Bentonite clays have long been used as additives in animal feed, aiming to improve pellet quality and prevent caking. Certain bentonites are also capable of deactivating aflatoxin B_(1) (AfB_(1)) in feed by adsorption, therefore, detoxifying the feed. However, a 10–fold difference in adsorption capacity has been observed among selected bentonites. The major mineralogical and chemical properties of smectites in determining their adsorption capacities for AfB_(1) are still poorly understood. Improved knowledge of the key controlling factors of aflatoxin adsorption to bentonite clays is needed to guide the selection, modification, and application of the clays as aflatoxin binders. The objective of this study was to test a hypothesis that a smectite's selectivity and adsorption capacity for aflatoxin was mainly determined by the size matching requirement on interlayer surface domains and the aflatoxin molecules. Three approaches were used to vary the size of nanometer-scaled nonpolar domains in the interlayer of smectites: 1) exchanging interlayer cations, 2) selecting natural bentonites with different cation exchange capacities (CEC), and 3) reducing charge density of a high CEC smectite. Six bentonites were fractionated, with their major mineralogical and chemical properties determined. Clay suspensions saturated with different cations were tested for aflatoxin adsorption. Some aflatoxin-smectite complexes were prepared and analyzed with FTIR and XRD. AfB_(1) adsorption isotherms were fitted with Langmuir, modified Langmuir with adsorption dependent affinity, and exponential Langmuir models. Divalent exchange cations with low hydration energy in general resulted in a much higher adsorption capacity and affinity for all six natural bentonite clays. Cations with smaller hydration radii tended to further enhance the adsorption process for aflatoxin on smectites. Charge density of smectite had shown significant effects on the adsorption capacity, affinity, and the isotherm shape. Aflatoxin adsorption isotherms on the six natural smectites and the CEC-reduced 5OK samples by Hofmann and Klemen effects suggested that there is an optimal CEC range between 80~110 cmol(+)/kg for the best aflatoxin binding smectites. When the smectite has a CEC within this range, the mineral has the highest affinity and adsorption capacity for AfB_(1). The aflatoxin adsorption results after cation exchange treatment, selection of different CEC smectites, and the CEC reduction on 5OK confirmed the importance of size and polarity matching on the nanometer scale in smectites’ adsorption for AfB_(1). All clay samples tested in this study were capable of adsorbing aflatoxin into interlayers, and the charge density seemed to have no effect on bonding strength.

The work presented in this thesis is divided into two parts. The first part is the sorption of Ni and Eu to granitic materials, and cation exchange capacity measurements for powdered and intact samples. The second part is method development on autoradiography. In the first part, static batch sorption experiments were carried out to study the relative sorption properties of different granitic rocks and minerals. Experimental data were described using non-electrostatic correction models such as the Langmuir, Freundlich and Linear models. Sorption data obtained for sorption in a constant pH environment and variable metal concentration were used to test the Component Additive Model (CAM). Sorption test studies carried out using energy dispersive X-ray microanalysis were used to map the sorption of Eu on an intact sample. The results showed the CAM was applicable for Ni sorption to BG but that it was not applicable for Eu sorption to any of the granitic rocks studied. The sorption data fitted the CAM in the following order; BG (1) > GA (0.7) > RG (0.5) > GG (0.2), GrG (0.2) for Ni sorption and RG (0.7) > BG (0.4) > GA (0.2), GG (0.2), GrG (0.2) for Eu sorption