Submitted in fulfillment of the requirements of the Degree of Doctor of Technology: Chemistry, Durban University of Technology, 2010. / The thermodynamic properties of mixtures involving ionic liquids (ILs) with alcohols or alkyl acetate or nitromethane at different temperatures were determined. The ILs used were methyl trioctylammonium bis(trifluoromethylsulfonyl)imide ([MOA]+[Tf2N]-) and 1-butyl-3- methylimidazolium methyl sulphate [BMIM]+[MeSO4]-. The ternary excess molar volumes (􀜸􀬵􀬶􀬷 E ) for the mixtures {methyl trioctylammonium bis (trifluoromethylsulfonyl)imide + methanol or ethanol + methyl acetate or ethyl acetate}and (1- butyl-3-methylimidazolium methylsulfate + methanol or ethanol or 1-propanol + nitromethane) were calculated from experimental density values, at T = (298.15, 303.15 and 313.15) K and T = 298.15, respectively. The Cibulka equation was used to correlate the ternary excess molar volume data using binary data from literature. The 􀜸􀬵􀬶􀬷 E values for both IL ternary systems were negative at each temperature. The negative contribution of 􀜸􀬵􀬶􀬷 E values are due to the packing effect and/or strong intermolecular interactions (ion-dipole) between the different molecules. The density and speed of sound of the binary solutions ([MOA]+[Tf2N]- + methyl acetate or ethyl acetate or methanol or ethanol), (methanol + methyl acetate or ethyl acetate) and (ethanol + methyl acetate or ethyl acetate) were also measured at T = ( 298.15, 303.15, 308.15 and 313.15) K and at atmospheric pressure. The apparent molar volume, Vφ , and the apparent molar isentropic compressibility, κφ , were evaluated from the experimental density and speed of sound data. A Redlich-Mayer type equation was fitted to the apparent molar volume and apparent molar isentropic compressibility data. The results are discussed in terms of solute-solute, solute- solvent and solvent-solvent interactions. The apparent molar volume and apparent molar isentropic compressibility at infinite dilution, 􀜸φ 􀬴 and κφ 􀬴, respectively of the binary solutions have been calculated at each temperature. The 􀜸φ 􀬴 values for the binary v systems ([MOA]+[Tf2N]- + methyl acetate or ethyl acetate or methanol or ethanol) and (methanol + methyl acetate or ethyl acetate) and (ethanol + methyl acetate or ethyl acetate) are positive and increase with an increase in temperature. For the (methanol + methyl acetate or ethyl acetate) systems 􀜸φ 􀬴 values indicate that the (ion-solvent) interactions are weaker. The κφ 􀬴 is both positive and negative. Positive κφ 􀬴, for ([MOA] + [Tf2N]- + ethyl acetate or ethanol), (methanol + ethyl acetate) and (ethanol + methyl acetate or ethyl acetate) can be attributed to the predominance of solvent intrinsic compressibility effect over the effect of penetration of ions of IL or methanol or ethanol. The positive κφ 􀬴 values can be interpreted in terms of increase in the compressibility of the solution compared to the pure solvent methyl acetate or ethyl acetate or ethanol. The κφ 􀬴 values increase with an increase in temperature. Negative κφ 􀬴, for ([MOA] + [Tf2N]- + methyl acetate or methanol), and (methanol + methyl acetate) can be attributed to the predominance of penetration effect of solvent molecules into the intra-ionic free space of IL or methanol molecules over the effect of their solvent intrinsic compressibility. Negative κφ 􀬴 indicate that the solvent surrounding the IL or methanol would present greater resistance to compression than the bulk solvent. The κφ 􀬴 values decrease with an increase in the temperature. The infinite dilution apparent molar expansibility, 􀜧φ 􀬴 , values for the binary systems (IL + methyl acetate or ethyl acetate or methanol or ethanol) and (methanol + methyl acetate or ethyl acetate) and (ethanol + methyl acetate or ethyl acetate) are positive and decrease with an increase in temperature due to the solution volume increasing less rapidly than the pure solvent. For (IL + methyl acetate or ethyl acetate or methanol or ethanol) systems 􀜧φ 􀬴 indicates that the interaction between (IL + methyl acetate) is stronger than that of the (IL + ethanol) or (IL + methanol) or (IL + ethyl acetate) solution. For the (methanol + methyl acetate or ethyl acetate) systems 􀜧φ 􀬴 values vi indicate that the interactions are stronger than (ethanol + methyl acetate or ethyl acetate) systems. / National Research Foundation; Durban University of Technology

