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Treatment of Aqueous Effluents Containing Phenol by the O(3), O(3)-UV, and O(3)-H(2)O(2) Processes: Experimental Study and Neural Network Modeling

CATORCENO, L. L. C.; NOGUEIRA, K. R. B.; TEIXEIRA, A. C. S. C.
Fonte: TAYLOR & FRANCIS INC Publicador: TAYLOR & FRANCIS INC
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
382.00168%
In this work, the oxidation of the model pollutant phenol has been studied by means of the O(3), O(3)-UV, and O(3)-H(2)O(2) processes. Experiments were carried out in a fed-batch system to investigate the effects of initial dissolved organic carbon concentration, initial, ozone concentration in the gas phase, the presence or absence of UVC radiation, and initial hydrogen peroxide concentration. Experimental results were used in the modeling of the degradation processes by neural networks in order to simulate DOC-time profiles and evaluate the relative importance of process variables.

Kinetic and mechanistic investigation of the ozonolysis of 2,4-xylidine (2,4-dimethyl-aniline) in acidic aqueous solution

MACHULEK JR., Amilcar; GOGRITCHIANI, Eliso; MORAES, Jose E. F.; QUINA, Frank H.; BRAUN, Andre M.; OLIVEROS, Esther
Fonte: ELSEVIER SCIENCE BV Publicador: ELSEVIER SCIENCE BV
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
372.01094%
The ozonolysis of 2,4-xylidine (2,4-dimethyl-aniline) in acidic aqueous solution was investigated by determining the major reaction products and their evolution as a function of the reaction time and their dependence on the pH of the reaction system. 2,4-Dimethyl-nitrobenzene and 2,4-dimethyl-phenol were found to be primary reaction products; their formation might be explained by electron transfer and substitution reactions. 2,4-Dimethyl-phenol was further oxidized yielding 2,4-dimethyl- and/or 4,6-dimethyl-resorcinol by electrophilic addition of HO(center dot) radicals. The best fitting phenomenological kinetic model and the good convergence of calculated and experimentally determined rate constants imply two additional competitive pathways of substrate oxidation: (i) electrophilic addition of HO(center dot) radicals and fast subsequent substitution would also yield the resorcinol derivatives. (ii) Substrate and isolated products are thought to be oxidized by hydrogen abstraction at the benzylic sites, but the corresponding products (alcohols, aldehydes, and carboxylic acids) could not be identified. Fe(II) was added to probe for the presence of H(2)O(2), but had no or only a minor effect on the kinetics of the ozonolysis. (c) 2009 Elsevier B.V. All rights reserved.

A New Indirect Electrochemical Method for Determination of Ozone in Water Using Multiwalled Carbon Nanotubes

CESARINO, Ivana; MORAES, Fernando C.; MACHADO, Sergio A. S.; PASSARETTIFILHO, Juliano; CARDOSO, Arnaldo A.
Fonte: WILEY-BLACKWELL Publicador: WILEY-BLACKWELL
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
489.1188%
A new electrochemical methodology has been developed for the detection of ozone using multiwalled carbon nanotubes (MWCNT). The method presented here is based on the reaction of ozone with indigo blue dye producing anthranilic acid (ATN). The electrochemical profile of ATN on an electrode of glassy carbon (GC) modified with MWCNT showed an oxidation peak potential at 750 mV vs. Ag/AgCl. An analytical method was developed using differential pulse voltammetry (DPV) to determine ATN in a range of 50-400 nmol L(-1), with a detection limit of 9.7 nmol L(-1). Ozonated water samples were successfully analyzed by GC/MWCNT electrode and the recovery procedure yielded values between of 96.5 and 102.3%.; Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); CNPq[151393/2009-5]

Estudo da degradação de corante têxtil em matrizes aquosas por meio dos processos oxidativos avançados O3-H2O2/UV e foto-Fenton.; Study on the degradation of a textile dye in aqueous matrices by the oxidative processes O3-H2O2/UV and photo-Fenton.

