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.

>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

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.

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.

Agricultural soil properties exhibit variation over field plot scales that can ultimately effect the yield. This study performs multiple spatial pattern analyses in order to design spatially dependent regression models to better understand the interaction between these soil properties. The Cation Exchange Capacity (CEC) and Calcium-Magnesium Ratio (CaMgR) are analyzed with respect to Calcium, Magnesium, and soil moisture values. The CEC and CaMgR are then used to determine impact on the yield values present for the field. Results of this study show a significant measure of model parsimony (0.979) for the Geographically Weighted Regression (GWR) model of the CEC with free Ca, Mg, and soil moisture as explanatory variables. The model for CaMgR using the same explanatory variables has a much lower measure of model fit. The yield model using the CEC and CaMgR as explanatory variables is also low, which is representative of the underlying processes also impacting yield.

Digital soil mapping (DSM) provides a cost-effective approach for characterizing the spatial variation in soil properties which contributes to inconsistent productivity. This study utilized Random Forest (RF) models to facilitate DSM of apparent soil electrical conductivity (ECa), estimated cation exchange capacity (CEC), and soil organic matter (SOM) in agricultural fields across the Lower Mississippi Alluvial Valley. The RF models were trained and tested using in situ collected ECa, CEC, and SOM data, paired with a bare soil composite of Landsat 9 imagery. Field data and imagery were collected during the study period of 2019 through 2023. Models ranged from fair to moderate in accuracy (R2 from 0.27 to 0.68). The contrasting performance between CEC/SOM and ECa models is likely due to the dynamic nature of soil properties. Accordingly, models could have benefitted from covariates such as soil moisture, topography, and climatic factors, or higher spectral resolution imagery, such as hyperspectral.

Mechanisms of adsorption of alkaline copper quat (ACQ) components in wood were investigated with emphasis on: copper chemisorption, copper physisorption, and quat adsorption. Various factors were investigated that could affect the adsorption of individual ACQ components in red pine wood. Copper chemisorption in wood was affected by ligand types coordinating with Cu and the stability of the Cu-ligand complexes in solution. For Cu-monoethanolamine (Cu-Mea) system, the prevailing active solvent species at the solution pH, [Cu(Mea)2-H]+ complexes with wood acid sites and loses one Mea molecule through a ligand exchange reaction. The amount of adsorbed Cu was closely related to the cation exchange capacity of wood. An increase in Mea/Cu ratio increased the proportion of the uncharged Cu-Mea complex and resulted in decreased Cu chemisorption in wood. Copper precipitation is also an important Cu fixation mechanisms of Cu-amine treated wood. X-ray diffraction analysis revealed that in vitro precipitated Cu was a mixture of copper carbonates (azurite and malachite) and possibly Cu2O. Higher concentration Cu-amine solutions retarded the Cu precipitation to a lower pH because of higher free amine in the preservative-wood system. The changes in zeta potential of wood in relationship to the quaternary ammonium (alkyldimethylbenzylammonium chloride: ADBAC) adsorption isotherm showed two different adsorption mechanisms for quat in wood: ion exchange reaction at low concentration and additional aggregation form of adsorption by hydrophobic interaction at high concentration. Because of the aggregation effect, when wood was treated with ACQ, high amounts of ADBAC were concentrated near the surface creating a steep gradient with depth. This aggregated ADBAC was easily leached out while the ion exchanged ADBAC had high leaching resistance. Free Mea and Cu of ACQ components appeared to compete with ADBAC for the same bonding sites in wood.

