Titanium dioxide (TiO2) is an established photocatalyst utilized for the photo-oxidation of organics in wastewater. Aqueous suspensions of TiO2 require separation and re-suspension steps to be used on an industrial scale. A method of immobilizing TiO2 within the mesoporous structure of silica has been developed at the University of Alabama. The objective of this thesis was to design and evaluate a bench-scale, continuous, photocatalytic reactor utilizing these films. This was accomplished in two phases of work: (1) batch reactions and (2) continuous reactions. The batch reactor was a one-liter standard photochemical reactor from Ace Glass. The continuous photocatalytic reactor designed for this study consisted of nine 12-inch long, 6-mm ID quartz tubes aligned around the medium-pressure, ultra-violet lamp (UV) used in the batch reactor. The tubes were coated on the inside with a thin film of mesoporous silica impregnated with TiO2 and connected in series with 6-inch pieces of Masterflex tubing. Experimental conditions were as follows: 190 ppm solutions of 2,4-dichlorophenol (2,4-DCP), UV lamp, TiO2 in either 0.05 wt% suspensions (slurry) or thin films of mesoporous silica (film); and/or 750 ppm hydrogen peroxide (H2O2). In batch and continuous experiments the UV/H2O2 and the UV/TiO2 (slurry)/H2O2 systems were the most successful with respect to the oxidation of 2,4 ? DCP. The loss of 2,4 ? DCP in continuous UV/TiO2 (film) systems was not significantly different from continuous UV only systems. However, the continuous UV/TiO2 (film)/H2O2 system degraded more 2,4 ? DCP than the systems utilizing UV light alone. The continuous reactor developed in this study showed enhanced by-product degradation using UV/TiO2 (film)/H2O2 over the UV/H2O2 system.

Philosophiae Doctor - PhD / This thesis firstly reports on the development and characterization of reagent-less and cobalt(III) sepulchrate[Co(Sep)³⁺] mediated biosensor platforms (biosensor platform 1 and biosensor platform 2), with human recombinant heme thiolate, cytochrome P450 3A4 isoenzyme (CYP3A4), as biorecognition component. Secondly, each biosensor platform was evaluated by using an entirely different category of compound as model substrate, with the overall objective being the development of alternative analytical method for the detection and quantification of each of these substrates,by amperometric transduction method. In this regard biosensor platform 1 was evaluated for the detection of 2,4-dichlorophenol, whereas biosensor platform 2 was evaluated for the detection of protease inhibitor (PI) HAART drug, indinavir. Fourthly, this dissertation also reports on the use of genetic engineering as complimentary method during biosensor investigations, as source for continuous supply of catalytically active biological recognition component. With respect to the preparation of the biosensors in particular, biosensor platform 1 was constructed by entrapping the commercially sourced full-length, wild type CYP3A4 on a pre-formed electroactive carrier matrix, consisting of Co(Sep)³⁺–modified nafion membrane on a glassy carbon electrode. In this regard, the nafion-Co(Sep)³⁺ composite was prepared by integrating the Co(Sep)³⁺ species into a pre-formed nafion film through manual drop-coating and mixing methods.