Santana, Caroline Martins
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 04/12/2009 PT
Relevância na Pesquisa
392.06824%
A indústria têxtil gera grandes volumes de efluentes com elevada carga orgânica, forte coloração e toxicidade. Neste trabalho, estuda-se o tratamento de solução aquosa contendo o corante Solophenyl Yellow Arle 154% por meio dos processos O3-H2O2/UV e foto-Fenton, avaliando-se as repostas: remoção de cor em 5 minutos, remoção de cor em 60 minutos, taxa máxima de remoção de cor e remoção de COT em 60 minutos. Os experimentos foram realizados em semibatelada com circulação usando um reator fotoquímico com campo de radiação anular coaxial, constituído de corpo cilíndrico em aço com refletor interno de alumínio para 12 lâmpadas fixadas simetricamente na superfície refletora e um tubo reator em quartzo de 0,7 L, posicionados verticalmente no eixo do refletor. Para o processo O3-H2O2/UV foram utilizadas lâmpadas Phillips TUV (36 W, 254 nm). A corrente gasosa contendo O3 foi introduzida no reator por meio de um difusor. Para o processo foto-Fenton foram utilizadas lâmpadas Sylvania (12 W cada, 300 400 nm) e concentração de Fe(II) de 0,25 mmol/L. Em ambos os processos, solução de peróxido de hidrogênio foi adicionada durante os 30 minutos iniciais de tratamento. As amostras foram analisadas por medidas de carbono orgânico total (COT) e remoção de cor (absorbância medida em 405 nm em espectrofotômetro UV-visível). Em ambos os processos utilizou-se o planejamento experimental Doehlert...

Efeitos do ozônio diluído em água no reparo de feridas monocorticais em fêmures de ratos induzidos ou não ao diabetes: estudo histomorfológico e histomorfométrico; Aqueous ozone solution irrigations on bone monocortical wound healing in femurs of Wistar rats induced or not to diabetes: histomorphological and histomorphometric study

Frascino, Alexandre Viana Monteiro
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 11/04/2011 PT
Relevância na Pesquisa
495.7911%
Alguns relatos encontrados na literatura sobre as propriedades da molécula de ozônio de interferir de maneira favorável na reparação de tecidos e da sua ação antimicrobiana têm fundamentado emprego do ozônio com fins terapêuticos no tratamento de diversas doenças. Nenhuma pesquisa ainda conseguiu comprovar, por meio de estudos padronizados, os efeitos terapêuticos sobre os processos de reparação óssea desta molécula triatômica de oxigênio quando diluído em água. Nesta investigação foram avaliados os aspectos histomorfológicos e histomorfométricos do processo de reparo tecidual ósseo após a irrigação com 100mL de 4ppm de ozônio diluído em água Milli-Q® durante a perfuração de feridas monocorticais padronizadas, realizadas por meio de broca trefina (2mm), após 7, 14 e 21 dias, em fêmures de ratos Wistar induzidos e não induzidos ao diabetes por injeção intraperitoneal de Estreptozotocina (STZ- Sigma®). Nos grupos controles as feridas foram irrigadas com de 100mL de água Milli-Q® pura. Os resultados histomorfológicos revelaram que os animais diabéticos que receberam o ozônio apresentaram intensa hemorragia, maior proliferação de vasos sanguíneos e trabeculado ósseo imaturo quando comparados aos animais diabéticos não submetidos à aplicação de ozônio em todos os períodos avaliados. Os animais não diabéticos que receberam ozônio apresentaram intenso infiltrado inflamatório e maior proliferação de vasos sanguíneos quando comparados aos animais do grupo controle. Comparativamente as feridas nos animais que receberam a irrigação por meio de água ozonizada mostraram maior proliferação de vasos sanguíneos e trabéculas ósseas mais imaturas quando comparados aos animais dos grupos que não receberam ozônio. A avaliação histomorfométrica mostrou as médias percentuais de trabéculas ósseas neoformadas. O estudo estatístico...

