Faculty of Applied Sciences
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Item Application of selected ionic liquids for different separation problems : liquid-liquid equilibria and activity coefficients at infinite dilution(2021) Kabane, Bakusele; Redhi, G. G.This work focusses on the application and pre-screening of selected ILs for different industrial separation problems based on limiting activity coefficients at infinite dilution, and liquid-liquid equilibrium data at different temperatures. The selected ionic liquids for pre-screening based on activity coefficients at infinite dilution data include (1,3- dimethyimidazolium dimethylphosphate, trioctylmethylammonium chloride, trihexyltetradecylphosphonium dicyanamide, 2,3-dihydroxypropyl-N-methyl-2- oxopyrrolidinium chloride, 2,3-epoxypropyl methyl-2-oxopyrrolidinium chloride) and deep eutectic solvent (1-butyl-3-methylimidazolium chloride + glycerol) at 1:2 molar ratio. These ionic liquids were tested in 33 solutes (alkanes, alkenes, alkynes, alcohols, tetrahydrofuran, ketones, aromatic hydrocarbons, thiophene, acetonitrile) and water at T = (313 – 343) K and at p = 101 kPa. The use of ionic liquid as a stationary phase on the column loading ranged between (30 – 36) % by mass. Thermodynamic functions at infinite dilution such as (Gibbs free energy, , entropy term, Tref and partial molar enthalpy, ) were also computed to further elucidate the types of intermolecular interactions existing between solutes and the investigated ionic liquids. The separation potential of the ionic liquids was determined from the selectivity ( ), and capacity ( ), values. Different ionic liquids (1-ethyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolim dicyanamide, 1,3-dimethylimidazolium dimethylphosphate) were also tested in the separation of azeotropic mixture (ethyl acetate/hexane) and in the desulfurization (thiophene/hexadecane or octane) process. The extraction process was conducted at varying temperatures, T = (308 and 298) K and at p = 101 kPa. The results were compared to previously published ionic liquids involving thermodynamic data found in the literature. The separation capacity was based on the calculated values of selectivities (S) and distribution ratio (β). The data was successfully correlated using the thermodynamic non-random two liquids (NRTL). From this study, it was found that the investigated ionic liquids showed some possible application for selected industrial separation problems.Item Thermodynamic properties of selected ionic liquids with carboxylic acids at several temperatures(2019-08-19) Ogundele, Oriyomi Pelumi; Redhi, Gan G.; Moodley, Kandasamy G.Over the years, ionic liquids (ILs) have become an essential tool in chemistry owing to their various applications such as catalysis, electrochemistry, pharmaceuticals, nanotechnology, biotechnology, separation and extraction processes, amongst many others. With respect to the above applications, ionic liquids have desired properties like low flammability, low vapour pressure, high thermal and chemical stability, good electrical conductivity and low volatility. Ionic liquids possess the ability of being “tailored” to meet specific needs for different applications due to the flexibility in their physicochemical properties. This is done by replacing or substituting the side chain length of cation or anion structure.This project focused on the thermodynamic as well as thermo-physical parameters of two-component combinations of ionic liquids (ILs) and carboxylic acids (ethanoic or propanoic or butanoic or pentanoic or 2-methylpropanoic acids) which were investigated at several temperatures. The ionic liquidsutilized for this research investigation includes: •1-ethyl-3-methylimidazolium ethylsulphate ([EMIM]+[EtSO4]−)•1-butyl-3-methylimidazolium methylsulphate ([BMIM]+[MeSO4]−)•N-2′, 3′-epoxypropyl-N-methyl-2-oxopyrrolidinium salicylate ([EPMpyr]+[SAL]−)•N-2′, 3′-epoxypropyl-N-methyl-2-oxopyrrolidinium acetate ([EPMpyr]+[OAC]−)•N-2′, 3′-dihydroxypropyl-N-methyl-2-oxopyrrolidinium chloride ([PYR-PDO]+[Cl]−)Density and speed of sound measurements were examined obtained for the following two component systems: {([EMIM]+[EtSO4]−) + pentanoic or 2-methylpropanoic acid, ([BMIM]+[MeSO4]−) + ethanoic or propanoic acid, ([EPMpyr]+[SAL]−) + ethanoic