Caffeine is a commercially important member of a group of purine alkaloids found in coffee, tea and cacao particularly. It is an important ingredient in beverages and most important chemical element of stimulating pharmaceuticals. Caffeine is either manufactured by total synthesis or as a by-product from the decaffeinated coffee manufacturing. To investigate the equilibrium relationship of caffeine in ion exchange systems, which are widely used for recovery and purification processes, was the aim of this study. The effects of initial caffeine concentration and pH of the solution on equilibrium were also investigated. Stock solutions of caffeine were prepared for screening of available adsorbents and cation exchange resins. A batch type operation was carried out in a shaker bath at 40 oC with 200 rpm agitation rate. After preliminary experiments, only Lewatit S100, which is a strongly acidic cation exchange resin with s-dvb copolymer matrix, was studied. For the analysis of samples, HPLC equipment with Shimadzu PDA Detector at 254 nm and Nucleosil 100 C18 column was used. As mobile phase, a mixture of 8% acetonitrile, 8% 2-Propanol, and 1% acetic acid was introduced at 1.5 mL/min flow rate. Results showed that, the caffeine uptake capacity of cation exchange resin was poor. A set of experiments were performed at three initial concentrations (0.005 M, 0.0075 M, and 0.01 M) and four different pH regions (acidic, slightly acidic, neutral, and basic). It was found that, at extreme pH conditions, the caffeine loading capacity of the resin was slightly increased. A significant effect of initial caffeine concentration, however, couldn&rsquo / t be observed. Due to the poor performance of gel type cation exchange resin and large molecular structure of caffeine molecule, Lewatit&rsquo / s SPC 112 macroporous resin was studied briefly for caffeine uptake performance. It was observed that SPC 112 has also poor but better loading capacity than S100 cation exchange resin.

A redox flow battery (RFB) is an electrochemical energy storage device in which the storage medium is in the form of liquid electrolyte, which is stored in external reservoirs separate from the cell stack. The storage capacity of such systems is limited by the size of the external tanks, making the RFB an ideal technology for grid level energy storage. The vanadium redox flow battery (VRB) is a particularly attractive variant of the RFB, due to its use of a single transition-metal element in both the positive and negative electrolytes. However, the performance of the VRB is affected by the cross-over of electrolytes through the ion-exchange membrane which separates the positive and negative electrolytes. Cross-over causes degradation of energy storage efficiency and long term capacity loss. Previous studies of ion cross-over have focused primarily on the measurement of ion diffusion across ion exchange membranes in the absence of electrical current. In this work a novel VRB cell is described in which ion cross-over can be measured directly in the presence and absence of electrical current. Measurements are made of cross-over using this cell with three different types of ion exchange membrane in both charge and discharge modes. The results reported in this work show that the rate of ion cross-over can be greatly enhanced or suppressed depending upon the magnitude of the current flow and its direction relative to the ion concentration gradient. / text

The effect of calcium uptake by hydration and diffusion from an adjacent calcium-rich soil on the performance of a geosynthetic clay liner (GCL) is examined for three cases. In Case 1 the GCL rested directly on a soil with a high calcium (1800 mg/l) concentration in the pore water (called “calcium rich soil” herein). Case 2 involved a GCL resting on 300 mm of soil with a low (200 - 300 mg/l) calcium concentration in the pore water (“foundation soil”) overlying the calcium rich soil. In the third (“control case”), the GCL only rested on the foundation soil. The overburden pressure was 15 kPa. The moisture content of GCL increased to 96%, 86% and 108% in the first 279 days for Cases 1, 2 and 3 respectively. Under isothermal conditions, the GCL moisture content decreased to 80% and 67% for Cases 1 and 2 respectively and increased to 113% for Case 3. After 1100 days, the hydraulic conductivity (k) of the GCL was 4×10-11 m/s for Case 3 but had increased up to about 7×10-11 m/s and 2×10-10 m/s for cases with and without the foundation layer respectively. The results are used to calibrate finite element models. A good correlation was found between k the bulk void ratio (eB) of GCL. Leakage and contaminant transport through 10 mm diameter hole in a geomembrane in a composite liner involving a GCL is examined at a stress of 100 kPa for hydraulic heads of 0.3 or 1 m. When permeated with distilled water, the interface transmissivity (θ) was about 2.3 × 10 11 m2/s. After 800 days of permeation with 0.14M NaCl there was only about 3% increase in the flow despite an order of magnitude increase in GCL permeability near the hole because θ decreased from 2.3×10-11 m2/s to 1.1×10-11 m2/s and controlled the leakage despite the increase in GCL permeability. Numerical modeling demonstrated reasonable agreement with the observed transport. / Thesis (Ph.D, Civil Engineering) -- Queen's University, 2010-09-09 12:20:42.298

