Síntese e caracterização de Zeólita NaY, e sua modificação com cobre, na adsorção de SO2 sintético

Abstract

Sulfur dioxide (SO2) is one of the main pollutants in the atmosphere, which contributes to global warming and causes a decrease in the pH of rainfall, which can cause environmental imbalances and degrade some monuments and buildings due to acidity. Most of the SO2 in the air comes from the burning of fossil fuels and industrial processes. Thus, the control of the emission of this gas has been investigated in order to reduce its concentration in the atmosphere and to avoid the harmful effects of the excess of this compound in the environment. One of the alternatives for this control is the use of FAU type zeolites (Faujasite) as a selective SO2 adsorbent. Zeolites can be found in nature or can be synthesized, however, the natural zeolites have impurities and limit their use in industrial processes, in this way, we seek ways to synthesize and perfect these zeolites for a better application as selective adsorbents. From this, the objective of the work was to synthesize the zeolite type NaY by the hydrothermal route from the sodium aluminate, colloidal silica, sodium hydroxide and water, maintained at 80 ºC and for 24 h in the greenhouse, followed by its modification with the Cu2+ ions and observation of the efficacy of the adsorbent formed. After the synthesis of the zeolite NaY, the ion exchange was performed with the copper (II) chloride, replacing Na+ ions with Cu2+ ion. The materials prepared were characterized by several physicochemical techniques, such as: Scanning Electron Microscopy coupled to an Energy Dispersion Spectrometer (SEM-EDX), X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), adsorption / desorption analysis of N2 and inductively coupled plasma atomic emission spectroscopy (ICP-OES). The SO2 adsorption tests with the synthesized and characterized adsorbents were performed by percolation in a fixed bed experimental system, using volumetric methods for the quantitative analysis of SO2 adsorbed. A great potential of the use of the synthesized zeolites and their respective ionic exchanges for SO2 separation was observed, since they had the better capacity of bed than the commercial zeolite; highlighting commercial CuY zeolites which increased almost 13 times their retention capacity when compared to commercial NaY zeolites.