Organic ligand complexation reactions at the mineral-water interface play an important role in several environmental and geochemical processes such as adsorption, dissolution, precipitation, pollutant transport, nutrient cycling, and colloidal stability. Although organic ligand surface complexation reactions have been extensively studied, a molecular level understanding regarding the mechanisms underlying the adsorption of such compounds is still limited. The purpose of the current study was to investigate the interactions between some common naturally occurring organic ligands and a common aluminosilicate clay mineral, kaolinite, using a combination of macroscopic and microscopic experimental methods. Molecular level information regarding the structure and binding mode of adsorbed species was obtained using in situ MIR-FTIR spectroscopy. Other experimental techniques including adsorption experiments, surface titrations, and surface complexation modelling were also employed in order to quantify and describe the macroscopic adsorption properties of the organic ligands examined. Three low molecular weight organic acids (oxalic, salicylic, and phthalic acid) and humic acid were chosen as representative organic ligands. Spectroscopic evidence revealed that low molecular weight organic acids are able to form both inner and outer sphere complexes on kaolinite, and the relative concentrations of these surface complexes varies with solution chemistry. Inner sphere coordination modes inferred are a mononuclear bidentate for oxalate (five-membered chelate ring) and phthalate (seven-membered chelate ring); and a mononuclear monodenate (six-membered pseudochelate ring) for salicylic acid. Similar coordination modes were shown to form on simpler mineral (hyrd)oxides. Elucidation of the coordination chemistry of these ligands can provide insights into the dissolution mechanisms of silicate minerals In contrast to low molecular weight organic acids, there was no evidence of inner sphere complexation by humic acid acids on kaolinite or gibbsite. The combined spectroscopic and macroscopic adsorption results suggest that cation bridging and van der Waals interactions are the two most probable mechanisms for the adsorption of humic acid by these mineral substrates. This finding casts doubts over the use of low molecular weight organic acids as humic acid analogs.

Atualmente os supermercados vêm utilizando para a exposição de carnes frescas, bandejas rígidas revestidas de filmes plásticos permeáveis a gases. Esse sistema protege a superfície da carne de possíveis contaminações e permite a seleção dos cortes pelo consumidor. No entanto, essa forma de acondicionamento limita a vida útil da carne, especialmente dos cortes com osso. Dessa maneira, o presente trabalho de pesquisa objetivou estudar a interação entre as diferentes tecnologias - embalagem com atmosfera modificada, ácidos orgânicos e antioxidante - aplicando-se diferentes concentrações de dióxido de carbono (CO2) combinado com o nitrogênio (N2) e monóxido de carbono (CO) (composições gasosas: C1: 99,6%CO2/0,4CO; C2: 19,6%N2/80%CO2/0,4%CO; C3: 49,6%N2/50%CO2/0,4%CO e C4: 50%CO2/50%N2;) e seus efeitos nas características físico-químicas, sensoriais e microbiológicas de bisteca e de costela suína, armazenadas a temperatura de 2+ 2 ºC por um período de 32 dias. Após a obtenção dos referidos cortes na sala de desossa, metade foram pulverizados com a solução de ácidos orgânicos (1% de ácido acético, 1% de ácido lático e 1% de ácido cítrico) e antioxidante (0,8% de ácido ascórbico), e a outra metade não foi pulverizada. A seguir, as amostras pulverizadas ou não, foram colocadas em bandejas plásticas rígidas dentro de saco-filme impermeável a gases. O conjunto, produto mais bandeja foi submetido a três diferentes misturas gasosas, sendo C1, C2 e C3 para costela e C2, C3 e C4 para bisteca. Foram realizadas avaliações físico-químicas, microbiológicas e sensoriais nos 0 (caracterização da matéria-prima), 1º, 5º, 13º, 19º, 25º e 32º dias. Concluiu-se que o uso das composições gasosas: 19,6%N2/80%CO2/0,4%CO e 49,6%N2/50%CO2/0,4%CO, para a bisteca, e a três composições para costela, mantiveram a estabilidade da cor visual e instrumental da carne, do osso e da gordura durante todo o período de estudo. O odor foi predominantemente ácido em todas as amostras desde o primeiro dia de análise. As concentrações de CO2 usadas não foram efetivas na redução das contagens microbianas devido a elevada carga microbiana inicial da matéria-prima. Houve prevalência de bactérias láticas em todas as amostras após o 19º dia, e a vida útil foi de no mínimo 13 dias para todos os tratamentos. / Supermarkets have been using