to the different granitic rocks. Values in brackets represent the ratio of Rd-predicted/Rd-calculated. Results from the application of the CAM showed it was not possible to predict the Rd of the bulk sample from the component minerals. Desorption studies at constant pH were analysed by calculating the hysteresis H. The results showed that the higher the Rd the higher the hysteresis. Surface complexation using JChess Geochemical Code was used to obtain surface complexation parameters for the metal-solid complex for sorption in variable pH and constant metal concentration. Experimental data were described by the mass action law to obtained proton stoichiometry at which the sorption edge is defined. Results showed the presence of NaCl decreased the sorption of Ni, and increased the sorption of Eu. Sorption kinetics experiments in different carbonate complexing environments were carried out to study the effect of carbonate on Eu sorption capacity and rate of sorption. Data were fitted to first and second order kinetic models to investigate the sorption rates. Results showed the sorption to be fast initially before reaching a steady state after more than 200 hours of equilibration. Kinetic data confirmed the low sorption capacity observed for quartz. Data obtained for sorption in a mixed radionuclide system were modelled using the Linear model and the surface complexation model. The surface complexation constants are correlated to the Rd values obtained from the linear sorption isotherms. Modelling the results using Rdmix and Rdsing showed that sorption was suppressed in a mixed system, with no effect observed for sorption to feldspar in single and mixed systems. Cation exchange capacity (CEC) measurements were undertaken to deduce a correlation between the CEC of powdered rock samples and intact sample using rock beakers developed from the British Geological Survey by applying the Bascomb method in which the pH was buffered to pH 8.1. Normalising the results using the surface area showed that the CEC of the rock beakers was 6 orders of magnitude greater than that of the powdered sample. In the second part, a method for differentiating two or more radionuclides using storage phosphor imaging plates coupled with the Storm Scanner system was tested. Initial results showed that it is possible to differentiate one radionuclide from another in a mixed system using different levels of shielding.

Three aromatic poly(arylene ether)s P2¡BP3¡BP4 were synthesized from bis(fluoride)4,4¡¨¡¨-Difluoro-3,3¡¨¡¨-bsi-trifluoromethyl-n¡¨-bisphenyl-[1,1¡¦;4¡¦,1¡¨;4¡¨,1¡¨¡¦;4¡¨¡¦,1¡¨¡¨]-quinquephenyl(n¡¨:2¡¨,3¡¨[G2];2¡¨,3¡¨,5¡¨[G3];2¡¨,3¡¨,5¡¨,6¡¨[G4]) with 4,4'-(9-Fluorenylidene)diphenol. The molecular weight of the polymer (Mw: 105-1.6¡Ñ105, PDI:1.5-2.2) was measured by gel permeation chromatography and the structure was confirmed by NMR spectra. Thermal stability was measured using Thermogravimetry and Thermomechanical Analysis. The polymer had a Td at 520¢J ~550¢J, and soft point at 310¢J. Young's modulus of polymer was (1.25-2.5Gpa). This polymer has high strength, modulus of elasticity, and thermal stability. The polymer consists of polyaromatic groups with bisfluoride monomer, (5, 6, 7 aromatic). We hypothesized that sulfonation of the polymer will exhibit high conductivity and great mechanical properties. Ion exchange capacities (IECs) were evaluated by acid¡Vbase titration. We sulfonated the polymer in order to apply to the proton exchange membrane fuel cell. The results showed after sulfonation of P4, IEC is 3.3(meq/g), and sulfonation of P2 showed that its proton conductivity is 75% more than Nafion117 at 80¢J with 0.28(S/cm). Keywords: proton exchange membrane, proton conductivity, Nafion, sulfonated, ion exchange capacity

