Os defeitos de fechamento de tubo neural constituem uma das malformações mais freqüentes na espécie humana, apresentando alta morbi-mortalidade. Sua etiologia é considerada multifatorial, estando envolvidos fatores genéticos e ambientais. Estes fatores estão relacionados principalmente com o metabolismo da homocisteína. Realizamos um estudo de caso-controle com o objetivo de estudar os fatores bioquímicos e genéticos relacionados ao DTN na nossa população. Em pares de afetados com DTN e suas mães e pares de pacientes normais e suas mães foram avaliados dosagem de folato, vitamina B12, homocisteína e polimorfismos da enzima metileno tetraidrofolato redutase (MTHFR), C677T e A1298C. A dosagem de folato nos casos foi 11,37 ng/mL(±6,72) e nos controles 5,64 ng/mL(±4,16) (p<0,001). O folato sérico das mães foi 7,27 ng/mL (±4,48) e 3,90 ng/mL (±1,77) nas mães controles (p<0,001). A média de dosagem de vitamina B12 foi de 641,88 pg/mL ((±262,21) nos casos e 743,27 pg/mL (±433,52) nos controles (p= 0,205). A média de dosagem de vitamina B12 nas mães dos casos foi 354,75 pg/mL (±142,06) e 465,25 pg/mL (±194,91) nas mães controles (p=0,004). O nível de homocisteína plasmático médio foi 6,89 μmol/L(±4,48) para os casos e 5,41 μmol/L (±2,55) para os controles (p=0,099). Nas mães dos casos a dosagem média de homocisteína foi 7,23 μmol/L (±2,64) e 7,00 μmol/L (±2,24) nas mães controles (p=0,666). Não houve diferença entre a freqüência dos genótipos C677T e A1298C da MTHFR nos casos e controles e suas mães. Para o polimorfismo C677T as freqüências dos alelo C e T foram respectivamente 0,6585 e 0,3414 nos pacientes com DTN; 0,6590 e 0,3410 nos controles; 0,6460 e 0,3540 nas mães dos casos e 0,6136 e 0,3860 nas mães controles. Para o polimorfismo A1298C as freqüências dos alelos A e C foram respectivamente 0,7436 e 0,2564 nos pacientes com DTN; 0,7610 e 0,2390 nos controles; 0,8055 e 0,1945 nas mães dos casos e 0,8065 e 0,1935 nas mães controles. Identificamos que indivíduos homozigotos 677TT apresentam um maior nível de homocisteína e este é inversamente relacionado com os níveis de vitamina B12. Estes achados sugerem que uma alteração metabólica relacionada ao metabolismo da homocisteína e principalmente devido à diminuição da vitamina B12 seja um fator de risco para DTN na nossa população. / Neural tube defects (NTD) are among the most common birth defect leading to great disabilities. The etiology is multifactorial, involving the combined action of both genetic and environmental factors. Those factors have been related to homocysteine metabolism. We performed a case control study in order to evaluate the biochemical and genetic factors related to NTD in the South of Brazil. A mother- NTD children pair and mother normal children were evaluated for folate, vitamin B12, homocysteine and two polymorphism of the methylene tetrahydrofolate reductase (MTHFR), C677T and A1298C. The folate level was 11,37 ng/mL (±6,72) in the NTD patients and 5,64 ng/mL(±4,16) in the controls (p<0,001). The folate was 7,27 ng/mL (±4,48) in the NTD mothers and 3,90 ng/mL (±1,77) in the control mothers (p<0,001). The level of vitamin B12 was 641,88 pg/mL ((±262,21) in the NTD case and 743,27 pg/mL (±433,52) in the controls (p= 0,205). The levels of vitamin B12 in the NTD mothers was 354,75 pg/mL (±142,06) and 465,25 pg/mL (±194,91) in the control mothers (p=0,004). The pasmatic homocysteine level was 6,89 μmol/L(±4,48) for the NTD cases and 5,41 μmol/L (±2,55) for the controls (p=0,099). The NTD mothers showed homocysteine level of 7,23 μmol/L (±2,64) and the controls mothers demonstrated 7,00 μmol/L (±2,24) (p=0,666). We could not observed a difference between the frequency of the genotypes C677T and A1298C in case and controls. The frequency of the alele C and T for the polymorphism C677T were respectively 0,6585 and 0,3414 for the NTD patients; 0,6590 and 0,3410 for the controls; 0,6460 and 0,3540 for NTD mothers; 0,6136 and 0,3860 for the control mothers. The frequencies of the allele A and C for the polymorphism A1298C were respectively 0,7436 and 0,2564 for NTD patients, 0,7610 and 0,2390 for controls; 0,8055 and 0,1945 for NTD mothers; 0,8065 and 0,1935 for controls mothers. We could demonstrated that the homozygous 677TT had a higher level of homocysteine and this was related to low level of vitamin B12. Those findings suggest that biochemical and genetic factors related to homocysteine metabolism and vitamin B12 deficiency are a risk factor to NTD in our population.