The explosive 2,4,6-trinitrotoluene (TNT) is currently a main ingredient in munitions; however the compound has failed to meet the new sensitivity requirements. The replacement compound being tested is 2,4-dinitroanisole (DNAN). DNAN is less sensitive to shock, high temperatures, and has good detonation characteristics. However, DNAN is more soluble than TNT, which can influence transport and fate behavior and thus bio-availability and human exposure potential. The objective of this study was to investigate the environmental fate and transport of DNAN in soil, with specific focus on sorption processes. Batch and column experiments were conducted using soils collected from military installations located across the United States. The soils were characterized for pH, electrical conductivity, specific surface area, cation exchange capacity, and organic carbon content. In the batch rate studies, change in DNAN concentration with time was evaluated using the first order equation, while adsorption isotherms were fitted using linear and Freundlich equations. Solution mass-loss rate coefficients ranged between 0.0002 h(-1) and 0.0068 h(-1). DNAN was strongly adsorbed by soils with linear adsorption coefficients ranging between 0.6 and 6.3 L g(-1), and Freundlich coefficients between 1.3 and 34 mg(1-n) L-n kg(-1). Both linear and Freundlich adsorption coefficients were positively correlated with the amount of organic carbon and cation exchange capacity of the soil, indicating that similar to TNT, organic matter and clay minerals may influence adsorption of DNAN. The results of the miscible-displacement column experiments confirmed the impact of sorption on retardation of DNAN during transport. It was also shown that under flow conditions DNAN transforms readily with formation of amino transformation products, 2-ANAN and 4-ANAN. The magnitudes of retardation and transformation observed in this study result in significant attenuation potential for DNAN, which would be anticipated to contribute to a reduced risk for contamination of ground water from soil residues.

Made available in DSpace on 2017-07-10T17:37:50Z (GMT). No. of bitstreams: 1 Loana Bergamo dos Santos.pdf: 1109658 bytes, checksum: 86a9ba08470cd16b7befaff7cd272ca6 (MD5) Previous issue date: 2011-03-30 / The constant search for sustainability of production systems have driven research to find alternatives to the problems arising from the intensification of production systems. In this context the present work was to study the effects of substitution of mineral nitrogen by chicken litter in oat and corn in succession and chemical characteristics of soil. Two experiments were conducted during the period from May 2009 to March 2010 in Oxisol area located at the experimental farm of the State University of Paraná, municipality of Rondon. The first test was conducted under a randomized complete blocks with eight treatments obtained from different combinations of chicken manure (applied in oat) and mineral N fertilization (applied in corn) and four replications. We studied the production of dry matter and nutrient accumulation in the straw of the oat crop, and yield components and yield of corn. In the second trial, after the corn harvest, we studied the chemical properties of soil under the design of randomized blocks in factorial scheme 8x3, with the eight combinations of fertilizer used in the first trial related to three depths of soil sampling (0 -5, 5-10 and 10-15 cm). Larger quantities of poultry litter in oat provided higher dry matter production and accumulation of N. All fertilization studied provided satisfactory average productivity for corn (8569 kg ha-1). The soil properties were changed with the use of poultry litter associated with mineral N fertilization. There was a decrease in pH, Ca, Mg, and increased the P, potential acidity, the cation exchange capacity and exchangeable Al with increasing proportions of poultry litter in relation to mineral N fertilization / A busca constante pela sustentabilidade dos sistemas de produção têm direcionado as pesquisas à buscar alternativas aos problemas oriundos da intensificação dos sistemas produtivos. Nesse contexto o presente trabalho teve como objetivo estudar os efeitos da substituição da adubação nitrogenada mineral pela cama de frango na cultura da aveia e do milho em sucessão e nos atributos químicos do solo. Foram conduzidos dois ensaios durante o período de maio de 2009 à março de 2010 em área de Latossolo Vermelho eutroférrico localizada na fazenda experimental da Universidade Estadual do Oeste do Paraná, município de Marechal Cândido Rondon. O primeiro ensaio foi conduzido sob o delineamento em blocos ao acaso com seis tratamentos obtidos a partir de combinações de quantidades crescentes de cama de frango aplicadas na aveia combinadas com a adubação nitrogenada mineral de cobertura aplicada no milho e quatro repetições. Estudou-se a produção de massa seca e acúmulo de nitrogênio pela cultura da aveia, e os componentes de produção e produtividade da cultura do milho. No segundo ensaio, após a colheita do milho, estudou-se os atributos químicos do solo sob o delineamento em blocos ao acaso em esquema fatorial 6X3, com as seis combinações de adubação utilizadas no primeiro ensaio associadas a três profundidades de amostragem do solo (0-5; 5-10 e 10-15 cm). A aplicação de cama de frango na cultura da aveia propiciou aumento da produção de massa seca e acúmulo de maior quantidade de N, enquanto a substituição de parte da adubação nitrogenada mineral pela cama de frango elevou os índices de produtividade da cultura do milho. Os atributos químicos do solo foram alterados pelos fatores estudados, ocorrendo a elevação dos teores de P, MO, Al trocável e acidez potencial, e redução do pH, K, Ca, Mg, soma de bases e saturação por bases.