>Magister Scientiae - MSc / There are huge amount of natural clinoptilolite available in South Africa which can be utilised for wastewater treatment of ammonia and chromium if their characteristics are properly known. However, these deposits have not been well characterised but in this study, the untreated clinoptilolite materials were fully characterised using techniques such as SEM-EDS, HRTEM-SAED, XRD, XRF, FTIR and BET. After acid pretreatment with several extractions, the pretreated samples were again characterised using the above mentioned techniques. These pretreated materials were used for NH₄⁺ and Cr³⁺ adsorption of wastewater. The three natural South African clinoptilolite samples used in this study were from ECCA Holdings (ESC and EHC samples) and Pratley (PC sample) deposits obtained from Western Cape and KwaZulu-Natal Province respectively. This study revealed that the chemical composition and mineral phases of South African clinoptilolites vary considerably from site to site, even clinoptilolite mined from the same deposit sites. The XRD analyses showed that Pratley clinoptilolite (PC) was the most pure clinoptilolite sample (81.41 %) compared to the purity of EHC (67.88 %) and ESC (44.0 %) sample. The ECCA Holdings untreated clinoptilolite samples contained dense phases such as quartz which was not found in Pratley sample. Quartz was found to be the most dominant impurity in both ECCA Holding sample. The cation exchange capacity (CEC) of ESC, EHC and PC samples were found to be 1.23, 1.81 and 2.90 meq/g respectively and these results were compared to that of XRF analyses. The acid solutions of 0.02 and 1.0 M HCl were used to pretreat natural clinoptilolite to determine the optimum acid concentration and number of extractions required to fully replace the exchangeable cations. The pretreatment results showed that 0.02 M HCl was the optimum acid concentration for acid pretreatment of clinoptilolite samples. Between 7 and 22 extractions were required to remove Na⁺, K⁺, Ca²⁺ and Mg²⁺ without causing much dealumination of the framework. Sodium ion was found to be weakly bound cation in the clinoptilolite framework, since it could be completely exchanged by H⁺ after 7 extractions with 0.02 M HCl acid solution. Potassium ion was found to be strongly bound in the clinoptilolite framework since it could not be completely exchanged during the acid pretreatment process even after 22 extractions. The HRTEM-SAED and BET results showed that ESC, EHC and PC were all polycrystalline and microporous materials respectively. It was found that the adsorption capacity of the treated Pratley clinoptilolite sample was increased by 36 % for NH₄⁺ removal, compared to that of the untreated PC sample. The adsorption study results showed that the pretreatment of clinoptilolite samples using 150 mL volumes of 0.02 M HCl with 7 acid extractions at 25 °C for ESC pretreated and EHC pretreated. The pretreatment of PC sample at 22 extractions could remove high percentage of NH₄⁺ (98.11 %) within a short contact time of 10 min. The pretreated Pratley clinoptilolite sample was found to be the best NH₄⁺ adsorbent (98.11 % NH₄⁺ removal) compared to EHC treated (93.89 % NH₄⁺ removal) and ESC treated (75.00 % NH₄⁺ removal) clinoptilolite samples. However, acid-pretreated Pratley clinoptilolite did not sufficiently remove Cr³⁺ (16.10 %) from synthetic wastewater showing that it is not a good adsorbent for this particular metal ion removal. Despite several studies that have been conducted on clinoptilolite, no study has been carried out on the pretreatment and comparison of sorption capacity of different South African clinoptilolites for the removal of NH₄⁺ from wastewater. This study has been able improve on the acid-pretreatment procedure for clinoptilolite. This study demonstrated that it is not only the acid concentration that is important but also the number of extractions needed to remove all the exchangeable cations from the clinoptilolite framework. This study has also been able to prove that South African clinoptilolite can treated ammonia from wastewater.

