Made available in DSpace on 2014-10-09T12:52:41Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:03:13Z (GMT). No. of bitstreams: 0 / Os experimentos de adsorção descontínuos foram realizados para remover azul de metileno de solução aquosa usando zeólitas sintetizadas a partir de cinza leve de carvão como adsorvente. Os estudos foram conduzidos para avaliar os efeitos do tempo de contato, concentração inicial do corante, parâmetros de ativação hidrotérmica, composição da cinza leve, quantidade do adsorvente, pH e temperatura sobre a adsorção. Um tempo de contato de aproximadamente 10 minutos foi suficiente para a adsorção do corante alcançar o equilíbrio. Os dados de equilíbrio foram analisados usando as isotermas de Langmuir e Freundlich e os resultados se ajustaram melhor à equação da isoterma de Freundlich. A eficiência de adsorção estava entre 72 a 98% sob as condições estudadas. O valor da constante de Freundlich para a capacidade de adsorção (KF) do azul de metileno no adsorvente foi 0,738 (mg/g) (L/mg)1/n. Os dados de adsorção foram ajustados aos modelos cinéticos de pseudoprimeira- ordem de Lagergren e pseudo-segunda-ordem e seguiram as cinéticas de pseudosegunda- ordem. As constantes de velocidade foram estimadas em diferentes concentrações iniciais. O mecanismo do processo de adsorção encontrado mostrou-se complexo, consistindo de adsorção superficial e difusão intrapartícula. Os parâmetros termodinâmicos foram avaliados indicando que o processo de adsorção do azul de metileno sobre a zeólita é espontâneo e exotérmico. / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP

>Magister Scientiae - MSc / In South Africa, water pollution problems have continued to increase due to increasing anthropogenic activities. The increasing number of organic contaminants in various water sources can be attributed to industrial development, population growth and agricultural run- off. These activities have impacted negatively on the availability and accessibility to sustainable clean water resources, exposing citizens to water borne diseases such as cholera, diarrhoea and typhoid fever; commonly reported among children. Advanced oxidation technologies such as dielectric barrier electrohydraulic discharge (EHD), also referred to as dielectric barrier discharge (DBD), have the ability to decompose persistent organics and eliminate microbes. DBD offers advantages such as efficiency, energy saving, rapid processing, use of few or no chemicals, and non-destructive impact on the ecosystem. The system is also capable of generating ozone, hydrogen peroxide, singlet oxygen, superoxide radicals, hydroxyl radicals and other active species. The combination of these reactive species has been reported to degrade biological and chemical pollutants rapidly and efficiently. In this study, the DBD system was optimized by investigating the effect of physico-chemical, electrical parameters and reactor configurations on Methylene Blue (MB) decolouration efficiency. The physico-chemical parameters included MB concentration, solution pH and conductivity, solution volume, NaCl electrolyte concentration in the electrode compartment and air flow rate. As for electrical parameters, the effects of voltage, electrode type and size on MB decolouration efficiency were studied. The effect of the aforementioned parameters on MB decolouration efficiency was assessed by varying one parameter at a time. The following physico-chemical parameters: time (from 0 - 60 minutes), pH (2.5 - 10.5), solution conductivity (5 - 20 mS/cm), MB concentration (0.5 – 10 mg/L), solution volume (500 – 2000 mL), NaCl electrode electrolyte concentration (10 – 50 g/L) and air flow rate (2– 4 L/min) were varied in their respective ranges under the applied experimental conditions: reactor air gap 2 mm, solution volume 1500 mL, NaCl electrolyte concentration of 50 g/L in the electrode compartment, voltage 25 V (7.8 kV), airflow rate 3 L/min, 0.5 mm silver electrode and a running time of 60 minutes. As for electrical parameters, voltage (from 20 - 25 V), electrode type (copper, silver and stainless steel) and electrode diameter (0.5 – 1.5 mm) were also altered individually at the applied experimental conditions. The reactor air gap was varied from 2 to 6 mm. At the same experimental