Degradação do antibiótico ciprofloxacina em solução aquosa por meio de processo oxidativo avançado baseado em ozônio.; Degradation of the antibiotic ciprofloxacin in aqueous solution by the advanced oxidation process based on ozone.

Baptistucci, Cíntia Bardauil
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 02/03/2012 PT
Relevância na Pesquisa
406.53414%
Os tratamentos convencionais de efluentes em geral não são eficientes para a degradação de compostos persistentes como os fármacos. Neste trabalho, estuda-se o tratamento de soluções aquosas contendo o antibiótico ciprofloxacina (CIP) por meio de processo oxidativo avançado baseado em ozônio. Para tanto, foram realizados experimentos em semi-batelada com recirculação de líquido em um reator (coluna de bolhas) com escoamento gás-líquido em contracorrente. Amostras de líquido foram retiradas e analisadas para medida das concentrações de CIP e de carbono orgânico total (COT); a concentração de ozônio no gás foi medida por espectrofotometria UV-vis. Estudaram-se os efeitos das seguintes variáveis quanto à degradação de CIP, por meio de um planejamento Doehlert: concentração de ozônio à entrada do reator (8-25 mgO3 L-1), pH (3,5-10,5) e concentração inicial de CIP (5-26 mg L-1). Avaliaram-se as seguintes variáveis dependentes por meio da análise de superfícies de resposta: variação de concentração de CIP em 2 minutos; taxa inicial de degradação de CIP e variação de concentração de COT em 30 minutos. Os resultados indicaram total degradação de ciprofloxacina em menos de 15 minutos, tanto por via direta...

Estudo da degradação do pesticida amicarbazona em meio aquoso por processo de oxidação avançada baseado em ozônio.; Study on the degradation of pesticide amicarbazone in aqueous systems by the ozone-based advanced oxidation process.

Vargas Garcia, Jahn Pierre
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 22/03/2013 PT
Relevância na Pesquisa
402.8307%
Muitos estudos têm sido realizados com intuito de desenvolver tecnologias capazes de minimizar o volume e a toxicidade dos efluentes industriais. Uma alarmante fonte de contaminação de efluentes aquosos são os pesticidas encontrados na forma de efluentes e resíduos industriais, agrícolas e domésticos, na aplicação direta para controle de pragas, na lavagem de produtos após a colheita e de maquinário na agroindústria e a lixiviação a partir de resíduos. O presente trabalho tem como objetivo avaliar a degradação do herbicida amicarbazona em solução aquosa, por oxidação por ozônio sob irradiação UV, em um reator fotoquímico tubular com escoamento anular, constituído por um tubo externo em vidro borossilicato Pyrex® (volume irradiado de 3,9 L), no interior do qual se adaptou uma lâmpada tubular germicida concêntrica (Philips, emissão em 253,7 nm). O reator é posicionado verticalmente e o líquido escoa pela região anular entre a lâmpada e a parede interna do tubo externo com fluxo descendente em contracorrente com o fluxo de gás. O reator é acoplado a um gerador de ozônio, sendo a mistura O2+O3 admitida ao reator por meio de um difusor de gases. A concentração de ozônio na fase gasosa foi monitorada por meio de espectrofotometria UV em 254 nm usando uma célula de fluxo em um equipamento Shimadzu MultiSpec-1501. Os efeitos da concentração de alimentação de O3 concentração inicial de amicarbazona...