Dissertation was submitted in fulfilment of the academic requirement for the Masters Degree in Technology: Chemistry, Durban University of Technology, 2011. / In this work, the binary and ternary excess molar volumes have been calculated from the density, ρ, measurements using an Anton Paar (DMA 38) vibrating tube digital densimeter. One component of the ternary systems studied was an ionic liquid. The ionic liquid used is methyl trioctylammonium bis(trifluoromethylsulfonyl)imide [MOA]+[Tf2N]-. Binary excess molar volumes were obtained for (1-butanol + ethyl acetate) and (2-butanol + ethyl acetate) systems at T = (298.15, 303.15, and 313.15) K. Ternary excess molar volumes were obtained for the mixtures {[MOA]+[Tf2N]- + 2-propanol or 1-butanol or 2-butanol + ethyl acetate} at T = (298.15, 303.15, and 313.15) K. The Redlich-Kister equation was fitted to the calculated binary excess molar volume data to obtain the fitting parameters which were used to calculate the partial molar volumes at infinite dilution. The calculated partial molar volume was used to better understand the intermolecular interactions of each component at infinite dilution. The Redlich-Kister parameters were also used in the Cibulka equation and the Cibulka equation was used to correlate the ternary excess molar volume data to give the fitting parameters. The binary excess molar volumes,VmE , for the (1-butanol + ethyl acetate) and (2-butanol + ethyl acetate) are positive at each temperature over the entire composition range. At high mole fractions of the alcohol for the binary systems (2-propanol or 1-butanol or 2-butanol + ethyl acetate), VmE is positive again, similar to the Cibulka ternary correlation. The positive V E m values are due to the breaking of intermolecular interactions in the pure components during the mixing process. The ternary excess molar volume,V E 123 , values are negative for all mole fractions. The negative values are due to a more efficient packing and/ or attractive intermolecular interactions in the mixtures than in the pure liquid. There is also a contraction in volume which can be attributed to electron-donor-acceptor type interactions between the ionic liquid and 2-propanol or 1-butanol or 2-butanol as well as ethyl acetate. / National Research Foundation.

No description available.

We were unable to verify the existence of ion mobility discontinuities in either superfluid helium at 1 K or liquid nitrogen. The velocity-field dependence in helium was described by an increased interaction with the normal fluid, due to an increase in the roton number density close to the ion surface. The mobility results in nitrogen were interpreted as being due to liquid motion, following a theory by Kopylov. The D.C. results showed that the effect of a grid on the transmission of an ion beam could be described by a field dependent grid transmission coefficient, independent of the ion velocity. The vortex ring transmission through a grid was a complex function of vorticity being captured by the grid, the capture and escape probabilities of the bare ions by vorticity, and the onset for vorticity propagating throughout the ion cell.

Biocompatible composites, generated from renewable biomass feedstock, are regarded as promising materials that could replace synthetic polymers and reduce global dependence on fossil fuel sources. Wood cellulose, the most abundant biopolymer on earth, holds great potential as a renewable biomass feedstock. To unlock the entire scope of potential benefits of this feedstock, the wood components - namely cellulose, hemicellulose and lignin - need to be separated and processed individually. Current methods to separate wood components, such as Kraft pulping for example, suffer considerable drawbacks and cannot be considered environmentally benign. This thesis aims to increase our understanding of the interaction between ionic liquids (ILs) and biomass, in order to develop superior biomass processing techniques necessary to ensure a rapid transformation of our society towards full sustainability. The first part of this work deals with the particular interaction of ILs with cellulose, and aims to investigate the structural requirements of ILs in order to qualify as a cellulose solvent. The cellulose-dissolving behaviour of selected alkanolammonium ILs was studied, and, combined with the results of an extensive literature review, a novel concept for the interaction of cellulose-dissolving ILs with cellulose was developed. It was postulated that efficient cellulose solvents need to position themselves in a distinct manner - with respect to the cellulose chain - in order to offer H-bond interaction sites with enhanced stability. As a result, alternative ions for cellulose-dissolving ILs were proposed, including oxazolium, 1,3-oxaphospholium, dimethylcarbamate, phosphate, nitrate, and nitrite. The second part of the work investigated the use of food-additive based ILs for the separation of wood lignin, and studied the influence of selected process parameters, such as extraction time, extraction temperature, IL moisture content, wood particle size, wood species, IL cation species, solvent composition, and IL recyclability on the lignin extraction efficiency. The lignin extract and the wood residues were characterised via infrared spectroscopy, elemental analysis, thermogravimetric analysis, differential scanning calorimetry, X-ray diffraction, and gel permeation chromatography. An extraction efficiency of e = 0.43 of wood lignin was achieved in one gentle extraction step ( T = 373 K, t = 2 h), and it was found that the presence of a co-solvent increased the extraction efficiency to e = 0.60. Gentle conditions during IL treatment did not decrease the crystallinity of the wood sample, and the extracted lignin had both a larger molecular mass and a more uniform molecular mass distribution, compared to commercially available Kraft lignin. The outcomes of both studies were critically evaluated, addressing existing drawbacks and restrictions that need to be considered, and possibilities for future work were suggested.

