微孔膜界面响应法对结晶介稳区宽度的精确测定

Accurate measurement of metastable zone width by microporous membrane distillation interface response technology

在膜蒸馏结晶过程的基础上,根据膜选择性脱除溶剂、膜孔区域成核导致通量骤减的原理,开发了一种以微孔膜界面响应结晶成核的新方法,精确测定高浓度、低透光溶液的结晶介稳区宽度.采用微孔膜界面响应法分别探究了氯化钠、硝酸钾和氯化铜几种二元水溶液体系的成核生长过程,并完成介稳区宽度测定.结果表明,微孔膜界面响应法的通量衰减转折点总是早于激光法的光强信号转折点,随温度的升高,跨膜通量升高,介稳区宽度增大;对于低透光率溶液体系,激光法的光强信号极低,无法测定,而微孔膜界面响应法则可以完成相应体系的成核响应和数据测定.

Based on the membrane distillation-crystallization process,a novel analysis technology was propsed,which introduced the microporous membrane as the nucleation response interface on the principle of membrane selective solvent removal and the flux decrease caused by nucleation of membrane pores,it can accurately determine the crystallization metastable zone width of high concentration and poor light transmission solution.The nucleation processes of sodium chloride,potassium nitrate and copper chloride in aqueous solutions were investigated,and the metastable zone width was further determined.The results show that the attenuation inflection point of the microporous membrane distillation interface response technology is always earlier than optical signal variation of laser intensity response technology,Both the transmembrane flux and the metastable zone width increase with the increas of temperature;for the low transmittance solution system,the light intensity signal of the laser intensity response is too low to be determined,but the microporous membrane interface response technology can complete the nucleation response and data determination.