A Surface Forces Apparatus (SFA) was used in this study to investigate the fundamental surface forces in oil sand processing research. Asphaltene coated surfaces were chosen as the research topic due to the critical role of asphaltenes in oil sands processing, from bitumen extraction, froth treatment to tailings treatment. To mimic the real surface state in industry processing, dip-coated asphaltene surfaces were prepared for surface force experiments. In this study, a SFA 2000 was used to determine intermolecular and surface forces of asphaltene in organic solvents (toluene and heptane). The force vs. distance curves, or so-called force profiles obtained provide valuable information on local material properties such as interaction energies, molecular conformation changes of the interacting asphaltene surfaces or films. Atomic force microscopy (AFM) was used to provide complementary information on the surface morphology of the prepared asphaltene surfaces. / Chemical Engineering

This research project is a part of our endeavor to developing a new hydrogen sulfide (H2S) splitting cycle for hydrogen production. In view of that the Bunsen reaction is the key step for the overall efficiency, the objective of this research is to develop an effective and efficient process to carry out the Bunsen reaction in the presence of organic solvents. Organic solvents can help dissolve iodine crystal, lower the reaction temperature and reduce the corrosiveness accompanying the reaction. Through screening of the ordinary organic solvents, aromatic hydrocarbons stood out and toluene was used in this project.<p> In order to study the Bunsen reaction rate in the presence of toluene, the iodine solubility in HI solution was extensively explored at room temperature. Although the iodine solubility in water is small (0.3404g/L at 25â), it was found that the iodine solubility in HI solution increases greatly as the [HI] increases. At lower [HI] (0~0.238 M), the iodine solubility is linear to [HI] with a relationship of [iodine solubility] = 0.57[HI] + 0.0030; at higher [HI] (0.238 ~7.6 M), the relationship of the iodine solubility and [HI] conforms to [iodine solubility]/[HI] = 0.190[HI] + 0.58.<p> In the second part, the iodine distribution behavior between HI solution and toluene phase was studied at room temperature. It was determined that the iodine distribution coefficient (D = [I2]HI solution/[I2]toluene) increases as the increase of [HI]. At lower [HI] (0~1.89 M), the distribution coefficient has a quadratic relationship with [HI] as D = 1.4027[HI]2 + 0.8638[HI] + 0.0088; at higher [HI] (1.89~7.54 M) the distribution coefficient is linear to [HI] with a relationship of D=5.5937[HI]-3.5632.<p> On the basis of the above work, in a semi-batch reactor, the Bunsen reaction rate in the presence of toluene was measured. In a mixture of toluene and water, iodine prefers to stay in toluene phase. The Bunsen reaction was readily initiated by feeding SO2 into water phase. Experimental results indicated that the rate of the Bunsen reaction in the presence of toluene is equal to the molar flow rate of feeding SO2 when the iodine concentration is higher than a certain value. This specific value depends on the reaction conditions, such as the interface area between water and toluene phase, the dispersion efficiency and the flow rate of SO2.

This research project is a part of our endeavor to developing a new hydrogen sulfide (H2S) splitting cycle for hydrogen production. In view of that the Bunsen reaction is the key step for the overall efficiency, the objective of this research is to develop an effective and efficient process to carry out the Bunsen reaction in the presence of organic solvents. Organic solvents can help dissolve iodine crystal, lower the reaction temperature and reduce the corrosiveness accompanying the reaction. Through screening of the ordinary organic solvents, aromatic hydrocarbons stood out and toluene was used in this project.<p> In order to study the Bunsen reaction rate in the presence of toluene, the iodine solubility in HI solution was extensively explored at room temperature. Although the iodine solubility in water is small (0.3404g/L at 25â), it was found that the iodine solubility in HI solution increases greatly as the [HI] increases. At lower [HI] (0~0.238 M), the iodine solubility is linear to [HI] with a relationship of [iodine solubility] = 0.57[HI] + 0.0030; at higher [HI] (0.238 ~7.6 M), the relationship of the iodine solubility and [HI] conforms to [iodine solubility]/[HI] = 0.190[HI] + 0.58.<p> In the second part, the iodine distribution behavior between HI solution and toluene phase was studied at room temperature. It was determined that the iodine distribution coefficient (D = [I2]HI solution/[I2]toluene) increases as the increase of [HI]. At lower [HI] (0~1.89 M), the distribution coefficient has a quadratic relationship with [HI] as D = 1.4027[HI]2 + 0.8638[HI] + 0.0088; at higher [HI] (1.89~7.54 M) the distribution coefficient is linear to [HI] with a relationship of D=5.5937[HI]-3.5632.<p> On the basis of the above work, in a semi-batch reactor, the Bunsen reaction rate in the presence of toluene was measured. In a mixture of toluene and water, iodine prefers to stay in toluene phase. The Bunsen reaction was readily initiated by feeding SO2 into water phase. Experimental results indicated that the rate of the Bunsen reaction in the presence of toluene is equal to the molar flow rate of feeding SO2 when the iodine concentration is higher than a certain value. This specific value depends on the reaction conditions, such as the interface area between water and toluene phase, the dispersion efficiency and the flow rate of SO2.

No description available.

