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.%作者研究了发酵液中威兰胶在乙醇溶剂作用下的沉淀行为,分析了乙醇质量浓度、pH值、盐离子种类和盐浓度等因素对威兰胶沉淀效果的影响,以及对沉淀物最终产物流变学性能的影响.确定威兰胶的最佳沉淀条件为:当添加2.5 mol/LCaCl2溶液使威兰胶发酵液中的最终电荷浓度达到0.1 mol/L,pH调至2.0,乙醇质量浓度为37.6 g/dL时,可以有效沉淀分离得到威兰胶,收率为92.5％,并保持良好的流变学性能,比对照条件下的乙醇用量节省了73.3％.
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