Sasol biological sludge, coal fine and gasification ash were the three waste streams involved in this study. The main concern is that on their own they are not suitable as growth mediums, the ash is alkaline (pH>12) with high salinity (total dissolved solids of 8000 mg ℓ-1). Fine ash is microporous (particle size diameter <250 μm) and forms cemented layers that can restrict root growth while, gasification ash in macroporous (most particle size diameter ranged between 1 and 75 mm) and has a low water holding capacity. Sludge is unstable and can inhibit gaseous exchange. However, these wastes potentially, have physical, biological and chemical attributes that make them suitable as hospitable growth medium. Sludge can promote micro-fauna activity and, provide plant available nitrogen (N) as well as phosphorus (P) the ash is poor in. On a short term bases and in the long term it can also contribute to cation exchange capacity (CEC). Fine ash can increase water holding capacity and gasification ash can improve gaseous exchange. It was hypothesized that if the ash was treated with sludge, pH will be reduced to between 5.5 and 8, and weathering will reduce salinity to less than 400 mSm-1, increase CEC and increase plant available N and P. Therefore, the main purpose of this laboratory column study was to establish combinations of these waste streams that hold promise as plant growth media, based on various chemical and physical criteria link to hospitable plant growth media, as well as the influence of weathering on the release of essential plant nutrients. A total of 51 mixtures (each weighing 2.6 kg) were formulated based on wet mass basis and divided into 6 groups based on sludge content (0, 10, 20, 30, 40 and 50%) and packed into columns, subjected to wetting and drying for 1 year (10 wetting and drying cycles) by passing through deionized water equivalent to the pore volume and allowing the mixtures to dry in between. The leachates were analysed using Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) and Kjeldahl procedures (for N release). Total elemental analysis was done using X-ray Fluorescence Spectroscopy (XRF) and acid digestion method. Particle size distribution was done using the sieve method. Cation exchange properties were assessed using ammonium acetate (NH4OAc), lithium chloride (LiCl) and potassium chloride (KCl) methods. Results indicated that sludge was critical for these mixtures,at a minimal content of 10% it increased the water holding capacity of the mixtures. In the mineralization of inorganic N at a lower limit of 20% sludgeenabled the production of plant available NH4+ and NO3- and less NO2-. Increasing sludge to 50% further reduced the production of NO2- in the mixtures. In terms of elemental release, mixtures without sludge were dominated by Na and the order of abundance was as follows; Na>K>Ca>Mg>P on mmol kg-1 but the introduction of sludge at a lower content limit of 10% changed the abundance of the elements as follows; P>Mg>Ca>Na>K on mmol kg-1. Sludge content as low as 10% reduced the pH of the mixtures to between 7.6 and 8 and EC to less than 400 mSm-1. However, increasing sludge to 50% increased the leachate EC dramatically and kept the EC high (415 mSm-1) till the end. Introduction of sludge at a low limit of 10 % content increased the CEC above 8 cmolc kg-1. The effects of fine ash on the water holding capacity of the mixtures were seen at the 10 % level, for example, mixture 13 with 10% fine ash had 0.3 mg kg-1, while mixture 12 with 0% fine ash had 0.27 mg kg-1. Increasing fine ash content above 40% increased pozzalanic properties, pH (>8), EC (>400 mSm-1), Na release and reduced CEC.Gasification ash is the biggest waste stream and utilizing these wastes as growth media will mean that it realistically will always dominate these mixtures. This study showed that on its own it will be a challenging environment. However, the amendent with sludge and fine ash resulted in some chemically and physically favourable changes in these media. It can be concluded that the main objective has been achieved and bio assay evalution of theses mixtures is recommended Copyright / Dissertation (MSc(Agric))--University of Pretoria, 2012. / Plant Production and Soil Science / unrestricted

A yellowing which develops in some plants growing on naturally calcareous soils is called lime-induced chlorosis. The problem is complex, as indicated by Brown and Holmes (1956) and Porter and Thorne (1955). Species and varieties of plants differ in their iron requirements, susceptibility to lime- induced chlorosis, and inter acting soil f actors which affect iron supply (Thorne et al 1950). Chlorosis of plants does not appear, therefore, to stem from a common causative factor. At least a part of this difference has been found to be associated with the plant roots. Thus, through the use of resistant root stock Wann (1941) was able to produce non-chlorotic grapes. These grapes grown under similar conditions without the resistant root stock would have been high1y chlorotic. Certain citrus root stocks have also been used on calcareous soils because they give citrus trees resistance to chlorosis.