Desenvolvimento e estudo de um sistema para tratamento de fenol e poluentes orgânicos emergentes (POE) por processos oxidativos avançados (POA) utilizando ozônio, peróxido de hidrogênio e radiação ultravioleta; Development and study of a system for the treatment of phenol and emerging organic pollutants (EOP) by advanced oxidation processes (AOP) using ozone, hydrogen peroxide and ultraviolet radiation

Nolasco, Felipe Rufine
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 29/04/2014 PT
Relevância na Pesquisa
386.24457%
O estudo avaliou a efetividade de um sistema para tratamento de soluções aquosas contendo poluentes orgânicos emergentes (POE), denominados interferentes endócrinos (IE). Baseado nos processos oxidativos avançados (POA), empregando ozônio, radiação UV, peróxido de hidrogênio e variação de pH, o estudo possibilitou determinar a relação ideal oxidante/poluentes e o custo/benefício dos tratamentos com melhores desempenhos, de degradação do padrão contendo hormônios 17?-estradiol (E2) e 17?-etinilestradiol (EE2), e outra contendo atrazina (ATZ). Para os estudos, foi utilizado um planejamento fatorial 23, para identificar as melhores opções de degradação. Os tratamentos iniciaram com soluções em concentrações de 600 ?g L-1 de ATZ, em quadruplicatas, por períodos de até 10 minutos. Posteriormente a avaliação dos melhores tratamentos, foi estudada a cinética de mineralização de soluções a 5 mg L-1 de ATZ, em até 90 min. A concentração de estudo adotada para os hormônios foi de 1 mg L-1. A determinação da ATZ e dos hormônios (E2 e EE2) foi realizada por cromatografia em fase líquida (CLAE), utilizando a extração em fase sólida (EFS) quando necessário. Para o estudo foram construídos dois sistemas de tratamento paralelamente acoplados (S1 - escala laboratorial e S2 - escala piloto)...

Potential of aqueous ozone to control aflatoxigenic fungi in Brazil nuts

Silva, Otniel Freitas; Morales-Valle, H.; Venâncio, Armando
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Conferência ou Objeto de Conferência
Publicado em /11/2011 ENG
Relevância na Pesquisa
519.90914%
The Brazil nut (Bertholethia excelsa) is an important non timber forest product (NTFP) from the Amazonian forest. Despite their nutritious value, Brazil nuts are susceptible to contamination with Aspergillus section Flavi fungi and consequently with aflatoxins. Since aqueous ozone reduces microorganisms population and has oxidant effect on aflatoxins, the effect of ozone on. Both natural and artificially contaminated Brasil nuts were studied in the present work. The former were inoculated with either 1x106 or 1x107 conidia mL-1 of A. flavus (MUM 9201). Previous assays were carried out to determine optimal parameters of the treatment. Different aqueous ozone contact time was assayed. The duration was controlled by the addition of a sodium formate solution. Such assays evidenced that the effect of ozone is almost immediate. Also, different ozone concentrations were assayed. The optimum ozone concentration depended on the initial viable spores on the nutshell. Also, the effect of the ozonization on the shell nut color was assessed by measuring chromaticity values of the treated fruits in the L*a*b* space coordinates. High concentrations of ozone affected both the luminosity and the hue of the nutshell. Finally, a concentrated aqueous ozone solution was assayed on both natural and artificially contaminated nuts. The remaining viable spores in the ozone solution were recorded and the rate of inactivation for each treatment was determined by assessing the ratio between the CFU of each treatment and the control. Ozonized nuts were also plated on MEA to recover the fungi population. Aqueous ozone was effective in reducing the conidia of Aspergillus flavus and the natural fungal population associated to Brazil nuts...

Cyclopiazonic acid degradation by aqueous ozone

Silva, Otniel Freitas; Venâncio, Armando
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Conferência ou Objeto de Conferência
Publicado em //2011 ENG
Relevância na Pesquisa
509.33195%
Ozone is a chemical agent with great potential to reduce mycotoxins, it was effective against to reduce some mycotoxins. In view of this it was aimed of this work study the Cyclopiazonic acid (CPA) degradation by aqueous ozone. The degradation of exogenously CPA introduced in mobile phase was confirmed by High performance liquid Chromatography (HPLC). In parallel it was tested the effect of sodium formate (SF), to evaluate the influence of this chemical to neutralize ozone after adding CPA to ozone reaction, since it is a chemical used to stop ozone reaction. Results shown that SF did not influence aqueous ozone to degrade the CPA, since the quickness of ozone reaction.

