obtain more information on the thermophysical and thermodynamic properties of ILs and their binary mixtures. This study will contribute to the data bank of thermodynamic properties of IL mixtures, so as to establish principles for the molecular design for chemical separation processes and to enhance the applications of ILs in certain aspects of research or industrial application.Item Synthesis and characterization of 2′,3′-epoxy propyl-N-methyl-2-oxopyrrolidinium salicylate ionic liquid and study of its interaction with water or methanol(Royal Society of Chemistry, 2016) Vasanthakumar, Arumugam; Bahadur, Indra; Redhi, Gan G.; Gengan, Robert MoonsamyImportant physico-chemical properties of ionic liquids (ILs) can be manipulated by adjusting the nature of the cation or anion. These properties are exploited in applications such as organic synthesis, catalysis and electrochemical processes to mention a few. In this work, the novel pyrrolidone ionic liquid N-(2′,3′-epoxypropyl)-N-methyl-2-oxopyrrolidinium salicylate [EPMpyr]+[SAL]− was synthesized using two steps and characterized. The temperature dependent density and speed of sound for ionic liquid, methanol, water, and their corresponding binary mixtures of {IL (1) + methanol or water (2)} were measured over the entire range of mole fractions at temperatures from T = (293.15 to 313.15) K in steps of 5 K, under atmospheric pressure. The calculated thermodynamic properties such as excess molar volume VEm, isentropic compressibility ks, intermolecular free length Lf, and deviation in isentropic compressibility Δks, were derived from the investigated density and speed of sound data. The resulting experimental data for excess molar volumes VEm, intermolecular free length Lf, and deviation in isentropic compressibility Δks, were well fitted to the Redlich–Kister polynomial equation. The effect of temperature and concentration on thermophysical properties was also provided.Item Efficient catalytic activity of ionic liquid-supported NiFe2O4 magnetic nanoparticle doped Titanium Dioxide nano-composite(IJCEA, 2016-12) Vasanthakumar, Arumugam; Redhi, Gan G.; Gengan, Robert MoonsamyIn this work the author disclose an effective and environment-friendly approach to the preparation of an ionic liquid supported, magnetic nanoparticle doped titanium oxide nanocomposite. The novel ionic liquid N-(2′, 3′-epoxypropyl)-N-methyl-2- pyrrolidonium salicylate was first synthesized and characterized by 1H-NMR, 13C-NMR, elemental Analysis and FTIR. It was subsequently used for the preparation of a composite material by traditional protocols. This ionic liquid is able to connect the NiFe2O4 magnetic nanoparticles with titanium dioxide via strong ionic liquid interactions. The composite was characterized by FT-IR, Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray (EDS) analysis, Transmission Electron Microscopy (TEM), High-Resolution Transmission Electron Microscopy (TEM) and Diffraction studies (DF). The catalytic activities of these composites were assessed by the reduction of nitro aniline with the aid of UV spectroscopy. Furthermore, the composite material was easily recovered and re-used with negligible loss of its catalytical activity.Item Analysis of lubricating grease by ICP-OES : a case study on preparation methodology(Asian Publication Corporation, 2016-01-30) Marume, Cathrine; Kumar, Bhajanthri Natesh; Redhi, Gan G.The aim of this study was to develop simple, cost effective and reliable sample preparation methods for the analysis of lubricating grease samples. Direct dilution, microwave digestion and emulsification methods were designed and compared for the analysis of Ca, B, Al, Na, Mo, Zn and Ba with inductively coupled plasma optical emission spectroscopy (ICP-OES). The direct dilution method gave most inconsistent results in terms of percentage recovery. The optimized microwave digestion and emulsification methods compared well and showed good reliability in terms of sensitivity and selectivity. The calibration curves resulting from oil emulsion has no significant difference with that of aqueous emulsions, but the stability of the emulsified samples was very low. The limit of detection and limit of quantification values obtained from the microwave digestion method were very low and therefore it is superior amongst the three methods for the analysis of various lubricating grease samples.Item Spectrophotometric determination of Cadmium(II) in water and soil samples using Schiff's bases(Asian Publication Corporation, 2016) Kumar, Bhajanthri Natesh; Kumar, S. Himagirish; Redhi, Gan G.A simple and rapid method was developed with the two novel Schiff ’s base ligands, (E)-N'-(2-hydroxy-5-nitrobenzylidene)isonicotinoylhydrazone and 2-(4-fluoro benzlideneamino)benzenothiol for monitoring the cadmium(II) in different water and soil samples. The two ligands react with cadmium(II) at pH 4.9/5.7 to form pale yellow/pale brown complexes with stoichiometric ratios of 1:1 (M:L). The complexes obeyed Beer’s law in the range of 2.0 and 2.5 mg L-1 with an excellent linearity in terms of the correlation coefficient of 0.99. The molar absorptivity and Sandell’s sensitivity of the complex systems were found to be 3.68 × 104, 4.32 × 104 L mol-1 cm-1 and 0.00298, 0.0034 μg cm-2, respectively. The limit of detection for cadmium(II) was noted as 0.042 and 0.063 μg L-1, respectively for these ligands. Furthermore, in vitro antimicrobial activities of both ligands and their complexes were successfully examined and reported.Item Synthesis, characterization and thermophysical properties of ionic liquid N-methyl-N-(2′,3′-epoxypropyl)-2-oxopyrrolidinium chloride and its binary mixtures with water or ethanol at different temperatures(Elsevier, 2016) Vasanthakumar, Arumugam; Bahadur, Indra; Redhi, Gan G.; Gengan, Robert Moonsamy; Anand, KrishnanA novel ionic liquid, namely, N-methyl-N-(2′,3′-epoxypropyl)-2-oxopyrrolidiniumchloride [Epmpyr]+[Cl]− was synthesized and characterized by different techniques such as NMR (1H and 13C), FTIR, and elemental analysis. The water content of the ionic liquid was checked by Karl Fisher titration. Further, the