The Nature Of The Extractant And Solvent Extraction Heat Dynamics Study

Solvent extraction is a kind of analytic technology. It is mainly used in analysis and separation. The assembly of this technology is simple and the manipulation is easy. So it is easy to realize massive production. The thermokinetic property of solvent extraction is an important aspect of solvent extraction and is mainly about the problem ot extraction equilibrium, reaction rate and activity energy. The study of thermokinetic property of solvent extraction will supply a thermokinetic basis for ion extraction system and will propel the development of extraction separation technology.It is supposed that the extractant of extraction organic phase is in the present of unimolecular, but practically many extractants have the structure of surfactant, they have the property of surfactant and are easy to form reversed micelles. The reversed micelles will affect the extraction evidently. But the research of the physical chemical property of this reversed micelles is not enough, so further study on reversed micelles is necessary. This study has profound significance on development of extraction and make for the study of microemulsions theory and surfactant in nonaqucous solvents.In this paper, the solvent extraction of Co2+, Y3+" and Ce3+ with l-phenyl-3-methyl-4-benzoyl-pyrazolane-5 has been studied. The equilibrium constants and thermodynamic functions have been obtained and the property of extractants has been studied by the microcalorimetric method.1. The chief contents and conclusions 1.1 Study of extraction thermokinetic propertyIn this paper, there ions (Co2+,Y3+and Ce3+) were extracted .The equilibrium equation of Co2+ is :And the equilibrium equation of Y3+and Ce3+ is:The reaction rate constant, reaction rate equation and activity energy were obtained and was calculated. The thermodynamic function were measured by microcalorimetric method. The determined was compared with the calculated results. 1.2 Study of extractant's propertyThe extractant in organic phase can come into being reversed micelles. Mass action model was used in the experiment.In this paper, saponification-salt of PMBP has been made first. And it is diluted by different organic solvent such as normal octane, decane, dodecane, tetradecane, hexadecane, benzene, toluene and oxycene.The formation of the function of reversed micelle for PMBP saponification-salt in above different organic phase was studied by using microcalorimetric method. The titrition power-time curves of reversed micelles were obtained. The critical micelle concentration(CMC); aggregation number(n), formation constant of micelle(Km) and the thermodynamic functions ( and )werecalculated.The saponification-salt for ?204 was made with the method mentioned above and received similar regularity. 2. The main innovative points2.1 Microcalorimetric method is a new method to determine the reaction heat of solvent extraction process.2.2 In the extraction organic phase, the aggregation number(n) is small, so the traditional method is difficult to determine the critical micelle concentration(CMC). In this paper, CMC was determined by Microcalorimetric method quickly and correctly.2.3 The determination of micelle's aggregation number(n) in extrantantorganic phase provided many important information to understand the extractant's state in extraction system. It established theoretical basis to understand the extractant's property.