Esta tese demonstra a aplicação da análise por injeção seqüencial (SIA) para determinação de sulfeto utilizando a química da formação do azul de metileno, a qual se baseia em dois reagentes: solução de cloridrato de dimetil p-fenileno diamina (DMPD) 3,63 mmol L-1 em meio de HCI 1,1 mol L-1 e solução de cloreto de ferro (III) 19 mmol L-1, também em meio de HCI 1, 1 mol L-1. Estas soluções foram aspiradas para dentro de uma bobina coletora do sistema SIA como duas zonas de reagente, entre as quais aspirava-se a solução da amostra. Em condições otimizadas o limite de detecção foi calculado em 40 &#181;g L-1 de S2-, com uma faixa dinâmica de resposta linear entre 0,05 e 2,0 mg L-1 . Esta faixa linear pode ser ampliada até 32 mg L-1 utilizando-se uma etapa de diluição in-line para concentrações maiores do que 2,0 mg L-1 de S2- . As características de robustez do sistema SIA que utiliza uma bomba de pistão, confere alta estabilidade para as curvas analíticas (precisão de 4%), minimizando a trabalhosa preparação de padrões de S2-. O método foi aplicado na determinação de sulfeto volatilizável por ácidos (AVS) em sedimentos coletados em reservatórios da região metropolitana de São Paulo (RMSP) e no reservatório de Barra Bonita no rio Tietê, localizado 270 km a jusante em relação à cidade de São Paulo. As concentrações de AVS foram 9 a 14 mg kg-1 nos sedimentos de Barra Bonita e entre 1,2 e 14 g kg-1 nos sedimentos dos reservatórios Billings, Pirapora e Rasgão. Esta tese também descreve o acoplamento da análise por injeção seqüencial com análise por fluxo monossegmentado (SI-MSFA) para determinação de sulfeto em níveis de concentração típicos de águas residuais. As curvas analíticas foram construídas por diluição in-line de uma única solução padrão. A robustez do método proposto foi verificada construindo-se curvas analíticas em diferentes dias de trabalho e comparando-se os coeficientes angulares, os quais apresentaram um desvio padrão relativo de 5,2% (n=5) para uma faixa de concentração entre 0,17 e 1,0 mg L-1 de S2-. A freqüência de amostragem foi de 38 análises por hora, com um limite de detecção de 40 &#181;g L-1. A adequabilidade do método SI-MSFA para realizar adições de padrão para determinação de S2- também foi descrita. Amostras simuladas foram analisadas pelo método proposto, apresentando taxas de recuperação entre 70 e 115%, demonstrando a adequabilidade do método SI-MSFA para realizar análise in-situ de S2- em estações automáticas de monitoramento. / This thesis demonstrates the application of sequential injection analysis (SIA) to perform sulfide determination using the methylene blue chemistry, based on two reagents: 3.63 mmol L-1 N,N dimethyl-p-phenylene diamine hydrochloride in 1.1 mol L-1 HCI solution and 19 mmol L-1 FeCl3, also in 1.1 mol L-1 HCI. These solutions are aspirated inside the holding coil of the sequential injection system as two reagent zones sandwiching the sample zone. Under optimized conditions, the detection limit was calculated at 40 &#181;g L-1 S2-, with a linear dynamic range from 0.05 to 2 mg L-1 S2-. This linear range can be extended up to 32 mg L-1 using in-line dilution for sulfide concentrations greater than 2 mg L-1. The robust characteristic of the SI system with syringe pump leads to very stable analytical curves (precision of 4%), minimizing the laborious preparation of sulfide standards. The method was applied in the determination of acid volatile sulfide in river sediments collected at the Metropolitan Area of São Paulo (MASP) City and at the Barra Bonita reservoir, located in the Tietê River, 270 km down river from São Paulo City. The concentrations of acid volatile sulfide were 9 to 14 mg kg-1 in the Barra reservoir and between 1.2 and 14 g kg-1 in sediments from Billings, Pirapora and Rasgão reservoirs. This thesis also describes the coupling of Sequential Injection with Monosegmented Flow Analysis (SI-MSFA) for determination of sulfide at typical concentrations in wastewaters. The analytical curves were constructed by in-line dilution of a single stock standard solution. The robustness of the proposed method was checked constructing analytical curves in different working days and comparing the slopes, which had a relative standard deviation of 5.2 % (n = 5) for a concentration window inside the monosegment between 0.17 and 1.0 mg L-1 S2-. The analytical throughput was 38 samples per hour and the limit of detection was 40 &#181;g L-1. The feasibility of the SI-MSFA approach to perform standard additions for S2- determination was also described. Simulated samples analyzed by the proposed method showed recoveries between 70 and 115%, demonstrating the feasibility of the SI-MSFA method to perform in-situ analysis of S2- in automatic monitoring stations.