Concerns over industrial emissions and nuclear waste have led to the need to study ways to sequester industrial gasses, and recycle nuclear fuel. Two projects were done to study solvent systems for these two problems using computational methods. Current methods for SO₂ sequestration are wasteful in that the gasses cannot be extracted from the solvent, and the solvent cannot be reused. One possible solution, which this work focuses on, is the use of an ionic liquid as a sequestration agent for the adsorption of SO₂. Separation technology for heavy elements has not changed for over 60 years and issues with radiation contamination and low efficiency lead to high solvent waste. Biphasic alkane-water extraction systems are a possible solution as they have been used for the extraction of heavy elements. This work focuses on characterizing the factors that control partitioning in biphasic systems which increase extraction efficiency.

Electrostatic interactions between charged species play a prominent role in determining structures and states of physical system, leading to important technological and biological applications. In coarse-grained simulations, accurate description of electrostatic interactions is crucial in addressing physical phenomena at larger spatial and longer temporal scales. In this thesis, we implement ENUF method, an abbreviation for Ewald summation based on non-uniform fast Fourier transform technique, into dissipative particle dynamics (DPD) scheme. With determined suitable parameters, the computational complexity of ENUF-DPD method is approximately described as O(N logN). The ENUF-DPD method is further validated by investigating dependence of polyelectrolyte conformations on charge fraction of polyelectrolyte and counterion valency of added salts, and studying of specific binding structures of dendrimers on amphiphilic membranes. In coarse-grained simulations, electrostatic interactions are either explicitly calculated with suitable methods, or implicitly included in effective potentials. The effect of treatment fashion of electrostatic interactions on phase behavior of [BMIM][PF6] ionic liquid (IL) is systematically investigated. Our systematic analyses show that electrostatic interactions should be incorporated explicitly in development of effective potentials, as well as in coarse-grained simulations to improve reliability of simulation results. Detailed image of microscopic structures and orientations of [BMIM][PF6] at graphene and vacuum interfaces are investigated by using atomistic simulations. Imidazolium rings and alkyl side chains of [BMIM] lie preferentially flat on graphene surface. At IL-vacuum interface, ionic groups pack closely together to form polar domains, leaving alkyl side chains populated at interface and imparting hydrophobic character. With the increase of IL filmthickness, orientations of [BMIM] change gradually from dominant flat distributions along graphene surface to orientations where imidazolium rings are either parallel or perpendicular to IL-vacuum interface with tilted angles. The interfacial spatial ionic structural heterogeneity formed by ionic groups also contributes to heterogeneous dynamics in interfacial regions.

Environmental and safety concerns have prompted an active quest for ―green‖ alternatives to / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2009.

This thesis is concerned with the study of different effects in protein ultrafiltration including device configuration, solution chemistry and membrane charge In the recent and more established literature membrane fouling remains a challenging problem that limits the wider application of ultrafiltration. Thus, investigations which can aid understanding and potentially reduce membrane fouling are of particular interest and in this study the problem has been addressed from several different angles Polyethersulfone membranes were studied at varying pH and two ionic strengths using bovine serum albumm and lysozyme as the model proteins. The study was conducted both in a stirred cell and a crossflow configuration in order to evaluate the influence of different system hydrodynamics on filtration This work was further substantiated through the application of filtration models An attempt was also made to modify the membrane surface by low temperature plasma modification with the intention to preferentially alter the characteristics of the membrane surface Both unmodified and plasma-modified polyethersulfone membranes were characterised using a range of analytical methods including flux data, streaming potential, contact angle and MWCO measurements to aid results interpretation. The research showed that MWCO data quoted by manufacturers is mostly greater than that obtained during laboratory studies The MWCO technique was also used to highlight differences between the unmodified and plasma-modified membranes demonstrating that the modification resulted in a membrane with tighter pores in the lower molecular weight region. Concentration polarisation effects were found to be reduced as a result of the plasmamodification The study of protein filtration at different pH and ionic strengths demonstrated that ionic strength effects were more pronounced than pH effects It was also shown that changes m the ionic strength can be used to alter the degree of protein rejection for the given system concentration polarisation was found to be higher during crossflow filtration compared to stirred cell filtration The thesis adds to existing knowledge in the area of ultrafiltration emphasizing the importance of device configuration, solution chemistry as well as the potential of charged membranes

Submitted in fulfillment of the academic requirements for the degree of Master of Applied Sciences (Chemistry), Durban University of Technology, Durban, South Africa, 2016. / 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. / M