Amitraz is a formamide acaricide used predominantly in the control of ectoparasites in livestock and honeybees. Amitraz hydrolysis is rapid and occurs under acidic conditions, exposure to sunlight and biodegradation by microorganisms. The main hydrolysis product of amitraz, 2,4-dimethylaniline, is recalcitrant in the environment and toxic to humans. An electrochemical method for the determination of total amitraz residues and its final breakdown product, 2,4-dimethylaniline, in spent cattle dip, is presented. Cyclic voltammetry at a glassy carbon electrode showed the irreversible oxidation of amitraz and 2,4-dimethylaniline. A limit of detection in the range of 8.5 x 10⁻⁸ M for amitraz and 2 x 10⁻⁸ M for 2,4-dimethylaniline was determined using differential pulse voltammetry. Feasibility studies in which the effect of supporting electrolyte type and pH had on electroanalysis of amitraz and its degradants, showed that pH affects current response as well as the potential at which amitraz and its degradants are oxidised. Britton-Robinson buffer was found to be the most suitable supporting electrolyte for detection of amitraz and its degradants in terms of sensitivity and reproducibility. Studies performed using environmental samples showed that the sensitivity and reproducibility of amitraz and 2,4-dimethylaniline analyses in spent cattle dip were comparable to analyses of amitraz and 2,4-dimethylaniline performed in Britton-Robinson buffer. In addition, the feasibility qf measuring amitraz and 2,4-dimethylaniline in environmental samples was assessed and compared to amitraz and 2,4-dimethylaniline analyses in Britton-Robinson buffer. Amitraz and 2,4-dimethylaniline were readily detectable in milk and honey. Furthermore, it was elucidated that 2,4-dimethylaniline can be metabolised to 3-methylcatechol by Pseudomonas species and the proposed breakdown pathway is presented. The biological degradation of amitraz and subsequent formation of 2,4-dimethylaniline was readily monitored in spent cattle dip. The breakdown of amitraz to 2,4-dimethylaniline and then to 3-MC was monitored using cyclic voltammetry.

M.Sc. / The addition of lignocellulosic fibres to thermoplastic polymers is known to increase the toughness of the polymers but it compromises the tensile strength. On the other hand, inorganic fillers like TiO2 are known to improve the tensile strength of polymers. These plant fibres have been used as adsorbents of metal pollutants in water. Best results were obtained when such materials were ground to fine powder but due to low density, the fibres float and form aggregates in water. Being highly biodegradable in nature makes plant fibres unsuitable for water treatment over lengthy periods of time. They cannot be used as standalone materials. Mixing these adsorbents with polymers, which cannot only act as support for the adsorbents but also disperse the fibres within it thus preventing leaching, is a cause for concern. This study was aimed at fabricating plant fibre-polymer composites that will have improved mechanical and thermal properties. These composites were to be tested for their ability to be used as metal ion adsorbents. The composites were fabricated using a melt-mix compounding method. Two thermoplastic polymers, EVA and PCL were each mixed with either lignin or SCB and TiO2 in different ratios. A rheomex mixer coupled with a single screw extruder which was attached to a sheet die was used to synthesise the composites. TGA and DSC were used for thermal propagation while the mechanical properties were investigated using an instron. Metal ion adsorption measurements were analysed using an atomic absorption spectrometer (AAS). These adsorbents were used to remove Cr(VI), Cr(III) and Pb(II), varying different environmental parameters like pH, concentration, time and adsorbent at constant temperature. The reinforcing effect of both lignin and SCB resulted to poor thermal and mechanical properties. This was shown by a decrease in onset degradation temperature and the tensile and toughness of the composites compared to the neat polymers. The incorporation of TiO2 on SCB-EVA composites, however, improved the mechanical strength and resulted in a thermally stable composite compared to counterpart composites without TiO2. This observation was surpassed at high filler loading as the addition of TiO2 resulted in a decrease of the properties. For the tensile strength, neat EVA recorded 11.35 MPa while 2% TiO2-EVA registered 12.49 MPa for example. For the same composite, the onset degradation temperature for EVA was 353 oC but shifted to 368 oC after the addition of TiO2. At higher filler loading, no effect was observed when adding TiO2.