The aim of this work is the preparation of porous polymeric membranes for liquid separations stable in organic solvents, high temperature and/or extreme acid or basic conditions. Polymeric membranes with these properties could replace more traditional and energy-expensive separation processes like distillation, competing with ceramic membranes due to their easy processability and scalability. A limited library of polymers have been successfully used for decades in water-based applications. They are however unstable in organic solvents without an additional treatment, which is usually a crosslinking reaction. In this dissertation different highperformance polymeric membranes and crosslinking strategies are presented and discussed, allowing their use in harsh environments. We present for the first time the preparation of porous membranes using poly(oxindole) derivatives. These polymers were prepared by superacid catalyzed polyhydroxyalkylation, which is a novel one-pot, room-temperature, metal-free polymerization method. The obtained polymers were fully characterized and then manufactured into membranes by the non-solvent induced phase separation method. The crosslinking of these membranes was achieved by different protocols. First, we reacted the oxindole group in the polymer backbone with a variety of dibromides of different chemical structure. Secondly, we incorporated a propargyl side group, followed by a crosslinking in hot glycerol. Moreover, the strategy of crosslinking using propargyl as pendant group was successfully demonstrated in membranes made of poly(benzimidazole) and poly(triazolebisphenol-AF). And thirdly, we prepared membranes from hydroxyl-functionalized poly(oxindole), and conducted a controlled thermal oxidation, which resulted in the crosslinking by phenoxy radicals. In each case, the resulting membranes achieved insolubility in polar aprotic organic solvents, high resistance in acid medium and had high decomposition temperatures. In each case, the resulting membranes achieved not only insolubility in polar aprotic organic solvents and resistance to acid media but also showed high decomposition temperatures. Finally, we demonstrated for the first time the preparation of porous membranes based on recycled poly(ethylene terephthalate) plastic bottles and their potential application for separations in an organic solvent medium.

Bio-based monomers are a more sustainable alternative to conventional oil-based monomers [1]. The bis-epoxide limonene dioxide from the epoxidation of the terpene limonene has shown potential for different applications [2]. One of those applications is the use of limonene dioxide as a crosslinking agent to improve the solvent resistance of nanofiltration membranes. Epoxidation of terpenes is conventionally done using meta-chloroperoxybenzoic acid (m-CPBA), using metal complexes with metals such as Tungsten, Titanium, and Cobalt, or different hydroperoxides. A greener method of epoxidation explored is the use of in situ generated dimethyldioxirane from the reaction of acetone and potassium peroxy-monosulfate (Oxone) [3]. The reaction uses sodium bicarbonate buffer in aqueous solution with a mixture of limonene and acetone. This project aims to synthesize different bis-, and tris-epoxides from different bio-derived terpenes including limonene, gamma-terpinene, geraniol, farnesol, and nerol using the reported method using Oxone and ultrasonication. Epoxidation using m-CPBA is also investigated to compare it to the Oxone method. In general, epoxidation using m-CPBA results in higher amount of epoxide, but the Oxone method presents a more sustainable alternative with good results. Successfully synthesized epoxides are used to crosslink polybenzimidazole nanofiltration membranes. Solvent testing in dimethylacetamide is used to inspect whether crosslinking is successful. Polyethylene glycol diglycidyl ether is a commercial bis-epoxide that was used to validate the crosslinking method. Crosslinking was successful, as confirmed by solvent testing and FT-IR analysis. Filtration testing showed that the permeance of the membrane was not affected by crosslinking, while the membrane’s rejection was increased from 10.29 ± 1.01 % to 17.23 ± 2.49 % after crosslinking using polyethylene glycol diglycidyl ether. Nerol and limonene bis-epoxides were successfully synthesized with high purity and were tested as crosslinkers. However, crosslinking was unsuccessful, as demonstrated by solvent testing. This project successfully synthesized bis-epoxides from different terpenes using a greener method of epoxidation. The possibility of successful crosslinking using the terpene-based crosslinkers should be further investigated.

Thesis (Ph.D. (Chemical Engineering))--North-West University, Potchefstroom Campus, 2009.

Thesis (Ph.D. (Chemical Engineering))--North-West University, Potchefstroom Campus, 2009.

Thesis (Ph.D. (Chemical Engineering))--North-West University, Potchefstroom Campus, 2009.

The focus of this dissertation was the development, synthesis and modification of polymers for the preparation of membranes for organic solvent nanofiltration. High chemical stability in a wide range of solvents was a key requirement. Membranes prepared from synthesized polymers as well as from commercial polymers were designed and chemically modified to reach OSN requirements. A solvent stable thin-film composite (TFC) membrane is reported, which is fabricated on crosslinked polythiosemicarbazide (PTSC) as substrate. The membranes exhibited high fluxes towards solvents like THF, DMF and DMSO ranging around 20 L/m2 h at 5 bar with a MWCO of around 1000 g/mol. Ultrafiltration PTSC membranes were prepared by non-solvent induced phase separation and crosslinked with GPTMS. The crosslinking reaction was responsible for the formation of an inorganic-type-network that tuned the membrane pore size. The crosslinked membranes acquired high solvent stability in DMSO, DMF and THF with a MWCO above 1300 g/mol. Reaction Induced Phase Separation (RIPS) was introduced as a new method for the preparation of skinned asymmetric membranes. These membranes have two distinctive layers with different morphologies both from the same polymer. The top dense layer is composed of chemically crosslinked polymer chains while the bottom layer is a porous structure formed by non-crosslinked polymer chains. Such membranes were tested for vitamin B12 in solvents after either crosslinking the support or dissolving the support and fixing the freestanding membrane on alumina. Pebax® 1657 was utilized for the preparation of composite membranes by simple coating. Porous PAN membranes were coated with Pebax® 1657 which was then crosslinked using TDI. Crosslinked Pebax® membranes show high stability towards ethanol, propanol and acetone. The membranes were also stable in DMF once crosslinked PAN supports were used. Sodium alginate polymer was investigated for the preparation of thin film composite membranes. Composite membranes were prepared using PAN and crosslinked PAN supports; these membranes were tested for methanol and DMF. Freestanding nanofilms fixed on alumina were also tested for methanol and DMF as well as many other harsh solvents. The alginate composite membranes showed excellent solvent stability and good permeances and a MWCO of around 1300 g/mol.