The current study investigated application of natural adsorbents in brine treatment. Brines are hypersaline waters generated in power stations and mining industries rich in Mg2+, K+, Ca2+, Na+, SO4 2- , Cl- and traces of heavy metals, thus there is a need for these brines to be treated to recover potable water and remove problematic elements. Natural adsorbents have been successfully used in waste water treatment because of their high surface area and high adsorptive properties when they are conditioned with acid or base. The investigation of pH showed that natural adsorbents did not perform well at low pH of 4 and 6. The adsorbents were able to work efficiently at the natural pH of 8.52 of the brine solution. These results show that natural adsorbents hold great potential to remove cationic major components and selected heavy metal species from industrial brine wastewater. Heterogeneity of natural adsorbents samples, even when they have the same origin, could be a problem when wastewater treatment systems utilizing natural clinoptilolite and bentonite are planned to be developed. Therefore, it is very important to characterize the reserves fully in order to make them attractive in developing treatment technologies.

Membrane chromatography was investigated as an alternative method to packed-bed chromatography for protein recovery. The purification of lysozyme from egg white with Natrix adseptTM weak cation-exchange membranes was investigated under two different binding configurations: (1) a non-flow, static set-up with variable pH and sodium chloride (NaCl) concentrations during the binding and elution steps, and (2) a dynamic, cross-flow set-up with recycle at pH 7.5 and no NaCl addition during binding. The weak cation-exchange membrane consisted of a carboxylic acid-based, environmentally-responsive hydrogel layer bonded to a polymer matrix. Lysozyme was chosen to illustrate protein-membrane binding interactions due to its well-characterized nature and positive surface charge over a large pH range. For the static binding set-up, two sources of lysozyme were studied: pure lysozyme and egg whites treated with 60 % (v/v) ethanol (ESEW). Elution of bound protein was performed with 1 M NaCl under two pH strategies: binding and elution at a constant pH, and binding at pH 4.5 and variable elution pH. The highest maximum total protein binding capacity for pure lysozyme and ESEW was observed at pH 4.5 with no NaCl addition; however, poor total protein and lysozyme activity recovery were achieved during separation. As well, other egg white proteins, such as ovomucoid, were observed to bind to the membrane surface at pH 4.5, despite possessing similar charge polarity to the anionic membrane surface, indicating a non-electrostatic binding mechanism during operation below the membrane’s pKa (4.7). Based on the conditions tested, the highest total protein and lysozyme activity recovery was demonstrated for the separation of lysozyme from ESEW at pH 7.5 binding and elution and no NaCl addition. In the dynamic binding study, very high pure lysozyme dynamic binding capacity was achieved at 10 % breakthrough (167.3 mg/ml membrane for a 0.35 mg/ml lysozyme solution). The lysozyme dynamic binding capacity was 2.2 times greater than the static binding capacity under similar conditions, significantly higher than published results for other cation-exchange membranes. The separation of lysozyme from four lysozyme sources was tested: pure lysozyme, ESEW, and aqueous egg whites with (ASEW) and without (AEW) 100 mM NaCl. The highest lysozyme activity recovery during separation and lysozyme purity was achieved from the ESEW feed. Lysozyme separation from aqueous egg whites was not as effective, likely due to a high concentration of negatively-charged protein impurities fouling the surface of the membrane. Competitive binding to the membrane limited lysozyme binding and reduced the purity of the recovery elution stream. The application of feed-side pressure during the separation of ESEW produced a high purity, high recovery lysozyme elution stream with a significant reduction in processing time; however, protein aggregates were observed to form on the membrane surface, limiting the applicability of high-pressure operation and reducing protein functionality in the elution stream. The weak cation-exchange membrane system was shown to successfully separate out a target protein from a low concentration protein mixture through electrostatic interactions, and may be further applied to other protein systems.