rigid trays covered with gas permeable films to expose fresh meat. This system keeps the meat surface free from contamination and allows the consumer choice, although this type of packaging shortens the meat shelf life, especially cuts with bone in. Thus, the aim of the present was to evaluate the interaction among the followed different technologies: modified atmosphere and spraying of organic acids with antioxidants solution in the meat surface. The effect of four types of modified atmosphere containing different carbon dioxide concentrations combined with nitrogen (N2) and carbon monoxide (CO) (C1: 99,6%CO2/0,4CO; C2: 19,6%N2/80%CO2/0,4%CO; C3: 49,6%N2/50%CO2/0,4%CO e C4: 50%CO2/50%N2) on physical, chemical, sensory and microbiological characteristics were evaluated in portioned pork chops and pork ribs stored during 32 days in a cooling chamber at 2+ 2 ºC. Half of the cuts obtained from the carcasses deboned at CTC were randomly assigned for spraying with a solution containing acetic acid (1%), lactic acid (1%), citric acid (1%) and ascorbic acid (0,8%) while the rest was not sprayed. Following, the samples were packaged in rigid plastic trays covered with impermeable film/bag and subjected to three different atmospheres (pork chops - C1, C2 and C3 and pork ribs - C2, C3 and C4). During storage the physical, chemical, microbiological and sensory evaluations were conducted in the following periods: 0 (raw material), 1, 5, 13, 19, 25 e 32 days. It was concluded that the use of following gas composition: 19,6%N2/80%CO2/0,4%CO and 49,6%N2/50%CO2/0,4%CO kept the color stability for pork chops and the three compositions for pork ribs, either subjective or objective, of the meat, bone and fat during all the period of the experiment. The odor was acid in all samples from the first day of analysis. The percentages of CO2 used in the experiment were not effective to reduce bacterial count because the raw material had high initial count. There was prevalence of lactic acid bacteria in all samples after the 19º day and shelf life was at least 13 days for all treatments.

The aim of this work was to study the influence of the pasteurization and filtration on selected chemical compounds in beer. Specifically, the influence on elemental composition, content of organic acids, carbohydrates and phenolic substances was studied. Optical emission spectrometry with inductively coupled plasma (ICP-OES) was used for elemental analysis of beer. Analysis of organic acids was evaluated by Ion chromatography. For analysis of carbohydrates was used High performance liquid chromatography with ELSD detector (HPLC-ELSD), phenolic compounds was evaluated by HPLC with diode array detector (HPLC-DAD). Data from analysis of beer was performed by usage of statistical methods (analysis of variance and principal component analysis). Parameters that showed the most significant differences between individual groups of beers were obtained. Correlations between the variables and the technological beer processing operations were found. 12 parameters of total 23 were affected. The effect of filtration and pasteurization was observed in content of the iron, silicon, potassium and magnesium, malate, monosaccharides glucose and fructose and phenolic compounds.

Orientador: Valquíria Cação Cruz-Polycarpo / Resumo: O objetivo deste estudo foi avaliar o efeito do butirato de sódio microencapsulado (BSM) em substituição ao antibiótico sobre o desempenho, hematologia, peso de órgãos do TGI, escores de lesão intestinal e contagem de oocistos nas excretas de frangos de corte desafiados com Eimeria spp. Para isso foram utilizados 1.050 pintos machos Ross, distribuídos em DIC, com seis tratamentos: CN (controle negativo)- ração basal (RB) (aves não desafiadas); CND- RB (aves desafiadas); 0,10%- RB + 1.000 mg/kg de BSM (aves desafiadas); 0,15%- RB + 1.500 mg/kg de BSM (aves desafiadas); 0,20%- RB + 2.000 mg/kg de BSM (aves desafiadas); AVL- RB + avilamicina (aves desafiadas), com cinco repetições. Aos 16 dias de idade, as aves foram inoculadas oralmente e individualmente com oocistos de Eimerias e as aves de CN, inoculadas com solução salina, para que também sofressem o estresse da inoculação. Observou-se maiores GPM e CRM nas aves não desafiadas em comparação às desafiadas na fase de 1 a 21 d, e na fase final de criação e melhor CA e FEP, mostrando o poder da inoculação com o protozoário. Não houve diferença nas variáveis hematológicas e bioquímicas entre as diferentes dietas fornecidas, porém frangos submetidos às Eimerias apresentaram queda nos valores normais após desafio, e demonstraram recuperação ao final da criação. Na alometria de órgãos do TGI, o peso do fígado apresentou-se superior nas aves que receberam aditivo. Já, o peso do pâncreas, mostrou-se superior nas aves suplementadas com... