Thesis (Ph. D.)--University of Wisconsin--Madison, 1964. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1969. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

A dissertation submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science in Engineering. October 2017 / Increasing concerns over environmental and geo-political issues on resources’ sustainability have driven the industries to shift their efforts to produce chemicals from renewable biomass. Amongst the lignocellulosic biomass, corncob contains cellulose, hemicellulose and lignin that are built in a compact structure which makes it difficult to access. Pre-treatment is then applied to make the content to be accessible to enzymatic hydrolysis which breaks down the polysaccharides to monomers. The sugar monomers can be converted to a wide range of bioproducts such as biofuels and bio-chemicals. The objective of the study was to determine, evaluate and optimize the best solvent system to pre-treat corn cob. In addition, the study evaluated the effect of pre-treatment parameters on the yield of cellulose and hemicellulose and attempt to develop a kinetic model to explain the dissolution. Lithium perchlorate, zinc chloride, phosphoric acid, sulphuric acid and sodium hydroxide were used during the pre-treatment, which was carried out at 70-80 ° C for 6 hours. Characterization of pre-treated samples showed a significant change in structure after pretreatment indicating disruption in cell wall of the lignocellulosic material. FTIR revealed a reduction in phenolic group; indicating that the lignin content has been reduced. The XRD patterns show that crystallinity was considerably reduced; this was shown by an increase in calculated crystallinity index (CrI) after LiClO4, ZnCl2, H3PO4 and NaOH pre-treatment. The CrI of raw corncob (CrI= 32.7%) increased to 46.2 %, 42.3 %, 55.6 % and 53.4 % of LiClO4, ZnCl2, H3PO4 and NaOH, respectively. The crystallinity index increased for pre-treated material, indicating that the amorphous cellulose is dissolved in the liquor, as well as lignin and hemicellulose removal This study has shown that LiClO4.2H2O pretreatment agent is an efficient solvent system to pretreat corncob which consecutively increase the accessibility of cellulose and hemicellulose from the solid fractions. The accessibility was confirmed by an ease hydrolysis of cellulose & hemicellulose to glucose & xylose respectively. An increase of nearly four times compared to the untreated corncob. The effect of reaction operating parameters i.e. Reaction time, temperature and solvent concentration was carried out and then optimized by response surface methodology (RSM) using Minitab 16. The target was to maximize the yield of cellulose and hemicellulose. It was discovered that the increase in temperature and reaction time increase the accessibility of cellulose and hemicellulose until an equilibrium is reached at 3 & half hours and 176 °c. The pretreatment solvent concentration was discovered to have an effect on the accessibility but not as much as temperature and time. The best pretreatment conditions to obtain high polysaccharides conversions to monomers were at 176°c for 3.5 hours using LiClO4.2H2O for 10 g of corncob. The results obtained from RSM were used to evaluate the temperatures profile, kinetic model for the corncob pretreatment as a function of temperature. The kinetics of pretreatment were studied by the amount of glucose, xylose and the lignin removed from the pretreated solids. The kinetic model of lignin removal and sugars accessibility was identified as a first-order reaction corresponding to the bulk phase for pretreatment time up to 24 hours. The rate constant results show that the kinetic rate increased with temperature. The activation energy for glucose, xylose and lignin were calculated to be 15.0 kJ/mol, 14.2 kJ/mol and 36.54 kJ/mol, respectively. / MT 2018

Succinic acid, a low molecular weight dicarboxylic acid was used to leach out heavy metals from Willamette Valley soil (contaminated separately with lead, copper, and zinc) in form of water-soluble organo-metal complexes. The research tasks included developing synthetic contaminated soils representative of those found at Superfund sites and making heavy metal adsorption and desorption studies. Fixed amounts of single-metal contaminated soil were treated with succinic acid under varying conditions of pH and organic ligand concentration. Based on the total metal mobilized into the aqueous phase, the optimum values of pH and organic acid were established for each metal. Since the direct determination of all species solubilized by the organic acid solution was not