This diploma thesis deals with the composting of biodegradace waste in selected plants. The goal was to determine the CEC according to Sandhoff and to create a proposal for the optimal composting technology of biodegradable materials in Trhový Štěpánov composting plant. Samples were taken from five selected plants, from the EKOSO Trhový Štěpánov composting plant, the municipalcomposting plant Votice, AGORY s.r.o. Želivec, kompostárny Jarošovice s.r.o. and the HANTÁLY composting plant in Velké Pavlovice. The thesis contains two interconnected parts, theoretical knowledge and practical part, where the results of laboratory analyzes are summarized.

This study sought to describe the current state fertility levels by analyzing 105,342 soil samples from different regions of the state of Rio Grande do Sul assigned by CCGL Technology. Thus, about 42% of the samples need to correct soil acidity. Phosphorus was the element that needs more attention in the soil correction. Potassium is present in most samples above the critical level suggesting a poor response to application in current models. Correction sulfur has potential response to crop yields in soya. In a second step, we used the data to study the balance of nutrients in the soil. The data were normalized and CTCpH7,0 was the parameter of soil divided into classes considering the normal distribution with a standard deviation for each class. The results showed that the base saturation to achieve the desired pH varied according to CTCpH7,0v soil. Soils with low CTCpH7,0 present trend lower percentage base saturation than a soil with CTCpH7,0 high. It was also found that the CTCpH7,0 soil influences the availability of the potassium equilibrium saturation. Soils with higher CTCpH7,0 require larger amounts of potassium to reach the critical level of 3% CTCpH7,0. The next step was to correlate the levels of elements in the soil and its relation to the levels shown by leaf analysis. For that were conducted soil sampling in grid 2 ha in an area in the municipality of Cachoeira do Sul, RS. This area was located soybean and collected samples of leaves and plants when they were in the flowering stage in the same spots where they were taken soil samples. Reading was also performed with the equipment GreenSeeker order to correlate them with samples of soil and leaves.The CTCpH7,0 soil, directly influences the availability of potassium in equilibrium saturation. Soils with higher cation exchange capacity tend to require larger amounts of potassium to reach the critical level of 3% of CTCpH7,0. The results of tissue samples of whole plants soybean correlate with the levels of potassium in the soil and its percentage in CTCpH7,0. Nevertheless the use of the analysis of the 3rd trifoliate leaf from flowering as a parameter for recommendation requires further study, as the results do not make clear the relationships between these elements in the leaves and in the soil. / A agricultura de precisão vem se consolidando como uma técnica para melhoria dos níveis de fertilidade do solo. Inicialmente o presente trabalho procurou abordar a situação atual dos níveis de fertilidade através da análise de 105.342 amostras de solo provenientes de diferentes regiões do estado do Rio Grande do Sul cedidos pelo CCGL Tecnologia na camada de 0 a 10 cm. Cerca de 42% das amostras apresentaram necessidade de correção da acidez do solo. O fósforo foi o elemento que necessita maior atenção na correção de solo por apresentar 61,8% das amostras em níveis abaixo do teor crítico. O potássio apresentou 72,1% das amostras acima do teor crítico sugerindo baixa resposta a aplicação nos modelos atuais. A correção com enxofre apresenta potencial de resposta a produtividade da cultura da soja. Em um segundo momento, utilizou-se os dados a fim de estudar o equilíbrio dos nutrientes no solo. Foi utilizado a CTCpH7,0 do solo como parâmetro divido em classes, considerando a distribuição normal com um desvio padrão para cada classe, a fim de estudar o comportamento da saturação de bases e do potássio na saturação. Os resultados demonstraram que a saturação por bases, para atingir o pH desejado, variou conforme a CTCpH7,0 do solo. Solos com baixa CTCpH7,0 apresentam tendência de menores percentuais de saturação por bases que um solo com CTCpH7,0 alta. Também se verificou que a CTCpH7,0 do solo influencia a disponibilidade do potássio no equilíbrio de saturação. Solos com CTCpH7,0 acima de 18 cmolc.dm-³ necessitam quantidades de potássio superiores a 240 ppm para atingir o teor crítico de 3% da CTCpH7,0. O próximo passo foi correlacionar os teores dos elementos no solo e sua relação com os teores apresentados pelas análises foliares. Para isso foram realizados amostragens de solo em grid de 2 ha em uma área de produção de soja no município de Cachoeira do Sul, RS. Nesta área foi implantada a cultura da soja e coletadas amostras de folhas e plantas quando estas se encontravam no estádio de florescimento nos mesmos pontos onde foram retirada as amostras de solo. Também realizou-se a determinação com o equipamento Greenseeker a fim de correlacionar os resultados com as amostras de folha e solo. Os resultados das amostras de tecido de plantas inteiras de soja se correlacionam com os teores de potássio no solo e seu percentual na CTCpH7,0. Apesar disso a utilização da análise foliar do 3° trifólio a partir do florescimento como parâmetro para recomendação ainda precisa ser melhor estudado, pois os resultados não deixam claras as relações entre os elementos nas folhas e estes no solo.