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Two weathered, petroleum contaminated soils were studied to determine if weathered products are amenable to bioremediation and to determine which TPH (total petroleum hydrocarbon) fractions were degrading during particular time frames under different remediation alternatives. Delineation of fractional degradation patterns results in inferences regarding the efficacy of different treatment methods on various petroleum products. A sandy loam and a clay soil were both studied to determine if soil matrix affects the degradation patterns. The experimental matrix included sacrificial static microcosms, soil columns and aerated slurry reactors. Both soils were evaluated under all bioreactor configurations using both a nutrient amended water and a water lacking nutrients. Controls were also used to evaluate abiotic losses. Biodegradation rates generally followed a biphasic pattern, initially rapid then followed by a slow or stagnant period. Degradation rates increased from static microcosms to soil columns to slurry reactors. The slow phase was controlled by the presence of recalcitrant compounds which decreased in number and concentrations from static microcosms to columns to slurry reactors, and generally with nutrient addition. Nutrient addition enhanced degradation for all sandy soil treatments, but only slurry reactor treatment for the clay soil. The entire TPH spectrum was broken down into five minute parcels based on GC elution time. The compounds that eluted quickest generally were the easiest to degrade. The fraction that effectively covered the TPH components in gasoline was well removed under all treatment modes. All nutrient amended studies resulted in rapid essentially complete removal of the light fractions within two weeks. The fraction encompassing the middle distillates such as diesel fuel and jet fuel was degraded under all treatment methods, however only the slurry reactors resulted in final TPH levels that would have met regulatory limits. Fractions that eluted after 15 minutes were not effectively degraded by the static microcosms or the soil columns for either soil, eliminating in situ bioremediation as a viable treatment alternative for crude oil, fuel oil and gas oil contamination, at concentrations present in this study. Persistence of recalcitrant compounds was the major factor leading to the poor biodegradation observed in the static microcosms and soil columns. Fractional degradation was highly dependent on the initial concentration of the fraction. Generally, fractions present in the largest concentrations degraded fastest. / Master of Science

Call number: LD2668 .T4 1985 S38 / Master of Science

Building on the development of a research agenda, the research used best practices in the UK and other developed countries to design the aims and objectives from which the methods were developed. Based on the research agenda, trends in household behaviour in Cameroon were examined in order to identify, and generate baseline information to provide a sound evidence base essential for robust policy development in education, capacity building in composting involving the third sector organizations in Cameroon. To determine attitudes, Q methodology was used. Factor analysis produced nine and eight factors representing distinct behavioural patterns of public concerns, opinions and beliefs in household waste management in Douala and Limbe. Interpreting these factors revealed 12 attitudes to household waste management practices and this will be used to design strategies. A waste composition analysis found the organic fraction >60% with the lowest per capita waste generation (0.86 kg) in the high income residential area (HIRA) and the highest (1.38 kg) in the low income residential area (LIRA) of Douala in the wet season. In the dry season, the medium income residential area (MIRA) had the highest (1.11 kg) with the lowest (0.71 kg) in the HIRA. For both seasons in Limbe, HIRA had the highest while the LIRA had the lowest. Pearson correlation and regression was used to show the relationship between waste generation and household size. The research determined barriers and success factors for composting as part of a strategy. Barriers included household hazardous waste (HHW) and odour at composting sites because more than 50% of the composted waste was food waste with high humidity especially in the wet season. This affected public acceptance to composting. A success factor is that the market for compost is increasing and is expected to increase to 30% by 2013. Added to this, more than 50% of the participating households showed positive intentions and willingness to composting. Hence, composting is expected to be a major economic activity for Cameroonians and become a national practice

