Emission of hazardous gases such as hydrogen sulphide (H2S) by a variety of industrial processes and as a result of agricultural activities has become an issue of great concern over the years. The control of these gases is needed to ensure public safety, to protect the environment, and lastly to comply with occupational and environmental regulations. Several techniques including biological and physicochemical methods have been applied to remove these gases from contaminated air streams. In this work, Zinc oxide (ZnO) nanoparticles were used to adsorb H2S gas at ambient temperatures. The effects of H2S concentration (80-1700 mg L-1), nanoparticle size (18, 80-200 nm), gas flow rate (200 and 450 mL min-1), temperature (1-41C) and adsorbent quantity (0.2-1.5 g) were investigated in the laboratory scale. A semi-pilot system was also developed and used to treat H2S emission from stored swine manure. The results show that when H2S concentration was increased the adsorption capacities (both breakthrough and equilibrium) increased and the nanoparticles reached the saturation state faster. When nanoparticles of different sizes were tested, it was observed that 80-200 nm particles got saturated with H2S faster than 18 nm particles. The adsorption capacities were higher with 18 nm particles than those with 80-200 nm. Temperatures did not have an effect on how fast the nanoparticles got saturated and on breakthrough adsorption capacity, but equilibrium adsorption capacity increased due to increase in temperature. The breakthrough and equilibrium adsorption capacities increased with increased quantity of nanoparticles. BET isotherm described the equilibrium data with higher accuracy as compared to other adsorption isotherms which were tested. Semi-pilot scale tests proved the effectiveness of 18 nm ZnO nanoparticles in capture of H2S emitted from stored swine manure. For an experimental period of approximately 100 minutes the level of H2S was reduced from an average initial value of 235.785.2 mg L-1 to a negligible level (an average value of 0.26 mg L-1) corresponding to an H2S removal of at least 99%. Semi pilot tests also showed that 18 nm ZnO nanoparticles were able to capture about 74% of NH3 that passed through the adsorption column.

Hydrometallurgical processing of sulphide concentrates is an attractive method for the selective extraction of valuable metals. The dissolution of minerals in a leaching process involves several electrochemical parameters that need to be investigated• to ensure the development and growth of the base metal industry in South Africa. A study has been carried out to elucidate the leaching mechanism of a nickel-coppercobalt sulphide concentrate in an oxidative pressure-acid medium. The sulphide concentrate studied in this research, comprises mainly of the minerals pyrrhotite, (Fe1_xS) with x = 0 to 0.2, pentlandite, (Ni,Fe)9S8 and chalcopyrite, (CuFeS2). The leaching behaviour of these minerals was successfully studied by means of Atomic Absorption (AA) measurements, Scanning '•Electron Microscopy (SEM) and Moss bauer spectroscopy, after leaching took place in an oxidative pressure-acid medium. The dissolution of the valuable metals was achieved effectively with recoveries of well over 90% for nickel, copper and cobalt under the specific conditions studied. Mechanical activation by means of ultra fine milling improved metal extraction with an average of approximately 40%, after a leaching period of 150 minutes. The most suitable conditions for the oxidative pressure-acid leaching of the mechanically treated nickel-copper-cobalt sulphide concentrate in a dilute sulphuric acid medium were found to be: particle size 80% - 10J.Lm; temperature l10°C; oxygen partial pressure 10 bar; sulphuric acid concentration 30 kg/ton; solids content 15% by mass and an impeller agitation rate of 800 r/min. The values of the apparent activation energies of nickel, copper and cobalt, extracted from the sulphide concentrate, were found to be 20.6 (± 4.4) kJ/mol K, 33.6 (± 4.2) kJ/mol K and 17.4 (± 3.5) kJ/mol K respectively. / Thesis (MIng (Chemical Engineering))--Potchefstroom University for Christian Higher Education, 2001

