| Rubidium,a valuable rare metal,has important applications in the fields of national defense,electronics,energy,medicine and so on.There are abundant rubidium resources in Salt Lake Brine in China.It is of great significance to develop efficient and green process for extracting rubidium from Salt Lake brine.The development of high-efficiency green process for extracting rubidium from Salt Lake brine has important research significance and worth on practical way.Currently,two problems need to be addressed in extracting rubidium from Salt Lake brine.First,the low concentration of rubidium ion in brine leads to high energy consumption and low efficiency in the separation process.Secondly,there are a large number of interference ions with similar structure and properties to rubidium ion,which requires selectivity in the separation process.Adsorption is a promising technology for rubidium enrichment.The core of this technology is to develop materials with superior selectivity,high adsorption capacity and fast adsorption kinetics for actual separation and enrichment process.In this paper,imprinted materials with high affinity and specificity for rubidium ion were prepared based on imprinting technology for efficient rubidium extraction.First,rubidium ion-imprinted polymer(Rb(?)-?P-1)was successfully obtained by bulk polymerization.In the preparation process,the coordination complexation of the selective ligand 18 crown 6 ether(18C6)and the template Rb(?)ion was realized according to the macrocyclic effect of crown ether.At the same time,the intermolecular hydrogen bond between 18C6 and functional monomer methacrylic acid(MAA)were formed,which allows crown ether to be bound to the polymer through radical thermal initiation cross-linking polymerization reaction.The existence of selective ligands makes a specific adsorption process to be achieved.During the research,the effects of preparation conditions on the performance of rubidium ion imprinted polymer were systematically investigated,and the imprinted polymer with better capability was obtained.Subsequently,a series of adsorption studies were carried out.The results show that Rb(?)-?P-1 reached the adsorption equilibrium at pH 9.8 for 6 minutes.The maximum saturated adsorption capacity was 213.076 mg·g-1.Moreover,it had selective adsorption capacity to Rb(?)ions in the presence of Li(?),Na(?),and K(?).In order to obtain polymers with smaller particle size for subsequent application,reduce the number of elution times,shorten the preparation time and solve the problem of embedding imprinted sites to improve the adsorption efficiency.In this work,rubidium ion imprinted polymer(Rb(?)-?P-2)was prepared by surface imprinting with silica as carrier,Rb(?),18C6,MAA,EGDMA and AIBN as template ions,selective ligands,functional monomers,crosslinkers and initiators,respectively.During the experiment,the matrix was modified by alkali catalysis,so that it had groups for the introduction of imprinting layer under radical polymerization process.The specific ability of the polymer was achieved also due to the presence of crown ether.The optimal rubidium ion imprinted material was obtained by optimizing the preparation conditions.The adsorption process of Rb(?)-?P-2 was determined by batch adsorption experiments,which was affected by solution pH,initial concentration and adsorption time.The results showed that RB(?)-?P-2 could quickly reach the adsorption equilibrium at pH 9.8 and had the largest saturated adsorption capacity(200.190 mg·g-1).Compared with imprinted and non-imprinted polymers,the maximum imprinting factor was 1.712,indicating that the imprinting process effectively increased the adsorption capacity of the material.The selectivity coefficients of Rb(?)-?P-2 in Rb(?)/Li(?),Rb(?)/Na(?),Rb(?)/K(?)binary mixtures were 2.633,1.404 and 1.131,respectively.In this study,the rubidium ion imprinted polymers with higher adsorption capacity were prepared by two methods,which provided some technical support for the enrichment of rubidium ions in the Salt Lake brine. |
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