Keywords: Penicillium purpurogenum, bioflocculant, polysaccharides, flocculation mechanism, electrovalent bond, kaolin suspension
Flocculation properties of bioflocculant MBF-7 produced by Penicillium purpurogenum in kaolin suspension
The properties and modes of flocculation for kaolin suspension with bioflocculant MBF-7 produced by Penicillium purpurogenum, were investigated. The results showed that the optimum pH and dosage for flocculation was above 8 and more than 40 mg L−1, respectively. Flocculating activity of MBF-7 was increased in the presence of Mg2+, Ca2+, Al3+, or Fe3+, especially in the presence of Ca2+, while monovalent Na+ and K+ had little enhancement. According to the zeta potential, FTIR and electrovalent bond tests, the mechanism of flocculation is suggested that coordination electrovalent bond is formed between Ca2+ and MBF-7, and then through coordination bridging between Ca2+ and kaolin, thus three-dimensional reticular flocs are formed via long chains of MBF-7.