or propanoic acid, [EPMpyr]+[OAC]−+ propanoic or butanoic acid, [PYR-PDO]+[Cl]−+ ethanoic or propanoic or butanoic acid) throughout the concentration of the ionic liquid at T= (288.15, 293.15, 298.15, 303.15, 308.15 and 313.15) K). Parameters such as excess molar volumes (VmE), isentropic compressibilities (ks) is entropic compressibilities deviation (Δks) and intermolecular free length (Lf) were computed from the measured values of densities and speeds of sound.The experimental data revealed that densities and speeds of sound value decrease with rise in temperature. Furthermore, excess molar volumes and is entropic compressibility deviation for all systems studied were found to be negative and increased with a rise in temperature. The negative outcomes obtained for excessmolar volumes of all the two-component systems studied suggest chemical interactions occur between unlike molecules in the component mixtures. These interactions are ascribed to formation of weak bonds and electron donor and acceptor complexes. Furthermore, the interaction interstices of IL gave some space for the acids to achieve structural arrangement.The Redlich-Kister equation was used to correlate the derived parameters; VmE, Δks and Lf whereas a least squares method was utilized in determining the fitting parameters and standard errors. These was done to check the precision of the measured data and the standard deviations which show moderately lower values for VmE, Δks and Lf with the examined temperatures for all the binary systems.Item Extraction and characterisation of cellulose nanocrystals (CNCs) from sugarcane bagasse using ionic liquids(2019) Mdletshe, Gcinile Pretty; Deenadayalu, Nirmala; Suprakas, S.Lignocellulosic materials have the potential to partly replace fossil-based resources as a source of bio-fuels, bio-chemicals, bio-composites and other bio-products. In this study, ionic liquids (ILs) were used in the pre-treatment of ground sugarcane bagasse (SCB). The ILs used were 1-butyl-3-methylimidazolium hydrogen sulphate or 1-butyl-3-methylimidazolium methyl sulphate at varied times. The ILs were able to remove lignin and hemicellulose from biomass. The IL [bmim][HSO4] had the highest amount of lignin removed after 12 h than all samples. Moreover, it resulted in the greatest cellulose amount. Milled SCB was pre-treated with IL/dimethyl sulphoxide (DMSO) mixtures. The IL [bmim][HSO4] was able to produce cellulose nanocrystals (CNCs) at 90 % IL and 100 % IL. The other IL failed to produce CNCs. Freeze drying the CNC suspension showed morphologies of long fibrous structures and rods which were evident in the scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images. The crystallinity index of cellulose in the form of CNCs was calculated from powder X-ray diffraction (P-XRD). Thermal analysis of the CNCs was obtained from thermogravimetric analysis (TGA). Attenuated total reflection-Fourier transform infrared (ATR-FTIR) was used to confirm the absence of lignin and hemicellulose in CNCs. The size distribution of CNCs was obtained by using a dynamic light scattering (DLS) which showed that all the CNCs for the 100 % IL [bmim][HSO4] pre-treatment had a length < 500 nm. It was found that [bmim][HSO4], with no DMSO, was the most effective in terms of cellulose dissolution and the crystal sizes of CNCs. The conversion of cellulose to CNCs was successful with a 80 % and 100 % conversion for 90 % [bmim][HSO4]/DMSO and 100 % [bmim][HSO4], respectively.Item Effect of mechanical and chemical pulping on ionic liquid fractionation of wood chips(2019) Hlongwa, Nhlanhla; Deenadayalu, Nirmala; Sithole, Bruce; Andrew, Jerome EdwardIn this study, a comparison of two pulping methods namely mechanical and chemical, on the dissolution of Eucalyptus grandis (E. grandis) wood chips was undertaken. The wood chip pulp was treated with an ionic liquid (IL): 1-allyl-3-methylimidazolium chloride to extract the cellulose. The IL was mixed with unbleached mechanical pulp (UBMP), bleached mechanical pulp (BMP), unbleached kraft pulp (UBKP) and bleached kraft pulp (BKP) in ratios of 10%, 20%, 30%. Each solution contained IL, wood pulp and 2-mL of 16 v/v % of dimethyl sulfoxide (DMSO). The 30 % IL pretreatment was the most effective IL pretreatment. The cellulose yield at 30 % IL