Supressão de Aspergillus produtores de aflatoxinas e ácido ciclopiazonico por ozônio; Aflatoxins and cyclopiazonic acid producer strains supressed by aqueous ozone

Silva, Otniel Freitas; Venâncio, Armando
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Conferência ou Objeto de Conferência
Publicado em 06/08/2008 POR
Relevância na Pesquisa
709.33195%
Ozone is a potential antioxidant substance with effect against microorganism. Four ozone concentrations (0, 1, 10 and 20 mg/L) were applied for 10 minutes to Aspergillus flavus and A. parasiticus spores suspensions (103 cfu/mL). Aqueous ozone was effective against both isolates at the lowest ozone concentration tested. Under the tested conditions, spores inactivation was from 91 to 100%. All ozone treatments performed effective fungi control. The two isolates used in these assays were screened for mycotoxin production by HPLC. The A. flavus strain produced cyclopiazonic acid and Aflatoxin B1 and the A. parasiticus strain produced Aflatoxins B1, B2, G1 and G2. The ozone effect on these mycotoxins was not evaluated.

Influence of disinfectant technologies on red bell peppers safety

Alexandre, E. M. C.; Fundo, J. F.; Pedro, D. Santos; Brandão, T. R. S.; Silva, C. L. M.
Fonte: Universidade Católica Portuguesa Publicador: Universidade Católica Portuguesa
Tipo: Conferência ou Objeto de Conferência
Publicado em //2006 ENG
Relevância na Pesquisa
399.18535%
The development of innovative technologies, promoting fruits and vegetables safety to reduce the risk of related food-borne diseases, is an actual concern. Several sanitizing agents for washing fruits and vegetables may be used to reduce the risk of microbial contamination. Traditional washing technologies utilize chlorine and hydrogen peroxide as sanitizing agents for fresh produce. More recently, ozone is being used as an innovative food processing technology that guarantees product safety, also increasing shelf life of fruits and vegetables. Its main advantage, when compared to traditional disinfectant technologies, relies on its potent antimicrobial action and non-toxic products decomposition. The objective of this work was to study the effectiveness of three sanitizing agents (sodium hypochlorite - used in a commercial available solution AMUKINA, hydrogen peroxide and ozone in aqueous solutions), on the reduction of Listeria innocua inoculated on red bell peppers. Results showed that ozone treatment allowed bacteria reductions identical to the ones attained with the traditional disinfectant solutions. On average, aqueous ozone allowed a decimal reduction of 2 cycles in Listeria innocua counts.

Influence of aqueous ozone, blanching and combined treatments on microbial load of red bell peppers, strawberries and watercress

Alexandre, Elisabete M. C.; Santos-Pedro, Dora M.; Brandão, Teresa R. S.; Silva, Cristina L. M.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em //2011 ENG
Relevância na Pesquisa
609.33195%
The effectiveness of ozone in aqueous solution treatment on microbial inactivation was studied for three combinations microorganism/food: Listeria innocua/red bell peppers (artificially inoculated), total mesophiles/strawberries, and total coliforms/watercress, with two concentrations (0.3 and 2.0 ppm). Blanching treatments (50–60 C) were also individually applied and in combination with ozone, for studying possible synergistic effects. In relation to ozone treatments, the highest microbial reductions were obtained for the highest concentration with the highest treatment time (3 min). Under those conditions, L. innocua/peppers, total mesophiles/strawberries and total coliforms/watercress were reduced respectively 2.8 ± 0.5, 2.3 ± 0.4 and 1.7 ± 0.4 log-cycles. However, a substantial portion of the microbial populations were reduced by water washing alone, and the presence of ozone generally added an additional reduction of 0.5–1.0 log-cycles. If ozone at the highest concentration is used, the treatment impacts on L. innocua/peppers and total mesophiles/strawberries load reductions were equivalent to a blanching at 50 C (for the same treatment times). Combining blanching and ozone did not generate synergistic effects, and in some situations microbial reductions were lower than the ones observed when treatments were applied independently.

