Recovery Characteristics of Welan Gum by Ethanol Precipitation from Fermentation Broths

Abstract:

Welan gum,a kind of soluble extracellular heteropolysaccharide,is widely used in the oil exploration for enhancing oil recovery and construction due to its perfect stability and rheological properties.The precipitation characteristics of welan gum in the ethanol-water solution were investigated in this study.The influence of ethanol concentrations,pH,salt types and salt concentrations on welan precipitation and its rheological properties were investigated and the optimum parameters were listed as follows: 2.5 mol/L of CaCl2 was added until Ca2+ concentration reached at 0.1 mol/L,pH 2.0 and 37.6% of ethanol concentration in the bulk mixture.Welan gum was effectively precipitated and separated from the fermentation broth and the recovery yield achieved at 92.5%.Moreover,the rheological properties of the welan gum were kept robust,and 73.3% ethanol dosage was economized compared to the control experiments.