pretreatment for UBMP, BMP, UBKP and BKP was 65.12%, 63.82%, 67.43%, 67.15%, respectively. This indicated that the kraft pulping method was more effective than the mechanical pulping method for the yield of cellulose after the IL pretreatment. The Crl value at 30 % IL pretreatment was highest for UBMP (72.03%) indicating that the pretreatment used was the least effective in reducing the cellulose crystallinity. The fractions of E. grandis wood chip namely, lignin, regenerated cellulose and hemicelluloses before and after the IL pretreatment, were characterized by a variety of analytical techniques such as High-Performance Liquid Chromatography (HPLC) (carbohydrates), Fourier Transform Infra-Red Attenuated Total Reflection (FTIR-ATR) (functional groups), Pyrolysis-Gas Chromatography /Mass Spectroscopy (Py-GC/MS) (lignin fractions), Ultraviolet/Visible spectroscopy (UV/Vis) (acid soluble lignin), Thermo Gravimetric Analysis (TGA) (degradation of pulp), X-Ray Diffraction (XRD) (crystallinity) and high resolution Scanning Electron Microscopy (SEM) (morphology). Kraft pulping was the most effective method for the yield of cellulose after the [AMIM][Cl]/DMSO pretreatment. The 30% [AMIM][Cl]/DMSO pretreatment gave the highest S/G ratio indicating that minimal bleaching was required.Item Thermodynamic properties of phosphonium-based ionic liquid mixtures at different temperatures(2018) Kabane, Bakusele; Redhi, Gan G.Ionic Liquids (ILs) are relatively newly formed types of solvents. As part of ongoing research, research groups and industries are focusing on solvents classified as ionic liquids, which have a low melting point,and they have been given great attention focusing on their thermophysical properties and applications. In order to utilize or industrially exploit these types of solvents, the understanding of intermolecular interactions and properties of pure liquids and their mixtures is important. Thermophysical properties of ionic liquid mixtures, especially density, viscosity and speed of sound are measured as a function of temperature. Accurate analysis on thermophysical properties of ionic liquids is more of paramount interest as they indicate the transformation of ionic liquids from small laboratory level to large-scale industrial implementation.In this study, new data for the binary mixtures containing {trihexyltetradecylphosphonium chloride ([P+14, 6, 6, 6] [Cl-]) IL and propanoic acid (PA)} and {1-ethyl-3-methylimidazolium tetrafluoroborate ([Emim][BF4]) + benzaldehyde or ethyl acetoacetate} were investigated under atmospheric pressure (p equivalent to 0.1 MPa) and at temperatures (293.15 to 313.15) K. Densities (ρ),viscosities (𝜂) as well as speeds of sound (𝑢)were measured over the whole range of mole fraction (𝑥𝑖= 0 to 1). The computed excess properties which includes excess molar volumes(𝑉mE), apparent molar volume (𝑉𝜙),intermolecular free length (Lf), isentropic compressibility(𝑘𝑠), deviations in viscosity (Δ𝜂), apparent molar isentropic compressibility (𝐾𝜙) and deviation in isentropic compressibility(Δ𝑘𝑠)were computed from the experimentally determined data of densities, viscosities and speeds of sound. In addition, measurements of activity coefficients at infinite dilution forvolatile organic compounds (alkenes, alcohols, alkanes, cycloalkanes, aromatic hydrocarbons, thiophene, ketones, acetonitrile, water and tetrahydrofuran) in the IL [trihexyltetradecylphosphonium-bis-(2, 4,4-trimethylpentyl)-phosphinate and trihexyltetradecylphosphonium chloride] were conducted at different temperatures.The obtained results and derived properties have been elucidated in terms of the interactions taking place among the solvent systems.Item Synthesis, characterization and application of novel ionic liquids(2018) Arumugam, Vasanthakumar; Redhi, Gyanasivan Govindsamy; Gengan, Robert MoonsamyIonic liquids (ILs) or molten salts at room temperature presently experience significant attention in many areas of chemistry. The most attractive property is the “tenability” of the physical and chemical properties of ILs by varying structure. The use of ILs in solvents demands information about their behaviour in the presence of other compounds including organic solvents such as alcohols or carboxylic acids or water, commonly used for products extraction. In