conditions, the free reactive species generated mainly H2O2 and O3, were detected and quantified using the Eisenberg and indigo methods, respectively. The optimum physico-chemical parameters were found to be MB concentration 5 mg/L, concentration of NaCl electrolyte used in the central compartment of the DBD reactor 50 g/L, solution pH 2.5, solution conductivity 10 mS/cm, air flow rate 3 L/min, solution volume 1500 mL and an optimum contact time of 30 minutes. The optimum electrical parameters were found to be: applied voltage 25 and 1.5 mm silver electrode. The following parameters MB concentration, solution conductivity and pH, applied voltage and reactor configuration significantly affected MB decolouration efficiency compared to parameters such as solution volume, the inlet air flow rate, electrode type and size and NaCl electrolyte concentration in the electrode compartment, which were less effective in enhancing MB decolouration. Moreover, for all DBD experiments performed at the applied experimental conditions, complete decolouration of MB was achieved in the first 30 minutes. However, trends between the optimized parameters and MB decolouration efficiency were mostly observed after 10 minutes. The optimized DBD system reduced the treatment time from 30 to 20 minutes without any chemical additives. Moreover, at 5 mg/L MB under the applied optimum conditions, it was proved that besides 99% of MB decolouration reached after 60 minutes, 53% of total organic carbon (TOC) removal was also achieved. The chemical oxygen demand (COD) characterizing MB toxicity was less than 5 mg/L before as well as after the DBD experiment. After 10 minutes of experiment under the following conditions: Applied voltage 25 V, MB concentration 5 mg/L, solution pH (in between 6.04 and 6.64), solution volume 1500 mL, air flow rate 3 L/min, 0.5 mm silver electrode and a contact time of 60 minutes, about 3.73 x 10-5 mol/L H2O2 was produced which decreased to 2.93 x 10-5 mol/L 10 minutes later, while O3 concentration was initially very low and could not be detected. However, 0.5 mol/L of O3 was detected after 20 minutes of operating time, thereafter, H2O2 concentration decreased continuously with time while that of O3 fluctuated as the treatment time increased. Likewise, the energy density for the production of free reactive species reached 0.87 g/ kWh in the first 10 minutes due to the presence of chromophoric functional groups such as =N+(CH3)2 in MB structure that had to be destroyed. Thereafter, the energy consumption decreased progressively to zero with an increase in treatment time due to the destruction of =N+(CH3)2 groups in MB structure with time. The correlation between the rise in the of H2O2 concentration and energy density after 10 minutes was probably due to dissociation of OH- OH bonds in H2O2 by UV light to yield OH radicals which unselectively may have attacked MB dye. Thus, MB decomposition in the current DBD reactor was mostly initiated by H2O2 and O3. The irradiation of H2O2 by UV light generated in the DBD system was found to accelerate dye decomposition in the first 30 minutes of the experiment. The UV-vis analysis of treated MB samples confirmed that the complete decolouration of MB achieved in the first 30 minutes was due to the destruction of the chromophoric [=N+(CH3)2] group in Methylene blue structure, while the FT-IR confirmed the presence of traces of various functional groups such as C=C, C=O, C=N, NH, NH3, NO2, etc. characteristics of carboxylic acids, amines, amides, nitrogen based compounds (salts), aliphatic and unsaturated by-products remaining in the bulk solution after treatment. The salts analysis after treatment showed that 16 mg/L of nitrates and nitrites and 1.1mg/L of sulphates mainly originating from air and MB decomposition were present in the treated samples. The EHD/DBD system used in this study offers an approach to partially treat water/wastewaters and its optimization was able to significantly enhance the decomposition of the target MB dye as indicated by the reduction of total organic carbon (TOC) from 8.3 mg/L to 3.9 mg/L. Compared to previous research, this study successfully optimised a complete double cylindrical dielectric barrier discharge (DBD) reactor at ambient condition without any chemical additives.