In Arctic tundra soils pH serves as an important parameter related to several biotic parameters such as, plant and microbial community composition, biodiversity, nutrient dynamics and productivity. Both abiotic and biotic factors, for instance, base saturation (BS) and plant nutrient uptake may exert a control on soil pH, while it is still unclear to what extent different factors can explain soil pH across different tundra vegetation types. The aim of this study was to investigate to what extent different abiotic and biotic factors influence soil pH in the humus layer across different tundra vegetation types. To do so, eight different tundra vegetation types of which four were underlaid by permafrost (Arctic Alaska) and four with no permafrost (Arctic Sweden) were studied in detail with regard to different properties affecting soil pH. I found that BS was the main factor controlling soil pH across the different vegetation types regardless if the soil was underlain by permafrost or not. Factors, such as, ionic strength or soil water content could not explain any overall pH variation and did only significantly affect the heath soils. Further, the uptake of the most abundant base cations (Ca2+, Mg2+ and K+) from meadow and heath vegetation revealed a high difference between plant functional groups within the same vegetation types. The higher dominance of slow growing woody species in heath vegetation which had a lower uptake corresponded with a lower BC content (especially (Ca2+), pH and BS in the humus soil relative the meadow meanwhile the content of K+ was more than three times higher in heath. Overall, this study suggests that the degree of neutralization (base saturation) regulates pH either via the influence of bedrock and hydrogeochemistry and/or via plant traits that affects the uptake and turnover of base cations.

Ce travail de thèse a pour but l’étude des effets de la contamination cationique sur lamembrane électrolyte afin d’élaborer des outils de caractérisation et de diagnostic de cette pollution.Premièrement, la caractérisation physico-chimique de membranes PFSA commerciales arévélé des paramètres pertinents de structure et de propriété, qui ont été étudiés en fonction de leurdépendance à la capacité d’échange ionique (IEC).Deuxièmement, les propriétés thermiques des membranes contaminées par des cations ontrévélé des changements dépendant fortement de l’acidité de Lewis du cation (LAS). Cette tendance aété corrélée à la nature de l’interaction des différents cations avec les groupements polaires de lachaîne polymère, révélée par FTIR.Enfin, l’influence du taux de pollution sur les différents paramètres thermiques et structurauxnous a permis de révéler ceux qui sont pertinents non seulement à l’identification mais aussi à laquantification de la pollution. Une application des courbes d’étalonnage a été réalisée sur desmembranes vieillies issues de systèmes réels après fonctionnement. / The purpose of this study was to experimentally determine the effects of cationiccontamination on PEMFC ionomers in order to elaborate characterization tools and new modes forpollution diagnosis.First, a large series of techniques were used to investigate the properties of commercial PFSAmembranes. Distinctive parameters concerning structure and properties were extracted as well as theirrelationship to ion exchange capacity (IEC).Second, the thermal properties of cation-contaminated membranes revealed changes that arehighly dependent on the Lewis Acid Strength of the cation (LAS). This trend was correlated with thenature of the interaction between the cations and the polar groups of the polymer chain, revealed byFTIR spectroscopy.Finally, the influence of the pollution level on the thermal and structural parameters allowedus to reveal not only the relevant parameters to the identification but also to the quantification ofpollution. An application of the different calibration curves was performed on aged membranescoming from real operating 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.

The thesis is about the processing of biological waste in the Czech composting plants with focus on the quality of the final compost. In 2016, there was more than 160 composting plants in the Czech Republic. The thesis is focused on the most widely used technologies in small composting plants in terms of their impact to the quality of the final product, including the follow-up of individual indicators during composting. The best technology in my work is based on a higher decomposition temperature (85 ° C) at the first stage of composting. The practical part of thesis is focused on the measurement of ion-exchange capacity according to Sandhof as a main material for the overall evaluation of the functionality of composting. The final value shows the compost quality of the individual composting plants in terms of ion exchange flexibility of the produced substrate. The best result was achieved with the combination of composting boxes and composting in the belt heaps. The value of the ion-exchange capacity with the best technology was 52.8 mval .100 g of the soil, with 77.9% of the distributed biowaste. You have to expect with an average annual costs of composting about 1,696,000 crounds in the Czech republic, when you are designing small functional composting plant with production of 2000 tons of the compost per year.