Ozonation of ethinylestradiol in aqueous-methanolic solution: direct monitoring by electrospray ionization mass spectrometry

Vieira,Karla M.; Nascentes,Clésia C.; Augusti,Rodinei
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2010 EN
Relevância na Pesquisa
397.34117%
The ozonolysis of ethinylestradiol (1), a synthetic steroidal estrogen, in an aqueous-methanolic solution was investigated. HPLC-UV analyses revealed that 1 was completely consumed after a 20 min reaction time either at pH 5 or 8. ESI(-)-MS (electrospray ionization mass spectrometry in the negative ion mode) monitoring also revealed the continuous consumption of 1 (detected as [1 – H]- of m/z 295) concomitantly with the emergence of oxidation products. Chemical structures were proposed for these products based on the data of MS and MS/MS (the m/z values and fragmentation profiles of the anionic specie, respectively). These data, in conjunction with the well-established knowledge about the reactivity of organic molecules toward ozone in aqueous solution, were evaluated and an unprecedented reaction route for the ozonation of 1 could thus be suggested. Hence, the first step in this reaction sequence was ascribed to involve a 1,3-dipolar cycloaddition of ozone at the phenolic ring of 1 yielding the di-hydroxylated product 2 (detected as [2 – H]- of m/z 311). The loss of acetylene as the unique dissociation channel for [2 – H]- thus confirmed that such hydroxylation occurred at the phenolic ring rather than the acetylenic moiety of 1. Subsequent oxidations were proposed to be the origin of a number of other products...

Potential of Aqueous Ozone to Control Aflatoxigenic Fungi in Brazil Nuts

Freitas-Silva, Otniel; Morales-Valle, Héctor; Venâncio, Armando
Fonte: Hindawi Publishing Corporation Publicador: Hindawi Publishing Corporation
Tipo: Artigo de Revista Científica
Publicado em 17/07/2013 EN
Relevância na Pesquisa
514.775%
This study aimed to verify the use of aqueous ozone as alternative technology for fungal control. Brazil nuts sterilized were inoculated with either 1 × 106 or 1 × 107 conidia mL−1 of Aspergillus flavus (MUM 9201) to determine optimal treatment parameters and different aqueous ozone contact times. These assays showed that the effect of ozone is almost immediate against A. flavus, and the optimum ozone concentration depended on the number of initial viable spores on the shell. The remaining viable spores in the ozone solution were recorded, and the rate of inactivation for each treatment was determined by assessing the ratio between the cfu of each treatment and the control. The ozonized nuts were also cultured to recover the fungal population. Aqueous ozone was effective in reducing the conidia of A. flavus and the natural fungal population associated with Brazil nuts. Aqueous ozone presented a great potential to reduce microorganisms counts in Brazil nuts with a great potential use in packing houses for decontamination step.

Responses of Dendrobium 'darrenn glory' and Mokara 'calypso jumbo' orchids to 1-methylcyclopropene and aqueous ozone postharvest treatments

