Characterisation of exopolymer R-202 isolated from Rhodococcus rhodochrous and its flocculating properties

[Display omitted] •The exopolymer produced by Rhodococcus rhodochrous shows flocculating activity.•The water-soluble bioflocculant is glycoprotein and is negatively charged.•It has fibrillar structure with high capillary forces to hold water molecules.•It contains functional groups (hydroxyl, carbox...

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Bibliographic Details
Published in:European polymer journal 2017-03, Vol.88, p.21-33
Main Authors: Czemierska, Magdalena, Szcześ, Aleksandra, Hołysz, Lucyna, Wiater, Adrian, Jarosz-Wilkołazka, Anna
Format: Article
Language:English
Subjects:
Analytical chemistry
Chemical analysis
Dosage
Exopolymer
Flocculating activity
Flocculation
Fourier transforms
Functional groups
Galactose
Infrared spectroscopy
Kaolin
Mannose
Molecular weight
Polymers
Rhodococcus
Rhodococcus rhodochrous
Sodium chloride
Sugar
X ray photoelectron spectroscopy
Zeta potential
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Summary:[Display omitted] •The exopolymer produced by Rhodococcus rhodochrous shows flocculating activity.•The water-soluble bioflocculant is glycoprotein and is negatively charged.•It has fibrillar structure with high capillary forces to hold water molecules.•It contains functional groups (hydroxyl, carboxyl, amine, amide) preferred for the flocculation process. The characterisation and flocculation behaviour of exopolymer R-202 produced by Rhodococcus rhodochrous were investigated. The water-soluble fraction of this polymer with the molecular weight of about 1.3×103kDa was found to be 62.86% of polysaccharide and 10.36% of protein. Chemical analysis showed the presence of reducing sugars, uronic acids, and amino sugars at the concentrations of 232.41μg/mg, 45.29μg/mg and 15.07μg/mg, respectively. The HPLC analysis revealed that the monosaccharide components of the studied exopolymer were mannose, glucose and galactose at the molar ratio of 12:6:1. The flocculating activity was measured using the kaolin suspension and the basic flocculation parameters of exopolymer were established. The highest flocculating activity of exopolymer R-202 was observed at a dosage of 2mg/L, a pH value 7.2 and in the presence of 10mM solutions of salts (NaCl, CaCl2, MgCl2 or FeCl2). This effect depended on the type of ions and increased in the order - Na+
ISSN:0014-3057
1873-1945
DOI:10.1016/j.eurpolymj.2017.01.008