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The objective of this study was to evaluate the effect of microencapsulated sodium butyrate (MSB) in substitution to antibiotics on performance, hematology, weight of organs of the GIT, intestinal injury scores and oocyst count in the excreta of broilers challenged with Eimeria spp. For this, 1,050 male Ross chicks were used, distributed in completely randomized design, with six treatments: NC - basal diet (BD) (non-challenged birds); NCC- BD (challenged birds); 0.10% - BD+1,000 mg/kg of MSB (challenged birds); 0.15% - BD+1,500 mg/kg of MSB (challenged birds); 0.20% - BD+2,000 mg/kg of MSB (challenged birds); AVL - BD + avilamycin (challenged birds), with five repetitions. At 16 days of age, the birds were inoculated orally and individually with Eimerias oocysts and the NC birds were inoculated with saline solution, so that they also suffered the stress of inoculation. Higher ABW and AFI were observed in the unchallenged birds compared to those challenged in the 1 to 21 day phase, and in the final breeding phase, better FCR and PEF, showing the power of inoculation with the protozoan. There was no difference in hematological and biochemical variables between the different diets provided, but chickens subjected to inoculation with Eimerias showed a drop in normal values after challenge, and showed recovery at the end of the rearing period. In the allometry of organs of the TGI, the liver weight was higher in the birds that received additive. The weight of the pancreas, on the ... (Complete abstract click electronic access below) / Mestre

L’acide 3-hydroxypropionique (3-HP) est une molécule plate-forme, particulièrement visée pour ses dérivés acrylés et les polyesters. Sa production par voie biotechnologique fait l’objet de nombreuses études, afin de les obtenir de manière biosourcée. Cependant, dans ces procédés, le 3-HP est dilué dans des milieux de fermentation contenant de nombreuses impuretés. De plus, l’accumulation de l’acide dans les milieux crée une forte inhibition sur les microorganismes producteurs. Nous proposons alors un procédé visant à extraire sélectivement le 3-HP du milieu de fermentation en même temps qu’il est produit afin de limiter son accumulation et de le purifier en continu. Les propriétés du 3-HP ainsi que les meilleures conditions de fermentation actuelles ont permis d’identifier l’extraction liquide-liquide réactive en contacteur membranaire comme une technique de choix. Nous avons tout d’abord élucidé le mécanisme réactionnel impliqué dans le système puis modélisé les équilibres associés afin de pouvoir prédire les rendements d’extraction en fonction de paramètres opératoires. Plusieurs méthodes de désextraction ont été testées, ce qui a permis de coupler les étapes d’extraction et de désextraction dans un procédé semi-continu mimant une production fermentaire. La modélisation dynamique de ce mode de fonctionnement a permis de prédire précisément les résultats expérimentaux. Les milieux ont alors été complexifiés afin de mieux représenter la réalité d’un milieu biologique en identifiant l’impact de chaque constituant. / 3-hydroxypropionic acid (3-HP) is a platform molecule targeted for its acrylated derivatives and polyesters. Its production through biological pathways is widely studied in order to make them bio-based. However, in such processes, 3-HP is diluted in fermentation broths containing many impurities. Moreover, the accumulation of the acid in the broths generates a strong inhibition towards the producing microorganisms. We suggest here a process aiming at extracting 3-HP selectively as soon as it is produced in order to reduce its accumulation and have it purified continuously. 3-HP properties as well as the current best fermentation conditions made us identify reactive liquid-liquide extraction in membrane contactors as promising technique. First, we elucidated the reaction mechanism of extraction in our system and then modeled the associated thermodynamic equilibria as a function of operating paramaters. Several back-extraction methods were tested and it allowed the coupling of the extraction and back-extraction steps in a semi-continuous process mimicking a biological production. The dynamic modeling of this operating mode made possible the accurate prediction of experimental results. The aqueous phase were then made more and more complex in order to better describe an actual fermentation broth and identify the influence of each component on the process efficiency in terms of yield, kynetics and selectivty.