Lophira lanceolata (Ll) et Carapa procera (Cp) sont des plantes oléagineuses, peu étudiées. Au Bénin, elles sont pourtant utilisées à des fins alimentaires, cosmétiques et thérapeutiques. Cette étude vise la caractérisation de leurs graines, coques et bois. Les huiles végétales de Ll ont été obtenues par différentes méthodes dont une aqueuse traditionnelle tandis que celle de Cp l’a été par utilisation d’hexane. De façon générale, les huiles de Ll montrent un profil nutritionnel riche en acides gras polyinsaturés (>50% m/m: masse pour masse). Outre ses propriétés chimiques meilleures, celle obtenue par le procédé traditionnel est plus riche en acides gras essentiels, en composés phytostéroliques comme le lupéol et en tocols. La torréfaction et l’utilisation d’enzymes ont également permis d’évaluer l’impact de ces méthodes sur la composition chimique des graines de Ll. Quant aux graines de Carapa p., elles présentent un profil plutôt abondant en acides gras monoinsaturés, en tocotriénols (85,56% m/m) et en lanostérols (28,03%, m/m). Les tourteaux, coques et bois des deux espèces montrent une variabilité chimique en composés pariétaux (extractibles, hémicelluloses, celluloses et lignines). Une caractérisation in fine des hémicelluloses de ces parties des deux plantes a permis de montrer qu’elles sont essentiellement de type glucuronoxylanes. Les extractibles de ces plantes ont également offert une large gamme de composés à connotations industrielles et pharmaceutiques positives. Enfin, les conditions optimales de la biosorbption du bleu de méthylène sur les coques de Lophira ont également été évaluées. Cette évaluation a permis de mettre en exergue la potentielle utilisation de ces résidus agroforestiers pour rendre potables les eaux usées industrielles / The chemical composition of wild oilseeds, such as Lophira lanceolata (Ll) and Carapa procera (Cp) of Benin is mostly unknown. Yet they undergo crafted transformations for food, cosmetic and therapeutic purposes. This study aims to characterize their seeds, hulls and woods. From these crops, different oils have been extracted. One of them has been produced in rural area according to aqueous ancestral method. On the whole, oils of Ll have presented an interesting nutritional profile. They are rich in polyunsaturated fatty acids (> 50% m/m: mass for mass), especially that extracted by artisanal process. Beyond its good chemical properties, it provides essential fatty acids, phytosterols such as lupeol and more tocols compounds. Roasting and the use of enzymes have also assessed the impact of these methods on the chemical composition of LI seeds. Differently, Cp oil’s has an abundant presence of MUFA, tocotrienols (85.56% w/w) and the richest composition in lanosterol (28.03%, m/m). The seeds cakes, hulls and wood of both species showed various distributions on chemical components (extractives, hemicellulose, cellulose and lignin). The characterization of hemicelluloses from different parts of plants has shown that they are essentially glucuronoxylans type. Extractives also offered a wide range of compounds mostly appreciated for industrial and pharmaceutical purposes. The chemical composition of the shells of Lophira was rich in organic compounds such as lignin (32.13%, dry weight) so their biosorbent capacity was evaluated. They showed methylene blue good adsorption capacity in aqueous solution, which highlighted their potential use in the purification of wastewater

O aumento significativo de micoses decorrentes do crescimento do número de indivíduos imunocomprometidos, da emergência de novas espécies de fungos patogênicos e do surgimento de patógenos resistentes aos antifúngicos atualmente utilizados é um sério problema de saúde pública. Nesse contexto, é extremamente desejável o desenvolvimento de novas técnicas para o controle de fungos. A TFD (terapia fotodinâmica), inicialmente desenvolvida como uma alternativa terapêutica para o câncer, é um processo que envolve a administração de um fotossensibilizador que se acumula preferencialmente nas células-alvo e que pode ser ativado por exposições à luz. A ativação do fotossensibilizador leva à formação de espécies reativas de oxigênio que são capazes de danificar