Preparação e modificação química de microesferas poliméricas magnéticas à base de metacrilato de glicidila e divinilbenzeno para remoção de cromo (VI) de meio aquoso

• Autor(a) principal: Formiga, Washington Jose Fernandes
• Data de Publicação: 2017
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UERJ
• Texto Completo: http://www.bdtd.uerj.br/handle/1/15655
• topic: Magnetic microspheres; glicidyl methacrylate; divinylbenzene; chemical modification; Cr(VI) removal; Microesferas magnéticas; metacrilato de glicidila; dinivilbenzeno; modificação química; remoção de Cr (VI); CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA::QUIMICA ORGANICA::POLIMEROS E COLOIDES

In this thesis, magnetic microspheres of poly(glycidyl methacrylate-co-divinylbenzene) were produced via suspension polymerization. These microspheres were first functionalized with ethylenediamine (DEA), diethylenetriamine (DETA) and triethylenetetramine (TETA) and subsequently alkylated with methyl iodide. The concentrations of divinylbenzene (DVB) and benzoyl peroxide (BPO) in the microspheres were studied. The microspheres were characterized by thermal analysis (TGA), infrared spectroscopy (FTIR-ATR), scanning electron microscopy, vibrating sample magnetometry (VSM), particle size analyzes. Microspheres with good morphological control were obtained. This material presented mean diameters in the range of 40-135 μm and superparamagnetic behavior. The increase in DVB concentration caused a decrease in the mean diameter of the microspheres. On the other hand, the increase in DVB concentration caused an increase in the mean diameter of the microspheres. Adsorption of Cr (VI) by the amino functionalized microspheres was pH-dependent, achieving better removal results at pH 2. In the quaternized copolymers, the adsorption was poorly pH dependent. The kinetics of adsorption was analyzed by three different kinetic models, pseudo-first order, pseudo-second order and intraparticle diffusion. The adsorptive process was best described by the pseudo-second order model. The model confirmed that chemisorption is the main mechanism of adsorption control. The equilibrium isotherm study indicated the best suitability for the Langmuir model. The maximum sorption capacity was at pH 2 and 318.15 K being 82.95 mg.g-1. For all the adsorbents, activation energy was obtained in the order of 20 kJ mol-1. The adsorbents had ΔH around 40 kJ / mol and ΔS of 150 J / mol.K. The results indicated an endothermic process, of chemical nature, and with negative ΔG values