The objectives of this research were to obtain the optimum operating conditions for a catalytic wet air process and to investigate their reaction kinetics. Either the ferrouscyanide (Fe(CN)64¡Ð) or the 2,4-dichlorophenol (2,4-DCP) solution was treated by the catalytic wet air oxidation (CWAO) process using three metal ions (Cu2+, Ce3+, and Mn2+) as catalysts or with the Mn/Ce composite oxide catalysts, respectively. In addition, the biodegradability of the effluent derived from the CWAO (2,4-DCP) process was studied. Results show that the effect of addition of the Cu2+ ion on the wet air oxidation (WAO) of Fe(CN)64¡Ð solution is significant because the Cu2+ ion plays in a role of catalyst, which may lower the activation energy (Ea) during the first-stage of the CWAO process. However, either the Ce3+ or Mn2+ ion did an adverse effect on the Fe(CN)64¡Ð removal, even they had a worse removal than that did by the WAO run without any catalyst addition. The Ea value of the first-stage in the WAO of the Fe(CN)64¡Ð solution process was calculated to be 40.5 KJ mol¡Ð1. On the other hand, the Ea values of the CWAO process with an addition of the Cu2+, Ce3+, or Mn2+ ion, were reduced to 14.1, 16.0, and 20.4 KJ mol¡Ð1, respectively. Obviously, the values of Ea can be reduced to promote the pollutants removal by an addition of suitable catalysts into the WAO process. It was observed that 2,4-DCP is difficult to be decomposed in the thermal pyrolysis process, but the conversion of 2,4-DCP is significant in the WAO process. With an application of the Mn/Ce composite oxide catalyst in the CWAO process to treat the 2,4-DCP solutions resulted in a better removal than that did by the WAO process. The higher the reaction temperature was applied, the higher 2,4-DCP removal was obtained. Also, the catalyst in a higher Mn/Ce molar ratio would increase the removal of 2,4-DCP during the CWAO runs, while the catalyst in a Mn/Ce molar of 7:3 showed the best 2,4-DCP removal of 96.5%. It is suggested that the reaction temperature of the CWAO process could be controlled 40 K lower than that required in the WAO run to reach an equivalent 2,4-DCP removal efficiency. The Ea value of the WAO of 2,4-DCP process performed in a semi-batch type reactor were 13.6 and 23.7 KJ mol¡Ð1, respectively, for the first-stage and the second-stage reactions. However, the Ea values of the both reaction stages in the CWAO of 2,4-DCP run were reduced to 9.1 and 5.7 KJ mol¡Ð1, respectively. If the CWAO of 2,4-DCP was performed in an up-flowing fixed -bed reactor, a second-order formula was found. Also, the activation energy and the frequency constant of the CWAO of 2,4-DCP run were calculated to be 11.9 KJ mol¡Ð1 and 0.96 sec¡Ð1. In the Microtox® toxicity tests, the TUa,15 values of the effluent from the CWAO run were below 8.26, when the CWAO process was operated at 433 K and at a space velocity of less than 11.0 hr¡Ð1, and the Mn/Ce (7:3) composite oxide as a catalyst. On the other hand, the toxicity of the 2,4-DCP could be reduced greatly by being treated in the CWAO process over the Mn/Ce (7:3) composite oxide catalyst. It is possible to treat the 2,4-DCP solution in a concentration less than 500 mg L¡Ð1 to meet the discharging regulation standards using a CWAO run, and followed by an activated sludge unit in which the retention time of the wastewater could be sorter than twelve hours.

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Doctor of Philosophy / Department of Civil Engineering / Alok Bhandari / Human activities generate large amounts of chlorinated phenolic chemicals that are often introduced into the soil environment during pesticide and insecticide application, industrial releases, and accidental spills. For example, 2,4-dichlorophenol (DCP), a derivative of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) can been found in soil within 24 hours of 2,4- D application. Horseradish peroxidase (HRP)-mediated polymerization has been proposed as an approach to remediate soils and groundwater contaminated by phenolic pollutants. Treatment with HRP results in the transformation of phenols into polyphenolic oligomers that sorb strongly or precipitate on soils surfaces. Although HRP-mediated chlorophenol stabilization has been studied extensively in surface soils, very limited scientific data is available that supports the application of this technology in subsurface materials. Hence, the focus of this study was to evaluate sorption and binding of DCP and products of HRP-mediated polymerization of DCP to model geosorbents representing subsurface geomaterials. These sorbents included two humin-mineral geomaterials and one mineral geosorbent derived from surface soils. Soil-water phase distribution of total solute in the HRP-amended systems was observed to reach equilibrium within 7 days in woodland humin-mineral soil (WHM), and within 1 day in agricultural humin-mineral (AHM) and model mineral geomaterials. For all the geomaterials used, water extraction data indicated the development of contact time-dependent resistance to extraction/dissolution of soil-associated DCP and DPP. Solute associated with WHM geomaterial was higher at the end of the study than that associated with AHM. Contact time increased DCP stabilization at all initial aqueous DCP concentrations studied. Results of this study suggest that DCP stabilization in organic geosorbents results from a combination of sorption and cross-coupling of DCP and precipitation of DPP; in inorganic soils, precipitation of DPP macromolecules is the dominant process. HRP-mediated stabilization of DCP in soils was effective and independent of the solution ionic concentration. The amount of DCP stabilized in the mineral soil was comparable to that stabilized in humin-mineral geomaterials. The research reported in this dissertation demosntrates the potential of HRP enzyme to stabilize DCP in subsurface geomaterials under variable contaminant and salt concentrations, thereby restricting its transport in the environment.