addition, the efficiency of chemical processes (synthesis, extractions and separations) is strongly influenced by the nature of ILs. In this study describes the synthesis and characterization of novel epoxy propyl substituted ionic liquids (ILs). The thermophysical properties of ILs and their binary mixtures with either water, alcohol or carboxylic acids were investigated and the results are discussed in terms of interactions through thermodynamic properties. Furthermore, 2-oxopyrrolidine (Pyr), 2-aminopicoline (Apic) and 1,4-diazabicyclo [2.2.2] octane (DABCO)-based dihydroxypropyl substituted ILs are synthesised and characterised successfully. These ILs were then used to synthesize and characterize a novel 4 th -generation multi-ionic IL. A significant application of this IL is the synthesis of a unique nanomaterial using magnetic iron nanoparticles, h-boron nitride and titanium dioxide. The nanomaterial was strategically used to reduce selected dyes and series of nitroanilines (NAs). The chapter 1 to 4 explains about the introduction, literature review, synthesis and thermophysical properties of ILs as well as thermodynamic properties of ILs. The fifth chapter of this study describe the synthesis, characterization and thermophysical properties of a novel 2′, 3′-epoxypropyl-N-methyl-2-oxopyrrolidinium chloride IL and its binary mixtures, with either water or ethanol. The density (ρ), and speed of sound (u), were measured for the above IL and its corresponding binary systems with either water or ethanol at different temperatures ranging from (293.15 to 313.15) K. The derived thermodynamic properties for instance excess molar volumes (V mE ), isentropic compressibility (k s ) deviation in isentropic compressibility (∆k s ) and intermolecular free length (L f ) were investigated from the ρ and u data, respectively. It is noted that V mE , k s ∆k s and L f values increase with increasing temperature. Derived properties such as V mE , and ∆k s 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 (Paper: I) The chapter six describes the synthesis and characterization of 2′, 3′-epoxypropyl-N-methyl-2-oxopyrrolidinium salicylate and 2′, 3′-epoxypropyl-N-methyl-2-oxopyrrolidinium acetate ILs. These ILs and their binary mixtures with either water or methanol were then studied to determine their thermophysical properties. The temperature dependent ρ and u for IL, 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 intervals of 5 K, under atmospheric pressure. The calculated thermodynamic properties such as V mE , k s ∆k s andL f , were derived from the investigated ρ and u data. The resulting experimental data for V mE , L f , and ∆k s , were well fitted to the Redlich-Kister polynomial equation. (Paper: II & III) The chapter seven reports the thermophysical properties of binary mixtures for the combination of 2′, 3′- epoxypropyl-N-methyl-2-oxopyrrolidinium chloride with carboxylic acids either ethanoic or propionic acids. The novel IL [EPMpyr] + [Cl] − was synthesized, and it has been mixed with ethanoic or propanoic acids. The influence of an epoxy group in this IL was more strongly affected with the acids, and their thermophysical properties at varied temperatures are discussed in term of density (ρ), viscosity (η), speed of sound (u), and refractive index (n) measurements. The ρ, u, η, and n of the IL, ethanoic acid, propanoic acid, and their corresponding binary mixtures {[EPMpyr] + [Cl] − (1) + ethanoic or propanoic acid (2)} were measured at T = (293.15-313.15) K and at P = 0.1 MPa. The theoretical thermodynamic properties of V mE , k s , ∆k s , and L f are calculated using experimental ρ and u data. The V mE and ∆k s values for both binary mixtures were found to be negative over the entire mole fraction range of compositions 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. This study is very important for industries because most of the ILs are viscous and have high pH values, so making their applications in industries are difficult. Hence these main disadvantages could be addressed and rectified simultaneously without drastically altering the nature of the IL by using various carboxylic acid combinations. Moreover, the thermophysical data and information about acid and IL mixtures will provide insight into the use of these ILs in acidic