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Aqueous industrial effluents containing organic pollutants, such as textile dyes and crude oil, represent environmental and human health concerns due to their toxicity and possible carcinogenic effects. Adsorption is the most promising wastewater treatment method due to its efficiency, ease of operation, and low cost. However, currently used adsorbents have either high regeneration costs or low adsorption capacities. In this work, new organic/inorganic hybrids based on hollow silica microspheres were successfully synthesized, and their ability to remove Methylene Blue from wastewater and crude oil from simulated produced water was evaluated. By employing four different silanes, namely triethoxy (octyl) silane, triethoxy (dodecyl) silane, trichloro (octadecyl) silane, and triethoxy (pentafluorophenyl) silane, hydro and fluorocarbons were grafted onto the surface of commercially available silica microspheres. These silica derivatives were tested as adsorbents by exposing them to Methylene Blue aqueous solutions and synthetic produced water. Absorbance and oil concentration were measured via a UV/Vis Spectrophotometer and an HD-1000 Oil-in-Water Analyzer respectively. Methylene Blue uptake experiments showed that increasing the adsorbent dosage and decreasing initial dye concentration might increase adsorption percentage. On the other hand, adsorption capacities were improved with lower adsorbent dosages and higher initial dye concentrations. Varying the initial solution pH, from pH 5 to pH 9, and increasing ionic strength did not seem to have a significant impact on the extent of adsorption of Methylene Blue. Overall, the silica derivative containing aromatic functional groups, Caro, was proven to be the most effective adsorbent due to the presence of π-π and cation-π interactions in addition to the van der Waals and hydrophobic interactions occurring with all four adsorbents. Although the Langmuir Model did not accurately represent the equilibrium data, it produced consistent maximum adsorption values and adsorption equilibrium constants. Preliminary experiments demonstrated the potential to recover and reuse the silica microspheres by washing with NaOH and organic solvents. The preferential adsorption of oil micro-droplets onto the surface of functionalized hollow silica microspheres was evidenced. However, preparing synthetic produced water that was stable enough to carry out kinetics experiments remained a challenge.

The nucleotide excision repair pathway (NER) has been shown to efficiently remove bulky base lesions from the DNA, including those induced by solar light. It has been suggested that the NER pathway may be involved also in removing smaller oxidative base lesions from the DNA. Oxidative damage in the cell is caused by cellular aerobic respiration, with base damage to the nucleotides of the DNA being the most biologically relevant. One of the most common oxidative base lesions in the genome is the 7 ,8-dihydro-8-oxoguanine (8-oxoG). This lesion is pre-mutagenic since it can base pair with equal efficiency to the correct cytosine base, or the incorrect adenine base during DNA replication. Oxidative damage, including 8-oxoG, is repaired primarily by the base excision repair (BER) pathway, which is a multi-step, multi-protein pathway similar to NER. One key protein involved in both BER and NER is the p53 protein, which can act as a transcription factor and protein regulator to influence DNA repair. We have used a recombinant non-replicating human adenovirus, Ad5HCMVlacZ, which expresses the ~-galactosidase (~-gal) reporter gene, to examine the role of several NER proteins and the p53 protein in the BER of oxidative damage in human cells. Methylene blue (MB) acts as a photosenstizer, and after irradiation by visible light (VL) produces reactive oxygen species that cause 8-0xoG in the DNA. By infecting several normal, NER deficient and p53 deficient -tumor, primary and transformed fibroblast cell lines with a MB+VL-treated Ad5HCMVlacZ reporter construct, we were able to determine the host cell reactivation (HCR) of the oxidatively damaged reporter. Results indicate that the HCR of the MB+VL-treated reporter and the expression of p53 are enhanced by UVC pretreatment in normal human fibroblasts, suggesting that p53 may be involved in inducible BER. In addition, increased expression of p53 facilitated by pre-infection of normal cells with p53 expressing Ad5p53wt similarly enhanced HCR in the normal fibroblasts, giving further evidence that increased expression of p53 alone enhances BER. In contrast, although UVC pretreatment of p53 compromised cells resulted in enhanced HCR, the enhanced HCR did not correlate with enhanced p53 expression, suggesting that enhancement in BER can result from both p53 dependent and p53 independent mechanisms. We report also that HCR of the MB+VL-treated reporter