lipídios, proteínas e ácidos nucléicos, provocando a morte da célula. A TFDA (terapia fotodinâmica antimicrobiana) pode ser utilizada tanto para o controle de micoses localizadas como para a eliminação de espécies patogênicas de fungos do ambiente. Neste estudo, foi avaliada a atividade fotossensibilizadora e foram testados parâmetros funcionais como concentração do fotossensibilizador (1 a 400 g mL-1); tempo de pré-incubação com o fotossensibilizador (0 a 60 min.); doses (90 e 180 kJ m-2) e intensidade de luz visível (50 W m-2) para a fotossensibilização de: (1) fotossensibilizadores comerciais atualmente utilizados na TFDA, como o azul de metileno (MB) e o azul de ortotoluidina (TBO), e (2) complexos nitrosilos de rutênio. Os experimentos foram conduzidos com conídios dos fungos-modelo Metarhizium anisopliae e Aspergillus nidulans. Tanto o MB como o TBO, na presença da luz, foram capazes de inativar os conídios das duas espécies de fungos. A inativação foi próxima de 100%, para ambas as espécies, quando a combinação apropriada (concentração do fotossensibilizador e tempo de exposição à luz) foi utilizada. Nenhum dos dois corantes, na ausência da luz, inativou os conídios das duas espécies. O tempo de pré-incubação com os fotossensibilizadores (MB e TBO) não foi um parâmetro determinante para a eficiência da fotoinativação dos conídios. De maneira geral, a inativação dos conídios foi maior nas fotossensibilizações com MB e TBO por 60 min do que nas por 30 min. Os conídios verdes e amarelos foram mais tolerantes à fotossensibilização com MB e TBO do que os conídios brancos e violetas, indicando que a pigmentação dos conídios influencia na fotoinativação. O nitrosilo de rutênio [Ru(NH.NHq)(tpy)NO](PF6)3 não foi capaz de inativar os conídios de nenhuma das espécies, em nenhuma das condições avaliadas. A fotoinativação dos conídios de M. anisopliae com MB e TBO não ocorreu quando a fotossensibilização foi conduzida em meio de cultura líquido PDB. / The significative increase of mycoses resulting from the growing number of immunocompromised individuals, from the emerging of new species of pathogenic fungi, and from the emerging of pathogens resistant to the antimycotics used nowadays is a serious public health problem. In such scenario, the development of new fungal control techniques is highly desirable. Initially developed as a therapeutical alternative for cancer, PDT (photodynamic therapy) is a process that involves the use of a photosensitizer that preferrably accumulates in the target-cells and that can be light-activated. The activation of the photosensitizer leads to the generation of reactive oxygen species that damage lypids, proteins, and DNA, and kills the cell. APDT (antimicrobial photodynamic therapy) can be used to control localized infections as well as to kill pathogenic fungi in the environment. In this study, we evaluated the photoinactivation by MB (methylene blue), TBO (toluidine blue), and nitrosyl ruthenium complexes in Metarhizium anisopliae and Aspergillus nidulans conidia. We also tested parameters such as photosensitizer concentration (1 to 400 g mL-1), pré-incubation time with the photosensitizer (0 to 60 min.), light doses (90 and 180 kJ m-2), and visible light irradiance (50 W m-2). Both MB and TBO photoinactivated the conidia of the two species of fungi. Inactivation was close to 100% for both species when the appropriate combination between photosensitizer concentration and light exposure time was used. None of the two dyes in the dark inactivated the conidia of the two species. Pre-incubation time with the photosensitizers (MB and TBO) was not a determinant parameter for photoinactivation efficiency. Conidia inactivation was higher in photosensibilizations with MB and TBO for 60 min than in those for 30 min. Green and yellow conidia were more tolerant to photosensibilization than mutants with white and violet conidia, indicating that conidia pigmentation influences photosensibilization. Nitrosyl ruthenium [Ru(NH.NHq)(tpy)NO](PF6)3 was not capable to photoinactivate conidia of any of the species, in any of the evaluated conditions. M. anisopliae conidia photoinactivation with MB and TBO did not occur when photosensibilization was conducted in PDB media.