Hydrometallurgical processing of sulphide concentrates is an attractive method for the selective extraction of valuable metals. The dissolution of minerals in a leaching process involves several electrochemical parameters that need to be investigated• to ensure the development and growth of the base metal industry in South Africa. A study has been carried out to elucidate the leaching mechanism of a nickel-coppercobalt sulphide concentrate in an oxidative pressure-acid medium. The sulphide concentrate studied in this research, comprises mainly of the minerals pyrrhotite, (Fe1_xS) with x = 0 to 0.2, pentlandite, (Ni,Fe)9S8 and chalcopyrite, (CuFeS2). The leaching behaviour of these minerals was successfully studied by means of Atomic Absorption (AA) measurements, Scanning '•Electron Microscopy (SEM) and Moss bauer spectroscopy, after leaching took place in an oxidative pressure-acid medium. The dissolution of the valuable metals was achieved effectively with recoveries of well over 90% for nickel, copper and cobalt under the specific conditions studied. Mechanical activation by means of ultra fine milling improved metal extraction with an average of approximately 40%, after a leaching period of 150 minutes. The most suitable conditions for the oxidative pressure-acid leaching of the mechanically treated nickel-copper-cobalt sulphide concentrate in a dilute sulphuric acid medium were found to be: particle size 80% - 10J.Lm; temperature l10°C; oxygen partial pressure 10 bar; sulphuric acid concentration 30 kg/ton; solids content 15% by mass and an impeller agitation rate of 800 r/min. The values of the apparent activation energies of nickel, copper and cobalt, extracted from the sulphide concentrate, were found to be 20.6 (± 4.4) kJ/mol K, 33.6 (± 4.2) kJ/mol K and 17.4 (± 3.5) kJ/mol K respectively. / Thesis (MIng (Chemical Engineering))--Potchefstroom University for Christian Higher Education, 2001

This thesis examines the bioleaching of six different Canadian nickel sulphide ores at pH levels above what is generally considered optimum (~ 2). The majority of work discussed in this thesis was conducted with a low-grade metamorphosed ultramafic nickel sulphide ore from Manitoba, Canada (Ore 3), which is not currently exploitable with conventional technologies. The ore contains 21% magnesium and 0.3% nickel. Nickel is the only significant metal value, and is present primarily as pentlandite. A substantial fraction of the magnesium is present as the serpentine mineral lizardite, making processing difficult with conventional pyro- and biohydrometallurgical techniques. The work with this ore has two equally important objectives: to minimize magnesium mobilization and to obtain an acceptable level of nickel extraction. Batch stirred-tank bioleaching experiments were conducted with finely ground ore ( 147 µm) with temperature and pH control. The first phase of experimentation examined the effect of pH (2 to 6) at 30 °C, and the second phase examined all combinations of three pH levels (3, 4 and 5) and five temperatures (5, 15, 22.5, 30, and 45 °C).

Durante a exploração de petróleo offshore (fora da costa), a injeção de água do mar no processo de recuperação secundária de petróleo, ocasiona a produção de sulfeto de hidrogênio (H2S) pela presença das bactérias redutoras de sulfato (BRS), que reduzem o sulfato presente na água em sulfeto. A produção intensiva de H2S tem sido um dos maiores problemas das indústrias petrolíferas, pois constitui-se uma das principais causas de corrosão em linhas de produção (tubulações), equipamentos e tanques metálicos. Os principais micro-organismos presentes em amostras salinas provenientes de tanques de armazenamento de água e óleo da indústria do petróleo são as bactérias anaeróbias heterotróficas totais (BANHT) e as bactérias redutoras de sulfato (BRS). Atualmente, a quantificação desses grupos microbianos é realizada através da técnica do Número Mais Provável (NMP) que estima o resultado em aproximadamente 28 dias. Neste trabalho foi utilizada a metodologia de produção semi-contínua de sulfetos biogênicos por 15 dias, numa tentativa de correlacionar com os resultados de quantificação de BANHT e BRS através da técnica convencional do NMP. Nesse caso, avaliou-se as condições mais adequadas para a produção biogênica de sulfetos em tanques, alterando-se parâmetros tais como salinidade, temperatura e composição do meio de cultura. Verificou-se que os aumentos da salinidade e da temperatura do meio implicaram na diminuição da atividade biogênica semi-contínua de geração de sulfetos. E conforme dilui-se o meio de cultura, o crescimento de bactérias foi reduzido, assim como a geração de sulfetos. A quantificação de BRS e BANHT foi avaliada pela técnica do NMP de acordo com o método