Navegando por Autor "Mendes, Gabriela Paupitz"

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Characterization and partitioning behavior of creosote in different matrices: soil, water, and air
(Water, Air, and Soil Pollution, 2020-07-24) Chiavone Filho, Osvaldo; Aranha, Rayanne Macêdo; Magalhães, Vivian Maria de Arruda; Mendes, Gabriela Paupitz; Soares, Lélia C. R.; Barbosa, Alexandre Muselli; Nascimento, Cláudio Augusto Oller do; Vianna, Marilda M. G. R.
Creosote is a multicomponent oil classified as a dense non-aqueous phase liquid (DNAPL) produced from coal tar distillation. The concept of phase distribution is critical in decision-making to remediate contaminated sites. The creosote mass transfer between sorbed, aqueous, vapor, and DNAPL phases is controlled by physicochemical characteristics, geology of the site, and environment conditions. This study evaluated phase distribution of the main polycyclic aromatic hydrocarbons (PAHs) of creosote in a sandy soil with low organic matter content. The creosote was collected from a contaminated site in São Paulo, Brazil, and was characterized by gas chromatography–mass spectrometry (GC-MS). Clean soil was collected upgradient from the same area. Initially, the soil was artificially contaminated with creosote. After, the contaminated soil was put in contact with clean water in sealed vials for 72 h. Samples of the soil, vapor, and liquid phases were collected and analyzed by GC-MS. In total, 50 compounds were identified in the creosote, and 9 PAHs were selected to be studied, which represented around 30% of total creosote mass. The major contaminant concentration was detected in the sorbed phase. For instance, naphthalene mass was distributed in sorbed (33.0%), DNAPL (1.5%), aqueous (3.4%), and vapor (0.2%) phases. The results provided an understanding of the contaminant species partitioning that occurs in a real contaminated site
Clay-based catalyst synthesized for chemical oxidation of phenanthrene contaminated soil using hydrogen peroxide and persulfate
(Elsevier, 2020-04) Chiavone Filho, Osvaldo; Magalhães, Vivian Maria de Arruda; Mendes, Gabriela Paupitz; Costa Filho, José Daladiê Barreto da; Cohen, Renato; Partiti, Carmem S. M.; Vianna, Marilda M. G. Ramos
Hydrocarbon contaminated sites are a critical issue. Soil is a complex substrate and its heterogeneity makes soil remediation a difficult task. Studies involving in situ chemical oxidation focusing on soil remediation are scarce in literature. Heterogeneous catalysts for oxidation process can be supported in clays. In this work, different claybased catalysts were synthesized. Concentrations of sodium hydroxide (NaOH), ferrous sulfate (FeSO4), and ferric sulfate (Fe3(SO4)2) were varied in accordance with a 23 experimental design. Modified clay catalysts (MCC) were applied in oxidation assays of phenanthrene (PHE) contaminated soil to evaluate the activation of two oxidants: sodium persulfate (SP) and hydrogen peroxide (HP). The experimental design response was the PHE removal. Most of the catalysts proved to be efficient in activating both oxidants and achieved around 80 % of PHE removal. Control assays showed that around 20 % of PHE can be naturally transferred from soil to the liquid phase. PHE removal did not occur during oxidation with raw clay (RC). The highest PHE removal was obtained using MCC 16 with HP, reaching 83 %. XRF analysis of MCC 16 indicated an increase of 160 % in iron content and the Mössbauer spectroscopy showed higher values of relative Fe3+ doublet area for MCC 16 than for RC. BET surface area measurements and scanning electron microscopy analysis suggested the impregnation of iron minerals on the MCC 16 surface. The catalyst proposed in this study can be applied in both in situ or ex situ remediation circumstances, reducing the environmental effects of organic contaminants
Tratabilidade de solo contaminado com naftaleno através de oxidação química: análises da fase sorvida, aquosa e vapor
