Study On Enrichment And Separation Of Metal Ions Using Amphiphilic POSS

Two kinds of modified Polyhedral OligomericSilsesquioxanes?POSS?with hydrophilic and hydrophobic structures were synthesized by amidation reaction,the enrichment and segregation properties with Cu²⁺,Cd²⁺and Al³⁺were analyzed and explored using flame-atomic absorption spectrometry?FAAS?and fluorescence spectrophotometry,.The main contents are as follows:1.Two kinds of hydrophilic POSS chelates were synthesized by amidation reaction between amino?-NH₂?of aminopropylisobutyl POSS?NH₂-POSS?and carboxyl?-COOH?of3-Mercaptopropionic acid?MPA?or 8-hydroxyquinoline-7-carboxylic acid?HQ?,and the resulting 3-mercaptopropionic acid modified cage silsesquioxane?MPA-POSS?and8-hydroxyquinoline-7-carboxylic acid modified cage silsesquioxane?HQ-POSS?having an amphiphilic structure,which were characterized by infrared spectroscopy?IR?,nuclear magnetic analysis?NMR?,thermogravimetric analysis?TG?,differential scanning calorimetry?DSC?and solubility analysis.2.As capture agent,the enrichment and separation performance of MPA-POSS with Cu²⁺and Cd²⁺in water was explored respectively.The results show that,in pH=6 acetic acid sodium acetate buffer solution and pH=9 Ammonia-ammonium chloride buffer solution,MPA-POSS can efficiently capture,enrich and separate trace Cu²⁺and Cd²⁺in aqueous phase respectively,the extraction rate high up to 99%and 98%,respectively,and the enrichment factor reach more than 50 times.The quantitative test of Cu²⁺and Cd²⁺in the enriched phase is carried out by FAAS.When the initial concentration of Cu²⁺in the aqueous solution was in the range of 10¹00?g·L^-1,the concentration and absorbance showed a good linear relationship,and the linear regression equation was A=0.0025C-0.005(C:?g·L^-1),in which correlation coefficient R²=0.9989,and relative standard deviation?RSD?was 1.73%?n=6?,detection limit of the method was 1.25?g·L^-1.When the concentration of Cd²⁺in aqueous solution is in the range of 0-40?g·L^-1,the concentration is linear to the absorbance,and the linear regression equation was A=0.00325C-0.0081(C:?g·L^-1),in which correlation coefficient R²=0.9916,RSD=2.33%?n=6?.The experiments show that MPA-POSS can easily,quickly and efficiently extract the trace Cu²⁺and Cd²⁺in water,and the whole process do not need heat,addother flocculants,and is no reagent residues.It provides a new way for the removal and pretreatment technology of metal ions.3.As a fluorescent reagent,the fluorescence properties of HQ-POSS and Al³⁺were investigated.The experimental results show that HQ-POSS can significantly increase the fluorescence intensity of the complex of HQ-POSS and Al³⁺in pH=7 ammonium acetatebuffer solution.When the initial concentration of Al³⁺is in the range of 0⁵0?g·L^-1,the concentration is linear with the fluorescence intensity,and the linear regression equation is F=0.0158C+0.2511(C:?g·L^-1),in which the linear correlation coefficient R²=0.9963,RSD=4.2%?n=6?,trace Al³⁺can be direct,rapid and accurate determinated.Using HQ-POSS as the complexing agent of Al³⁺,the enrichment and separation properties of HQ-POSS with Al³⁺were investigated.The experimental results show that HQ-POSS can efficiently enrich Al³⁺in pH=4.5 acetic acid sodium acetate buffer solution.This method can form flocculent with Al³⁺without adding flocculant at room temperature,and can achieve rapid enrichment and separation of Al³⁺.The concentration of Al³⁺in the enriched phase HQ-POSS-Al complex was determined by fluorescence spectrophotometry.Between0²00?g·L^-1,the concentration of Al³⁺has a linear relationship with the fluorescence intensity,and the linear equation is F=0.00329C+0.3542(C:?g·L^-1),in which the correlation coefficient R²=0.9941,RSD=3.8%?n=6?.The Al³⁺in tap water was enriched,separated and determined by this method.The average detection amount of Al³⁺was 0.043 mg·L^-1?n=5?,and the recoveries were between 95.3%and 109.3%.The experiment shows that HQ-POSS can not only enrich and separate Al³⁺in aqueous solution quickly and efficiently,but also can be stable and reliable to analyze and determine its concentration,which provides a new method for the removal,enrichment and monitoring of Al³⁺in water environment.4.The enrichment and separation mechanism of Cu²⁺,Cd²⁺,and Al³⁺with amphipathic POSS was investigated using particle size analysis,Zeta potential analysis,and optical microscope observation.The excellent enrichment and separation performance of the amphiphilic POSS is mainly determined inherent molecular structure.When the amphiphilic POSS dissolve in solution,its own amphiphilic structure enables it to rapidly self-assemble form suspended particles.At this time,the medium in the solution will have a certain influence on the formation of suspended particles,and when the effect is large,it can directly promote the aggregation of suspended particles.When the metal ions are added,the hydrophilic group complexed with metal ions,rapidly capture metal ions.When metal ions are combined with the amphiphilic POSS,the change of surface charge makes the suspended particles more beneficial to be further agglomerated into a large lump condensate suspended in aqueous solution,which can be enriched and separated efficiently through a simple and fast way.The amphiphilic MPA-POSS and HQ-POSS described in this paper can rapidly and efficiently enrich and separate metal ions at room temperature,which simplifies the traditional enrichment and separation technology without adding flocculants to promote separation,and provides a new way for the removal and preconcentration of metal ion pollutants.