Navegando por Palavras-chave "Percarbonato De Sódio"

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    Aplicação do Percarbonato de Sódio no tratamento de efluente aquoso simulado contendo Amoxicilina utilizando processos oxidativos avançados
    (Universidade Federal de São Paulo (UNIFESP), 2020-10-29) Oliveira, Isaac Henrique Molina de [UNIFESP]; Moraes, José Ermirio Ferreira de [UNIFESP]; Universidade Federal de São Paulo
    The wastewater of the pharmaceutical industry, in many cases, contains residues of several medicines. Antibiotics, for example, are toxic substances that can trigger the growth of resistant microorganisms, leading to a serious public health problem. Advanced Oxidative Processes (AOP) have been widely studied for the treatment of this type of effluent, as they are methods based on the generation of hydroxyl radicals, a highly reactive species, able to destroy several toxic organicsseveral toxic organics. In the present work, the application of sodium percarbonate (SPC) was investigated, as a source of hydrogen peroxide, in the Fenton, photo-Fenton and UV/SPC processessource of hydrogen peroxide, in the Fenton, photo-Fenton and UV/SPC processes was investigated. Amoxicillin, which is one of the most consumed antibiotics in Brazil, was used as a model pollutant, simulating an effluent from the pharmaceutical industry, adopting an initial concentration of 100 mgC L-1. The tests were carried out in a batch system with recirculation, composed of a photochemical reactor coupled to a mixing tank. Experiments were carried out in order to evaluate the influence of the main parameters on the amoxicillin mineralization, such as pH (3 and 10), the type of iron ions source (Fe2+ and Fe3+), the initial concentration of iron ions (0.26; 1.0 and 2.0 mmol L-1) and UV radiation. According to the experimental data obtained, it was possible to observe that the application of SPC showed promising results in the oxidation of amoxicillin, showing mineralization percentages of 65.8% in just 30 minutes and 88.4% in 120 minutes of reaction, by conventional photo-Fenton process (using ions Fe2+). The use of the modified photo-Fenton process (using ions Fe3+) unfolded to be a viable alternative too, reaching a mineralization of 85.7% in 2 hours by the photo-Fenton process. The Doehlert experimental matrix was used to evaluate the modified Fenton and photo-Fenton processes (using ions Fe3+) systematically, evaluating the influence of the molar rate of the SPC solution in terms of the equivalent amount of H2O2 (0.730-2.205 mmolH2O2 min-1) and the initial concentration of ferric ions (0.26-1.56 mmol L-1) in the total organic carbon removal performance. According to the data obtained, for the Fenton process, the most favorable condition was with a high concentration of Fe3+ (1.560 mmol L-1) and a moderate SPC feed rate (1.470 mmolH2O2 min-1). In the case of the photo-Fenton process, for a better removal, low concentrations of Fe3+ (0.585 mmol L-1) and a moderate SPC feed rate (1.470 mmolH2O2 min-1) would be indicated.
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    Combinação de percarbonato e persulfato de sódio para remediação por oxidação quimica em solos brasileiros
    (Universidade Federal de São Paulo (UNIFESP), 2021) Nishikawa, Gustavo [UNIFESP]; Freitas, Juliana Gardenalli de [UNIFESP]; Universidade Federal de São Paulo
    The management of contaminated areas and the search for alternatives for the remediation of these areas brought about a constant evolution in techniques. One of the techniques developed is the use of oxidizing chemicals, in processes called In Situ Chemical Oxidation. Different types of oxidants have been applied, such as permanganates, peroxides, and persulfate, among others. The objective of this work was to evaluate the efficiency of sodium percarbonate (PCS) as an oxidizer, considering its impacts on the soil and the potential of its application in combination with sodium persulfate (PS). The chemical properties of three soils: Red Oxisols, Red Yellow Oxisols and Quartzipsamments were evaluated before and after contact with the oxidants PCS and H2O2 at 14 g L-1 and 50 g L-1, to evaluate the effects of oxidants on these soils. Given the characteristics of each oxidant, different effects were observed in the water and soil matrices such as alkaline conditions for the tests with PCS, variations in the concentrations of DO, variations in the concentrations of micro and macronutrients. The evaluation of the interaction of the PCS with the PS in the presence of soil was carried out through batch tests with the variation of the proportions between the oxidants, in which the physical-chemical properties of the solutions were evaluated over time. Another process evaluated was the efficiency of oxidants for anthracene degradation, either alone or in combination, also from batch tests. The results indicated a better efficiency of the PCS in the removal of anthracene mass, compared to the PS and the combined use of these two oxidants. The tests with the combination of these two oxidants showed, in the studies of the physical-chemical parameters, the observation of changes in the values of Eh, pH, OD, where alkaline conditions were probably explained due to the presence of the carbonate ion, OD values higher than those observed in individual processes in relation to the isolated use of PS and lower Eh values also in relation to isolated use compared to PS. Due to these observed physical and chemical changes, it is estimated that the combined use of oxidants can also, based on the characteristics imputed by the PCS (pH, OD and H2O2), promote the activation of the PS, generating a possible improvement of the oxidative process. Thus, the combination of oxidants can have potential use, but it is a complex process, especially when in the presence of soil. Thus, further studies are needed to elucidate the best conditions for remediation.