(2018-07-23) Mendes, Gabriela Paupitz; Chiavone Filho, Osvaldo; Vianna, Marilda Mendonça Guazzelli Ramos; ; ; ; Lima, Andressa Bastos da Mota; ; Silva, Douglas do Nascimento;
A contaminação do solo por hidrocarbonetos policíclicos aromáticos (HPAs) é um assunto cada vez mais discutido. O naftaleno (NAP) é um HPA e está entre os 16 poluentes prioritários listados pela Agência de Proteção Ambiental dos Estados Unidos (USEPA). Os processos oxidativos avançados podem ser aplicados para remediação das áreas contaminadas com HPAs através do uso de agentes oxidantes, como o persulfato. Esse oxidante pode sofrer ativação alcalina ou por íons de ferro, entre outras formas. O objetivo desse trabalho foi a avaliação de ensaios de tratabilidade através da aplicação de oxidação química em solo arenoso artificialmente contaminado com naftaleno. Foram feitas extrações sólido-líquido e líquido-líquido das fases sorvida e aquosa, respectivamente, segundo métodos da USEPA. As amostras coletadas foram analisadas por cromatografia gasosa acoplada à espectrometria de massa (GC-MS). A fase vapor também foi coletada e analisada no GC-MS. A partir dos ensaios realizados de acordo com planejamento fatorial 2³ + 3 pontos centrais, foi possível obter as condições ótimas para a reação em estudo: [PS] = 18,37 g L -1 ; [FeSO4] = 4,25 g L -1 ; e pHinicial = 3,00. O percentual de degradação atingido foi de 82,61±1,19%. Mais de 60% do NAP no sistema foi transferido para a fase vapor, no início do processo. Ao final da reação, mais de 99% do NAP presente no vapor foi removido. Em relação à concentração de NAP no solo, foi possível atingir níveis abaixo do valor de intervenção estipulado pela Companhia Ambiental do Estado de São Paulo (CETESB). Os ensaios cinéticos foram ajustados adequadamente a um modelo de primeira ordem, indicando que o tempo de degradação é diretamente proporcional à concentração de NAP no sistema.
Treatability studies of naphthalene in soil, water and air with persulfate activated by iron(II)
(Elsevier, 2020-04) Chiavone Filho, Osvaldo; Mendes, Gabriela Paupitz; Magalhães, Vivian M. A.; Soares, Lélia C. R.; Aranha, Rayanne Macêdo; Nascimento, Cláudio Augusto Oller do; Vianna, Marilda M. G. Ramos
Chemical oxidation was applied to an artificially contaminated soil with naphthalene (NAP). Evaluation of NAP distribution and mass reduction in soil, water and air phases was carried out through mass balance. Evaluation of NAP distribution and mass reduction in soil, water and air phases was carried out through mass balance. The importance of the air phase analysis was emphasized by demonstrating how NAP behaves in a sealed system over a 4 hr reaction period. Design of Experiments method was applied to the following variables: sodium persulfate concentration [SP], ferrous sulfate concentration [FeSO4], and pH. The system operated with a prefixed solid to liquid ratio of 1:2. The following conditions resulted in optimum NAP removal [SP] 1⁄4 18.37 g/L, [FeSO4] 1⁄4 4.25 g/L and pH 1⁄4 3.00. At the end of the 4 hr reaction, 62% of NAP was degraded. In the soil phase, the chemical oxidation reduced the NAP concentration thus achieving levels which comply with Brazilian and USA environmental legislations. Besides the NAP partitioning view, the monitoring of each phase allowed the variabilities assessment over the process, refining the knowledge of mass reduction. Based on NAP distribution in the system, this study demonstrates the importance of evaluating the presence of semi-volatile and volatile organic compounds in the air phase during remediation, so that there is greater control of the system as to the distribution and presence of the contaminant in the environment. The results highlight the importance of treating the contaminant in all its phases at the contaminated site

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Navegando por Autor "Mendes, Gabriela Paupitz"