Desenvolvimento de métodos analíticos visando a especiação de ferro em águas com detecção por imagens digitais
Data
2021-08-20
Autores
Lima, Leon de Oliveira 
Orientadores
Naozuka, Juliana
Tipo
Dissertação de mestrado
Título da Revista
ISSN da Revista
Título de Volume
Resumo
A determinação da concentração de Fe é uma importante informação para avaliação da qualidade da água. As propriedades organolépticas da água, tais como cor e sabor podem variar em função da concentração de Fe, além de ocasionar problema de desenvolvimento de depósitos em canalizações e aparecimento de bactérias associadas a Fe(II), chamadas de ferro-bactérias, provocando a contaminação biológica da água na própria rede de distribuição. Por estes motivos, o Fe constitui um padrão de potabilidade, tendo sido estabelecida a concentração limite de 2,4 mg L-1 na Portaria 2.914 do Ministério da Saúde. No Estado de São Paulo, estabelece-se o limite de 15 mg L-1 para a concentração de ferro solúvel (Fe(II)) em efluentes descarregados na rede coletora de esgotos seguidos de tratamento. É importante identificar as espécies de Fe em ambientes aquáticos, principalmente as espécies com diferentes estados de oxidação, uma vez que apresentam diferentes biodisponibilidades e podem alterar propriedades físico-químicas e toxicológicas de outros elementos e substâncias orgânicas no meio. Desta forma, estudos de especiação química são de suma importância e, portanto, o presente trabalho visou desenvolver métodos para a determinação da concentração total de Fe e das espécies inorgânicas de Fe (Fe(II) e Fe(III)) em amostras de águas naturais (doce, subterrânea, de mar e mineral), após reações de complexação e óxido-redução, e utilizando imagens digitais adquiridas por smartphone. O uso de imagens digitais permitiu a quantificação em água de torneira, pois não foram observadas interferências, com recuperações de 108 e 98 %, após derivatização com tiocianato ou fenantrolina, respectivamente. Os resultados mostraram que as concentrações de Fe total e inorgânico ficaram abaixo do limite de detecção (LOD), após complexação com tiocianato (0,0130 mg L-1) ou com fenantrolina (0,0272 mg L-1), utilizando imagens digitais. Por fim, ficou evidenciado que as concentrações de Fe nas amostras estiveram abaixo do limite máximo permitido para águas naturais (1 mg L-1), de acordo com a norma estadual e do limite de padrão de potabilidade para consumo humano (2,4 mg L-1) pela norma nacional vigente. Assim, as principais vantagens no uso de imagens digitais são praticidade, rapidez, baixo custo, minimização do uso de reagentes e na geração de resíduos, e possibilidade de portabilidade.
The determination of the concentration of Fe is important information for the assessment of water quality. The organoleptic properties of water, such as color and flavor, can vary depending on the Fe concentration, in addition to causing a problem with the development of deposits in pipes and the appearance of Fe(II)-associated bacteria, called iron-bacteria, causing contamination biological water supply in the distribution network itself. For these reasons, Fe constitutes a standard for potability, having established the threshold concentration of 2.4 mg L-1 at 2.914 Ordinance of the Ministry of Health. In the State of São Paulo, establishes the limit of 15 mg L-1 for the concentration of soluble iron (Fe (II)) in effluents discharged into the sewage system followed sewage treatment. It is important to identify Fe species in aquatic environments, especially species with different oxidation states, since they have different bioavailability and can alter physicochemical and toxicological properties of other elements and organic substances in the environment. Thus, chemical speciation studies are of paramount importance and therefore the present study intends to develop methods for the determination of the total concentration of Fe and inorganic species of Fe (Fe (II) and Fe (III)) in water samples natural (sweet, underground, sea and mineral), after complexation reactions and oxidation-reduction, using digital images acquired by smartphone. The use of digital images permitted quantitation in tap water, were observed as interference with recoveries of 108 and 98 % after derivatization with thiocyanate or phenanthroline, respectively. The results showed that total and inorganic Fe concentrations were below the detection limit (LOD) after complexation with thiocyanate (0,0130 mg L-1) or with phenanthroline (0,0272 mg L-1) using digital images. Finally, it was evidenced that the Fe concentrations in the samples were below the maximum limit allowed for natural waters (1 mg L-1), according to the state standard and the standard limit for potability for human consumption (2,4 mg L-1) by the current national standard. Thus, the main advantages of using digital images are practicality, speed, low cost, minimization of the use of reagents and waste generation, and the possibility of portability.
The determination of the concentration of Fe is important information for the assessment of water quality. The organoleptic properties of water, such as color and flavor, can vary depending on the Fe concentration, in addition to causing a problem with the development of deposits in pipes and the appearance of Fe(II)-associated bacteria, called iron-bacteria, causing contamination biological water supply in the distribution network itself. For these reasons, Fe constitutes a standard for potability, having established the threshold concentration of 2.4 mg L-1 at 2.914 Ordinance of the Ministry of Health. In the State of São Paulo, establishes the limit of 15 mg L-1 for the concentration of soluble iron (Fe (II)) in effluents discharged into the sewage system followed sewage treatment. It is important to identify Fe species in aquatic environments, especially species with different oxidation states, since they have different bioavailability and can alter physicochemical and toxicological properties of other elements and organic substances in the environment. Thus, chemical speciation studies are of paramount importance and therefore the present study intends to develop methods for the determination of the total concentration of Fe and inorganic species of Fe (Fe (II) and Fe (III)) in water samples natural (sweet, underground, sea and mineral), after complexation reactions and oxidation-reduction, using digital images acquired by smartphone. The use of digital images permitted quantitation in tap water, were observed as interference with recoveries of 108 and 98 % after derivatization with thiocyanate or phenanthroline, respectively. The results showed that total and inorganic Fe concentrations were below the detection limit (LOD) after complexation with thiocyanate (0,0130 mg L-1) or with phenanthroline (0,0272 mg L-1) using digital images. Finally, it was evidenced that the Fe concentrations in the samples were below the maximum limit allowed for natural waters (1 mg L-1), according to the state standard and the standard limit for potability for human consumption (2,4 mg L-1) by the current national standard. Thus, the main advantages of using digital images are practicality, speed, low cost, minimization of the use of reagents and waste generation, and the possibility of portability.