do FDA em 2011 e de Harrigan em 1998. Este último subestima a população microbiana, desconsiderando os limites e erros provenientes da técnica / During off-shore oil recovery, seawater injection for secondary oil recovery, produces hydrogen sulphide (H2S), due to the presence of sulphate reducing bacteria (SRB), that reduces sulphate from seawater to sulphide. The massive production of H2S is presently one of the main problems in the petroleum industries, constituting one of the main causes of corrosion in production lines (dutes), equipments and tanks. The main microbial species found in this type of saline samples comes from water and oil storage tanks in the petroleum industry, being general anaerobic heterotrophic bacteria (GAHB) and sulphate reducing bacteria (SRB). Presently, the quantification of those microbial groups is made through a technique known as Most Probable Number (MPN). This quantification is obtained in around 28 days. In the present work a methodology based on the semi-continuous production of sulphide during 15 days was conducted, in an attempt to correlate these results with the quantification of GAHB and SRB cells through conventional MPN technique. In this case, the most suitable conditions for biogenic sulphide production in tanks, was studied through the evaluation of environmental parameters such as salinity, temperature and culture medium composition. It could be observed that an increase in salinity and temperature of the medium produced a marked decrease in the semi-continuous biogenic production of sulphide. In relation to the culture medium, its dilution promoted a decreased in cell growth, consequently in the production of sulphides. The quantification of SRB and GAHB was evaluated through the MPN technique, according to procedures suggested by FDA in 2011 and Harrigan in 1998. It was observed that this last procedure underestimated the microbial population, due to the lack of information about limits and standard deviations

Lithium-ion batteries (LIBs) are an integral part of consumer electronic devices and electric vehicles. There is a growing need for LIBs with higher capacity, rate performance and cycling stability. At the anode electrode these challenges are being addressed for instance by utilising materials with higher theoretical capacity compared to graphite (372 mAh/g) or by optimising the morphology of materials through nanostructuring of the electrode. In this thesis the former is investigated by synthesising a reduced graphene oxide (rGO) tin sulphide (SnS2) hybrid, and the latter by self-assembly of rGO sodium titanate and rGO titanium dioxide (TiO2) nanorods. In Chapter 2, SnS2 is investigated due to its high theoretical capacity as an anode material (645 mAh/g), low cost and environmental benignity. SnS2 nanoparticles were grown directly on rGO sheets which provide a conductive framework and limit the detachment of tin particles which undergo large volume changes during alloying reactions. However, a fast decrease in capacity was observed. Post-mortem analysis of the electrodes showed that rGO becomes irreversibly passivated suggesting that additional measures to retain effective charge transport between the low weight percent conductive additive and the active phase during cycling are required. An alternative material system based on nanorods of intercalation materials (sodium titanate and TiO2) wrapped by rGO sheets was chosen to investigate self-assembly in anodes to address the low packing density of nanomaterials. A drop-casting method was used to align rGO-sodium titanate nanorods through evaporation driven self-assembly (Chapter 3) which relies on a combination of electrostatic repulsive forces originating from the rGO coating, and liquid crystal phase formation at high concentrations, facilitated by the high aspect ratio nanorods. As reference, non-aligned films were prepared by adjusting the pH of the nanorod dispersion. Freestanding aligned and non-aligned films were converted to rGO-TiO2 (Chapter 4). The volumetric capacity of the self-assembled films was double that of non-aligned films, and up to 4.5 times higher than traditional casted electrodes using the same material. Further, up to rates of 4 C, the self-assembled films outperformed the non-aligned films. These films showed no sign of capacity fading up to 1000 cycles, which together with post-mortem analysis confirms that these assembled structures are maintained during battery cycling.

