Adsorção do herbicida glifosato utilizando argila bentonita: avaliação experimental e modelagem matemática

• Ano de defesa: 2025
• Autor(a) principal: Xavier, Cinthia Sany França
• Orientador(a): Vieira, Fernando Fernandes
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso embargado
• Idioma: por
• Instituição de defesa: Universidade Estadual da Paraíba
• Programa de Pós-Graduação: Programa de Pós-Graduação em Ciência e Tecnologia Ambiental - PPGCTA
• Departamento: Pró-Reitoria de Pós-Graduação e Pesquisa - PRPGP
• País: BR
• Palavras-chave em Português: Remoção de pesticidas; Cinética de adsorção; Isotermas de equilíbrio; Coluna de leito fixo
• Área do conhecimento CNPq: ENGENHARIAS
• Link de acesso: https://repositorio.uepb.edu.br/handle/123456789/72150

Contamination of natural and wastewater by herbicides such as glyphosate has become one of the major environmental challenges of modern society. Although its use is targeted, glyphosate application can lead to soil and water pollution, resulting in environmental degradation, public health risks, and ecological imbalances. In this context, the aim of this study was to evaluate the removal of glyphosate from aqueous solutions through adsorption processes, conducted in both batch systems and fixed-bed columns, using bentonite clay in its natural and calcined forms. Clay preparation involved washing, drying, manual grinding, calcination at 500 °C, and sieving through a MESH 100 screen. In the batch adsorption experiments, the effects of solution pH, adsorbent mass, contact time, and initial adsorbate concentration were investigated. The study also included an analysis of adsorption kinetics and equilibrium using isotherm models. For fixed-bed adsorption, a 2³ factorial experimental design was employed to assess the influence of initial pollutant concentration (Co), bed mass (M), and flow rate (Q) on saturation time (tsat) and adsorption capacity (qsat). Results showed that the points of zero charge (pH_PZC) for the natural and calcined clays were 6.77 and 4.12, respectively. Adsorption was more efficient at pH 4 for natural clay and at pH 6 for calcined clay. In the batch experiments, adsorbent mass did not have a significant effect on glyphosate removal by natural clay, considering the response variable % removal. Adsorption equilibrium was reached within 30 minutes, and the pseudo-second-order model best described the kinetic behavior of the process. The Langmuir isotherm provided the best fit for the equilibrium data. In fixed-bed experiments, shorter saturation times (tsat) were observed with increasing Co and Q, and decreasing M. The adsorption capacity (qsat) increased with higher Co and lower Q and M. Among the evaluated analytical models, the Yan model best represented the breakthrough curve behavior. In summary, both batch and fixed-bed adsorption systems showed strong potential as advanced treatment alternatives for water and effluents contaminated with glyphosate.