A new instrument using a time-of-flight (TOF) mass filter (MF) for resonance enhanced multiphoton ionization (REMPI) studies of gas phase molecules was developed. This instrument was designed to make use of the selectivity of the REMPI process and the sensitivity of a TOF-MF with a microchannel plate detector. A pulsed valve inlet system was tested to determine its effectiveness in “cooling” molecules but it was not used for the bulk of the studies performed. The instrument was tested using molecular and atomic bromine, atomic carbon, and atomic iodine. The atomic bromine, carbon, and iodine, were generated by the photodissociation of molecular bromine, hydrocarbons, and methyl iodide respectively. Nitrogen gas in air was used to test the pulsed valve system. The instrument was then used to conduct REMPI studies of five dichlorotoluene (DCT) isomers (2,4-DCT; 2,5-DCT; 3,4-DCT; 2,6-DCT; and 2,3-DCT). REMPI studies of six dichloroaniline (DCA) isomers, including 2,5-DCA; 3,4-DCA; 3,5-DCA; 2,6-DCA; 2,4-DCA; and 2,3-DCA were conducted. Six isomers of dichlorophenol (DCP) were studied (2,5-DCP; 3,4-DCP; 3,5-DCP; 2,3-DCP; 2,4-DCP; and 2,6-DCP). It was determined that the 2,3-DCP; 2,4-DCP; and 2,6-DCP isomers photodissociated to form CCl, which itself could be observed through a REMPI process. The results from the REMPI studies of the dichloroaromatics and data from previous ultraviolet, infrared, and RAMAN studies of these molecules was used in order to assign the observed peaks. The observed 0,0 π→π* transition energies of the dichloroaromatics studied were used along with ultraviolet 0,0 π→π* transition energies from previous works in order to discuss substituent effects. A qualitative method of predicting the relative location of 0,0 π→π* transition energies of dichloroaromatics was developed.