The freshwater dinoflagellate species, Ceratium hirundinella (C. hirundinella) possesses unique characteristics, such as a thecal-plate cell covering of cellulose, spines and flagella. Unlike most other algae and cyanobacteria, C. hirundinella cells are relatively large in size (up to 450 μm in length and 50 μm in width). These unique characteristics (e.g. cell covering and flagella) and adaptations (e.g. spines) give the dinoflagellate cells the ability to reduce their sinking rate from the euphotic zone and to migrate easily through the water column. When source water contains high concentrations of C. hirundinella cells, water treatment problems and poor aesthetic water quality can be expected. These water treatment problems may include 1) the disruption of coagulation and flocculation, 2) clogging of sand filters and 3) taste and odour problems when cells penetrate into the final water. In Chapter 9 of this study, a list of operational guidelines (including alert levels) and recommendations to assist managers and operators of plants when C. hirundinella cells are causing water treatment problems. During events of high C. hirundinella concentrations in source water, managers and operators of conventional water treatment plants need strategies to optimize coagulants and unit processes. Thus when source water contains motile nuisance algae, such as C. hirundinella, in moderate or abundant quantities, it is advisable to conduct jar stirring test experiments using both turbidity and total photosynthetic pigment (or chlorophyll-a) analyses as indicators of appropriate coagulant choice and dosages. The aims of this study are summarized as follows:  To optimize coagulants and conventional water treatment processes by implementing relevant algal removal strategies and indicators during jar stirring test experiments,  To investigate the changes in surface charge (known as zeta potential) on C. hirundinella cells before and after adding coagulants as part of the treatment processes,  To investigate the physical and chemical impacts on the morphology of C. hirundinella cells after coagulation, flocculation and sedimentation,  To identify organic compounds that may be responsible for taste and odour problems associated with C. hirundinella,  To investigate the efficiency of pre-chlorination on the removal C. hirundinella cells when dosing various coagulants, and  Give recommendations and operational guidelines relevant for a conventional water treatment plant to improve C. hirundinella removal A combined water treatment system (Phipps and Bird Model), consisting of a six paddle jar test apparatus and six sand filter columns, was used to simulate conventional processes (coagulation, flocculation, sedimentation and rapid sand filtration). Source water samples containing relatively high C. hirundinella concentrations (> 500 cell/mℓ) were collected from Benoni Lake (26º10’50.40’’S; 28º17’50.11’’ E) in plastic containers and stored as a homogenous sample in a 200 litre container under laboratory conditions (± 22 °C). Samples were collected from the source water as well as after sedimentation (from the supernatant or sludge) to determine turbidity, total photosynthetic pigment analyses (chlorophyll) and for phytoplankton analyses. Flocs (containing C. hirundinella cells) were collected from the sludge or sediment for scanning electron microscopy investigations and to perform zeta potential analyses. Concentrated C. hirundinella samples were frozen at -80 °C according to the proposed sampling protocol for organic compound analyses. Results obtained from this study proved that using the relevant indicators to determine the appropriate coagulant dosages during jar stirring tests may generally improve the removal of problem-causing algae, such as C. hirundinella cells. Improved algal removal efficiencies will subsequently ensure final water with good aesthetic quality. The surface charge (zeta potential) on C. hirundinella cells can be used to evaluate the best coagulation conditions within an operating window of -10 mV to +3 mV when dosing various coagulants. Scanning electron microscopy investigations revealed major damaging effects to C. hirundinella cells when dosing high Ca(OH)2 concentrations. However, when dosing lower Ca(OH)2 concentrations, in combination with organic polymer, better C. hirundinella cell removal efficiencies with less damaging effects to cells was observed. This study also indicated that the pre-chlorination, without causing cell lyses, can be applied to render the highly motile cells immobile which will subsequently assist the coagulation unit process. The aesthetic quality (e.g. tastes and odours) of drinking water may be influenced when C. hirundinella cells release organic material into the water as a result of cell lyses. Organic compounds, such as fatty acids and dicarboxylic acids can lead to taste and odour problems which associate with the presence of C. hirundinella. Organic compounds also serve as precursors for the formation of harmful chlorine by-products formed during chlorination. / PhD (Environmental Sciences), North-West University, Potchefstroom Campus, 2015

