Síntese e caracterização de poliuretano à base de óleo de Mabea fistulifera Mart. e sua utilização para remoção de corantes têxteis / Synthesis and characterization of Mabea fistulifera Mart. oil based polyurethane its use for textile dyes removal

AUTOR(ES)
FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

31/05/2011

RESUMO

Hard polyurethane polymers (PU-1, PU-2, PU-3 and PU-4) were developed in this study, obtained from polyols derived from Mabea fistulifera Mart oil. The chemical modification of the oil occurred through an in situ hydroxylation reaction employing acetic acid, hydrogen peroxide and sulfuric acid. The reaction conditions were optimized using a factorial composite central planning 22. The poliols obtained with functionality above 2.0 were considered ideal for the synthesis of the hard polyurethanes (PUs). The preparation of the polymeric materials involved polyaddition reactions of a polyol (glycerin, polyethylene glycol and polyol from M. fistulifera) and an isocyanate (TDI 80/20). The obtained PUs were analyzed by Fourier Transform Infrared Spectroscopy (FTIR) and the spectra confirmed the formation of polyurethanes through the appearance of bands that are characteristic of the NH ligations in urethanes and amide II in the 3,304 cm-1 and 1,533 cm-1 regions. The scanning electron microscopy (SEM) revealed the presence of microcells with heterogeneous shapes and sizes on the polymers surface. The PUs were also characterized by Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). The PU-3 polymer was submitted to a degradation test and proved to be susceptible to the attack of Aspergillus niger. The duration of this experiment was of 216 hours and the Halo Zone technique was used to monitor this biodegradation. The synthesized PU-3 polymer showed greater capability for the removal of dyes in aqueous solution and was used in the adsorptive tests. The studies on the adsorption of the Direct Red 80 (DR80) and Reactive Blue 21 (RB21) dyes by the PU-3 polymer included: equilibrium, kinetic and thermodynamic studies. The Langmuir and Freundlich models were used to characterize the adsorbent/dyes system. The maximum stipulated capacity using Langmuir was of 10.37 mg g-1 for the DR80 and 13.54 mg g-1 for the RB21 in conditions of the pH adjusted to 2 and at 25 oC. The adsorption process follows the pseudo-second order kinetics for both dyes. The thermodynamic parameters showed that the adsorption process is spontaneous and endothermic (positive ΔH) and favorable (negative ΔG). The developed adsorption process was applied to an actual sample of industrial effluent containing RB21 and DR80 and a removal percentage of 94.5% for the RB21 and 100% for DR80 were observed after the treatment.

ASSUNTO(S)

poliol corantes adsorção poliuretano quimica analitica polyurethane dyes adsorption polyol

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