density, ρ, and speed of sound, u, were measured for the above ionic liquid and the corresponding binary systems with water or ethanol at different temperatures ranging from (293.15 to 313.15) K. The derived thermodynamic properties for instance excess molar volumes, VE m isentropic compressibility, κs, and deviation in isentropic compressibility, Δκs, were investigated from the density and speed of sound data, respectively. It is noted that density and speed of sound of the ionic liquid and its binary mixtures were decreased with increase in temperature, whereas excess molar volume, isentropic compressibility, and deviation in isentropic compressibility values increased. Derived properties such as excess molar volumes, and deviation in isentropic compressibility data were fitted to the Redlich-Kister polynomial equation. The measured and calculated data were interpreted in terms of intermolecular interfaces and structural effects between similar and dissimilar molecules upon mixing.Item Ionic liquid based high performance electrochemical sensor for ascorbic acid in various foods and pharmaceuticals(Elsevier, 2016-07-18) Kumar, Bhajanthri Natesh; Arumugam, Vasanthakumar; Chokkareddy, R.; Redhi, Gan G.In the present study, 1-butyl-3-methyl imidazolium tetra fluoroborate ionic liquid (IL), boron nitride (BN) and magnetite nanoparticles (Fe3O4NPs) based nanocomposite (IL-BN-Fe3O4NPs) was successfully synthesised and used to fabricate glassy carbon electrode (GCE) for the determination of ascorbic acid (AA). The nanocomposite was characterized by Fourier transformation infrared spectroscopy (FTIR), x-ray diffraction spectroscopy (XRD), scanning electron microscopy (SEM), electron diffraction spectroscopy (EDS) and transmission electron micros-copy (TEM) techniques to observe the surface morphology. Cyclic voltammetry (CV) was performed to assess the electrochemical performance of IL-BN-Fe3O4NPs/GCE towards ascorbic acid (AA) in 0.1 M phosphate buffer solu-tion (PBS) at pH 7. The CV results obtained reveal that the significant enhancement of anodic peak current with increased sensitivity and conductivity. The differential pulse voltammetric results obtained indicates the linear increment of electrochemical signals with an increase in the concentration of AA in the range of 1–12 μM. Based on the calibration plot, limit of detection and limit of quantification were calculated and found to be 0.042 and 0.139 μM respectively. The electrochemical sensor showed outstanding sensitivity, selectivity, repeat-ability and stability. In addition to this IL-BN-Fe3O4NPs/GCE sensor was practically applied for the routine analysis of AA in various food and pharmaceutical samples.Item Industrial application of ionic liquids for the recoveries of spent paint solvent(Elsevier, 2016) Moodley, Kandasamy; Mabaso, Mbongeni Hezekia; Bahadur, Indra; Redhi, Gan G.The recovery of industrially valuable organic solvents from liquid waste, generated in chemical processes, is economically crucial to countries which need to import organic solvents. In view of this, the main objective of this study was to determine the ability of selected ionic liquids, namely, 1-ethyl-3-methylimidazolium ethylsulphate, [EMIM][ESO4] and 1-ethyl-3-methylpyridinium ethylsulphate, [EMpy][ESO4] to recover aromatic components from spent paint solvents. Preliminary studies done on the liquid waste, received from a paint manufacturing company, showed that the aromatic components were present in the range of (6–21)% by volume. The separation of the aromatic components was performed with the ionic liquids listed above. The phases, resulting from the separation of the mixtures, were analysed with a gas chromatograph (GC) coupled to a FID detector. Chromatograms illustrate that the chosen ZB-Wax-Plus column gave excellent separation of all components of interest from the mixtures, including the isomers of xylene. The concentrations of aromatics recovered from the spent solvents were found to be in the % ranges of (13 − 33) and (23–49), respectively for imidazolium and pyridinium based ionic liquids. These results also show that there is a significant correlation between π-character of ionic liquids and the level of extraction. It is therefore concluded that ionic liquids have the potential for macro-scale recovery of re-useable solvents present in liquid waste emanating from paint manufacture.Item Separation of aromatic solvents from oil refinery reformates by a newly designed ionic liquid using gas chromatography with flame ionization detection(Wiley Online Library, 2015-02-26) Bahadur, Indra; Singh, Prashanth; Kumar, Sudharsan; Moodley, Kandasamy; Mabaso, Mbongeni Hezekia; Redhi, Gan G.The aim of this study was to determine whether the new ionic liquid, N,N-dimethyl-2-oxopyrrolidonium iodide, synthesized in our laboratory is a suitable solvent for the separation of aromatic components benzene, toluene, ethylbenzene, and xylenes from petroleum mixtures (reformates) in liquid–liquid extraction. In pursuance of the above aim, a method to extract all components of a mixture, containing four aromatic components simultaneously, was developed. A new ionic liquid and a previously used liquid were compared for their extraction abilities. These ionic liquids were, respectively, N,N-dimethyl-2-oxopyrrolidinium iodide and 1-ethyl-3-methyl imidazolium ethyl sulfate. The concentrations of each benzene, toluene, ethylbenzene, and xylenes component in the extract and raffinate phases were measured by gas chromatography with flame ionization detection as volume percent to determine the extraction ability of the ionic liquids. The results obtained for both the reformate samples and model mixtures indicated that the new ionic liquid was effective as an extracting solvent for the recovery of aromatic components from reformates. Also the analysis results, using gas chromatography with flame ionization detection, for the reformate samples were as good as the results obtained by a local oil refinery. The extraction results also show that the developed method is very suitable for the separation and analysis of aromatic components in reformates.