conditions, thereby enabling the development of processes for future industries. Additionally, the measurements of thermophysical properties were used to calculate thermodynamic properties, which lead to a better understanding of the interactions amongst unlike molecules and hydrogen bonds in binary mixtures. (Paper: IV) In summary, the first four publications describes the synthesis, characterization and thermophysical properties of 2′,3′-epoxypropyl substituted 2-oxopyrrolidinium cation-based novel ILs with various anions such as chloride, acetate and salicylate. These ILs were characterized by FTIR, 1 H NMR, 13 C NMR and elemental analysis to confirm the chemical structure of the ILs. The binary mixtures of ILs with either water or methanol or ethanol were carefully prepared. Experimental measurements of the thermophysical properties of ρ, u, η and n, selected solvents, and their binary mixtures at various temperatures, across the entire mole fraction ranges of ILs, were determine. Thermodynamic properties of V mE , k s , ∆k s and L f were calculated from ρ, and u data. These thermodynamic properties were correlated using the Redlich-Kister polynomial equation. Molecular interactions, especially H-bonding and other interaction effects that occur between ILs and molecular solvents were discussed. The chapter eight discusses the synthesis and characterization of novel 4 th generation amino trismethyl phosphonate (ATMP) based IL such as [DABCO, PYR, APIC-PDO] + [ATMP] - and their application to the synthesis and characterization of partially oxidized h-boron nitride modified nanomaterial with copper ferrite magnetic nanoparticles (NPs). This nanomaterial was characterized through various spectroscopic, microscopic and surface morphological techniques. Thereafter it was used as environmentally friendly heterogeneous catalyst for the reduction of a series of NAs and dyes such as 2-nitroaniline (2-NA), 3-nitroaniline (3-NA), 4-nitroaniline (4-NA), 4-nitro-1,2-phenylenediamine (4-NPD), methylene blue and allura red to their corresponding amino analogues. The rate constant, order of reaction, activation energy and constant ratio were calculated for each substrate. The order of reduction, was 4-NPD > 4-NA > 3-NA > 2-NA. Kinetic studies indicated either zero or pseudo-first order reactions. Furthermore, kinetic studies at various temperatures such as 25, 30, 40, 50 and 60 o C as well as the range of various quantities of catalyst such as 0.015, 0.030 and 0.045 ml (0.2mg/ml concentration) showed that either an increase in temperature or the amount of catalyst increased the rate of the reaction. It was found that the nanomaterial is an efficient catalyst in aqueous solution at ambient temperature, and the processes for recovery were simple. It was re-used more than seven times with negligible loss of its catalytic activity. It is envisaged that new industrial applications of the ILs and their nanomaterials will emanate in the future. (Paper: V) The chapter nine describes the synthesis, characterization and application to the reduction of NAs which were made using 2′,3′- epoxypropyl-N-methyl-2-oxopyrrolidinium salicylate IL, NiFe 2 O 4 NPs and titanium dioxide (TiO 2 ). Here IL was used as a bonding or capping agent to synthesize NiFe 2 O 4 NPs doped TiO 2 nanocomposite. This nanocomposite was characterized by various microscopic and surface morphological studies. The nanocomposite displayed a good catalytic activity for the reduction of 2-NA to 2-aminoaniline and can be recovered as well as recycled easily. (Paper: VI)Item Density, speed of sound, refractive index and activity coefficients at infinite dilution for ionic liquids(2018) Mgxadeni, Ncomeka; Deenadayalu, Nirmala; Ramjugernath, Deresh; Naidoo, ParamespriIn this study the experimental density, speed of sound, and refractive index for binary mixtures of an ionic liquid (IL): 1-butyl-3-methylimidazolium nitrate and activity coefficients at infinite dilution of organic solutes in the ionic liquid: 1-butyl-3-methylimidazolium hydrogen sulfate were determined. The density, speed of sound, and refractive index of 1-butyl-3-methylimidazolium nitrate in pyridine or acetonitrile or thiophene have been reported at T = 298.15 K, 303.15 K, 308.15 K, 313.15 K and 318.15 K using an Anton Paar DSA 5000M