Vetiver grass is a viable vegetative absorbent and erosion barrier; in addition the valuable oils extracted from its roots are playing an increasing role in the perfume, food and pharmaceutical industries. The quantity and quality of oil extracted from the vetiver grass depends strongly on location of growth, and the extraction and separation techniques adopted. The aim of this research project is to evaluate whether the harvesting and extracting of essential oils from locally grown vetiver grass would be a feasible business idea, as well as, which extraction technique will give the highest yield of vetiver oil. The extraction methods tested are solvent extraction, hydro distillation and supercritical carbon dioxide extraction. Due to the lack of supercritical fluid extraction equipment available a large portion of the research project was on the design and setup of a supercritical fluid extraction unit. The experimental investigations undertaken using solvent extraction in a soxhlet apparatus with hexane as the extracting agent gave an average yield of +-1.6% for a 5 hour run which is slightly lower than the yield of 1.91% for a 5 hour run stated in literature. According to the experimental results, yields of up to approximately 2% for hexane extraction can be achieved by increasing the extraction time to 12 hours. The vetiver roots were also hydro-distilled in a clevenger apparatus for 16 hours (extraction time); this produced a yield of approximately 0.18 to 0.35%. According to literature hydrodistillation of vetiver roots in a similar apparatus resulted in an average yield of 1.8% for a 16 hour run. This showed that the heavier components of the vetiver oil were not released during the hydro-distillation extraction. Research shows that supercritical carbon dioxide extraction (SCE) produces the highest yields ranging from 2.9 to 3.74% when using the recommended parameters of 190 bar and 50°C. Experimentally a yield of approximately 2.3% was achieved by SCE at 180 bar and 40°C. This yield is lower than that seen in literature due to the lower operating temperature and pressure; however SCE gives a higher yield than the other methods tested in this investigation. The composition of the vetiver oil extracts were analysed using gas-chromatography techniques and this showed that a large percentage of nootkatone is present when using the hydro distillation technique, whilst a large percentage of zizanoic acid was present when using the solvent extraction technique. However a minimal percentage zizanoic acid with higher percentages of nootkatone and khusimol are present in the SCE extracts. The solvent extraction technique gives high yield with high percentage invaluable zizanoic acid whereas hydro-distillation gives very low yields but no zizanoic acid with high percentages valuable nootkatone and khusimol. SCE gives slightly higher yields of vetiver oil than solvent extraction and it contains very minimal zizanoic acid with higher percentages of nootkatone and khusimol. It was therefore concluded that SCE would be the best extraction method for these particular vetiver roots. For a pilot scale SCE extractor the total annual sales was estimated as R 453 420 and the total operating costs per annum were estimated to be R 4 839 813. Therefore from this preliminary feasibility study it is seen that the total operating costs far exceed the total annual sales and hence the business is not profitable. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2012.

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of requirements for the degree of Master of Science. Johannesburg, 2014. / Unable to load abstract.

A dissertation submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, in fulfilment of the requirements for the degree of Master of Science in Engineering. Johannesburg, 2016 / The feasibility of extracting iron from iron(III) oxide bearing materials with acetylacetone has been under investigation for many years. This is an alternate, environmentally friendly process for the recovery of iron compared to conventional processes that are energy intensive, have numerous costly process steps and produce large quantities of greenhouse gases. Iron(III) oxide bearing waste materials can be used in this process which reduces its environmental impact as it would not require waste storage. This study investigated the feasibility of reducing the reaction time of the liquid phase extraction of iron from iron ore fines by performing the extraction at elevated pressures and temperatures. It was found that that the extraction under pressure was dependent on temperature, pressure, particle size and solid to liquid ratio. It was found that at high temperatures and long extraction times, an unknown secondary reaction occurs that consumes the desired product, iron(III) acetylacetonate, and inhibits the recovery of these crystals. This results in lower extraction yields. It was found that the side reaction was largely dependent on the temperature of the system and the amount of iron(III) acetylacetonate present. The effects of the side reaction could be limited by lower operating temperatures and reducing the total reaction times. An optimum conversion of iron(III) oxide to iron(III) acetylacetonate of 47.2% was achieved for synthetic iron (III) oxide (> 95 wt% Fe2O3) at a total extraction time of 4 h, 160 °C, 0.025 g:1 mL, operating pressure of 1700 kPa, initial N2 feed pressure of 1010 kPa and 375 rpm stirrer speed. The optimum extraction of iron from iron ore fines (> 93 wt% Fe2O3) to iron(III) acetylacetonate was found to be 20.7% at 4 h, 180 °C, 0.025 g:1 mL and operating pressure of 1900 kPa, initial N2 feed pressure of 1010 kPa and 375 rpm stirrer speed. These are the optimum conditions where the side reaction is limited to improve the recovery and desired reaction conversion capabilities of the process. The operation under pressure yielded lower conversions than that of the atmospheric leaching process developed by Tshofu (acetylacetone water system under reflux). It was also found that it was not possible to reduce the extraction time and achieve comparable extractions when operating at higher temperatures and pressures. The formation of an additional unwanted product would also lead to unnecessary treatment costs in an industrial process. Hence, it was found that pressure leaching as an alternative is not currently viable due to the lower yields and associated high costs. Atmospheric leaching seems to be the most economically feasible option until a better alternative is found. / MT2017