Thesis (MSc)- Stellenbosch University, 2001. / ENGLISH ABSTRACT: Wood is composed of three main components: cellulose, hemicellulose and lignin. Cellulose is the main structural polymer, whereas the function of lignin in plants is to impart rigidity to the cells, to waterproof the vascular system, and to protect the plant against pathogens. A group of microorganisms, called white-rot fungi, are able to selectively degrade the lignin and hemicellulose from wood leaving the cellulose virtually untouched. The most widely studied fungus of this group is the basidiomycete Phanerochaete chrysosporium, which has become a model organism in studies of lignin degradation. Lignin is a large, heterogenous and water insoluble polymer and therefore the enzymes needed to degrade it have to be extracellular and non-specific. There are a number of enzymes that are involved in the degradation of lignin, including lignin peroxidases, manganese dependent peroxidases and laccases. Laecases are blue copper oxidases that require molecular oxygen to function, whereas lignin peroxidases and manganese peroxidases are heme proteins that require hydrogen peroxide. Phanerochaete chrysosporium has all three of these enzymes, as well as a system for producing the hydrogen peroxide that is necessary for peroxidases to function. For both scientific and industrial purposes, it is important to obtain linkage maps of the positions of genes in the genome of an organism. Most fungi, including P. chrysosporium, lack easily identifiable phenotypical markers that can be used to map the position of genes relative to each other on the genome. Previous methods of mapping genes in P. chrysosporium involved auxotrophic mutants, radioactivity, or the use of hazardous chemicals. Here we describe an automated DNA-sequencing based mapping technique that eliminates many of the problems associated with previous techniques. Portions of the genes to be mapped were amplified from homokaryotic single basidiospore cultures using gene specific primers using the polymerase chain reaction (PCR) technique. The PCR products were sequenced to determine the segregation of alleles. Two previously mapped lignin peroxidases, lipA and lipC, were used to develop this method, and the results obtained corresponded to the known genetic linkage. A newly characterised 13-glucosidase encoding gene from P. chrysosporium was also mapped. Linkage was found between the 13-glucosidase gene and a histone (Hl) encoding gene. In P. chrysosporium the lignin peroxidase isozymes are encoded by a family of at least ten genes. Previous studies with P. chrysosporium BKM-F-1767 in defined media, wood and soil have shown differential expression of the lignin peroxidase isozymes. In this investigation the levels of expression of lignin peroxidases in P. chrysosporium ME446 cultures grown in nitrogen or carbon limited defined liquid media, as well as on aspen wood chips were determined by competitive reverse transcriptase polymerase chain reaction (RT-peR). These results were compared to those previously obtained from P. chrysosporium BKM-F-1767 to evaluate strain specific variation in the expression of lignin peroxidases. The results indicate that, although there were many similarities in the patterns of lignin peroxidase expression, there were also enough differences to conclude that there were strain specific variations in the temporal expression of the lignin peroxidases. To conclude, a fast and cost effective method for mapping genes in P. chrysosporium was developed. Also, we showed that strain specific variation in temporal expression of lignin peroxidases occurs. / AFRIKAANSE OPSOMMING: Hout bestaan uit drie hoof komponente nl. sellulose, hemisellulose en lignien. Sellulose is die hoof strukturele polimeer, terwyl die funksie van lignin in plante is om die selle te versterk, die vaskulêre sisteem waterdig te hou, en die plant teen patogene te beskerm. 'n Groep mikroërganisms, bekend as witvrotswamme, kan lignien en hemisellulose selektief uit die hout verwyder, terwyl die sellulosevesels oorbly. Vanuit hierdie groep swamme is die meeste navorsing op die basidiomiseet Phanerochaete chrysosporium gedoen Lignien is 'n groot, heterogene polimeer en is onoplosbaar in water. Die ensieme wat benodig word om lignien afte breek is daarom nie-spesifiek en kom ekstrasellulêr voor. 