vibrating U-tube densimeter and a RXA 156 refractometer. The derived properties namely: excess molar volume, isentropic compressibility and change in refractive index were calculated from density, speed of sound and refractive index, respectively. The results are discussed in terms of molecular interactions (hydrogen bond, dipole-dipole, or ion-solvent or interactions). The negative deviation of excess molar volume and the positive deviation in change in refractive index clearly indicates the strong interaction of 1-butyl-3-methylimidazolium nitrate with pyridine or acetonitrile or thiophene in solution. The positive values of isentropic compressibility for the system indicates that the mixtures were more compressible than the ideal mixture. The Redlich Kister smoothing polynomial was used to fit the excess molar volume and deviation in isentropic compressibility data. The Lorentz-Lorenz equation was used to predict the experimental density, or refractive index data and to correlate the excess molar volume. Gas liquid chromatography was used to determine activity coefficients at infinite dilution for 28 polar and non-polar organic solute: alkanes, cycloalkanes, alkenes, alkynes, aromatic hydrocarbons, alcohols, aldehydes, thiophene, pyridine and acetonitrile in an IL: 1-butyl-3- methylimidazolium hydrogen sulfate ([BMIM][HSO4]). The measured values of activity coefficients at infinite dilution for the solutes in [BMIM][HSO4] were carried out at T = (313.15, 323.15, 333.15) K. Partial molar excess enthalpies at infinite dilution of the organic solutes in the ionic liquid have been calculated from the temperature dependence of activity coefficients at infinite dilution. The selectivity and capacity values for separation problems namely: hexane/benzene, heptane/benzene, cyclohexane/benzene, ethanol/benzene, heptane/pyridine, heptane/thiophene and methanol/acetone at T = 323.15 K were calculated and compared to literature values for similar ionic liquids, sulfolane and N-methyl-2- pyrolidinone (NMP). The IL [BMIM][HSO4] gave both the highest selectivity and limiting capacity for the heptane/thiophene separation and would therefore be a suitable entrainer for this separation. New data from this study reveals that [BMIM][HSO4] may be proposed as a replacement solvent for the separation of sulphur or nitrogen compounds from alkanes.Item Use of 1-ethyl-3-methylimidazolium ethyl sulfate for liquid-liquid equilibria for ternary mixtures(2017) Mohale, Tshepang; Deenadayalu, NirmalaThis thesis forms part of the Durban University of Technology Thermodynamics Research Unit’s project which is aimed at developing a method for determination of the liquid-liquid equilibria (LLE) data for the azeotrope {methanol + water} with an ionic-liquid (IL) using DSA5000M to assess the efficiency of the ionic liquid to be used in liquid-liquid extractions for the recovery and recycling of methanol from petroleum refinery. The objective of this study was to determine the liquid-liquid equilibria data of the azeotrope {methanol + water} using 1-ethyl-3-methylimidazolium ethyl sulfate ionic liquid with the intention to recycle methanol from the Fischer-Tropsch (FT) process by- products in petroleum industries and to utilize it in gasoline additives in a new methanol to gasoline (MTG) petroleum process. LLE studies of systems containing alcohols and water are important due to the increasing demands of oxygenated compounds to produce lead free gasoline. Light alkanols such as methanol and ethanol are reported to be suitable compounds in order to produce lead free gasoline, but the use of methanol in gasoline blends can cause phase separation problems in: 1. dry conditions, these are due to its partial solubility in saturated hydrocarbons. 