Durante a exploração de petróleo offshore (fora da costa), a injeção de água do mar no processo de recuperação secundária de petróleo, ocasiona a produção de sulfeto de hidrogênio (H2S) pela presença das bactérias redutoras de sulfato (BRS), que reduzem o sulfato presente na água em sulfeto. A produção intensiva de H2S tem sido um dos maiores problemas das indústrias petrolíferas, pois constitui-se uma das principais causas de corrosão em linhas de produção (tubulações), equipamentos e tanques metálicos. Os principais micro-organismos presentes em amostras salinas provenientes de tanques de armazenamento de água e óleo da indústria do petróleo são as bactérias anaeróbias heterotróficas totais (BANHT) e as bactérias redutoras de sulfato (BRS). Atualmente, a quantificação desses grupos microbianos é realizada através da técnica do Número Mais Provável (NMP) que estima o resultado em aproximadamente 28 dias. Neste trabalho foi utilizada a metodologia de produção semi-contínua de sulfetos biogênicos por 15 dias, numa tentativa de correlacionar com os resultados de quantificação de BANHT e BRS através da técnica convencional do NMP. Nesse caso, avaliou-se as condições mais adequadas para a produção biogênica de sulfetos em tanques, alterando-se parâmetros tais como salinidade, temperatura e composição do meio de cultura. Verificou-se que os aumentos da salinidade e da temperatura do meio implicaram na diminuição da atividade biogênica semi-contínua de geração de sulfetos. E conforme dilui-se o meio de cultura, o crescimento de bactérias foi reduzido, assim como a geração de sulfetos. A quantificação de BRS e BANHT foi avaliada pela técnica do NMP de acordo com o método do FDA em 2011 e de Harrigan em 1998. Este último subestima a população microbiana, desconsiderando os limites e erros provenientes da técnica / During off-shore oil recovery, seawater injection for secondary oil recovery, produces hydrogen sulphide (H2S), due to the presence of sulphate reducing bacteria (SRB), that reduces sulphate from seawater to sulphide. The massive production of H2S is presently one of the main problems in the petroleum industries, constituting one of the main causes of corrosion in production lines (dutes), equipments and tanks. The main microbial species found in this type of saline samples comes from water and oil storage tanks in the petroleum industry, being general anaerobic heterotrophic bacteria (GAHB) and sulphate reducing bacteria (SRB). Presently, the quantification of those microbial groups is made through a technique known as Most Probable Number (MPN). This quantification is obtained in around 28 days. In the present work a methodology based on the semi-continuous production of sulphide during 15 days was conducted, in an attempt to correlate these results with the quantification of GAHB and SRB cells through conventional MPN technique. In this case, the most suitable conditions for biogenic sulphide production in tanks, was studied through the evaluation of environmental parameters such as salinity, temperature and culture medium composition. It could be observed that an increase in salinity and temperature of the medium produced a marked decrease in the semi-continuous biogenic production of sulphide. In relation to the culture medium, its dilution promoted a decreased in cell growth, consequently in the production of sulphides. The quantification of SRB and GAHB was evaluated through the MPN technique, according to procedures suggested by FDA in 2011 and Harrigan in 1998. It was observed that this last procedure underestimated the microbial population, due to the lack of information about limits and standard deviations

Neste trabalho foram estudados os fenômenos fotoinduzidos apresentados pelos vidros calcogenetos de composições: Ga IND.10Ge IND.25S IND.65 e Ga IND.5Ge IND.25As IND.5S IND.65. Estes vidros ao serem iluminados com luz que possui energia próxima a do bandgap apresentam vários fenômenos fotoinduzidos. Sendo assim um estudo sistemático em função da potência, tempo de iluminação e do comprimento de onda foi efetuado. Para energias acima da banda proibida ocorre a fotoexpansão, variação do índice de refração e fotoclareamento. Por outro lado, para energias abaixo da banda proibida não foi observada nenhuma variação do volume; no entanto foi detectado um fotoescurecimento. Estes fenômenos mostraram ser irreversíveis, visto que ao serem levados a tratamento térmico a temperatura próxima a temperatura de transição vítrea, os vidros não recuperaram sua forma original. Várias técnicas experimentais foram usadas tais como: microscopia de força atômica, perfilometria, espectro de absorção óptica, espectroscopia na região do infravermelho, espalhamento Raman, EDX, EXAFS e RBS para caracterização dos fenômenos fotoinduzidos e elucidar o mecanismo envolvido. Os resultados obtidos a partir de EXAFS, Infravermelho, RBS e EDX indicaram a incorporação de oxigênio na superfície dos vidros quebrando assim as ligações Ge-S. Foi observado que a magnitude da fotoexpansão depende da atmosfera usada durante a irradiação. Um estudo comparativo entre o vidro e o filme depositado foi realizado. Foi mostrado através de espalhamento Raman e Infravermelho que os tipos de ligações presente no filme depositado é diferente daquela do vidro original. Os mesmos fenômenos fotoinduzidos foram também detectados nos