gene was substantially reduced in SV40-transformed XP-C cells, with little or no reduction in SV40-transformed XPA, XPD, XPF, XPG and CSB cells, suggesting a role for the XPC protein in the BER ofMB+VL-induced DNA damage. In particular, the XPC protein appears to be involved in both the constitutive and inducible aspects of BER, as the HCR of the MB + VL-treated reporter was reduced in 3 UVC pretreated as well as untreated XP-C primary human fibroblast strains. In addition, pre-infection of cells with Ad5p53wt, resulted in an enhanced HCR of normal but not XP-C deficient fibroblasts consistent with a p53 dependent involvement of the XPC protein in BER of MB+VL-treated DNA. Additional studies were also conducted to determine the cell sensitivity of normal and NER deficient SV40-transformed cell lines to MB and MB+VL. The results show that MB alone and MC+VL are toxic to cells, and that cells deficient in NER are not more sensitive to MC or MB+VL compared to NER proficient normal cells. In fact, the NER deficient cell lines were more resistant to MB alone compared to NER proficient normal cells. In particular, although the SV40- transformed XP-C cell line showed a significant reduction in HCR of the MB-Vl-treated reporter gene, suggesting a deficiency in the repair of MB+VL-induced DNA damage, the SV40-transformed XP-C cells were not more sensitive to MB or MB+VL. This suggests that the toxicity of human cells to MB and MB+VL results primarily from damage to cellular components other than DNA such as membrane structures including the mitochondria and lysozomes as has been reported for other photosensitizers. / Thesis / Master of Science (MSc)

Yes / Coprecipitation method was used to prepare non-stoichiometric pristine copper and iron layered double hydroxide (LDH) doped with zirconium and embedded with reduced graphene oxide. The composite materials (ZrRGOCuFe LDHs) were studied for the photodegradation of methylene blue (MB) dye as a model contaminant from an aqueous solution. These composites were fully characterized by X-rays diffraction (XRD), Scanning electron microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR), Photoluminescence (PL), Raman spectroscopy and Electrochemical Impedance Spectroscopy (EIS). The results of Raman, Photoluminescence and Electrochemical Impedance Spectroscopy revealed the presence of oxygen defects level in the composites. Such defects are believed to be essential for boosting the catalytic potential of the composites. The secondary pollution manifested by transition metal ions is usually tackled by inducing heterogeneous catalysis. Herein, pristine CuFe LDH has been doped with Zr and RGO moieties to realize heterogeneous catalysis within ZrRGOCuFe LDH dopants. An admirable band ranging between 1.74 and 2.0 eV was obtained for the doped materials. The remarkable photodegradation efficiency of 95.2% was achieved by using heterogeneous photocatlyst Zr0.6RGOCuFe LDH within 75 min at a pH of 7, photocatalyst dosage of 1.0 g/L and methylene blue dye solution of 10 ppm under visible light irradiation. The total organic content (TOC) analysis has revealed removal of 92% organic content. Moreover, the catalyst has the potentia to maitain sufficient stability and reusability capacity even after three successive cycles. The reaction kinetics and proposed photocatalytic mechanism were also explained in detail.

Diagnosis techniques and treatments for Escherichia coli mastitis in the dairy bovine were evaluated in two experiments. The first experiment evaluated eosin methylene blue agar as a method of distinguishing E.coli from other gram-negative mastitis pathogens. Escherichia coli will usually produce a green metallic sheen on eosin methylene blue agar. One hundred and twenty-nine milk samples or gram-negative isolates from milk samples were used to compare eosin methylene blue agar to a commercial biochemical test strip (the accepted standard). There was an intermethod agreement of 96.9% and a k-value of 93.7% indicating excellent agreement beyond chance between test methods. Eosin methylene blue agar is a reliable method for differentiation of E. coli from other gram-negative mastitis pathogens. The second experiment evaluated the efficacy of frequent milk-out as a treatment for E. coli mastitis. Sixteen Holstein dairy cows were divided into 2 blocks and randomly assigned to 1 of 4 treatment groups: 1) non-infected, not frequently milked-out, i.e. not treated (NI-NT), 2) experimentally infected with E. coli, not treated (EC-NT), 3) non-infected, frequently milked-out (NI-FMO), and 4) experimentally infected with E. coli, frequently milked-out (EC-FMO). Hours to bacterial, clinical and systemic cure were not different between the EC-NT and EC-FMO treatment groups. Serum a-lactalbumin concentrations were evaluated between treatment groups as a measure of udder health. Serum a-lactalbumin concentrations were higher in cows in the EC-NT treatment group than cows in the NI-NT, NI-FMO and EC-FMO treatment groups at 12 hours post-experimental challenge. Serum a-lactalbumin concentrations were higher in cows in the NI-FMO treatment group than in cows in the NI-NT, EC-NT and EC-FMO treatment groups at 36 hours post-experimental challenge. Results from this study do not support frequent milk-out as a treatment for E. coli mastitis. / Master of Science

