Oxidation in Acidic Medium of Lignins from Agricultural Residues |
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Authors: | Gisele Aparecida Amaral Labat Adilson Roberto Gonçalves |
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Institution: | (1) Departamento de Biotecnologia (Debiq), Escola de Engenharia de Lorena—EEL/USP, Caixa Postal 116, 12.602–810 Lorena, SP, Brazil |
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Abstract: | Agricultural residues as sugarcane straw and bagasse are burned in boilers for generation of energy in sugar and alcohol industries.
However, excess of those by-products could be used to obtain products with higher value. Pulping process generates cellulosic
pulps and lignin. The lignin could be oxidized and applied in effluent treatments for heavy metal removal. Oxidized lignin
presents very strong chelating properties. Lignins from sugarcane straw and bagasse were obtained by ethanol–water pulping.
Oxidation of lignins was carried out using acetic acid and Co/Mn/Br catalytical system at 50, 80, and 115 °C for 5 h. Kinetics
of the reaction was accomplished by measuring the UV-visible region. Activation energy was calculated for lignins from sugarcane
straw and bagasse (34.2 and 23.4 kJ mol−1, respectively). The first value indicates higher cross-linked formation. Fourier-transformed infrared spectroscopy data of
samples collected during oxidation are very similar. Principal component analysis applied to spectra shows only slight structure
modifications in lignins after oxidation reaction. |
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Keywords: | Sugarcane bagasse Sugarcane straw Oxidation in acidic medium Chelating agents FTIR PCA |
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