Li Pik Ha Ivy. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (leaves 83-87). / Abstracts in English and Chinese. / TABLE OF CONTENTS --- p.i / LIST OF FIGURES --- p.v / LIST OF TABLES --- p.vii / ABSTRACT --- p.viii / ACKNOWLEDGEMENT --- p.x / DECLARATION --- p.xi / ABBREVIATIONS --- p.xii / Chapter Chapter one --- Introduction / Chapter 1.1 --- Background --- p.1 / Chapter 1.2 --- Polysaccharides isolated from Ganoderma Lucidum --- p.4 / Chapter 1.3 --- Conventional methods for molecular weight (MW) determination of polysaccharides --- p.6 / Chapter 1.3.1 --- Osmometry --- p.7 / Chapter 1.3.2 --- Light Scattering --- p.8 / Chapter 1.3.3 --- Intrinsic Viscosity --- p.8 / Chapter 1.3.4 --- Size Exclusion Chromatography (SEC) --- p.9 / Chapter 1.3.5 --- Mass Spectrometry --- p.10 / Chapter 1.4 --- Matrix-assisted Laser Desorption / Ionization Mass Spectrometry --- p.12 / Chapter 1.5 --- MALDI-TOF Mass Spectrometry of polysaccharides --- p.13 / Chapter 1.6 --- Outline of project --- p.15 / Chapter Chapter two --- Instrumental and experimental / Chapter 2.1 --- Instrumentation --- p.18 / Chapter 2.1.1 --- Laser-based ion source --- p.18 / Chapter 2.1.2 --- Time-of-flight (TOF) analyzer --- p.19 / Chapter 2.1.3 --- Ion deflector --- p.23 / Chapter 2.1.4 --- Detector and data acquisition system --- p.23 / Chapter 2.2 --- Experimental --- p.26 / Chapter 2.2.1 --- Isolation of water-soluble polysaccharides from Ganoderma Lucidum by water extraction --- p.26 / Chapter 2.2.2 --- Isolation of water-soluble polysaccharides from Ganoderma Lucidum by dimethyl ssulfoxide (DMSO) extraction --- p.26 / Chapter 2.2.3 --- Fractionation of water-soluble polysaccharides by Gel Permeation Chromatography (GPC) --- p.27 / Chapter 2.2.4 --- Bradford protein assay --- p.28 / Chapter 2.2.5 --- Phenol / sulfuric acid assay --- p.28 / Chapter 2.2.6 --- Sample preparation in MS --- p.28 / Chapter 2.2.7 --- Calibration of MALDI-TOF-MS --- p.29 / Chapter 2.2.8 --- Data analysis --- p.29 / Chapter Chapter three --- Extraction and purification of water-soluble polysaccharides from Ganoderma Lucidum / Chapter 3.1 --- Introduction --- p.30 / Chapter 3.2 --- Experimental --- p.32 / Chapter 3.2.1 --- Extraction efficiency --- p.32 / Chapter 3.2.2 --- Dialysis --- p.32 / Chapter 3.2.3 --- Signal suppression effect --- p.32 / Chapter 3.2.4 --- Sevag method --- p.33 / Chapter 3.2.5 --- Trichloroacetic acid (TCA) precipitation --- p.33 / Chapter 3.2.6 --- Bradford Protein Assay --- p.34 / Chapter 3.2.7 --- Phenol sulfuric acid assay --- p.34 / Chapter 3.3 --- Results and discussion --- p.35 / Chapter 3.3.1 --- Extraction efficiency --- p.35 / Chapter 3.3.2 --- Purification of crude polysaccharides --- p.37 / Chapter 3.3.3 --- Desalting --- p.38 / Chapter 3.3.4 --- Deproteination --- p.40 / Chapter 3.3.4.1 --- Monitoring of protein contents --- p.40 / Chapter 3.3.4.2 --- Monitoring of carbohydrate contents --- p.45 / Chapter 3.3.4.3 --- Deproteination using Sevag and TCA procipitation method --- p.47 / Chapter 3.4 --- Conclusions --- p.54 / Chapter Chapter four --- Evaluation of MW and MWD of water-soluble Polysaccharides extracted from Ganoderma Lucidum / Chapter 4.1 --- Introduction --- p.55 / Chapter 4.2 --- Experimental --- p.58 / Chapter 4.2.1 --- Aqueous DHB matrix --- p.58 / Chapter 4.2.2 --- Aqueous DHB/NH4F matrix --- p.58 / Chapter 4.2.3 --- Aqueous DHB matrix in TA solution --- p.58 / Chapter 4.2.4 --- Aqueous DHB/NH4F matrix in TA solution --- p.59 / Chapter 4.2.5 --- Aqueous DHB/NH4F matrix with sodium salt in TA solution --- p.59 / Chapter 4.2.6 --- Aqueous DHB/NH4F matrix with potassium salt in TA solution --- p.59 / Chapter 4.2.7 --- Fractionation of water-soluble polysaccharide extracted by DMSO by Gel Permeation Chromatography (GPC) --- p.59 / Chapter 4.2.8 --- Ultra-violet absorption spectrometry (UV-VIS) --- p.60 / Chapter 4.3 --- Results and discussion --- p.60 / Chapter 4.3.1 --- Development of matrix and solvent system for water-soluble polysaccharides --- p.60 / Chapter 4.3.2 --- MW and MWD of water-soluble polysaccharides extracted from Ganoderma Lucidum --- p.64 / Chapter 4.3.2.1 --- Water extraction --- p.65 / Chapter 4.3.2.2 --- DMSO extraction followed by water-back extraction --- p.70 / Chapter 4.4 --- Conclusions --- p.79 / Chapter Chapter five --- Concluding remarks --- p.82 / References --- p.84