Almasi,Parviz; Mohamed,Mahmud Tengku Muda; Anwar,Parvez; Ahmad,Siti Hajar; Kadir,Jugah
Fonte: Instituto Agronômico de Campinas Publicador: Instituto Agronômico de Campinas
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2015 EN
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713.5644%
AbstractOrchids possess a very special place amongst ornamental plants. But high ethylene sensitivity and early flower senescence of orchid result in a short vase life and rapid quality deterioration which is of great concern for the growers, traders and consumers. An attempt was made to study the influence of 1-methylcyclopropene (1-MCP) (0 and 300 nL L–1) and аquеous ozone (0 and 5.2 nL L–1) in prolonging vase life and maintaining quality of two cut orchid hybrids Dendrobium 'Darren Glory' (DDG) and Mokara “Calypso Jumbo” (MCJ). Results showed that orchid hybrids exhibited differences in their ethylene sensitivity, vase life, 1-aminocyclopropane-1-carboxylic acid (ACC) content and ACC oxidase activities. Pre-treatment with 1-MCP resulted in reduced ethylene production, vase life, ACC content and ACC oxidase activities, but increased bud opening %. Pre-treatment with аquеous ozone failed to influence all those parameters except bud opening %. Interaction effects of hybrid and 1-MCP were significant for ethylene production, hybrid and ozone for vas life, 1-MCP and ozone for bud opening %, and hybrid, 1-MCP and ozone for ethylene production and vase life. Aqueous ozone markedly contributed to the inhibition of microbial growth in vase solution. Pre-treatment of the cut orchid flowers with 300 nL L–11-MCP...

Aqueous-ozone irrigation of bone monocortical wounds in hyperglycemic rats

Frascino,Alexandre Viana; Mantesso,Andrea; Corrêa,Luciana; Deboni,Maria Cristina Zindel
Fonte: Sociedade Brasileira para o Desenvolvimento da Pesquisa em Cirurgia Publicador: Sociedade Brasileira para o Desenvolvimento da Pesquisa em Cirurgia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/05/2013 EN
Relevância na Pesquisa
615.13426%
PURPOSE: To analyze the effects of aqueous ozone irrigation over bone healing in hyperglycemia-induced rats. METHODS: Forty-eight male Wistar rats were allocated into Group H (hyperglycemic) or Group N (control). Monocortical bone wound were performed on femurs' anterolateral face. Wounds were treated with a trans-operatory single irrigation of 100ml of aqueous ozone [0.004mg/ml] whereas control groups received 100ml of pure water (Milli-Q®). Histomorphological and histomorphometrical analyses were accomplished after seven, 14 and 21 days. Kruskal-Wallis and Mann-Whitney statistical tests were applied for bone neoformation quantification and assessment. RESULTS: Aqueous ozone wounds irrigated revealed diffuse hemorrhage and increased neoformed of blood vessels number. There was no statistical significant difference in bone trabeculae neoformation. After seven and 14 days, the number of osteoclasts was higher in aqueous ozone groups than in those treated with pure water. CONCLUSION: Independently of blood glucose levels, aqueous ozone allowed an increase in blood vessels neoformation and osteoclast migration, without affect bone trabeculae neoformation.

Hydrogen Isotope Effects and Mechanism of Aqueous Ozone and Peroxone Decompositions

Lesko, Timothy M.; Colussi, A. J.; Hoffmann, Michael R.
Fonte: American Chemical Society Publicador: American Chemical Society
Tipo: Article; PeerReviewed Formato: application/pdf
Publicado em 07/04/2004
Relevância na Pesquisa
485.17355%
Hydrogen peroxide exalts the reactivity of aqueous ozone by reasons that remain obscure. Should H_2O_2 enhance free radical production, as it is generally believed, a chain mechanism propagated by (·OH/·O_2^-) species would account for O_3 decomposition rates in neat H_2O, ^HR_(-O_3), and in peroxone (O_3 + H_2O_2) solutions, ^(HP)R_(-O_3). We found, however, that:  (1) the radical mechanism correctly predicts H^R_(-O_3) but vastly overestimates ^(HP)R_(-O_3), (2) solvent deuteration experiments preclude radical products from the (O_3 + HO_2^-) reaction. The modest kinetic isotope effect (KIE) we measure in H_2O/D_2O:  ^HR_(-O_3)/^DR_(-O_3) = 1.5 ± 0.3, is compatible with a chain process driven by electron- and/or O-atom transfer processes. But the large KIE found in peroxone:  ^(HP)R_(-O_3)/^(DP)R_(-O_3) = 19.6 ± 4.0, is due to an elementary (O_3 + HO_2^-) reaction involving H−O_2^- bond cleavage. Since the KIE for the hypothetical H-atom transfer:  O_3 + HO_2^- →(2ℏ) HO^3· + ·O_2^-, would emerge as a KIE^(1/2) factor in the rates of the ensuing radical chain, the magnitude of the observed KIE must be associated with the hydride transfer reaction that yields a diamagnetic species:  O_3 + HO_2^- HO_3^- + O_2. HO_3^-/H_2O_3 may be the bactericidal trioxide recently identified in the antibody-catalyzed addition of O_2(^1Δ_g) to H_2O.