O 2,4-diclorofenol (2,4-DCF), poluente modelo usado neste trabalho, é um composto empregado na produção de pesticidas, herbicidas e anti-sépticos, e comumente encontrado em efluentes industriais, sendo considerado um poluente prioritário devido a sua elevada toxicidade e alto poder de persistência no ambiente. Este trabalho objetivou estudar a degradação do 2,4-DCF em reator fotoquímico tubular com coletores parabólicos compostos (CPC) irradiado pelo Sol, operado em batelada com recirculação e admissão contínua de peróxido de hidrogênio à vazão de 11 mL min-1. A oxidação do poluente foi baseada no processo foto-Fenton catalisado por tris(oxalato) ferrato(III) (FeOx), investigando-se os efeitos das seguintes variáveis: concentração inicial de 2,4-DCF ([2,4-DCF] = 21-520 mgCL-1), concentrações de oxidante ([H2O2] = 9,9-130 Mm) e de fotocatalisador ([FeOx] = 0,2-1,8 mM) e área de coleta de fótons (0,196-0,98 m2), estudadas a partir de um planejamento Doehlert em múltiplos níveis. A foto-oxidação foi monitorada por medidas da concentração de carbono orgânico total (TOC) e oxigênio dissolvido (OD), tendo sido identificadas condições com remoção de TOC alcançando 99,8% em 90 minutos de tratamento. Nas análises estatísticas dos resultados, os efeitos da área de coleta de fótons e da concentração de H2O2 concordaram com o comportamento esperado, sugerindo, porém, efeitos sequestradores de radicais hidroxila quando a concentração de H2O2 é alta. A partir dos dados experimentais, obteve-se um modelo de redes neurais, usado para previsão da taxa de remoção de TOC em função do tempo. Através do método HIPR (Holdback Input Randomization Method) e dos pesos associados a cada variável de entrada da rede neural, avaliou-se a importância relativa das variáveis de entrada. De maneira geral, os resultados comprovaram a viabilidade do processo foto-Fenton catalisado por tris(oxalato) ferrato III e irradiado pelo Sol para o tratamento de efluentes aquosos contendo 2,4-diclorofenol. / 2,4-dichlorophenol (2,4-DCF), the model pollutant selected in this work, is a compound used in the production of pesticides, herbicides, antiseptics, and commonly found in industrial wastewaters. It is considered a priority pollutant due to its high toxicity and high persistence in the environment. This study investigated the degradation of 2,4-DCF in a tubular photochemical reactor with compound parabolic collectors (CPC) irradiated by the sun, operated in batch with recirculation and continuous feed of hydrogen peroxide at a flow rate of 11 mL min-1. The oxidation of the pollutant was based on the photo-Fenton process catalyzed by tris (oxalate) ferrate (III) (FeOx). The effects of the following variables were investigated: initial concentration of 2,4-DCF ([2,4-DCF] = 21-520 mgCL-1), concentrations of oxidant ([H2O2] = 9,9-130 Mm)); photocatalyst ([FeOx]= 0,2-1,8 mM)), and photon collection surface (0,196-0,98 m2), according to a Doehlert design on multiple levels. The photo-oxidation was monitored by measurements of the concentration of total organic carbon (TOC) and dissolved oxygen (OD). Conditions with TOC removal achieving 99.8% within 90 minutes of treatment were identified. The statistical analysis of the results showed that the effects of photon collection area and the concentration of H2O2 agreed with the expected behavior, but suggests scavenging effects of hydroxyl radicals when the concentration of H2O2 is high. From the experimental data, a model of neural networks was obtained and used to predict the rate of TOC removal with time. Using the method HIPR (Holdback Input Randomization Method) and the weights associated with each input variable to the neural network, the relative importance of input variables was determined. Overall, the results proved the feasibility of photo-Fenton process catalyzed by tris(oxalate) ferrate III and irradiated by the sun, for the treatment of aqueous effluents containing 2,4-dichlorophenol.