This diploma thesis studied the interaction of ionic and amphiphilic fluorescent probes with polyelectrolytes. The research of such colloidal system could be helpful in deeper understanding of interactions between polyelectrolytes and surfactants. The aim of this thesis was to determine whether ionic or amphiphilic probes are suitable for this research. Two polyelectrolytes, sodium polystyrene sulfonate and hyaluronan were used in this study. Interactions of polyelectrolytes with fluorescent probes (4-Di-2-Asp, methylene blue, dodecyl acridine orange, DiO and DiA) were studied in this work. Then cationic surfactant cetyltrimethylamonium bromide was added to this system. Samples were studied using fluorescence and UV/VIS spectroscopy. Emission and absorption spectra of these probes were recorded. This experiment was based on hypothesis that due to positive charge these probes will bind to the negatively charged polyelectrolyte. Formation of dimers or other aggegates was presumed for fluorescent probes dodecyl acridine orange and methylene blue. When 4-Di-2-Asp was used,changes in fluorescence intensity and absorption spectra in connection with possible formation of aggregates was supposed to be observed. It should be noted that formation of dimers for 4-Di-2-Asp is not described in literature. The formation of dimers wasn't clearly demonstrated during the measurement. Formation of dimers was observed only with dodecyl acridine orange. Probes DiO and DiA were used only in the study of the interaction with polyelectrolytes. These fluorescent probes showed up as inappropriate, because they adsorbed on tube walls. When cationic surfactant was added to hyaluronan-fluorescent probe system, surfactant pushed away fluorescent probe and bonded electrostatically to negatively charged groups of polyelectrolyte.

This master thesis deals with the study of thermodynamic and structural aspects of the interactions of humic acids with organic ions. Methylene blue (dye) was used as a model organic ion. The interactions were studied by isothermal titration calorimetry, dissolution calorimetry and by diffusion in diffusion cells.

M. Tech. (Department of Chemistry, Faculty of Applied and Computer Sciences), Vaal University of Technology. / For centuries the contamination of surface water has been problematic, especially in third world countries whereby socio-economic issues are prevalent. With the development of various technologies for surface water rehabilitation, adsorption has been found to be the most viable due to its lower cost implications. As such the development of innovative adsorbents which are synergistic to the low cost method have been sought. Herein, the use of fossil coral limestone from Mauritius as adsorbents for the removal of Pb(II), Cr(VI) and methylene blue is presented. The pristine material (PCLS) was thermally treated by calcination to temperatures 800°C (CLS-800) and 900°C (CLS-900) and chemically treated by using an acid HCl (ACL) and base NaOH (BCL). The optimum conditions found for chemical and thermal treatment of the pristine material were used for the one pot synthesis of magnetite and maghemite calcium carbonate based nanocomposites. The pristine fossil coral limestones were characterized by scanning electron microscopy (SEM), energy dispersive X-ray (EDS), X-ray fluorescence XRF), X-ray diffractometer (XRD), Brunauer, Emmett and Teller (BET) and Fourier transformed infrared (FTIR) spectroscopy, UV visible spectrophotometer (UV/vis) and Photolumiscent spectroscopy (PL). Surface morphology of the material was found to contain an interconnected framework of pores, with a surface area of 20.45 m2/g and pore with of 4.04 nm. Thermal treatment of the material was found to increase the surface area of the materials to 64.10 and 63.28 m2/g for CLS-800 and CLS-900. The surface morphology of the calcined materials compared to the pristine were fibrous like and irregularly shaped for CLS-800 and CLS-900 respectively. The FTIR revealed the dominant surface groups to be (-C-O) and (-C=O) asymmetric stretch of the in and out of plane bend of carbonate (-CO32-), with the composition of the material being 91.76 % (-CaO) and 3.32% SrO. The thermally treated materials also exhibited vibrations of asymmetric stretch, which are characteristics of the carbonates as with the pristine material. However, EDS