The freshwater dinoflagellate species, Ceratium hirundinella (C. hirundinella) possesses unique characteristics, such as a thecal-plate cell covering of cellulose, spines and flagella. Unlike most other algae and cyanobacteria, C. hirundinella cells are relatively large in size (up to 450 μm in length and 50 μm in width). These unique characteristics (e.g. cell covering and flagella) and adaptations (e.g. spines) give the dinoflagellate cells the ability to reduce their sinking rate from the euphotic zone and to migrate easily through the water column. When source water contains high concentrations of C. hirundinella cells, water treatment problems and poor aesthetic water quality can be expected. These water treatment problems may include 1) the disruption of coagulation and flocculation, 2) clogging of sand filters and 3) taste and odour problems when cells penetrate into the final water. In Chapter 9 of this study, a list of operational guidelines (including alert levels) and recommendations to assist managers and operators of plants when C. hirundinella cells are causing water treatment problems. During events of high C. hirundinella concentrations in source water, managers and operators of conventional water treatment plants need strategies to optimize coagulants and unit processes. Thus when source water contains motile nuisance algae, such as C. hirundinella, in moderate or abundant quantities, it is advisable to conduct jar stirring test experiments using both turbidity and total photosynthetic pigment (or chlorophyll-a) analyses as indicators of appropriate coagulant choice and dosages. The aims of this study are summarized as follows:  To optimize coagulants and conventional water treatment processes by implementing relevant algal removal strategies and indicators during jar stirring test experiments,  To investigate the changes in surface charge (known as zeta potential) on C. hirundinella cells before and after adding coagulants as part of the treatment processes,  To investigate the physical and chemical impacts on the morphology of C. hirundinella cells after coagulation, flocculation and sedimentation,  To identify organic compounds that may be responsible for taste and odour problems associated with C. hirundinella,  To investigate the efficiency of pre-chlorination on the removal C. hirundinella cells when dosing various coagulants, and  Give recommendations and operational guidelines relevant for a conventional water treatment plant to improve C. hirundinella removal A combined water treatment system (Phipps and Bird Model), consisting of a six paddle jar test apparatus and six sand filter columns, was used to simulate conventional processes (coagulation, flocculation, sedimentation and rapid sand filtration). Source water samples containing relatively high C. hirundinella concentrations (> 500 cell/mℓ) were collected from Benoni Lake (26º10’50.40’’S; 28º17’50.11’’ E) in plastic containers and stored as a homogenous sample in a 200 litre container under laboratory conditions (± 22 °C). Samples were collected from the source water as well as after sedimentation (from the supernatant or sludge) to determine turbidity, total photosynthetic pigment analyses (chlorophyll) and for phytoplankton analyses. Flocs (containing C. hirundinella cells) were collected from the sludge or sediment for scanning electron microscopy investigations and to perform zeta potential analyses. Concentrated C. hirundinella samples were frozen at -80 °C according to the proposed sampling protocol for organic compound analyses. Results obtained from this study proved that using the relevant indicators to determine the appropriate coagulant dosages during jar stirring tests may generally improve the removal of problem-causing algae, such as C. hirundinella cells. Improved algal removal efficiencies will subsequently ensure final water with good aesthetic quality. The surface charge (zeta potential) on C. hirundinella cells can be used to evaluate the best coagulation conditions within an operating window of -10 mV to +3 mV when dosing various coagulants. Scanning electron microscopy investigations revealed major damaging effects to C. hirundinella cells when dosing high Ca(OH)2 concentrations. However, when dosing lower Ca(OH)2 concentrations, in combination with organic polymer, better C. hirundinella cell removal efficiencies with less damaging effects to cells was observed. This study also indicated that the pre-chlorination, without causing cell lyses, can be applied to render the highly motile cells immobile which will subsequently assist the coagulation unit process. The aesthetic quality (e.g. tastes and odours) of drinking water may be influenced when C. hirundinella cells release organic material into the water as a result of cell lyses. Organic compounds, such as fatty acids and dicarboxylic acids can lead to taste and odour problems which associate with the presence of C. hirundinella. Organic compounds also serve as precursors for the formation of harmful chlorine by-products formed during chlorination. / PhD (Environmental Sciences), North-West University, Potchefstroom Campus, 2015

