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A possible remediation strategy that involved washing with complexing reagents(s) [disodium ethylenediaminetetraacetate (Na2EDTA) alone or in combination with bis-(2-hydroxyethyl)dithiocarbamate (HEDC)] was evaluated with an urban soil that had been field contaminated with excesses of heavy metal (HMs). Heavy metals (Cd, Cu, Mn, Ni, Pb and Zn) were targeted for removal. The aqueous solution that resulted from, washing was treated with zero-valent (ZV) magnesium (Mg0) or bimetallic mixture (Pd0/Mg 0 or Ag0/Mg0) to release the chelating reagent(s) from their heavy metal complexes. During this reaction, the heavy metals were precipitated from solution as hydroxides or became plated on to the surface of the excess ZV reagent. Thus, an appreciable fraction of the mobilized Pb and Cu and a portion of Zn became cemented to the surface of the ZV metal whereas most of the Fe and Mn were removed from solution as insoluble hydroxides. After filtration and pH re-adjustment, the demetallized solution was then returned to the soil to extract more heavy metals. After three washing cycles with the same reagent, it was observed that the sparing quantity of EDTA (10 mmoles) had mobilized 32--54% of the soil burden heavy metals (5 mmoles), but only 0.1% of the iron had been removed. / A 1:1 (mol/mol) mixture of EDTA and HEDC proved to be approximately equally efficient at HM extraction despite more than a three-fold reduction (3 mmoles) in the quantity of reagents. Three washing with the same reagent mobilized some 49% of the Pb, 18% of the Zn and 19% of the Mn but only 7% of the Cu and 1% of the Fe from the test soil.

Organochlorine (OC) compounds that include several pesticides as well as an array of industrial chemicals were very efficacious for their intended use but were also characterized by deleterious environmental impacts when released either intentionally or inadvertently. Their lipophilic nature, long persistence in the environment and threat to human health caused all the developed countries to ban the production of these chemicals as well as restricted the use of formulations containing these material for food production. / A number of scientists have become involved in the development of intentional degradation methods/techniques for these compounds using zero-valent metals or bimetallic mixtures. To date, there is no single, simple and continuous procedure available to completely dechlorinate lindane or pentachlorophenol (PCP). This work describes the complete dechlorination of lindane and pentachlorophenol by zero-valent Zn, Fe and Fe/Ag bimetallic mixture as well as a supercritical fluid extraction technique for a more efficient mass transfer of the substrates to the surfaces of the metal catalyst. The dechlorination reaction occurs on the surface of metal particles with the removal of all the chlorine atoms from lindane and PCP in a matter of minute, and yields completely dechlorinated hydrocarbon molecules and chloride as products. (Abstract shortened by UMI.)

Article 21 of the Insolvency Act states that the estate of the solvent spouse transfers to the curator of the insolvent spouse's sequestrated estate. The solvent spouse then has the burden to request the release of property vested in the curator of the insolvent estate. In accordance with Article 21(2), the spouse is required to prove a lawful title on the property. Should the spouse be able to prove a lawful title on the property, the curator is obligated to release the property. Although the constitutionality of this temporarily "deprivation" of the solvent spouse of her rights has already been confirmed by the Constitutional Court; it imposes drastic limitations to his/ her rights. The Insolvency Act does not incorporate procedural measures by means of which the curator has to establish whether the solvent spouse has exempted his/ her from the proof burden. In the same breath, the Constitution and the Promotion of Administrative Justice Act warrant that "everyone has the right to administrative action that is lawful. reasonable and procedurally fair." If the curator's actions, in accordance with Article 21. conform to the administrative procedures as set out in the Promotion of Administrative Justice Act, the spouse shall be entitled to administrative actions which are procedurally fair as concluded within the Promotion of Administrative Justice Act. The conclusion is proof that the actions of the curator, in accordance with Article 21 of the Insolvency Act, is indeed administrative by nature and that the solvent spouse has the right to administrative actions which is procedurally fair as prescribed in the Promotion of Administrative Justice Act, as well as the right to reasons for not being granted the release of property. / Thesis (LL.M. (Estate Law))--North-West University, Potchefstroom Campus, 2007.