of the pristine compared to that of the calcined materials show a decline in the carbon and oxygen content, due to calcination. The XRD analysis confirmed the orthorhombic structure of aragonite, while CLS-800 was rhombohedral calcite with newly developed (-CaO) peaks. CLS-900 showed complete removal of CaCO3 polymorphs with more (-CaO) peaks. The surface morphology of the chemically modified samples show irregularly shaped surface. The XRD analysis confirmed that chemical treatment did convert the materials to a different polymorph. The FTIR of the chemically modified materials compared to the pristine, were found to reveal a removal of the vibrations of the asymmetric stretch associated with carbonates. However, vibrations associated with (-CaO) were observed. The SEM of the nanocomposites was observed to deviate from sphericity with variable size distribution. The materials were both red and blue shifted due to their variable sizes. Their UV/vis revealed absorption bands in the visible region. The adsorption analysis was done by varying parameters such as time, pH, concentration and temperature. The data was such that the highest capacity for the pristine material was found to be 37.24, 39.26 and 69.42 mg/g for MB, Pb(II) and Cr(VI) respectively. The removal of MB and Pb(II) pollutants were due to physical adsorption, as observed from the good fitting to pseudo first order model (PFOM). The removal of Cr(VI) was due chemisorption and the good fit on pseudo second order model (PSOM). The adsorption process was supported on a heterogeneous surface whereby multilayer adsorption could occur. Adsorption was spontaneous and feasible, exothermic for MB and Pb(II) and endothermic for Cr(VI) at all the studied temperatures as observed from thermodynamics. The adsorption of methylene blue was found to be more favourable on adsorption compared to photo-degradation Chemical modification was observed to increase adsorption and the maximum removal capacities for PCLS, ACL and BCL for Cr(VI) ions were 69.42, 65.04, 64.88 mg/g, Pb(II) ions 39.36, 74.11, 78.34 mg/g and methylene blue 37.24, 46.28, 46.39 mg/g, respectively. Uptake of Cr(VI) and methylene blue on ACL and BCL was feasible on a heterogeneous surface whereby multilayer adsorption took place. Monolayer adsorption on a homogenous surface of ACL and BCL was observed for Pb(II) uptake. The uptake of Pb(II) was exothermic on PCLS and ACL while methylene blue only on PCLS. The adsorption of Cr(VI) ions onto PCLS, ACL and BCL and methylene blue dye onto ACL and BCL were endothermic in nature. The adsorption process was spontaneous and feasible at all the studied temperatures. Thermal modification further increased the adsorption uptake of the pollutants. The recorded uptake for Cr(VI) and Pb(II) were 99.12 and 98.42 mg/g onto CLS-800 and CLS-900, respectively. The adsorption process was found to be physisorption, due to the good fit on PFOM. In addition, the adsorption occurred on a heterogeneous surface whereby multilayer adsorption was possible. The removal of Cr(VI) was found to be exothermic for both the materials and Pb(II) was found to be endothermic. The materials were tested for their reusability to up to four cycles, whereby the removal on the fourth cycle were 16.87, 63.60, 73.13 mg/g for Cr(VI), 9.87, 64.19 and 70.95 mg/g for Pb(II) on PCLS, CLS-800 and CLS-900. While the leaching test for PCLS, CLS-800 and CLS-900 for the release of Ca2+ into solution was found to be within the permissible limits of world health organisation (WHO). The as synthesized nanocomposites increase adsorption of the pollutants. Maximum capacities were found to be 345.34, 388.31, 377.92 and 375.35 mg/g for Pb(II) onto magnetite-PCLS, magnetite-CLS, maghemite-PCLS and maghemite-CLS, respectively and 308.01, 335.3, 335.29 and 335.27 mg/g for Cr(VI) onto magnetite-PCLS, magnetite-CLS, maghemite-PCLS and maghemite-CLS, respectively. From the data it was observed that the maghemite samples were much more favourable for the removal of the pollutants. The removal was due to chemical adsorption, as observed from the good fit onto PSOM and intraparticle diffusion (IPD), whereby surface adsorption was the rate limiting step. The adsorption process was heterogeneous and multilayer, while thermodynamic data reveal that adsorption was spontaneous and favourable at the studied temperature.

