Investigation Into The Structure Modification Of The Substituted Phenols And Its Extraction Performance Toward Rubidium?Cesium

Rubidium and cesium resources in the brine of salt lake in western China are abundant.However,the separation and extraction of rubidium and cesium in high efficiency is a remaining problem for comprehensive development and utilization of the salt lake.It has been found that extraction of rubidium and cesium by substituted phenol is one of the effective methods for solving this problem.Therefore,it is of great significance to synthesis substituted phenols that have high selectivity and separation efficiency for rubidium and cesium extraction to come over the restriction of low selectivity of currently available substituted phenols.In order to investigate the relationship between the molecular structure of extractants and their extraction performance,seven kinds of substituted phenols with various substituents have been synthesized,then used them and 4-tertbutyl-2-(?-methylbenzyl)phenol(t-BAMBP)as extranctant to study their extraction performance for potassium,rubidium and cesium.The main contents of this paper are shown as follows:1.Firstly,in order to acquire the best reaction conditions for synthesis of substituted phenols,reaction temperature,reaction time,the ratio of reactants and the amount of catalyst were investigated.The optimal reaction conditions are: reaction temperature 140 °C,reaction time 3 h,nstyrene ? nphenol=1.0 ~ 1.4,nphosphoric acid? nphenol = 0.34.Under the optimal reaction conditions,seven kinds of the substituted phenols were synthesized,namely 2-(?-methyl benzyl)phenol,4-methyl-2-(?-methyl benzyl)phenol,4-ethyl-2-(?-methyl benzyl)phenol,4-isopropyl-2-(?-methyl benzyl)phenol,4-tertamyl-2-(?-methyl benzyl)phenol,4-fluoro-2-(?-methyl benzyl)phenol,2,4-dimethyl-6-(?-methyl benzyl)phenol.In addition,the reaction mechanism was put forward by IR and GCMS analyzing,reasonable separation and purification procedures were applied for obtaining substituted phenols.2.Secondly,the diluents of extraction system have great influence on the separation performance of phases and extraction properties of ions in the extraction process.Therefore,selection proper diluents are of critical importance for achieving high extraction performance.Herein,we selected a series of solvents as diluents,which are cyclohexane,n-heptane,n-octane,n-dodecane,benzene,toluene,xylene,n-hexanol and n-octanol,and employed t-BAMBP as extractant to investigate the stability of extraction systems as well as their extraction efficiency towards K,Rb and Cs.Considering the stability of extraction systems,physical-chemical properties and toxicity of diluents,the nonpolar cyclohexane was employed as diluent and good extraction performance achieved.3.To explore the extraction performance of substituted phenols towards Rb and Cs in the salt lake brine,we synthesized seven kinds of substituted phenols and used them and 4-tertbutyl-2-(?-methylbenzyl)phenol(t-BAMBP)as extractant to study their extraction performance(distribution ratio D,extraction efficiency E and selection factor ?)towards rubidium and cesium at the room temperature.Ultimately,theextraction performance of substituted phenols was detailedly studied in terms of its structure,electronic density,steric hindrance,hydrogen bond interaction and solubility effect etc.The results reveal that the extraction selectivity of substituted phenols towards potassium,rubidium and cesium is determined by the synergistic effect of electron density and steric hindrance of the oxygen atom of phenolic hydroxyl group.The substituted phenols possessing electron donating group on the para-position of phenolic hydroxyl group had good extraction performance,and their selectivity increased with the increasing of the length of alkyl chains.