Adsorção e fotodegradação de corantes, amarelo crepúsculo e azul brilhante, para tratamento de efluentes de indústrias alimentícias
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2013-04-26
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Universidade Federal de Goiás
Resumo
Effluents that are discarded by food industry are important sources of water
pollution, as they may contain high concentrations of organic matter and intense
color. We used the technique of design of experiments to evaluate the influence of
some variables in the study of adsorption of food colors, sunset yellow and brilliant
blue. The “batch” method was used to assess the effects of variaable: contact
time, pH0 and concentration of the adsorbate in the adsorption process of colors
in hydroxide double layered system CaAl-LDH-NO3. The LDH was synthesized by
coprecipitation at pH variable and characterized by X-ray diffraction, infrared spectroscopy,
electron microscopy scanning thermogravimetric analysis, zeta potential,
surface area and pore volume. adsorption assays were performed as a function of
contact time, pH0, dye concentration and temperature. Results showed that the pH
affects the surface charge of the adsorbent and the degree of dissociation of the
anionic dyes. Among the initial pHs (4 and 10) for sunset yellow and (6 and 10)
to brilliant blue, as the pH0 increases, decreases the amount of dye removed. Langmuir
equation was that more adequately described the equilibrium data, obtaining
a maximum adsorption of 398.41 mg/g for sunset yellow and 108.23 mg/g for brilliant
blue. In the process of photodegradation by direct photolysis using ultraviolet
radiation, the efficiency of decolourisation percentages reached 98 % for the yellow
dye twilight and 97 % to bright blue. The absorbance spectra for two samples
of colorants showed a decrease of characteristic absorption bands of these materials
throughout the irradiation time. The photodegradation was also performed on
solid after adsorption, the visually observable discoloration of the material and confirming
the degradation process by XRD. Adsorption, and photodegradation were
effective also in the treatment of synthetic effluent (mixture the dyes sunset yellow
and brilliant blue), presenting virtually the same kinetics observed for removing
discoloration of dyes individually.
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SÁ, F. P. Adsorção e fotodegradação de corantes, amarelo crepúsculo e azul brilhante, para tratamento de efluentes de indústrias alimentícias. 2013. 109 f. Tese (Doutorado em Química) - Universidade Federal de Goiás, Goiânia, 2013.