2. the presence of water from ambient humidity or in storage tanks, this depend on unfavourable distribution factor between aqueous and the hydrocarbon phase. To determine the possibility of separating methanol from water using ionic liquid, the liquid-liquid equilibria data was determined at room temperature, T = 298.15 K and atmospheric pressure to investigate whether it separate from water and/or a non-phase separation if it is used as an additive. The experimental data generated was compared to that of the literature for the system {methanol (1) +toluene (2) + dodecane (3)} and showed good agreement with the literature data with only maximum deviation of ± 0.0015 in the mole fraction using density calculations and ± 0.0092 in the mole fraction when using refractive index calculations The selectivities and distribution coefficients for this system were also calculated and the maximum deviation between the two methods (nD and ρ) was ± 1.33 in selectivities and found to be ±0.001 for distribution coefficients. The maximum deviation in distribution coefficients from literature when using nD calculations for system 1 was ±0.04 and ±0.01 for ρ. For the selectivity values the deviation from that of literature of nD when compared was found to be ± 1.28 and 0.29 for ρ respectively. The selectivity values from the density calculations were found to be in the range 2.82 – 7.66 for this system with the distribution coefficient values reported in the range 0.17 – 0.23. In the second system (system 2) the generated experimental data was also compared to that of the literature for the system {water (1) + methanol (2) + cyclohexane (3)} and in good agreement with literature values with only maximum deviation of ± 0.0091 in the weight fraction based on density calculations. The selectivities and distribution coefficients were also calculated and the maximum deviation between the literature and the experimental data was computed to be at ± 0.0003 for selectivity and ±0.09 in distribution coefficient. The selectivity values were found to be in a range 0.00 - 0.04 for this system and were constant throughout the phases but significantly less than one; with the distribution coefficient values in the range 0.00 – 0.008. For 1-ethyl-3-methylimidazolium ethyl sulfate system (Ionic liquid system) the selectivity values were not constant throughout the two-phase region and the values were found to be in the range 0.63 -0.99 still below one which indicates that the ionic liquid used in this study could not be considered as a potential solvent for the separation of the investigated azeotrope. The distribution coefficients for this system were determined and found to be in the range 0.23 – 0.74. The certainty and reliability of experimentally measured tie-line data was ascertained by applying Othmer-Tobias (OT) correlations and the Non-Random, Two Liquid (NRTL) parameters. The OT correlations for system 1 was linear and indicated the certainty of the five tie-lines prepared for this system. In system 2 the OT correlation was not linear and indicated extensively high errors as well as high systematic multiplicative and additive errors in calculations of mole fractions. For the IL system the OT correlation was linear throughout the whole tie-line range and indicated the adequate precision, which denotes that the investigation was carried out with minimal random and systematic errors and indicated the efficiency of the DSA 5000 M to generate the liquid-liquid equilibria data. All the ternary systems were well correlated and in good agreement with the estimated NRTL data. It was only system 1{methanol (1) + toluene (2) + dodecane (3)} that gave a high maximum deviation ( %RSMD) of 1.288 when using the RI measurements with the minimum error margin of 0.6320, this account as to why RI measurements were not applied in other systems (system 2 and ionic liquid system). Similarly for the same system; system 1{methanol (1) + toluene (2) + dodecane (3)} when using the density measurements; the NRTL model gave a maximum deviation of 0.5620 and minimum error margin of 0.2590. The NRTL obtained for system 2 {water (1) + methanol (2) + cyclohexane (3)} gave the maximum deviation of 0.5752 and minimum error margin of 0.0127. The NRTL for the ionic liquid ternary system {[EMIM][EtSO4](1) + methanol (2) + water (3)}showed a good agreement between the experimental data and the NRTL model tie- line data with the %RSMD of 1.0201 on the upper limit and 0.1620 as a lower deviation.Item Selective extraction of lignin from lignocellulosic biomas using ionic liquids(2016) Mkhize, Thandeka, Y.; Deenadayalu, Nirmala; Reddy, P.Globally there is a drive for the use of renewable materials for the production of biofuels or high-end value chemicals. The current production of chemicals from crude oil refining is unsustainable and leads to global