Study On Extracting Neodya4ium With Microemulsion Membrane

Microemulsions used as liquid membranes exhibit several advantages, including high efficiency, saving on energy, and easy operation. Some problems in coarse emulsion separation can be solved using microemulsions, such as leakage, swell and the difficulties of demulsification. A lot of research on the separation of metal ion, organic compounds and biological compounds with microemulsions were reported in literature in this decade. In our work, modified surfactants were studied: a lipophilic group was in-comed so that there are two lipophilic groups and a hydrophilic group in a surfactant molecular. Microemulsions can be prepared by using these surfactants without midchain alcohol. However, when the microemulsin was mixed with feed liquid stable emulsion was formed, which made it difficult to enrich and recover the separated material.In the following study the branched chain alcohols, polyalcohols and the alcohols with cyclic structure were investigated, and benzyl alcohol was found can be used as co-surfactant of microemulsions without emulsiflcation and leakage during the extraction process. Microemulsion formulations were determined through the studying the phase behavior. The thermomechanical stability was verified by measuring the interfacial tension and calculating the thermodynamic function of the microemulsion system.The technological conditions of extracting Nd3+, such as initial Nd3+concentration, volume ratio of feed phase to microemulsion et al were studied using uniform design, and optimum technological conditions were obtained. Under these optimum conditions, the extraction rate will be greater than 98%.The experimental apparatus was developed using microemulsions membrane-micropore filter membrane. The effect on extracting Nd3+ was discussed, the thermodynamic functions were calculated, and the dynamical equation was deduced, the theoretical data well agree with experimental data. With this new apparatus a 90% extraction rate was obtained. The enrichment rate increased more than 10 times. The best enrichment coefficient is 24.3, which is much higher than the values of 3 and 6.5 in the literature, and is a great progress in this research. Another important progress is the development of new extraction method by combining liquid membrane and solid membrane, with which not only the enrichment rate was improved, but also the separation and aggregation between microemulsion phase and feed phase, and the resultant solvent losing and solvent pollution were avoided.