A low volatility diethylene glycol aqueous solution is concentrated via vacuum membrane distillation with a sheet PP raicroprous membrane which is prepared by thermally induced phase separation method. The effects of trans-membrane pressure, feed's initial flow, temperature, concentration on the rejection performance are investigated. The rejection rates are higher than 98.5% in experimental range. A new concept of critical contact angle, when the membrane is at wetting state, is put forward, then, the mathematical models which are used to calculate contact angle and critical contact angle are listed as well. It is noted that the behavior of feed's penetration into the membrane take a key part on the rejection rate of diethylene glycol. The degree of feed's penetration into the membrane increases with decreasing the difference between contact angle and critical contact angle. It is proposed that the increase of hydrophobicity of membrane is an important approach to improve rejection performance of such membrane distillation process.%采用热致相分离法聚丙烯平板微孔膜,进行二甘醇(低挥发性)水溶液的真空膜蒸馏实验研究.探讨过膜压差和料液初始流量、温度、浓度对二甘醇截留效果的影响；提出了临界接触角的概念,并得到了计算膜蒸馏操作状态的液-固接触角及临界接触角的数学模型.研究表明:实验范围内的截留率高于98.5％；二甘醇截留效果由料液穿过膜孔程度控制,液-固接触角与临界接触角的差值越小,料液穿过膜孔程度越高；提高微孔膜的疏水程度是提高该类膜蒸馏过程截留效果的重要途径.
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