warming effects. Biomass is the most attractive renewable energy source for biofuel or fine chemical production. Sugarcane bagasse is a by-product of the sugar milling industry and is abundantly available. In this study lignin was sequentially extracted using ionic liquids. The ionic liquids (ILs) 1-ethyl-3-methylimidazolium acetate ([Emim][OAc]) and triethylammonium hydrogen sulfate ([HNEt3][HSO4]) were used to fractionate the sugarcane bagasse. The pre-treatment of sugarcane bagasse was carried out at different temperatures ranging from 90 - 150 0C and reaction times ranging from 1 - 24 h in a convection oven at a 10 % biomass loading. Both ILs were able to dissolve the raw bagasse samples at 120 0C with [Emim][OAc] giving a lignin maxima of 28.8 % and a low pulp yield of 57 % after 12 h; [HNEt3][HSO4] gave a lignin recovery of 17.2 % and low pulp yield of 58.5 % after 6 h. Regenerated lignin was obtained by adding ethanol/ water to the mixture followed by vacuum filtration. The regenerated pulp materials were characterized by Scanning Electron Microscope (SEM) to study the morphology; Fourier Transform Infrared Spectroscopy (FTIR) to study the characteristic bands and thermal analysis to study the thermal stability.Item Processing of dissolving pulp in ionic liquids(2015) Tywabi, Zikhona; Sithole, B.; Deenadayalu, NirmalaThis thesis forms part of the Council for Scientific and Industrial Research, Forestry and Forest Products Research Centre (CSIR-FFP) biorefinery project which aims at developing and implementing novel industrial processes production of cellulose textile fibres. The focus of this study is to investigate the dissolution of South African Eucalyptus raw (unbleached) and final (bleached) dissolving pulp and saw dust wood in an ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate [Emim][OAc] and the co-solvents [dimethylsulfoxide (DMSO)] or [dimethylformamide (DMF)] mixtures, to obtain regenerated cellulose by the further addition of water and acetone. The IL/co-solvent mixtures were able to dissolve the raw and final pulp samples at 120 ˚C for 6 hours whereas the sawdust wood dissolved in 10 hours. The IL/DMF mixture gave higher cellulose recoveries of 41.88 % for the raw pulp, 49.89 % for the final pulp sample and 32.50 % for sawdust wood while the IL/DMSO mixture gave a recovery of 15.25 % for the raw pulp sample, 36.25 % for the final pulp sample and 17.83 % for the sawdust wood sample. The regenerated cellulose materials were characterized by Fourier Transformer Infrared Spectroscopy (FTIR), Nuclear Magnetic Resonance (NMR), Scanning Electron Microscopy (SEM), Thermo gravimetric Analysis (TGA) and Powder X-Ray Diffraction (pXRD), and compared with a standard microcrystalline of cellulose. It was observed that the FTIR and NMR spectra of the regenerated cellulose and MCC were similar which then indicates that no chemical reaction occurred during the dissolution and regeneration process of cellulose. SEM and X-ray diffraction (XRD) patterns of the results showed that after dissolution the cellulose I (native form), the crystalline structure was completely converted into cellulose II (amorphous) structure, and this was due to the removal of lignin and decrease in cellulose crystallinity. TGA results showed that the regenerated cellulose samples have higher char yields compared to the MCC which is due to the IL remaining in the regenerated cellulose. It was also observed that the addition of the co-solvents decreased the viscosity of the IL mixture, facilitating dissolution of the cellulose that led to additional swelling and reduction of the recalcitrant nature of the cellulose crystalline structure and intermolecular interactions. This led to increased accessibility and dissolution of the cellulose. The findings in this study have the potential to bring ILs closer to applications for biomass technology in particular for an economically viable dissolution method for biomass because ILs have a benefit of being easily separated from the anti-solvent, which provides a simple solution for IL recycle ability and re-use. The novel aspect of this study is: . This is the first study in the South African context to examine the influence of the lignin on the dissolution and regeneration of Eucalyptus sawdust wood and dissolving pulp.