Oxidation of telluropyrylium dyes with ozone, chlorine, and bromine. Differing regiochemical and kinetic behavior with respect to oxidations of oxygen-, sulfur-, and selenium-containing dyes

Detty, Michael; Friedman, Alan
Fonte: The American Chemical Society: Organometallics Publicador: The American Chemical Society: Organometallics
Tipo: Abstract Formato: 31371 bytes; application/pdf
EN_US
Relevância na Pesquisa
391.1946%
Oxidations of telluropyrylium dyes 1-3 with ozone in water, chlorine in carbon tetrachloride, or bromine in carbon tetrachloride gave second-order rate constants of greater-than-or-equal-to 10(9) L mol-1 s-1 using stopped-flow techniques to measure rates of oxidation. Aqueous ozone gave initial oxidation of the tellurium atoms of 1-3 to produce hydroxytelluranes 4-6, respectively. Oxidative addition of chlorine or bromine across a tellurium atom of 1-3 gave the corresponding tellurium(IV) dihalides. With excess ozone, a second oxidation was observed with a second-order rate constant of (1.3 +/- 0.1) X 10(6) L mol-1 s-1. Chalcogenopyrylium dyes 7-10 which contain only oxygen, sulfur, and/or selenium heteroatoms reacted with smaller rate constants for oxidation. Chlorine and bromine gave second-order rate constants within 1 order of magnitude of those of telluropyrylium dyes for reactions with 7-10. Ozone was more than 100 000 times less reactive toward chalcogenopyrylium dyes 7-9 relative to telluropyrylium dyes 1-3 with second-order rate constants (1.1 +/- 0.1) X 10(4) L mol-1 s-1 for 7, (8.5 +/- 0.9) X 10(3) L mol-1 s-1 for 8, and (5.4 +/- 0.6) X 10(3) L mol-1 s-1 for 9. With dyes 7-10, ozone destroyed the pi-framework of the dye while chlorine and bromine gave mono- and dihalogenation of the trimethine bridge of the dye.

Cr(VI) formation during ozonation of Cr-containing materials in aqueous suspension - implications for water treatment

van der Merwe,W; Beukes,JP; van Zyl,PG
Fonte: Water SA Publicador: Water SA
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2012 EN
Relevância na Pesquisa
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Ozonation, or advanced oxidation processes (utilising ozone decomposition products as oxidants) are widely used in industrial wastewater and drinking water treatment plants. In these applications the use of ozone is based on ozone and its decomposition by-products being strong oxidants. In this paper, the possible oxidation of non-Cr(VI) Cr-containing materials suspended in water during ozonation, is presented. This study is of particular interest within the South African context, considering that South Africa holds the majority of global chromium ore resources and has the largest Cr-related industry in the world. Chromium also occurs commonly in other industrial waste materials and is a naturally-occurring element in the crust of the earth. Results indicated that in situ formation of Cr(VI) is possible during aqueous ozonation. pH had a significant influence, since the decomposition products of aqueous O3, i.e. hydroxyl radicals formed at higher pH levels, were found to be predominantly responsible for Cr(VI) formation. Increased ozonation contact time, water temperature and solid loading also resulted in higher Cr(VI) concentrations being formed.