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

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

Steam assisted gravity drainage (SAGD) has been demonstrated as a proven technology to unlock heavy oil and bitumen in Canadian reservoirs. Given the large energy requirements and volumes of emitted greenhouse gases from SAGD processes, there is a strong motivation to develop enhanced oil recovery processes with lower energy and emission intensities. In this study, the addition of solvents to steam has been examined to reduce the energy intensity of the SAGD process. Higher oil recovery, accelerated oil production rate, reduced steam-to-oil ratio, and more favorable economics are expected from the addition of suitable hydrocarbon additives to steam. A systematic approach was used to develop an effective hybrid steam/solvent injection to improve the SAGD process. Initially, an extensive parametric simulation study was carried out to find the suitable hydrocarbon additives and injection strategies. Simulation studies aim to narrow down hybrid steam/solvent processes, design suitable solvent type and concentration, and explain the mechanism of solvent addition to steam. In the experimental phase, the most promising solvents (n-hexane and n-heptane) were used with different injection strategies. Steam and hydrocarbon additives were injected in continuous or alternating schemes. The results of the integrated experimental and simulation study were used to better understand the mechanism of hybrid steam/solvent processes. Experimental and simulation results show that solvent co-injection with steam leads to a process with higher oil production, better oil recovery, and less energy intensity with more favorable economy. Solvent choice for hybrid steam/solvent injection is not solely dependent on the mobility improvement capability of the solvents but also reservoir properties and operational conditions such as operating pressure and injection strategy. Pure heated solvent injection requires significant quantities. A vaporized solvent chamber is not sustainable due to low latent heat of the solvents. Alternating steam and solvent injection provides heat for the solvent cycles and increases oil recovery. Co-injection of small volumes (5-15% by volume) of suitable solvents at the early times of the SAGD operation considerably improves the economics of the SAGD process.

Heavy metals in the environment are a source of some concern because of their potential reactivity, toxicity, and mobility in the soil. Soil contamination by metals is placing human and environmental health at risk through possible contamination of food chain. / Soil washing can be used to remove metals from the soil. Chemical treatment involves the addition of extraction agents that react with the contaminant and leach it from the soil. The liquid, containing the contaminants, is separated from the soil resulting in a clean solid phase. Six chelating reagents, EDTA, Citric acid, ADA, DTPA, SCMC, and DPTA, were employed to determine the relative extraction efficiencies of the six chelating reagents for the target metals. Recycling of chelating reagent was the main interest of this study. The experiments were divided into four parts: (1) preliminary studies on the preparation and characterization of soil that included grinding, sieving, soil texture measurements, total metals content post digestion and the distribution of metals in different soil fractions as well as (2) a comparison of the extraction efficiencies of six chelating reagents toward Cu, Pb, Zn, Fe, and Mn. Additionally, the chelating reagent was liberated and recycled by treatment of the metal-complexes with disodium diethyl dithiocarbomate (DEDTC). Additionally, supercritical CO2 was used to extract metal-DEDTC complexes using various surfactants to maintain the metal-DEDTC complexes in suspension. Finally, (4) magnesium metal was evaluated as an alternative method for liberating the water-soluble chelating reagent from the complex so as to be able to recycle this reagent as well. / The different approaches were promising in terms of recycling the chelating reagents that suggests a means of optimizing the experimental conditions in future applications.

Polychlorinated biphenyls (PCBs) are toxic, stable organic contaminants that are present in air, water, soil, plants and animals all around the world. The market for PCB treatment technologies is estimated to be $300 to $600 million (Canadian dollars) for the year 2000, and will expand in future years. Existing treatment technologies to remove PCBs from soil are underutilized because they are more expensive than landfilling and incineration. This thesis presents a laboratory study of an innovative PCB remediation process that will extract PCBs from soil in-situ for subsequent destruction above ground. This remedy will remove PCBs from surficial soil without the need for excavation. Two laboratory studies were conducted on field-contaminated soil. The first experiment evaluated the effectiveness of hexane, methyl isobutyl ketone, and ethyl acetate in removing PCBs from soil. Ethyl acetate and MIBK were equally effective, removing 99% and 98% of PCBs from dry soil in 4 days, respectively. In the second experiment, soil was exposed to ethyl acetate for varying amounts of time, and some of the samples were treated a second time with fresh solvent. PCB removal increased as treatment time was increased from 10 minutes to 50, 250, and 1250 minutes, but the rate of PCB removal decreased as treatment time increased. The second 10-minute extraction removed an additional 1--10% of the remaining PCBs.

Thesis (M App Sc) -- University of South Australia, 1992