O 2,4-diclorofenol (2,4-DCF), poluente modelo usado neste trabalho, é um composto empregado na produção de pesticidas, herbicidas e anti-sépticos, e comumente encontrado em efluentes industriais, sendo considerado um poluente prioritário devido a sua elevada toxicidade e alto poder de persistência no ambiente. Este trabalho objetivou estudar a degradação do 2,4-DCF em reator fotoquímico tubular com coletores parabólicos compostos (CPC) irradiado pelo Sol, operado em batelada com recirculação e admissão contínua de peróxido de hidrogênio à vazão de 11 mL min-1. A oxidação do poluente foi baseada no processo foto-Fenton catalisado por tris(oxalato) ferrato(III) (FeOx), investigando-se os efeitos das seguintes variáveis: concentração inicial de 2,4-DCF ([2,4-DCF] = 21-520 mgCL-1), concentrações de oxidante ([H2O2] = 9,9-130 Mm) e de fotocatalisador ([FeOx] = 0,2-1,8 mM) e área de coleta de fótons (0,196-0,98 m2), estudadas a partir de um planejamento Doehlert em múltiplos níveis. A foto-oxidação foi monitorada por medidas da concentração de carbono orgânico total (TOC) e oxigênio dissolvido (OD), tendo sido identificadas condições com remoção de TOC alcançando 99,8% em 90 minutos de tratamento. Nas análises estatísticas dos resultados, os efeitos da área de coleta de fótons e da concentração de H2O2 concordaram com o comportamento esperado, sugerindo, porém, efeitos sequestradores de radicais hidroxila quando a concentração de H2O2 é alta. A partir dos dados experimentais, obteve-se um modelo de redes neurais, usado para previsão da taxa de remoção de TOC em função do tempo. Através do método HIPR (Holdback Input Randomization Method) e dos pesos associados a cada variável de entrada da rede neural, avaliou-se a importância relativa das variáveis de entrada. De maneira geral, os resultados comprovaram a viabilidade do processo foto-Fenton catalisado por tris(oxalato) ferrato III e irradiado pelo Sol para o tratamento de efluentes aquosos contendo 2,4-diclorofenol. / 2,4-dichlorophenol (2,4-DCF), the model pollutant selected in this work, is a compound used in the production of pesticides, herbicides, antiseptics, and commonly found in industrial wastewaters. It is considered a priority pollutant due to its high toxicity and high persistence in the environment. This study investigated the degradation of 2,4-DCF in a tubular photochemical reactor with compound parabolic collectors (CPC) irradiated by the sun, operated in batch with recirculation and continuous feed of hydrogen peroxide at a flow rate of 11 mL min-1. The oxidation of the pollutant was based on the photo-Fenton process catalyzed by tris (oxalate) ferrate (III) (FeOx). The effects of the following variables were investigated: initial concentration of 2,4-DCF ([2,4-DCF] = 21-520 mgCL-1), concentrations of oxidant ([H2O2] = 9,9-130 Mm)); photocatalyst ([FeOx]= 0,2-1,8 mM)), and photon collection surface (0,196-0,98 m2), according to a Doehlert design on multiple levels. The photo-oxidation was monitored by measurements of the concentration of total organic carbon (TOC) and dissolved oxygen (OD). Conditions with TOC removal achieving 99.8% within 90 minutes of treatment were identified. The statistical analysis of the results showed that the effects of photon collection area and the concentration of H2O2 agreed with the expected behavior, but suggests scavenging effects of hydroxyl radicals when the concentration of H2O2 is high. From the experimental data, a model of neural networks was obtained and used to predict the rate of TOC removal with time. Using the method HIPR (Holdback Input Randomization Method) and the weights associated with each input variable to the neural network, the relative importance of input variables was determined. Overall, the results proved the feasibility of photo-Fenton process catalyzed by tris(oxalate) ferrate III and irradiated by the sun, for the treatment of aqueous effluents containing 2,4-dichlorophenol.