Thesis (M.S.)--Mississippi State University. Dave C. Swalm School of Chemical Engineering. / Title from title screen. Includes bibliographical references.

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

published_or_final_version / Civil Engineering / Doctoral / Doctor of Philosophy

A high speed stirring apparatus was constructed for following the kinetics of very rapid solvent extractions. Reactions with half-lives of 15 seconds can be followed with good precision. Experimental data obtained with the device are shown to be superior to kinetic data for the same reaction obtained with batch shakers and cruder stirring devices. The apparatus was used to determine the rate law for the extraction of copper by 2-hydroxyl-5-nonylbenzophenone oxime(I) and 5-dodecyl-2-hydroxylbenzophenone oxime(II). The rate law for the extraction of copper by I catalyzed by 5,8-diethyl-7-hydroxy-6-dodecanone oxime(III) was also determined. Equilibrium data are used to characterize the stoichiometry of the extracted complexes. Compound I, which is an aromatic β-hydroxyoxime, extracts copper as the 2:1 neutral chelate. Compound III, which is an aliphatic α-hydroxyoxime, has a much more complicated extraction chemistry. Experimental evidence indicates the existence of a conventional 2:1 neutral chelate, a neutral (possibly polymeric) complex, and a singly charged 1:1 complex which extracts as an ion pair with a monovalent anion. Distribution constants between chloroform and water were also determined for each ligand. The experimentally observed distribution constants for I and II are much lower than constants derived from theoretical calculations. Compound III has a partitioning constant which is in good agreement with its theoretically calculated value. The rate equations for the extraction of copper by I and II, and for the extraction of copper by I catalyzed by III, are all first order in metal ion, second order in ligand, and inverse first order in hydrogen ion. The catalytic rate law is first order in each ligand. In the case of the reactions which are second order in ligand, the rate determining step is proposed to be the aqueous phase reaction of a 1:1 intermediate complex with the second ligand molecule. Knowledge of the partitioning constants of the ligands, which in turn provides their aqueous phase concentrations, leads to the calculation of second order reaction rate constants of 1.2 x 10('7)M⁻¹s⁻¹ for I and 1.1 x 10('7)M⁻¹ for II. In the case of the catalytic mechanism, the rate law cannot be used to discern which ligand reacts in the rate determining step. If the reactive 1:1 intermediate is assumed to be with I, then a catalytic rate constant of 9.5 x 10('9)M⁻¹s⁻¹ is obtained. A catalytic pathway proceeding through a 1:1 intermediate with III is also possible, but this complex is too poorly defined for calculating a rate constant. A kinetic study of the back extraction of copper into water from an organic solution of its 2:1 complex with I indicates three pathways. The chelate partitions into water and releases its coordinated ligands in a solvolysis reaction. Both hydrogen ion and III catalyze the stripping reaction. In the case of catalysis by III, a mixed ligand complex is proposed to partition. In conclusion, the "homogeneous phase" mechanism is found to be the better mechanistic interpretation of these reaction systems. Unlike the interfacial model, this mechanism can account for all the observed phenomena, is supported by independent measurements, and conforms to the vast body of chemical data already acquired on extraction systems.

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