possible, a computer speciation program called MICROQL was used to determine the concentration of metal species in solution containing several metals and potential ligands. The results indicate that succinic acid is capable of significantly altering the partitioning of metals between the soil and the aqueous phase. Higher concentrations of the organic acid resulted in higher removal of metal from the soil. In case of lead and copper, low pH (3.5) succinic acid flushing solution was found to be the most effective, while a pH range of 4.5-5.5 was deemed optimum for zinc. The results also established that the extent of removal of any metal depended not only upon the the stability constant of the organo-metal complex, but also on its mode of retention within the soil. / Graduation date: 1993

Many important atmospheric processes are determined by the chemical composition of aerosols, including organic material. Dicarboxylic acids are a commonly detected class of organic material in urban, rural, and remote sites across the globe. Understanding the surface behavior of these molecules is imperative in characterizing the atmospheric fate of these molecules in aerosols, especially at an aerosol surface. In fact, little is known about their orientation, solvation, or pH dependence. This dissertation explores in molecular level detail the concentration and pH behavior of low molecular weight dicarboxylic acids at the air/water interface, which is used as a model for an aerosol surface. The solvation of the carboxylic head groups is shown to be dependent upon the length of the alkyl backbone. Indeed, the solvation of the head groups changes dramatically from very weakly solvated to typical surface solvation to near bulk solvation as the backbone increases. The orientation and conformation at the surface is fully explored to explain these differences in solvation. The pH dependence of surface adsorption is characterized, and it is shown that some acids are only surface active if they are fully protonated while others may still be surface active in singly or fully deprotonated forms. Using a combination of vibrational sum frequency spectroscopy (VSFS), surface tension, and computational modeling, the behavior at the air/water interface of four of the most relevant surface-active dicarboxylic acids (malonic, succinic, glutaric, and adipic acid) is completely described. VSFS, a surface specific optical technique, provides details about the solvation, orientation, and number density at the surface while surface tension measurements provide corollary information about the surface density. The use of computational modeling aids and confirms the spectral analysis while also providing molecular level details about the surface adsorption of the acids studied. By investigating the concentration and pH dependence of these molecules, molecular level detail is obtained which enables a complete description of these acids at an air/water interface and provides pertinent surface information on these atmospherically important organic molecules. This dissertation includes both previously published and unpublished co-authored material.

There is a huge global challenge to establish alternative forms of energy in order to cope with the increasing worldwide energy demand, currently based on finite fossil fuel reserves. In the transportation sector, renewable liquid fuels, such as bio-ethanol and biodiesel which are made from biomass and are substitutes for the petroleum-derived gasoline and diesel, have received increasing interest. In spite of their recent development, the biofuel industries cannot compete with conventional liquid fuels because of their higher costs. Decisive changes are required to improve their economic sustainability, such as the establishment of novel processes that utilize their by-products for the production of value-added chemicals. In this study, the bioconversion of glycerol, which is the main by-product of the biodiesel industry, to succinic acid by using the bacterium Actinobacillus succinogenes has been investigated both experimentally and computationally. Initially, the cells were adapted to accept a glycerol rich environment by performing a series of experiments. Cells from the best experiment from each run were used as inocula for the next experiment. Batch fermentations were then performed in small scale anaerobic reactors (SARs) and in lab-scale bench top reactors (B-TRs) by using the new ‘adapted’ strain. The maximum succinic acid yield, productivity and final concentration obtained from this bioprocess were found to be 1.29 g/g, 0.27 g/L/h and 29.3 g/L, respectively. Moreover, cells have also