The objective of this study was to evaluate the capability of a lipopolysaccharide, produced by Trichosporon mycotoxinivorans CLA2 using residue of biodiesel processing, to flocculate two different solids in suspension. In addition, the emulsifying activity and the stability of this lipopolysaccharide in response to pH and temperature variations and in the presence of some electrolytes were evaluated. The lipopolysaccharide was used in concentrations ranging from 20 to 80 mgL-1 to flocculate 100 gL-1 of kaolin and 50 gL-1 of charcoal. The results indicated that the flocculating capability for each suspended particles reached 80 % and 78.79 % after 14 min, respectively. Other tests indicated that the emulsifying activity is weakly affected by temperature, pH and NaCl. In addition, the surfactant activity was assessed by the droplet diameter method and tension surface measurement. The surface tension of pure water decreased gradually with an increase in the biopolymer concentration until a minimum of 52 m Nm-1 with a CMC value of 4.54 mgL-1. These findings demonstrated a potential use of the bioemulsifier in flocculation and emulsification processes, which are also favored by its reduced toxicity compared to those of widely used commercial polymers.
Keywords: Biodiesel residue; Bioemulsifier; Flocculation; Lipopolysaccharide.