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Adsorção do glifosato utilizando materiais naturais e resíduos industriais: equilíbrio e cinética

2025-10-15T13:05:49Z

Title: Adsorção do glifosato utilizando materiais naturais e resíduos industriais: equilíbrio e cinética Author: Bertolo, Jéssica Piovesan First advisor: Cabrera, Liziara da Costa Abstract: Contamination of water bodies by glyphosate, one of the most widely used herbicides in agriculture, and its main metabolite AMPA, represents an environmental and public health concern. In this study, the removal of these compounds by adsorption was investigated using natural materials and modified industrial waste. Different materials were evaluated, including slag, bag filter smoke and sand from the foundry industry, as well as clinoptilolite zeolite and activated carbon of commercial origin. The modification of the materials was performed by immersion in solutions of different reagents such as CuSO₄, SDS, AgNO₃, Fe(NO₃)₃, CTAB and ZnO. The comparative study of materials with and without modification was developed by analyzing the effect of solution pH and chemical modification of the materials on glyphosate removal. The material with the highest removal was selected for dosage (0.625, 1.25, 2.5, 2.5, 5.0, 10, 25 g L-1), kinetics (0.17, 0.5, 1, 2, 4, 8, 16, 24, 36, 54 and 72 h) and isotherm (0.25, 0.5, 1.0, 1.5, 2.5, 5.0 and 7.5 mg L-1) studies. The adsorption studies were carried out in a batch system, volumes of 40 mL and temperature of 25 °C. Transmittance analyses were performed by Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) with EDS microprobe, BET analysis and determination of Zeta Potential (ZP). The determination coefficient (r2), correlation coefficient (r) and chi-square (χ2) were used to determine the calibration curve and adjust the kinetic and equilibrium models. In the study of adsorption between different materials with and without treatment, the bag filter smoke in its natural form (without modification) showed the best performance (100% removal). The experiments demonstrated that the removal of glyphosate by smoke was not influenced by pH, reaching 100% removal under the conditions tested (pH 4, 7 and 10), with a quantification limit of the analytical method of 0.025 mg L⁻¹. In the dosage study, using an initial glyphosate solution of 5 mg L⁻¹, removal was total for a smoke dosage of 25 g L⁻¹ and reached 87.91% for a dosage of 1.25 g L⁻¹. This last concentration was considered the most viable, balancing efficiency and lower material consumption, in accordance with water potability standards. Adsorption reached equilibrium after 8 hours of contact, with a maximum capacity of 5.39 mg g⁻¹. The process kinetics followed the Avrami model, while the adsorption isotherm was best represented by the Temkin model. The quantification of glyphosate in the samples was determined by LC-MS after derivatization with FMOC-Cl. The results confirm that tobacco is highly efficient in glyphosate removal, eliminating more than 95% of an initial concentration of 5 mg L⁻¹ without the need for pH adjustment. These findings reinforce the potential of residual materials as sustainable alternatives for contaminant removal, contributing to the improvement of polluted water treatment strategies. Publisher: Universidade Federal da Fronteira Sul Type: Dissertação

Impacto dos agrotóxicos em peixes de riachos do sul do Brasil: avaliação de biomarcadores bioquímicos e fisiológicos

2025-10-15T13:03:22Z

Title: Impacto dos agrotóxicos em peixes de riachos do sul do Brasil: avaliação de biomarcadores bioquímicos e fisiológicos Author: Medeiros, Jéssica First advisor: Reynalte-Tataje, David Augusto Abstract: The use of pesticides has gradually increased over time, driven by the need to expand food production to meet population demand and reduce crop losses. However, the improper use of these compounds can lead to serious human health issues and cause environmental imbalances, with both acute and chronic effects on living organisms. Furthermore, many of these substances persist in the environment for long periods without undergoing significant degradation. This study was conducted at 36 sampling points across twelve streams within the Comandaí and Piratinim river basins, regions characterized by intense agricultural activity, with the objective of assessing the impact of pesticides on the health of two fish species. To achieve this, samples of Bryconamericus iheringii and Mimagoniates inequalis were collected and analyzed to investigate the effects of oxidative stress, acetylcholinesterase enzyme activity, and the condition factor. Additionally, water samples were examined to detect the presence of pesticides. The results indicated that sites with higher agricultural activity exhibited elevated concentrations of these compounds. Pesticides such as atrazine, azoxystrobin, and malathion were detected at different sampling points, highlighting the direct influence of agriculture on water quality. Overall, increased levels of acetylcholinesterase and lipid peroxidation, along with a decrease in the condition factor, were observed in environments with higher concentrations of these contaminants. Publisher: Universidade Federal da Fronteira Sul Type: Dissertação