Magister Scientiae - MSc / The current study investigated application of natural adsorbents in brine treatment. Brines are hypersaline waters generated in power stations and mining industries rich in Mg2+, K+, Ca2+, Na+, SO4 2- , Cl- and traces of heavy metals, thus there is a need for these brines to be treated to recover potable water and remove problematic elements. Natural adsorbents have been successfully used in waste water treatment because of their high surface area and high adsorptive properties when they are conditioned with acid or base. The investigation of pH showed that natural adsorbents did not perform well at low pH of 4 and 6. The adsorbents were able to work efficiently at the natural pH of 8.52 of the brine solution. These results show that natural adsorbents hold great potential to remove cationic major components and selected heavy metal species from industrial brine waste water. Heterogeneity of natural adsorbents samples, even when they have the same origin, could be a problem when wastewater treatment systems utilizing natural clinoptilolite and bentonite are planned to be developed. Therefore, it is very important to characterize the reserves fully in order to make them attractive in developing treatment technologies. / South Africa

Reaction rate data at 50oC was generated in a batch reactor over a wide range of initial concentrations in the reaction mixture. In each case the reaction was allowed to reach equilibrium. Equilibrium conversion data clearly indicated that it is important to consider the non-ideality of the system. The NRTL activity model proved to be the most suitable model to calculate the activity based equilibrium constant, as the percentage standard deviation of the equilibrium constant calculated in this manner was only 7.6% for all the different experiments as opposed to 17.8% when the equilibrium constant was based on concentration. The NRTL parameters used were obtained from Gmehling&Onken (1977) who determined the parameters from vapour liquid equilibrium. The Langmuir-Hinshelwood kinetics proposed by Song et al. (1998) and Pöpken et al. (2000) provided an excellent representation of the reaction rate over a wide concentration range with an AARE of 6% and 5% respectively. It was shown that when the NRTL activities were used in the rate expression that a power law model provided a similarly accurate prediction of the reaction rate (AARE = 4.1%). When the Eley-Rideal reaction expression (in terms of the adsorption of methanol and water) was used, a slight improvement was achieved (AARE = 2.4%). As both the Langmuir-Hinshelwood and Eley-Rideal models require separate experiments for the measurement of adsorption constants, it seems that the activity based power law model should be the kinetic expression of choice. It can be concluded that a two parameter activity based rate expression predicts the reaction rate with similar accuracy as the multi-parameter adsorption models. This indicates that it is not necessary to know the concentration on the resin surface (adsorption models) or in the resin gel (absorption models) when describing the reaction rate as long as the bulk liquid phase activities can be adequately described. / Dissertation (MEng (Chemical Engineering))--University of Pretoria, 2007. / Chemical Engineering / unrestricted