Thesis (PhD) -- tellenbosch University, 2014. / ENGLISH ABSTRACT: This study is part of the continuing global research effort dedicated to finding alternative aquafeed ingredients, which not only replace fish meal and fish oil as sources of essential nutrients in aquafeeds, but also provide specialist functional properties when included in feeds. Due to constraints in supply of fish meal and fish oil originating from wild capture fisheries, the continually growing aquafeed industry requires new sources of raw materials for the production of high quality feeds. The aim of the study was to investigate the specialist functional properties of feed ingredients (with emphasis on immune-stimulation potential) derived from fish processing waste after enzymatic hydrolysis by endogenous proteolytic enzymes (autolysis). Further aims were to (i) quantify effects of these feed ingredients on production performance of two species relevant to the South African aquaculture industry, namely Mozambique tilapia Oreochromis mossambicus and South African abalone Haliotis midae, (ii) compare performance to commercially available enzymatically produced feed ingredients, and (iii) separate the functional effects of these fish processing waste derived feed ingredients from the acid used to preserve them against bacterial spoilage during the autolysis process. Oil recovered after autolysis of rainbow trout viscera proved to be an attractive feed ingredient due to favourable effects on the non-specific cellular immune function of both Mozambique tilapia and South African abalone. However, in South African abalone, increased immune function due to inclusion of fish oil was accompanied by a significant decrease in production performance. The inclusion of hydrolysed proteins, obtained by autolysis of fish waste, in aquaculture feeds also improved non-specific immunity and survival of Mozambique tilapia significantly – independently of the preserving acid – although the same was not observed for South African abalone. Production performance was dependent on dietary hydrolysed protein inclusion levels in both species; excessive inclusion resulted in decreased production performance. The performance of dietary hydrolysed protein from autolysis and those from commercial production processes were significantly different, possibly as a result of different raw material origins and production processes. It is further shown that formic acid can contribute to improved water stability in abalone feeds, a novel mode of action not previously described. The study concludes that the simple autolysis process for processing of fish waste can provide aquafeed ingredients with immune stimulatory potential, which can contribute to improved production performance in the Mozambique tilapia and the South African abalone. The result can contribute to improved sustainability of the aquafeed industry, through substitution of fish meal and fish oil derived from capture fisheries with processed fish waste components. / AFRIKAANSE OPSOMMING: Hierdie studie vorm deel van die voortdurende en wêreldwye soeke na nuwe akwakultuur voerbestanddele wat nie net vismeel en –olie kan vervang as bron van noodsaaklike voedingstowwe nie, maar wat ook gespesialiseerde funksionele eienskappe openbaar wanneer dit in akwavoere ingesluit word. As gevolg van beperkings in die voorsiening van vismeel en –olie afkomstig vanaf wilde visserye, word die voortdurend groeiende akwavoer bedryf genoodsaak om nuwe grondstowwe te benut vir die vervaardiging van hoë kwaliteit voere. Die doelwit van die studie was om moontlike gespesialiseerde funksionele eienskappe (met spesifieke klem op potensiële immuun-stimulasie) van voerbestanddele te ondersoek wat herwin is vanaf reënboogforel proseseringsafval, na ensiematiese hidrolise d.m.v. endogene ensieme teenwoordig in die afval (outolise). Verdere doelwitte was om (i) effekte op produksie prestasie van hierdie bestanddele te kwantifiseer in twee akwakultuur spesies relevant tot die Suid- Afrikaanse bedryf (naamlik die Mosambiekse kurper Oreochromis mossambicus en die Suid- Afrikaanse perlemoen Haliotis midae), (ii) om produksie prestasie te vergelyk met kommersieel beskikbare voerbestanddele voorberei d.m.v. ensiemtegnologie, en (iii) om die moontlike effekte van die voerbestanddele te skei van die van die sure gebruik om die bestanddele te preserveer tydens die outolitiese proses. Daar is bevind dat olie herwin na outolise van reënboogforel ingewande ‘n goeie voerbestanddeel is wat gunstige effekte op die nie-spesifieke, sellulêre immuniteit van beide Mosambiekse kurper en Suid-Afrikaanse perlemoen gehad het. In die Suid-Afrikaanse perlemoen het verbeterde immuunfunksie gepaard gegaan met ‘n verswakking in produksie prestasie. Die gehidroliseerde proteïen komponent van ge-outoliseerde prosesseringsafval het ook beduidende verbetering in nie spesifieke immuniteit en oorlewing van Mosambiekse kurper tot gevolg gehad - onafhanklik van die preserverende suur - maar dieselfde is nie in die Suid-Afrikaanse perlemoen waargeneem nie. Produksie prestasie was afhanklik van die insluitingsvlakke van gehidroliseerde proteïen in beide spesies en dit is bevind dat oormatige insluiting produksie nadelig beïnvloed. Prestasie van proteïen afkomstig van outolise en die van ‘n kommersiële produksieproses het beduidend verskil, moontlik as gevolg van verskillende grondstowwe en prosesseringstegnieke. Daar is verder vir die eerste keer getoon dat mieresuur ‘n beduidende verbetering in waterstabiliteit in sekere perlemoenvoere teweeg kan bring. Die studie kom tot die slotsom dat die eenvoudige outolise proses funksionele akwavoerbestanddele kan produseer wat kan bydra tot ‘n verbetering in produksie prestasie in die Mosambiekse kurper en Suid-Afrikaanse perlemoen. Die resultaat kan bydra tot verbeterde volhoubaarheid van die akwavoer bedryf, deur vismeel en –olie afkomstig van wilde visserye, te vervang.