Tratamento de água de abastecimento do meio rural por coagulação orgânica e dupla filtração em areia e carvão ativado granular

2025-10-15T12:25:33Z

Title: Tratamento de água de abastecimento do meio rural por coagulação orgânica e dupla filtração em areia e carvão ativado granular Author: Martins, Renata Welter First advisor: Alves, Alcione Aparecida de Almeida Abstract: Drinking water is a fundamental resource for ensuring the quality of human life, however, safe access has become a challenge, especially due to the increasing exposure to sources of pollution from inadequate discharge of industrial waste, agricultural activities and sewage, as well as the frequently reported periods of scarcity. In this sense, the investigation of new technologies and improvement of already consolidated technologies in water treatment becomes a viable and fundamental alternative to guarantee safe access to drinking water. This research presents the investigation of a new treatment configuration, the Continuous Fixed Bed Reactor (CFBR), organic post-coagulation and final disinfection in the treatment of surface water of a small rural community in the interior of Rio Grande do Sul. The research was divided into two stages: the first contemplated the pre-treatment stage, where the clarification of raw surface water was carried out with the use of an organic coagulant, the second and main stage contemplated the treatment through the CFBR. The first stage investigated the clarification of raw surface water using an organic coagulant. For this purpose, a 2³ full factorial design was employed. The maximum optimization of the independent variables coagulant dosage, agitation speed, and contact time was considered, based on the removal of the dependent variables apparent color and turbidity. In the second stage, rapid filtration was used in a double-layer granular filter in the CFBR, with layers composed of quartz sand (0.25 m) and granular activated carbon (GAC) (0.45 m) in downward flow, with final disinfection coupled to the CFBR. In this stage, the efficiency was based on meeting the potability parameters described in MS Ordinances Nº 5/2017 and Nº 888/2021, with the physical-chemical parameters being monitored: apparent color, turbidity, pH, electrical conductivity, alkalinity, and free chlorine, and microbiological parameters: total coliforms and Escherichia coli. The monitoring of the hydraulic parameters pressure drop and surface application rate (SAR) was also considered. The clarification results indicated the removal of approximately 52% of apparent color and 47% of turbidity, with an optimal coagulant dosage of 0.83 mL L-1, agitation of 245 RPM and 10 minutes of contact time, providing a favorable condition for subsequent application of the treatment in the CFBR. The results of the analysis of the physicalchemical parameters of the CFBR were subjected to statistical analysis to determine the variation between the clarified water entering the treatment and the water treated by the complete cycle, where a significant difference (p < 0.05) was observed for: free chlorine, pH, electrical conductivity, apparent color and turbidity. Furthermore, the treatment in the CFBR owes its efficiency guaranteed by meeting the potability parameters at the end of the treatment. The CFBRoperated under conditions up to the consumption of eleven bed volumes (0.03283 m³). Under these conditions, a maximum surface application rate of 165.09 m³m-2day-1 was applied, reaching a maximum head loss of 99 cm at the end of the operation. The treatment configuration investigated in this research indicated promising results for the potabilization of surface water intended for public supply, being an alternative to fill the gap of the fragility of water treatment systems in rural areas. Publisher: Universidade Federal da Fronteira Sul Type: Dissertação

Manutenção da vegetação nativa e qualidade de vida de agricultores no município de Cerro Largo, Rio Grande do Sul

2025-10-15T12:17:47Z

Title: Manutenção da vegetação nativa e qualidade de vida de agricultores no município de Cerro Largo, Rio Grande do Sul Author: Schereder, Ana Letícia First advisor: Lima, Daniela Oliveira de Abstract: Brazil has a rich biodiversity and vast areas of native vegetation that provide fundamental ecological functions. In addition to its environmental benefits, native vegetation also positively influences people's quality of life, especially in subjective and psychological aspects related to human well-being. However, in rural areas, this same vegetation can limit the area available for productive activities, which may impact the quality of life of farmers from a financial perspective. Despite this complex interaction between ecological benefits and economic challenges, the relationship between the presence of native vegetation and farmers' quality of life remains underexplored. This study aimed to understand how the presence of native vegetation influences the quality of life of farmers. A total of 43 rural properties, ranging from 10 to 20 hectares in size, were analysed and divided into two groups: those with less than 10% of native vegetation (without forest) and those with more than 30% of native vegetation (with forest). Data were collected through questionnaires addressing economic, social, environmental, and psychological aspects. The results indicated that, despite some differences, as the number of hours dedicated to a secondary occupation per week, most variables were not different between the two groups studied. This result is positive, as it suggests that both groups have a similar quality of life in economic, social, environmental, and psychological aspects, indicating that maintaining native vegetation on small rural properties is compatible with farmers' quality of life. Publisher: Universidade Federal da Fronteira Sul Type: Dissertação