In this study, the composite of aluminum metal-organic framework MIL-68(Al) and reduced graphene oxide (MA/RG) was synthesized via a one-step solvothermal method, and their performances for pnitrophenol (PNP) adsorption from aqueous solution were systematically investigated. The introduction of reduced graphene oxide (RG) into MIL-68(Al) (MA) significantly changes the morphologies of the MA and increases the surface area. The MA/RG-15% prepared at RG-to-MA mass ratio of 15% shows a PNP uptake rate 64% and 123% higher than MIL-68(Al) and reduced graphene oxide (RG), respectively. The hydrogen bond and pi-pi dispersion were considered to be the major driving force for the spontaneous and endothermic adsorption process for PNP removal. The adsorption kinetics, which was controlled by film-diffusion and intra-particle diffusion, was greatly influenced by solution pH, ionic strength, temperature and initial PNP concentration. The adsorption kinetics and isotherms can be well delineated using pseudo-second-order and Langmuir equations, respectively. The presence of phenol or isomeric nitrophenols in the solution had minimal influence on PNP adsorption by reusable MA/RG composite.

Microbial fuel cells (MFC) are an emerging renewable technology which converts complex organic matter to electrical power using microorganisms as the biocatalyst. A variety of biological relevant organic matters such as glucose, acetate and ethanol have been utilized for the successful operation of a MFC. In this regard, the investigation of a MFC inoculated with ethanol oxidizing bacteria is of particular interest for this research due to its ability to simultaneously produce electricity while reducing ethanol pollution (a type of volatile organic carbon (VOC) pollutant) with potential use in modified biological air pollution control technology such as biofiltration. In this research, ethanol-oxidizing microbial species isolated from soil and compost samples were identified, with Acinetobacter calcoaceticus being the dominant strain. In order to understand the metabolism of the anode microbial cells, which is considered to be the key dictating the performance of a MFC, a systematic analysis/optimization of the growth rate and biomass production for A. calcoaceticus were carried out. A maximum specific growth rate with a final biomass concentration of 1.68 g/l was derived when aerated at a rate of 0.68 vvm. It has been recognized that one of the principle constraints in increasing the current density of MFCs is the electron transfer from the bacteria to the anode. In this sense, the addition of a redox mediator, which facilitates the process of the electron transfer, is desired for the efficient operation of a MFC. Thionine, methylene blue (MB), resorufin and potassium ferricyanide that have been profusely utilized as effective mediator compounds in many MFC studies, however, specific information on the biomass sorption of these compounds was lacking and therefore were selected for this research. All mediators tested were reduced biologically in A. calcoaceticus inoculated samples as indicated by the color transition from the pigmented oxidized form to the colorless reduced form. Subsequent tests on mediator color removal revealed that physical adsorption by the biomass, aggregation as well as precipitation accounted for a significant portion of the color loss for thionine and MB. It was speculated that the fraction of the initial mediator concentration sequestered, aggregated and/or precipitated no longer contributed to the electron transfer process, resulting in a current production which was proportional to the measurable mediator concentration remained in anode solution. To verify this hypothesis, chronoamperometric measurements were conducted for various mediator systems at known initial and measurable concentrations. The data obtained on the current produced were in good agreement with the theoretical predictions calculated from the actual mediator concentration, suggesting that the current produced depended on the concentration of mediator remaining in solution. Finally, the microbial reduction kinetics and the cytotoxicity of potassium ferricyanide were analyzed. The reduction of potassium ferricyanide followed zero order kinetics with the specific reduction rate increased as the initial mediator concentration increased from 1 mM to 200 mM. Inhibitory effects on cell growth were observed at initial potassium ferricyanide concentration of 50 mM.