The 2,4-Dichlorophenol (2,4-DCP) solution (400 mg L¡Ð1) was treated by a wet air oxidation (WAO) process at temperatures of 393¡Ð453 K under a total pressure of 3.0 MPa using either Mn /£^-Al2O3 or Mn-Ce /£^-Al2O3 composite oxide as a catalyst. A COD reduction was found only 19.2% within 60 min if the WAO process was performed in a semi-batch type reactor without any catalyst addition; however, a higher COD removal of 69.4% or 71.4% was achieved when the Mn /£^-Al2O3 or Mn-Ce /£^-Al2O3 oxide was applied in the WAO process, respectively. A catalytic wet air oxidation (CWAO) of 2,4-DCP solution using the Mn-Ce /£^-Al2O3 oxide as a catalyst was conducted in another up-flowing fixed-bed reactor at 433 K under a pressure of 3.0 MPa in a space velocity of 4.0 hr¡Ð1. The COD reduction of the solution of 2,4-DCP was found above 61.4%. Also, both BOD5 and COD values in the effluent from the CWAO process was examined, and the BOD5/COD ratio was about 0.64. On the other hand, it is possible to treat the 2,4-DCP solution (¡Õ400 mg L¡Ð1) to meet the discharging regulation standard (COD¡Õ100 mg L¡Ð1) began in 1998 at Taiwan using a CWAO run and followed by an activated sludge treatment unit. The Ea values of the CWAO of 2,4-DCP using the Mn /£^-Al2O3 oxide as a catalyst were 20.77 KJ mol¡Ð1 and 23.99 KJ mol¡Ð1, respectively, for the first-stage and the second-stage reaction, respectively. In addition, the Ea values of the CWAO of 2,4-DCP over the Mn-Ce /£^-Al2O3 oxide were 14.77 KJ mol¡Ð1 and 23.30 KJ mol¡Ð1, respectively, for the first-stage and the second-stage reaction. Obviously, the Mn-Ce /£^-Al2O3 oxide does a better job in reducing the activation energy of the CWAO of 2,4-DCP than the Mn /£^-Al2O3 oxide does. Unfortunately, 2,4-DCP is hardly decomposed to become a low molecule weight carbon acids by the WAO run undergoing at 493 K without any catalyst addition. Several intermediates, such as 2-chlorophenol, phenol, catechol, oxalic acid, and formic acid, of the effluent from the CWAO of 2,4-DCP run over the Mn-Ce /£^-Al2O3 oxide were determined with a high-performance liquid chromatography.

Made available in DSpace on 2014-07-29T15:13:41Z (GMT). No. of bitstreams: 1 dissertacaoCarlaLouly.pdf: 1077366 bytes, checksum: b65a73f51a856c3912b92c4b294caf0e (MD5) Previous issue date: 2008-08-15 / This study aimed to identify 2,6-dichlorophenol (2,6-DCP) in Amblyomma cajennense and to evaluate its role in A. cajennense and Rhipicephalus sanguineus courtship. Hexanic extract from attractive females was purified by solid phase extraction and the phenol was identified by the single ion monitoring method using GC/MS. In an olfactometer, the responses of A. cajennense and R. sanguineus males to females, control rubber septa or rubber septa impregnated with 2,6-DCP at 50, 500, and 5000 ng, respectively, were studied. 2,6-DCP was identified in A. cajennense extract and the males oriented themselves toward the concentration of 500 ng. These septa and the females were recognized as copula partners. The septa treated with 2,6-DCP did not attract and were not even recognized by the R. sanguineus males, whereas the females were recognized. Due to the presence of 2,6-DCP in A. cajennense and the results of biological bioassays, it was concluded that this compound acts as an attractant and mounting sex pheromone in this tick, but it does not play any role in R. sanguineus courtship. / Este estudo teve por objetivo identificar o 2.6-dichlorophenol (2,6-DCP)em Amblyomma cajennense de e avaliar seu papel na cópula de A. cajennense e de Rhipicephalus sanguineus. O extrato hexânico de fêmeas atrativas purificado pela extração da fase contínua e o fenol foi identificado pelo método da monitoração do íon usando o GC/MS. Em um olfatômetro, foram estudadas as respostas de machos de A. cajennense e de R. sanguineus às fêmeas, a septos de borracha ou a septos de borracha impregnados com o 2,6-DCP a 50ng, 500ng, e 5000ng. No extrato de fêmeas de A. cajennense 2,6-DCP foi identificado, os machos orientaram-se para a concentração de 500ng, e estes septos e as fêmeas foram reconhecidos como parceiros para a cópula. Os septos tratados com o 2,6-DCP não atraíram e nem foram reconhecidos pelos machos de R. sanguineus. Devido à presença de 2,6- DCP na espécie A. cajennense e aos resultados dos ensaios biológicos, concluiu-se que este composto atua como um feromônio sexual de atração e de monta nesta espécie, mas não desempenha nenhum papel na cópula do R. sanguineus .