grown successfully in both synthetic and biodiesel-derived crude glycerol, indicating that it is not necessary to remove the impurities that biodiesel-derived glycerol contains. Subsequently, an unstructured model that accounts for substrate and product inhibition was developed in order to predict the behaviour of experiments starting from different initial conditions. Model predictions were found to be in good agreement with experimental data obtained for both systems (SARs and B-TRs). Batch and fed-batch systems were optimized using the developed model to obtain high succinic acid productivity. Optimization results showed that productivity increased by 31% for batch and 79% for fed-batch systems. The corresponding optimal values were computed to be equal to 0.356 g/L/h for batch and 0.488 g/L/h for fed-batch systems. A semi-mechanistic model for the fungal fermentation on solid state rapeseed meal (i.e. the other main by-product of the biodiesel industry) was also constructed for small scale tray bioreactors. This fermentation targets to increase the nutrient factor of the rapeseed meal by decomposing its macromolecules to simple compounds which can then be used as a generic medium. The developed model effectively predicts the fungal growth, the temperature fluctuations and the moisture content inside the bed and the produced extracellular enzymes that break the complex compounds of rapeseed meal (i.e. proteins) to free amino acids. The economic sustainability of biodiesel production was investigated by the construction of a plant model of an integrated biodiesel biorefinery for the production of fuels (biodiesel) and chemicals (succinic acid) in Aspen Plus®. For a biodiesel plant with capacity of 7.8 ktons per year, it was found that the plant’s profitability can be increased by 60% (considering a 20 years plant life and an interest rate of 7%) if a fermentation and recovery process for producing succinic acid is added. The integrated biorefinery scheme demonstrated the highest profits (€ 9.95 M.) when compared with other scenarios which either purified or disposed of the glycerol. These results illustrate the critical role of glycerol when it is utilized as a key renewable building block for the production of commodity chemicals. It is clear, based on this work, that future studies targeting the sustainable development of biodiesel biorefineries should focus their investigation on novel bio-processes, like the succinic acid fermentation, supplementing the production of fuels with the co-production of platform chemicals.

Succinic Acid (SA) was continuously produced using glucose and a Mg2CO3(OH)2 slurry as feed. Glucose feed concentrations of 20 and 40 g ℓ-1 were employed with corresponding Mg2CO3(OH)2 slurry concentrations of 60 and 120 g ℓ-1. The reactor pH was passively maintained between 6,4 and 6,8 by the buffer properties of the slurry in conjunction with the pH adjusted glucose feed. The suspended cell (SC) reactor was operated at 37°C with dilution rates varying between 0,04 h-1and 0,6 h-1. Groperl® particles were used as inert supports in the biofilm reactor; dilution rates of 0,11 h-1 to 1 h-1 were investigated. Two SC fermentations were conducted for the 20 g ℓ-1 glucose feed concentration and one for the 40 g ℓ-1. All SC fermentation runs were operated in excess of 12 days, while the biofilm run lasted 6,5 days. Fermentations were terminated only after contamination by lactic acid bacteria was observed. SC fermentations with the glucose feed concentration of 20 g ℓ-1 achieved a maximum SA productivity of 5,2 g ℓ-1h-1 at 0,6 h-1 with a corresponding SA yield of 0,65 g g-1. SC fermentations with the glucose feed concentration of 40 g ℓ-1 achieved a maximum SA productivity of 3,76 g ℓ-1h-1 at 0,4 h-1 with a SA yield of 0,82 g g-1. The results were comparable to the other continuous studies with Actinobacillus succinogenes, despite the fact that either biofilms or membranes were employed in these studies. The preliminary biofilm study demonstrated the capability of A. succinogenes to produce SA in high productivities and yields. SA productivities and yields for the dilution rates of 0,33 h-1 and 1,0 h-1, were 5,72 g ℓ-1h-1 (0,95 g g-1) and 12 g ℓ-1h-1 (1,0 g g-1), respectively. The biofilm reactor at 0,33 h-1 achieved twice the SA productivity of the SC reactor at 0,3 h-1 with a 42 % increase in SA yield. Copyright / Dissertation (MEng)--University of Pretoria, 2012. / Chemical Engineering / unrestricted

