Production of a bioflocculant by Aspergillus parasiticus and its application in dye removal |
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Authors: | Deng Shubo Yu Gang Ting Yen Peng |
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Affiliation: | aDepartment of Environmental Science and Engineering, Tsinghua University, Beijing 100084, PR China bDepartment of Chemical and Biomolecular Engineering, National University of Singapore, 10 Kent Ridge Crescent, 119260 Singapore |
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Abstract: | Aspergillus parasiticus was found to produce a bioflocculant with high flocculating activity for Kaolin suspension and water-soluble dyes. Results showed that the carbon and nitrogen sources favorable for the production of the bioflocculant were corn starch and peptone, and an optimal condition of 28 °C, initial pH 5–6 and shaking speed of 150 rpm. The highest flocculating efficiency achieved for Kaolin suspension was 98.1%, after 72 h cultivation. The bioflocculant was mainly composed of sugar (76.3%) and protein (21.6%), and an average molecular weight of 3.2 × 105 Da. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectra showed that amino, amide and hydroxyl groups were present in the bioflocculant molecules. The bioflocculant was effective in flocculating some soluble anionic dyes in aqueous solution, in particular Reactive Blue 4 and Acid Yellow 25 with a decolorization efficiency of 92.4 and 92.9%, respectively. The decolorization efficiency was dependent on the flocculant dosage and solution pH. XPS result shows that the amine groups in the bioflocculant were protonated at pH 5, and thus the positive bioflocculant was attracted to the negatively charged dye molecules. The amino and amide groups in the bioflocculant molecule are believed to play an important role in flocculation from the viewpoint of electrostatic interaction. |
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Keywords: | Aspergillus parasiticus Flocculation performance Bioflocculant Dye removal XPS and FTIR |
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