filmes depositados, os quais foram estudados e caracterizados também de maneira sistemática. Como aplicação destes fenômenos fotoinduzidos, a fotoexpansão foi usada para a produção de redes de difração. ) As medidas de eficiência de difração e as imagens de microscopia de força atômica demonstraram que a fotoexpansão cria uma rede de relevo na superfície do vidro / We report the photoinduced phenomena observed in two chalcogenide glass compositions: Ga IOGe2SS6eSGasGe2sAssS6s. These glasses present several photoinduced phenomena when exposed to light having energy comparable to bandgap energy. Systematic study has been carried out in function of power density, exposure time and wavelength. Samples exposed to energy above the bandgap the photoexpansion, photorefraction and photobleaching has been observed. Otherwise, to energy below the bandgap a photodarkening was detected without volume variation. These phenomena are irreversible since the surface does not restore the original structure when annealing to the glass transition temperature. To Characterize and understand the mechanism processes of the photoexpansíon effect, atomíc force mícroscopy, perfilometry, absorption spectra, ínfrared absorption, Raman, EDX, EXAFS and RBS has been used before and after illumination of the glass samples. The EXAFS, infrared, RBS and EDX data showed that íllumínatíon leads to an introduction of oxygen ín the glass structure breaking Ge-S intermolecular bonds followed by the formatíon of Ge-O bonds. We observed that the magnitude of the photoínduced expansíon of the GaGeS glass ís strongly dependent on the atmosphere used. Comparative study has been performed between glass and filmo Infrared and Raman data shown a different bonding behavior ín the film prepared prevíously from the glass. Under irradíation, the same photoínduced phenomenon already detected on the glass samples are observed on the thin film and also characterized systematically. As applícation of the photoinduced phenomenon, photoexpansíon effect has been used to produce díffraction gratíngs. Atomic mícroscopy images and diffractíon efficiency data indícate that photoexpansíon leads to relíef gratíng on the glass surface

O H2S é um gás que causa preocupação devido aos efeitos que pode provocar a saúde, a corrosão sobre alguns materiais e a redução do poder calorífero no aproveitamento de biogás, mesmo quando presente em baixas concentrações. O uso de biogás como fonte energética tem crescido nos últimos anos, impulsionando a remoção do sulfeto de hidrogênio, uma vez que a presença de tal gás reduz a capacidade calorífica do biogás e causa danos às instalações. Diante disso, várias técnicas são utilizadas na remoção de H2S, sendo uma delas, a adsorção. Os processos de separação por adsorção são muito utilizados para a remoção de poluentes gasosos de misturas gasosas. Neste trabalho foram realizados experimentos da adsorção do H2S sobre lodo seco, em coluna de leito fixo, para obtenção da capacidade de adsorção dinâmica do lodo e como esta seria afetada pelas variáveis de processo: concentração de alimentação e vazão de alimentação. Para tanto, foi concebida e instalada uma unidade de bancada de adsorção em leito fixo, com facilidades experimentais necessárias para testes dinâmicos, com o emprego da técnica de interpretação de curvas de efluência, um método útil para a avaliação do desempenho de um adsorvente em colunas de leito fixo. Testes preliminares mostraram que a unidade de bancada apresentou versatilidade, podendo ser operada com vazões de até 5 L/ min e concentração de H2S na mistura gasosa de até 500 ppm. Os resultados obtidos mostraram que a capacidade de adsorção do lodo seco foi muito baixa, com valores variando de 3,30 x 10-5 a 2,54 x 10-3 mg de H2S/g de lodo seco e existência de caminhos preferenciais no leito. / It is widely known that H2S is a gas which causes preoccupation due to the potential risks to health, corrosion in materials and reduction of the calorific value, even when present in low concentrations. The application of biogas as an energetic source has increased in last years, promoting the hydrogen sulphide removal, so that H2S presence can reduce the biogas energetic capacity and cause damage in the installations. Therefore, many techniques are used to H2S removal, one them is adsorption. The adsorption separation processes are widely used in the removal of pollutants gaseous from gas mixtures. In this work, experiments were performed on the adsorption of H2S the dry sludge in a fixed bed column, aiming to obtain the dynamic adsorption capacity and how this would be affected by the process variables: feed concentration and feed flow rate . For that, we designed and installed a bench unit to fixed bed adsorption with necessary experimental facilities for dynamic tests with the use of the technique of interpretation breakthrough curves, an useful method for evaluating the performance of an adsorbent columns fixed bed . Preliminary tests showed that the bench unit has presented versatility and efficiency and it can be operated at flow rates up to 5 L/min and H2S concentration in the gas mixture up to 500 ppm. The results showed that the adsorption capacity of the dried sludge was very low , with values varied from 3.30 × 10-5 to 2.54 × 10-3 mg H2S/g of dry sludge and the existence of preferential paths in the bed .