'n Aantal ensieme is by die afbraak van lignien betrokke, insluitend lignienperoksidase, mangaanperoksidase en lakkase. Lakkase is 'n blou koperoksidase wat suurstof benodig vir aktiwiteit. Lignienperoksidase en mangaanperoxidase is heemproteïene en benodig waterstofperoksied. Phanerochaete chrysosporium het al drie van hiedie ensieme, sowel as 'n sisteem wat waterstofperoksied produseer. Vir beide wetenskaplike en nywerheidsdoeleindes is koppelingskaarte wat die posisie van gene in die genoom van 'n organisme aandui noodsaaklik. Die meeste swamme, P. chrysosporium ingesluit, het geen fenotipiese merkers wat maklik van mekaar onderskei kan word nie, en dit is dus moeilik om 'n kaart van die ligging van gene op die genoom te bepaal. Vorige metodes om gene in P. chrysosporium te karteer het auksotrofiese mutante, radioaktiwiteit of gevaarlike chemikalieë gebruik. Ons beskryf 'n metode wat van automatiese DNA-volgordebepaling gebruik maak en wat baie van die tekortkominge van die ou metodes oorkom. Dele van die gene is met geen-spesifieke PKR-amplifikasie uit kulture van homokariotiese enkel basidiospore verkry en die DNA-volgorde is bepaal om die segregasie van die allele te ondersoek. Twee gene waarvoor 'n koppelingskaart alreeds uitgewerk is, fipA en lipt), was gebruik om hierdie metode te ontwikkel. Die resultate stem ooreen met die bekende genetiese koppeling tussen hierdie gene. 'n Geen wat onlangs in P. chrysosporium ontdek is, nl. I3-glucosidase, is ook met hierdie metode gekarteer. Koppeling is met 'n histoon (Hl) geen gevind. Die lignienperoksidase isoensieme in P. chrysosporium word deur 'n familie van ten minste tien gene gekodeer. Vorige navorsing met P. chrysosporium BKM-F-1767 in gedefineerde media, hout en grond het getoon dat 'n variasie in die uitdrukking van lignienperoxidase isoensieme voorkom. In hierdie ondersoek is 'n kultuur van P. chrysosporium ME446 in stikstof- of koolstof-beperkende vloeibare media opgegroei, as ook op aspen houtblokkies. Die vlak van uitdrukking van die lignienperoksidases is deur middel van die omgekeerde transkripsie polimerasekettingreaksie (RT-PKR) bepaal. Die resultate vir P. chrysosporium ME446 is vergelyk met vorige resultate van P. chrysosporium BKM-F-1767 om te bepaal of stamspesifieke variasies in die uitdrukking van lignienperoksidases voorkom. Daar is 'n aanduiding dat, alhoewel soortgelyke patrone in die vlakke van lignienperoksidase uitdrukking voorkom, daar ook noemenswaardige verskille is. Hieruit kan afgelui word dat stamverwante variasie van lignienperokisdase uitdrukking voorkom. Ten slotte, ons het 'n vinnige, goedkoop metode om die gene in P. chrysosporium te karteer ontwikkel. Ons het ook bewys dat stam-spesifieke variasie in die uitdrukking van die lignienperoxidase gene voorkom.

Thesis(PhD)--Stellenbosch University, 2008. / ENGLISH ABSTRACT: Aminopolycarboxylic acids (APCAs) are chelating agents widely used to inactivate various metal ions by complex formation in industrial and household applications. Ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA) are the widely used agents. Their use is under scrutiny due to their persistence in the environment because they cannot readily biodegrade. This led to the introduction of readily biodegradable agents namely ethylenediaminedisuccinic acid (EDDS) and iminodisuccinic acid (IDS) as alternatives especially to EDTA. Therefore, there was an interest to study the separation of EDDS, IDS and other APCAs using a simple, quick and accurate method. Capillary electrophoresis was used to determine the separation and speciation of iminodisuccinic acid with various metal ions at various pH levels. Speciation modelling was also utilized to compare and validate the presence and distribution of metal-ligand species. The obtained CE results were compared with speciation profiles and a reasonable agreement was obtained. The degradation studies at various time intervals for the metal-ligand (ML) complexes of DTPA, S,S-EDDS, IDS and R,S-IDS with various metal ions (Cd2+, Cr3+, Cu2+, Fe3+, Mn2+, Pb2+ and Zn2+) at pH 7 and 9 was evaluated using CE. New peaks were observed in some ML complexes when the pH was changed from pH 9 to 7. Sharp peaks were seen for CuL (L = DTPA, S,S-EDDS, IDS and R,S-IDS), FeDTPA and FeEDDS at both pH s. While small broad peaks were observed for FeIDS, CrL and MnL complexes. CuDTPA and CuEDDS complexes showed a greater stability over some considerable time as compared to CuIDS, CuR,S-IDS and other metal complexes at pH 9. This work also investigated the effect of various cationic electroosmotic flow (EOF) modifiers and counter anions on the CE separation of EDTA, EDDS and IDS as Cu(II) complexes. The performance of the modifiers was evaluated in terms of migration times, resolution and plate numbers. The best