Application of Ionic Liquid in Extraction and Separation of Metal

Application of Ionic Liquid in Extraction and Separation of Metal
　　Room temperature ionic liquid (IL) is a kind of novel green solvent. Their non-inflammability and non-volatility provided advantages for using them as a replacement to volatile organic compounds (VOCs) in solvent extraction processes. Moreover, the higher extraction efficiency of metal ions in some IL-based extraction system brought them more attention . Recently, extraction has become a key field for applying IL in analytical chemistry . In this dissertation, the following techniques were developed in application of IL extracting and separating metal ions.One part is preparing Chitin(chitosan) /Cellulose biosorbent using Ionic Liquids for Ni( II) adsorption,the other part is neodymium magnets impregnating the XAD-7 resin with Cyanex923/[C8mim][PF6] to extract rare earths(RE).This article get a kind of environment-friendly biosorbents by a more "green"preparation process-the chitin(chitosan)/cellulose biosorbents are prepared by ionic liquid dissolution and regeneration process. Chitin(chitosan) and cellulose are dissolved by using the ionic liquid 1-butyl-3-methyl-imidazolium chloride ([C4inim]Cl) as a solvent under microwave to produce hydrit biosorbent. By this means, the disadvantage of chitin and chitosan for adsorption could be effectively overcomed. The results of applying them for Ni(II) adsorption proved well validity of the biosorbents for adsorbing heavy metal ions. Among the prepared biosorbents, freeze-drying chitosan/cellulose biosorbent was indicated to possess higher adsorption capacity together with better stability. Satisfactory performance of the biosorbent could be attributed to its microstructure created by chitosan and cellulose as the SEM revealed. Interaction of the two components and the resulting material’s adsorption ability to Ni(II) were confirmed by IR and XPS. Isotherms and desorption further validated the conclusion mentioned.
　　Operational parameters such as pH,agitation time,adsorbent concentration,temperature and initial ion concentration were also studied.The chitin(chitosan)/cellulose biosorbents studied in this paper have the following advantages that make it particularly attractive to be used for heavy metal ions adsorption in environment. Firstly, raw materials of the biosorbents are the most abundant biopolymer in nature. Secondly, preparation of the biosorbents by IL was an environment-friendly process with no acid, base or volatile organic solvent was used, and the IL used could be recovery and reused. Moreover, IL could take part in a temple effect for producing porous networks. Thirdly, http://www.chinamagnets.biz
 Since no cross-linking agent or blending polymer was used, the biosorbents could be biodegradable. Thus, application of the biosorbents for adsorbing heavy metal ion in wastewater was a green process without secondary pollution.A kind of solvent (ionic liquid) impreganated resin (IL-SIR) was developed herein for ameliorating imidazolium-type IL-based liquid-liquid extraction of metal ions. In this study, [Cgmim][PF6] containing Cyanex 923 was immobilized on XAD-7 resin for solid-liquid extraction of rare earth (RE). The Solid/Liquid Extraction is a kind of separation mode by using RTIL-based solvent impregnated resins (SIR), which were prepared directly by impregnating the XAD-7 resin with Cyanex923/[C8mim][PF6], consequently, forming a liquid film on the resin. The method can reduce the equilibrium time effectively (shortening equilibrium time from 40 min to 20 min), enhance the extraction efficiency (increasing extraction efficiency from 29% to 80%) , without increasing the loss of [C8mim][PF6]. With a homogeneous IL film containing extractant on surface, the novel IL-SIR contributed to increasing contact area of IL phase with aqueous phase, reducing dosage of Cyanex 923/[C8mim][PF6], ameliorating physic phenomena- emulsification and phase-separating during extraction process. In additional, temperature had less effect on the solid-liquid extraction, adsorption capacity of IL-SIR to Sc(III) was higher than that to Y(III).