Whey is a by-product of cheese manufacture, containing a mixture of proteins of commercial value, each having unique attributes for nutritional, biological and food ingredient applications. A tremendous amount of whey, normally treated as a waste product, is produced worldwide each year. This work describes the cation-exchange adsorption of the two major whey proteins, alpha-lactalbumin (ALA) and beta-lactoglobulin (BLG) with the purpose of optimising a process for isolating them from whey. Adsorption of pure BLG and ALA was studied onto SP Sepharose FF using 0.1M acetate buffer. Batch experiments were carried out at various pH values for ALA and BLG, and the relevant Langmuir isotherm parameters, dissociation constant, Kd, and maximum binding capacity, qm, were determined. The optimum pH for separation was chosen to be pH 3.7. At pH 3.7, both Kd and qm pertaining to ALA were found to have higher numerical values than those of BLG, implying different characteristics of adsorption of the two proteins on this adsorbent. The Kd for the former protein was almost four times larger than the latter, while qm was 1.3 times higher. Packed-bed column adsorption was performed using a 1-ml column at pH 3.7, flow rate 1 ml/min and initial concentration of 3 mg/ml for BLG and 1.5 mg/ml for ALA both in 0.1M sodium acetate buffer. The t1/2 for the resulting ALA breakthrough was 75% longer than its BLG counterpart. The above results suggest the possibility of the occurrence of competitive adsorption between the proteins when adsorbed simultaneously. In traditional batch uptake experiments, the kinetic rate constants of ALA and BLG in both the single- and two-component systems were determined using the simple kinetic model. The values so obtained implied that BLG was adsorbed faster than ALA. In the confocal laser scanning microscopy experiments, the different behaviour of ALA and BLG in the single-component system with regard to their penetration within the adsorbent beads suggested that the two proteins have different transport mechanisms governing their adsorption. The two-component system results showed that ALA was able to displace BLG in spite of the lower affinity of the former protein to the adsorbent. The packed-bed adsorption and elution of a mixture of ALA and BLG were then investigated under the above conditions but using a 5-ml column. BLG breakthrough occurred first, and its concentration in the outlet exceeded its feed value by 1.6 fold before declining to the feed value, followed by the breakthrough of ALA. ALA displaced and eluted all the BLG from the column in a pure form. Pure ALA could then be eluted with good recovery. The single- and two-component breakthrough curves for ALA and BLG were simulated by the simple kinetic model using the isotherm parameters, but the overshoot phenomenon could only be predicted after correcting these parameters. The evidence of the competitive nature of adsorption observed in binary mixtures was used to develop a facile separation procedure for the two proteins from aqueous solutions of whey concentrate powders. A novel consecutive two-stage separation process was developed to separate ALA and BLG from whey concentrate mixtures. Almost all the BLG in the feed was recovered, with 78% being recovered at 95% purity and a further 20% at 86% purity. In addition, 67% of ALA was recovered, 48% at 54% purity and 19% at 60% purity. The correction factors employed for the pure binary mixture were used to simulate the breakthrough curves of the two proteins in experiments conducted with whey concentrate in each of the two stages of the novel separation process, and there was agreement between the experimental and theoretical results.