results were observed when Tetradecyltrimethylammonium bromide (TTAB) and Cetyltrimethylammonium bromide (CTAB) was used as modifiers in order to reverse the EOF in the fused silica capillary. This resulted in short analysis time and better peak shapes. The effect of different counteranions attached to EOF modifiers on the separation was also shown. It was also found that the counter anions of EOF modifiers used influences the separation of the complexes. The EOF modifiers namely Cetyltrimethylammonium chloride (CTAC) and Tetradecyltrimethylammonium chloride (TTAC) were further utilized for the determination of EDTA in South African river waters and industrial effluents. A method for the simultaneous separation of Fe (III) complexed with EDTA, S,S -EDDS and IDS was developed by CE and high-performance liquid chromatography (HPLC). The recalcitrant EDTA is used in combination with readily biodegradable analogues like EDDS and IDS in many commercial products. The methodology performance was evaluated in terms of linearity, limit of detection (LOD), limit of quantitation (LOQ) and reproducibility for both CE and HPLC methods. The LOD values obtained from HPLC were low when compared with CE. The applicability of both methods was demonstrated for the analysis of cosmetic products such as foam bath and shower cream. The results obtained by both CE and HPLC were found to be comparable and are in good agreement. / AFRIKAANSE OPSOMMING: Aminopolikarboksiel sure (APCAs) is komplekseer middels wat algemeen gebruik word om verskillende metaal ione te deaktifeer deur kompleks vorming in industriële en huishoudige toepassings. Etileendiamientetraasynsuur (EDTA) en dietileentriamienpentaasyn suur (DTPA) is die mees algemene APCA s. Hul gebruik word deesdae noukerig ondersoek as gevolg van hul volharding in die omgewing. Daar is n intense soektog na bio-afbreekbare agente soos etieleendiamiendisuksien suur (EDDS) and iminodisuksien suur (IDS) wat as plaasvervangers kan dien vir nieafbreekbare EDTA. Daar is dus n behoefte om te kyk na eenvoudige, vinnige en noukeurige metodes vir die bepaling van EDTA, EDTA , IDS en ander APCA s. Kapillere elektroforese (CE) was gebruik vir die skeiding en spesiering van iminodisuksien suur met verskillende metale by verskillende pH s. Spesiasie modellering was ook gebruik om die teenwoordigheid en verspreiding van metaal- spesies te vergelyk. Die CE uitslae was met die spesiasie profiele vergelyk en n redelike ooreenkoms was gevind. Die degraderings studies as n funksie van tyd was met CE bestudeer vir verskillende metal-ligand (ML) samestellings van DTPA, S,S-EDDS, IDS en R,S-IDS met verskillende metal ione (Cd2+, Cr3+, Cu2+, Fe3+, Mn2+, Pb2+ en Zn2+) by pH 7 en 9. Nuwe pieke was opgemerk in sommige ML samestellings wanneer die pH van pH 9 na 7 verander. Hoë pieke was vir CuL (L = DTPA, S,S-EDDS, IDS and R,S-IDS), FeEDTA en FeEDDS by alle pH s gevind. Lae, breë pieke was vir FeIDS, CrL en MnL komplekse gevind. CuDTPA en CuEDDS komplekse het n goeie stabiliteit gewys oor ʼn redelike tyd as dit met CuIDS, CuR,S-IDS en ander metal komplekses by pH 9 vergelyk word. In hierdie werk was die effek van verskillende kationiese elektro-osmotiese stroom (EOF) modifiseerders ook ondersoek. Veral die effek wat teen ioone op die CE skeidings het van EDTA, EDDS en IDS asook Cu(II) komplekse was ondersoek. Die effek van die modifiseerders was ondersoek en ge-evalueer in terme van migrasie tye, resolusie en plaat getalle. Die beste skeidingskondisies was bereik wanneer tetradesieltrimetielammonium bromied (TTAB) and setieltrimetielammonium bromied (CTAB) as modifiseerders gebruik word. Hierdie kondisies het ook aanleiding gegee tot korter ondersoek tye en beter piekvorme. Die effek van verskillende teen ioone wat aan die EOF modifiseerders gekoppel was het ook interresante resultate opgelewer. Die EOF modifiseerders setieltrimetielammonium chloried (CTAC) en tetradesieltrimetielammonium chloried (TTAC) was ook gebruik vir die bepaling van EDTA in Suid Afrikaanse rivier waters en industrieel afloop. ʼn Metode vir die gelyktydige skeiding van Fe(III) met EDTA, S,S’-EDDS en IDS was met behulp van CE en hoedruk vloeistof chromatography (HPLC) ontwikkel. Die metodologie was ondersoek ingevolge lineariteit, limiet van deteksie (LOD), limiet van kwantifisering (LOQ) en die herhaalbaarheid van CE en die HPLC metodes. Die LOD waardes verkry vanaf HPLC was swakker vergeleke met die verkry deur CE. Die toepaslikheid van al die metodes was vir die ontleding van kosmetiese produkte soos bad skuim en stortbad room getoets. Die uitslae deur CE en HPLC was vergelykbaar en ʼn goeie ooreenkoms was gevind.