Bentonita silanizada multifuncional obtida por reação ultrarrápida com aquecimento por micro-ondas

• Ano de defesa: 2019
• Autor(a) principal: Queiroga, Líbia Nayane Fernandes de
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal da Paraíba; Brasil; Química; Programa de Pós-Graduação em Química; UFPB
• Palavras-chave em Português: Bentonita; Silanização; Micro-ondas; Adsorção; Pigmentos; Bentonite; Silanization; Microwave; Adsorption; Pigments; CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA
• Link de acesso: https://repositorio.ufpb.br/jspui/handle/123456789/18939

In this work, the bentonite was silanized with 3-aminopropyltrimethoxysilane (APTMS) without solvent and with solvent in a microwave reactor. The solvent-free study was performed by varying the time at 5, 15 and 30 min. The influence of the solvent was studied using polar solvents (ethylene glycol, ethyl alcohol and isopropyl alcohol) and non-polar solvents (hexane and toluene). The subsequent reaction performed with glutaraldehyde was investigated. Infrared and 29Si NMR spectroscopies were used to monitor the immobilization process, while the degree of functionalization was calculated using elemental CHN analysis and thermogravimetric analysis. X-ray diffraction and transmission electron microscopy (TEM) were performed to evaluate changes in basal spacings. The degree of silanization of the bentonite was larger at a short reaction time. Microwave silanization allowed ultra-fast bentonite functionalization to produce a wide range of functional materials. The modified solids were used to remove Cu (II) and 5R violet reactive dye from aqueous solutions. Parameters such as mass, contact time and initial concentration of Cu (II) cations and pH, contact time and initial concentration for the dye were investigated. Copper retention occurred in the silanized solids BENT-NH2/EG and BENT-NH2/15min with a saturation time of 40 min and a maximum sorption capacity of 1.04 mmol g -1 for copper (II) and 107.4 mg L-1 for the dye. The sorption equilibrium data were adjusted using the Langmuir, Freundlich and Temkin isotherms as well as the adjustment of the experimental data to the kinetic models of pseudo-first order, pseudo-second order and Elovich. The silanized solids obtained by microwave irradiation behaved as good adsorbents for the rapid removal of Cu (II) and textile dye from aqueous solution and as antibacterial Escherichia coli and Staphylococcus aureus. New pigments were obtained based on solids modified with amino group and glutaraldehyde for oil paint formulation. Studies on the stability/photodegradation of the dye amino-imino bentonite composites were performed by using spectrophotocolorimetric analysis. Aging tests revealed the high stabilities of the prepared pigments even after 450 h of light exposure. The results suggested that the organobentonites are good adsorbents for Violet 5R dye and their resulted composites behaved as stable pigments.