Síntese e caracterização de nanoquitosanas magneticas por sonoquímica e sua aplicação na remoção de azo compostos

Abstract

Magnetite chitosan were prepared inone quick step using different proportions of chitosan by co-preciptation combined with ultrasonication. After synthesis, the materials were modified with glutaraldehyde and epichlorohydrin. The samples were characterized by Transmission Electron Microscopy (TEM), X-Ray Powder Diffraction (XRPD), Fourier Transform Infrared (FTIR) Spectroscopy, Thermal Gravimetric Analysis (TGA) and the magnetic behavior was studied by Vibrating Sample Magnetometer (VSM) and curves of the ZFC_FC. Then caracterization of the samples, the nanocomposites were applied as adsorbent of the dyes reactive black 5 and methil orange. The incorporation of magnetic nanoparticles (NPMs) in the matrix of chitosan was also confirmed by FTIR and TGA techniques. The identification of the system was realized by XRPD and the results showed that the cristaline fase present in all the nanocomposites is magnetite, presenting an average crystallite size ranging r from 11 to 14 nm. TEM images allowed to identify spheroidal morphology nanoparticles with average diameter between 10 and 24 nm. The samples presented superparamagnetic behavior and saturation magnetization real (Msr) range from 57 to 73 emu. g -1 and d which had a block temperature below room temperature. From the adsorption results for azo dyes can be seen that the samples modified with glutaraldehyde and epichlorohydrin have a pH optimum adsorption egual 4. From the adsorption isotherms was possible to verify that the crosslinking reactions decrease the maximum adsorption capacity the nanocomposite unmodified. The kinetic study showed that the kinetic model pseudossegunda order is the most fitting to describe the behavior of the experimental behavior of the samples. Through adsorption isothems was observed that the modification with glutaraldehyde and epichlorohydrin decrease the maximum adsorbed amount relative to the unmodified material. Thus This new synthetic route by the aid of ultrasound has a great potential to replace the strategies traditionally employed for obtaining this material or other nanocomposites. Based on these results, can be seen that the new synthetic route with the assistance of ultrasonic irradiation has great potential to replace strategies traditionally used for obtaining this material or other nanocomposites, since the strategy used reduces the synthesis time for minutes, improves dispersion of the magnetite in the chitosan matrix and produces nanocomposites with good coloring rise adsorption capacity and high saturation magnetization.