Síntese, caracterizacao e aplicação de uma matriz híbrida de sílica gel organofuncionalizada com 3-aminopropiltrietoxisilano na adsorção de íons metalicos tóxicos em meio aquoso

Abstract

The array synthesized in acidic medium, via sol-gel process consists of tetraethylorthosilicateand 3-aminopropyltriethoxysilane. Investigate the feasibility of using the hybrid array on adsorption treatment of metal ions in aqueous medium. With the purpose to study the adsorption of metal ions of environmental interest. The array of organofuncionalizada silica gel with 3-aminopropyltriethoxysilane was synthesized and successfully through the characterization by elemental analysis it was possible to spot the carbon content (8.86%) and nitrogen (3.28%) and hydrogen (3.41%) anchored in the array. The use of thermogravimetric analysis enabled the study of thermal stability as well as the decomposition of group anchored in the array, and can be used in temperatures below 200ºC, in studies of adsorption of metal ions. The data obtained from the thermal analysis allowed the determination of the degree of organofunctionalization(3,55x10-3molg-1). The infrared spectroscopic analysis allowed the visualization of the characteristic vibrational movements of the silanol groups anchored and the amino group in the array. With the scanning electron microscopy it was noted that the array has rounded and flattened morphology, demonstrated the homogeneity of clusters with the average size less than 5 μ m. Analysis by x-ray diffraction showed that the array is amorphous, by presenting a band in the region of 22.5° in 2 axis θ.Thespecific area obtained by nitrogen and by the data model of Brunauer, Emmett and Teller. In preparing the array for the adsorption of ions using the ion Cd2 + as a reference for the optimization of the data obtained through the adsorption isotherms of Langmuir and Freündlich, were as featured the use of 20 mg of the array, the contact time for 30 minutes at room temperature of 25° C and the ideal pH was 5.0. The hybrid matrix presented in monolayer adsorption to selectivity in accordance with Langmuir isotherm, for presenting the correlation coefficients of the Langmuir equation near R² = 1.0000, for most ions in study. The maximum adsorption capacity of monolayer coverage (qm) were: 6.7672; 0.0966; 0.0441; 0.5066; 0.9986; 0.3140 mg g-1 array to the ions Cd2+, Pb2+, Cu2+, Cr3+, Ni2+ and Zn2+, respectively to unielementary solutions. Multielementary solutions the maximum adsorption capacity ofmonolayer coverage (qm) were 0.0941; 0.1023, 0.2854; 0.3515; 0.3127 and 0.2648 mg g-1 array to the ions Cd2+, Pb2+, Cu2+, Cr3+, Ni2 + and Zn2+, respectively.