A determination of corrosion inhibitors in engine coolants represent a difficult analytical problem due to their different physicochemical properties. Nowadays a lot of instrument methods are needed to determine them. The aim of this work was the development of methods for their determination using only one instrumentation. Capillary zone electrophoreses was chosen as a suitable technique. Three electrophoretic methods for three groups of corrosion inhibitors were developed. Firstly, method for determination of inorganic anions was developed in range from 5 to 50 ppm with limit of detection around 1 ppm. Background electrolyte contains sodium chromate, CTAB and CHES solution. Analytes were detected indirectly at 450 nm. Another method was for determination of organic acids anions. They were determined in range from 5 to 500 ppm. Limit of detection for each analyte was around 1 ppm. Measurement was made with PDC a CTAC water solution. Indirect detection was used for this determination at 350 nm. Last developed method can be use for determination of aryltrizoles in range from 5 to 500 ppm. Limit of detection was around 1 ppm. As a background electrolyte was used sodium tetraborate solution. The developed methods were validated and their suitability for determination of corrosion inhibitors in real...

Volvo Cars är ett välkänt företag som säljer bilar över hela världen. Idag skickar Volvo Cars sin kylvätska till leverantörer för analys. Processen är komplicerad och tar mycket tid. Det finns ett intresse hos Volvo Cars att själva kunna analysera kylvätskan. För att kunna göra detta krävs det att en metod som de kan använda för att analysera kylvätskan utvecklas. Examensarbetet syftar till att utveckla en metod som gör det möjligt att analysera koncentrationen av organiska syror i Volvos kylvätska. Analysen ska göras med hjälp av en High Performance Liquid Chromatography - HPLC. De organiska syrorna är inhibitorer som skyddar material i motorn från korrosion när det kommer i kontakt med kylvätskan. Metoden utvecklas i flera steg, det är viktigt att veta hur olika organiska syror kan analyseras med en HPLC. HPLC-analyser är mycket beroende av de intrumentella inställningarna. Inställningarna som ändrar när metoden utvecklas är pH, typ av kolonn, våglängd på detektorn, flödeshastighet i kolonnen, injektionsvolymen, sammansättning av eluent (lösningsmedel) och analystid. Kalibreringskurvor konstrueras för att sedan kunna användas i fortsatta studier. Tre av fem organiska syror som skulle analyseras var möjliga att analysera med två olika metoder. Den enda skillnaden mellan metoderna var våglängden på detektorn. En av de organiska syrorna hade en mer linjär kalibreringskurva vid en högre våglängd. / Volvo Cars is a well-known company and they are selling their cars all over the world. Today, Volvo Cars send their engine coolant to the supplier of engine coolant for analysis. This process is complicated and takes a lot of time. It is in the interest of Volvo Cars to be able to analyze the engine coolant themselves. In order to do that, a method where they can analyze the engine coolant must be developed. This exam work aim to develop a method where it is possible to analyze the concentration of organic acids in Volvo´s engine coolant with a High Performance Liquid Chromatography - HPLC. The organic acids are inhibitors that protect the materials in the engine from corrosion when in contact with the engine coolant. The method is developed in several steps. First it is important to know how different organic acids could be analyzed with an HPLC. HPLC-analysis is very dependent of the instrumental parameters. The parameters you change when developing a method are pH, kind of column, wavelength of the detector, kind of detector, flow rate in the column, injections volume, composition of the eluent (solvent) and, analysis time. Calibration curves are created and could be used as a reference in further analysis. Three of the five organic acids that were supposed to be analyzed were possible to analyze. Three organic acids were analyzed with one method and the two remaining organic acids with another method. The only difference between the methods is the wavelengths of the detector.