A dissertation submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the Degree of Master of Science in Engineering. March 2019 / Depleting fossil fuels and the increasing energy demand has necessitated the move to alternative renewable forms of energy. Lignocellulosic biomass is a renewable and sustainable source for highly valuable bio-based chemicals and material production in a biorefinery system. The effective fractionation of the main components of lignocellulosic biomass (cellulose, hemicellulose and lignin) into usable forms is a crucial step in unlocking an economically viable, high-value product producing biorefinery. The main concern associated with the conversion of lignocellulose is overcoming biomass recalcitrance using pretreatment while still maintaining a green, cost-effective and energy efficient process. Over the last decade, molten hydrate salts have been used for isolated cellulose dissolution, however very few studies have been done to check their ability in lignocellulosic biomass pretreatment. The aim of the study was to compare seven molten hydrate salt solvent systems including unary, binary and ternary mixtures of ZnCl2.4H2O, LiClO4.3H2O and Urea for the effective pretreatment of corncob in terms of physicochemical properties and pretreatment efficiencies and to optimise these efficiencies. The molten salt hydrate pretreatment systems used in this study are aimed at fractionating the corn cobs biomass into a solid fraction which mostly contains cellulose and lignin as the major components, while the liquid fraction contains hemicellulose as the main component. The pretreatment experiments were carried out at 70 for 60 minutes at a biomass: solvent ratio of 1:10. Physicochemical change after pretreatment was checked by FTIR, XRD and SEM. The most efficient solvent mixture was identified by gravimetric analysis for its ability to fractionate the biomass into a cellulose and lignin rich solid fraction and a hemicelluloserich liquid fraction. The effect of solvent pretreatment operating variables (temperature, time and solvent concentration) was investigated to maximize cellulose recovery, hemicellulose recovery in the liquid fraction and lignin recovery from the biomass by response surface methodology (RSM) approach using a central composite design (CCD). Physicochemical analysis showed a decrease in crystallinity and an increase in surface area after the pretreatment in all the MHS solvents tested. This work has successfully shown the use of ZnCl2.4H2O/ Urea, to pre-treat and fractionate corn cob with high recovery of cellulose (100%), low recovery of hemicellulose (42%) and lignin (44%) when compared to the other proposed systems. Through the RSM approach, optimum pretreatment conditions obtained Abstract were: 90 min, 120 oC and concentration of 71.32%/28.68 (w/w) ZnCl2.4H2O/ Urea. At these conditions, the predicted recovery for cellulose, hemicellulose and lignin 99.03%, 27.18% and 72.43% respectively with a desirability of 0.902. The actual recovery was 91%, 29% and 68% for cellulose, hemicellulose and lignin respectively at the same conditions. For a better understanding of the dissolution kinetics and thermodynamics of cellulose, hemicellulose and lignin dissolution in ZnCl2.4H2O/ Urea solvent system, a kinetic study was carried out. The results reveal the dissolution to be a 1st order kinetics and the obtained activation energy for cellulose, hemicellulose and lignin dissolution were 14.10 kJ.mol-1, 11.29 kJ.mol-1 and 7.606 kJ.mol-1 ,respectively. that the dissolution process for all three components are endothermic and endergonic. The -0.190; -0.195 kJ.mol-1) showed that the process of dissolution of hemicellulose occurred more rapidly and produced more stable products. It was concluded that ZnCl2.4H2O/ Urea pretreatment provided a potential way to fractionate lignocellulosic biomass which can improve the effective utilization of all feedstock fractions. / E.K. 2020

Poly butylene succinate (PBS) is a biodegradable plastic polymer that has physical and mechanical properties similar to common petroleum plastics like polypropylene (PP) and polyethylene (PE). PBS may be produced from petroleum or bio-based feedstocks, or by a hybrid combination of petroleum and bio-based resources. Producers are reducing content of petroleum components used for the production of PBS, and by doing so are seeking potential environmental performance improvements. In this study, ???hybrid??? PBS refers to the production of PBS polymer from bio-based succinic acid (SAC) sourced from sorghum and petroleum-based 1, 4-butanediol (BDO). Given its biodegradability, PBS is commercially used for compostable bags and agricultural mulching film applications. A recent study in Ontario identified composite materials made with PBS blended with natural fibres like switchgrass (SG) as promising for applications in automotive products. Such novel composite materials are touted as potential bio-based alternatives to conventional petroleum-based plastics. Of the few studies that have considered the environmental performance of PBS materials, none have assessed the potential environmental impacts of a hybrid PBS composite. Therefore, this study undertook a life cycle assessment (LCA) of SG reinforced hybrid PBS composite (hybrid composite). LCA is an environmental management technique that is used to assess environmental aspects (inputs and outputs) and potential environmental impacts of a product or service throughout its life cycle. The analysis considered a cradle-to-gate system boundary and evaluated eleven environmental performance indicators. The environmental performance of the hybrid composite was compared to a conventional glass fibre (GF) reinforced polypropylene (PP) composite (baseline composite), a material that is widely used in automotive components. Results showed that the production of the hybrid composite in comparison to the baseline composite decreased potential impact for most of the assessed indicators: cumulative energy demand by 40%, waste heat by 23%, global warming potential by 35%, smog by 2%, carcinogens by 54%, non-carcinogens by 172%, respiratory effects by 22% and ecotoxicity by 45%. Increases in the values of impact indicators were apparent for ozone depletion, acidification, and eutrophication by 43%, 16%, and 322%, respectively. Analysis revealed that dominant influences on results were not related directly to the bio-based make-up. Rather, the biggest influence on the environmental performance of composite production were the sources of heat used in petroleum-based materials, the energy mix in electricity for bio-based materials, the type of reinforcing fibre and the co-product treatment methodology used. The study helps fill a gap in knowledge regarding bio-based chemicals and hybrid biodegradable plastic composites, and points to opportunities for future research on feedstocks for industrial composite materials. The importance of this study is that it helps to identify the environmental strengths and weaknesses associated with the production of the hybrid composite specifically, and bio-based materials more generally. It points to alternative material substitution options for use in the automotive industry. In this study, life cycle assessment exemplifies multidisciplinary methodologies, which seek to traverse the boundaries between the social and natural sciences and disciplines to support more sustainable policy decisions for a bio-economy. The systematic nature and the widely applicable consequences of this LCA study have the potential to contribute to industrial and business management, and reach the public policy arena in an effort to drive environmental and social change.

In this study, the ability of pharmaceutical cocrystals on improving solubility and dissolution behaviour of poorly water soluble drug has been studied by a novel technique SDI300 UV imaging surface dissolution system. Pharmaceutical cocrystals of poorly water soluble drug carbamazepine (CBZ) were synthesized, which are 1: 1 carbamazepine - nicotinamide (CBZ-NIC) cocrystal, and 2:1 carbamazepine - succinic acid (CBZ-SUC) cocrystal. Firstly, dissolution and solution mediated phase transformation behaviour (SMPT) of CBZ-NIC cocrystal was studied by in situ techniques of UV imaging and Raman spectroscopy. This study has shown that in situ UV imaging and Raman spectroscopy with a complementary technique of SEM can provide an in depth understanding of cocrystal dissolution processes. It has been found that CBZ-NIC cocrystal including other polymorphs of CBZ III and I and mixture are converting to CBZ DH during dissolution. The influence of surfactants, SLS and Tween 80, on the solubility and dissolution behavior of the CBZ-NIC cocrystal has been studied. Results show that the SMPT of CBZ III and CBZ-NIC cocrystal can be altered by inclusion of a surfactant in dissolution medium. However, CBZ III and CBZ-NIC cocrystal have shown different transformation behavior with different surfactants. The solubility and dissolution behaviour of CBZ-NIC cocrystal, CBZ-SUC cocrystal in four biomedia (simulated gastric fluid, pH1.2 HCl buffer, simulated intestinal fluid, and pH 6.8 PBS buffer) were studied. Results have shown that equilibrium solubility of CBZ samples varied in different media. The two cocrystals dissolution rates show different trends as that of parent drug CBZ III. This can be explained by that the formation of cocrystal change the dissolution ability of CBZ III.