Orientador: Marise Aparecida Rodrigues Pollonio, Sílvia Tondella Dantas / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-26T00:03:06Z (GMT). No. of bitstreams: 1 Dantas_FiorellaBalardinHellmeister_D.pdf: 14117695 bytes, checksum: 4532bc383166205549d251332c6b58f3 (MD5) Previous issue date: 2014 / Resumo: Neste trabalho estudaram-se os parâmetros promotores da sulfuração negra em produto cárneo em conserva na busca de estratégias tecnológicas para reduzir ou evitar sua ocorrência. Na primeira parte do trabalho foram avaliados os parâmetros de processamento e embalagem que promovem a sulfuração negra em carne bovina em conserva (corned beef) acondicionada em latas de aço determinando-se assim quais são os aspectos a serem controlados na condição atualmente utilizada nas plantas de processamento do produto. Em seguida avaliou-se a composição das manchas negras formadas e a exposição do aço base, que permitiram verificar que a presença da mancha de sulfuração negra estava sempre associada à exposição metálica, principalmente na região de recravação onde há maior solicitação mecânica do verniz. Esse fato indicou que apesar da possibilidade de permeação dos íons de enxofre pelo verniz, para a reação ocorrer há necessidade de falha na camada de verniz em qualquer região da lata. Verificou-se também que as manchas eram compostas de aminoácidos e outros componentes do produto, assim como carbono e oxigênio, mostrando a influência do processo de acondicionamento do produto na ocorrência da sulfuração negra. Foram avaliadas também as possibilidades de adição de zinco à formulação do produto e do verniz epóxi fenólico alumínio, as quais permitiram verificar que o tratamento térmico de 125 ºC por 65 min combinado com concentração de zinco de 10 mg.kg-1 foi o que apresentou menor incidência de sulfuração na tampa e indicaram que a utilização de verniz interno epóxi fenólico com alumínio mais 6% de zinco é uma opção na prevenção da reação de sulfuração negra. Por fim, através de solução modelo, avaliou-se a influência da adição de agente quelante (EDTA ¿ sais do ácido etilenodiamino tetracético) no produto. Os resultados obtidos na quarta e última parte deste trabalho mostraram que a adição de EDTA à solução catalisadora foi eficiente quanto à prevenção da reação de sulfuração negra, porém há necessidade de estudos futuros para determinação da concentração adequada e avaliação de sua influência na ação do nitrito de sódio em relação à cor e à segurança alimentar / Abstract: The present work studied the parameters that promote sulfide black in corned beef in order to find technological strategies to reduce or prevent its occurrence. Firstly, it was evaluated the packaging and processing parameters that promote sulfide black in corned beef and determined which aspects that should be controlled in the condition currently used in product processing plants. Then, it was evaluated the composition of the black spots and iron exposure which allowed to verify that the black stain was always associated with the metal exposure, since most of the cans exhibited stain along the double seam. This fact indicated that despite the possibility of permeation of sulfur ions through the lacquer to the reaction occurrence a fail in the coating layer is required in some can region. It was also verified that the black stain was comprised of amino acids and other components coming from the product, including carbon and oxygen, showing the effect of the packaging process in the occurrence of sulfide black. The influence of the addition of zinc in canned meat product and in the internal lacquer of the package was also evaluated to prevent the reaction. The results showed that the heat treatment of 125 ºC/65 min with zinc concentration of 10 mg.kg-1 presented the lowest incidence of spots in the lids, furthermore the results suggest the use of lacquer epoxy phenolic with aluminium and 6% of zinc as an option in the sulfide black prevention. Finally, using model solution it was evaluated the influence of EDTA (ethylenediaminetetraacetic acid salts) addition in canned meat product. Results suggest the use of EDTA as an option in the sulfide black prevention, but future studies using the product are necessary to determine the appropriate concentration and assessment of their influence on the action of sodium nitrite in relation to color and food safety / Doutorado / Tecnologia de Alimentos / Doutora em Tecnologia de Alimentos