PhD (Department of Chemistry, Faculty of Applied and Computer Sciences), Vaal University of Technology. / Water is a basic resource to mankind. The environment is deteriorating daily due to industrial pollution of water resources. Industrial effluents containing organic pollutants such as dyes are undesirable even at low concentrations in the environment. Natural biomaterials have been applied as adsorbents for dye removal from water systems, however, their application has been limited by their low adsorption capacity. Much attention has been focused on the chemical modification of natural biomass via grafting processes. The modification of natural polymers by graft copolymerization is a promising technique since it functionalizes a biopolymer thus imparting desirable properties. The purpose of the study was to prepare and optimize the working conditions for the pine-magnetite bionanocomposites (PMC) as adsorbents and as photocatalysts modifiers. First, this work focuses on the synthesis and optimization of reaction variables in the preparation of PMC for the removal of methylene blue (MB). The thesis also explores the synthesis of acrylamide and acrylic acid-grafted PMC, resulting in the formation of acrylamide-grafted PMC (GACA) and acrylic acid-grafted pine-magnetite bionanocomposites (GAA), respectively. The grafting of functional groups such as –CO, –NH2 onto cellulose from acrylamides is also explored in detail. The adsorption conditions optimized were used to investigate the adsorption efficiency of GAA and GACA on MB. Finally, the application of PMC and GAA as modifiers for amorphous TiO2 and N-doped TiO2was carried out. The photocatalytic bionanocomposites from PMC (namely PMC–a-C,TiO2 and PMC–a-C,NTiO2) and those from GAA (labeled GAA–a-C,TiO2 and GAA–a-C,NTiO2) are compared by their photocatalytic efficiency on the degradative removal of an alkaline dye mixture formed from Reactive red 120 (RR 120) and Rhodamine B (Rh B). The synthesis procedure for PMC involved treating pinecone biomass with 0.15 M NaOH solution to remove unwanted plant extracts and the subsequent coating of the treated pinecone with iron oxide magnetic particles through a co-precipitation method. The variables used for the experiments were volume of NH4OH (5 to 40 cm3), reaction temperature (40 to 100 °C), effect of time (15 to 60 min) and mass (1.0 to 3.5 g). The PMC and acrylic acid grafted pine-magnetite composite (GAA) were probed for structural morphology and surface properties using various surface characterization instrumental techniques. Strong chemical interactions between pinecone magnetite and acrylic acid were demonstrated by thermogravimetric (TGA), differential thermal analysis (DTA) and X-ray photoelectron spectroscopy (XPS) for these unique bionanocomposites as such suggesting high chemical stability. Grafting acrylic acid was shown by XPS to form polyacrylic acid on the surface of the bionanocomposites and thus capping the surface groups. Significant differences in size were shown by transmission electron spectroscopy (TEM) and scanning electron microscopy (SEM); i.e., smaller particle sizes (Ave = 13.0 nm) for GAA and slightly larger for PMC (Ave = 14.0 nm). Brunauer Emmett Teller (BET) surface analysis demonstrated a larger surface area, pore volume and pore diameter (59.9 m2.g-1, 0.2254 cm3.g-1 and 28.14) for GAA compared to PMC. These characteristics coupled with the point of zero charge for GAA (pHpzc = 6.8) were critical in enhancing the efficiency of GAA adsorption of MB at pH 12 and further enable GAA to have a higher desorption efficiency of up to 99.7% after four cycles of washing with 0.10 M HCl. The adsorption kinetics and isotherm studies indicated that the adsorption process follows the pseudo second order kinetics and Langmuir isotherm respectively. The adsorbent also showed improvement in the adsorption capacity and reusability promising to be used for the removal of dyes in a prototype scale. GAA and MB adsorption mechanism was confirmed to be through intra particle diffusion. The overall performance of the GAA bionanocomposites is hinged on the formation of polyacrylic acid on the surface, its structural morphology, and the enhanced surface properties. Most importantly, the plant-based materials (lignin and cellulose) provide an environment that is rich with surface (–COOH and –OH) groups for the attachment of the magnetite nanoparticles while the polyacrylic acid stabilizes the magnetite onto the pinecone nanoparticles while reducing the point of zero charge for increased adsorption of cationic species. The photocatalytic bionanocomposites were fabricated from the adsorptive bionanocomposites using a simple solgel process in which ~10 wt.% of PMC and GAA, respectively, were used as a starting agent. Titanium butoxide was used as a precursor, acetylacetone as a dispersant and ethylene diamine as a nitrogen source. Using this procedure, amorphous carbon-doped titania (a-C,TiO2) and amorphous carbon and nitrogen co-doped titania (a-C,NTiO2) were fabricated except that the biopolymer was not added. Two sets of amorphous titania bionanocomposites were fabricated. One set was the nitrogen doped forms that had been modified with PMC and GAA (PMC–a-C,TiO2 and GAA–a-C,NTiO2). The other set of photocatalytic bionanocomposites produced in this work were without nitrogen (PMC–a-C,TiO2 and GAA–a-C,TiO2). TEM and SEM micrographs showed that all the photocatalysts consisted of globular, smooth aggregates of nanosized a-CTiO2 and a-C,NTiO2 which decreased in size with N-doping and the incorporation of GAA and PMC to as low as <30 nm. Surface chemical analysis through FTIR, XPS and EDS confirmed the presence of C, O, Ti and N (for the N-doped photocatalysts). In addition, it was demonstrated that N-doping into TiO2 had taken place, albeit with most of the N incorporated as organic nitrogen. It was further demonstrated that because of the absence of high temperature calcination, the process chemicals played a significant role in doping the photocatalysts with carbon resulting in the promotion of photocatalytic activity for a-C,TiO2 to the point of surpassing that of, a-C,NTiO2 and all the PMC-modified photocatalytic bionanocomposites. a-C,TiO2 had an overall 94% removal of the dyes, Rhodamine B (RhB) and Reactive red 120(RR 120), under UV illumination. The benefit of co-doping a-TiO2 with C, N and the biopolymers was realized with the incorporation of GAA as a modifier. The result was 97% removal of the dyes by GAA–a-CTiO2 and 99% for GAA–a-C,NTiO2. It was further observed that the degradation of the binary mixture of the dyes (RhB and RR 120) proceeded through the zero order kinetics for the a-C,TiO2 based photocatalysts and first order kinetics for the N-doped photocatalysts. The work, has, therefore demonstrated the applicability of plant-based biopolymers in the fabrication of nanoadsorbents and nanophotocatalysts. While the photocatalytic degradations were carried out under UV-light, there still remains a number of possible avenues that researchers can build on to improve the visible light-driven photocatalytic bionanocomposites. The research work has proven the effectiveness of novel pinecone magnetic nanoparticle materials and TiO2-based photocatalyst for the degradation of undesirable dyes from wastewater.

The innate immune system in vertebrates is considered to lack specific memory. To investigate innate immune system based immunological protection mediated by cells that are not part of the acquired immune system the Tübingen recombination activation gene1 (rag1)t26683 mutant (MT) zebrafish was chosen. Molecular analysis demonstrated MT zebrafish kidney cells expressed Non-specific Cytotoxic cell receptor protein-1 (NCCRP-1) and Natural Killer cell (NK) lysin but lacked T cell receptor (TCR) and immunoglobulin (Ig) VH1, VH2, VH3 and VH4 expression. Differential counts of peripheral blood leukocytes indicated that MT fish had decreased lymphocyte populations (34.7%) compared to rag1+/+ wild-type (WT) fish (70.5%), and increased granulocyte populations (34.7%) compared to WT (17.6%). Further, endocytic functions of phagocytes from MT fish were compared to WT fish. No significant differences in the selective and non-selective mechanisms of uptake in phagocytes were observed between MT and WT zebrafish. For the first time it was shown that zebrafish phagocytes utilize macropinocytosis and Ca2+ dependant endocytosis mechanisms for antigen uptake. These characterization studies suggest that MT zebrafish provide a unique model for investigating innate immune responses because fully functional innate defenses are present without the influence of lymphocytes and lymphocyte associated acquired immune responses. To conduct such large scale investigations the first ongoing rag1t26683 mutant zebrafish breeding colony was established. To meet special husbandry needs of immunodeficient MT zebrafish, standard rearing protocols were advanced and the information was made available to the zebrafish community at: http://www.cvm.msstate.edu/zebrafish/index.html. Multiple trials were conducted to evaluate the potential for memory of the innate immune system. Significant reduction in mortality was observed in MT vaccinated zebrafish upon secondary exposure to Edwardsiella ictaluri when compared to unvaccinated, MT fish. This documents for the first time, that MT zebrafish, lacking an acquired immune system, are able to mount a protective immune response to Edwardsiella ictaluri and generate protection upon a repeated encounter to the same pathogen. The observed protection is long lasting and mediated by the innate immune system, but a specific mechanism is not yet defined.

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