Preparation And Adsorption Properties Of Metal Ion Imprinted Polymer Microspheres

The determination of low levels of analytes relies generally on a suitable separation/pre-concentration process. Molecular recognition-based separation techniques have received much attention in various fields because of their high selectivity for target molecules. Molecular imprinting technique (MIT) is becoming increasingly recognized as a powerful technique of preparing synthetic polymers that contain tailor-made recognition sides for certain molecules. It has an extensive application in purification separation, immunoassay, enrichment, biomimics and other relevant fields for its predetermination specificity and practicability of molecule recognition. The introduction of ion- imprinted polymers (â…¡P) in trace and ultratrace analysis provides vital breakthroughs in pre-concentration or separation chemistry. With the preparation of tailor-made materials, â…¡P-SPE offers an approach to the recovery of valuable and rare metals from lean ores, minerals and dilute solutions and to the removal of heavy metal pollutants from industrial wastes. This work is focused on the preparation of novel metal ion-imprinted polymers and their adsorption properties. This thesis consists of the following three parts:1. A brief overview is given for the principle of MIT, the preparation and application of molecular imprinted polymers (MIP), metal ion-imprinted polymers(â…¡P),and the studies in the rapidly developing and exciting area of â…¡P-SPE.2. A new complexant 1-acrylthiosemicarbazone was prepared by the reaction of acryhoyl chloride with thiosemicarbazide. Two kinds of new polymerizable complexes were prepared by using Hg(â…¡), Cd( â…¡) (ionic template) and 1-acrylthiosemicarbazone .The â…¡P microspheres were prepared with suspension polymerization by ethylene glycol dinethaerylate (EGDMA) and polymerizable complexes with 2,2'-azobisicobutyronitrile (AIBN) as initiator,toluene as poregen. Hg( II )-IIP/Cd( II )-IIP microspheres were obtained by leaching with 6M HC1 (1MHC1+1%TU). The polymerizable complexes,the polymerizable complexes, the IIP microspheres (before and after leaching) and non-IIP microspheres were characterized by EA(element analysis), IR(infrared), DSC(differential scanning calorimetry), XRD(x-ray diffraction ), SEM (scanning electron microscoph), NSA (nitrogen sorption analysis)and IPC-AES(inductively coupled plasma atomic emission spectrometry) studies. It was showed that the morphology of the IIP microspheres were influenced by many factors including stirring speed, dispersant, O/W and progenic solvent. These leached IIP microspheres could pick up Hg( II )/Cd( II) ions from dilute aqueous solution. The percent enrichment, distribution ratio and selectivity coefficients of the target metal ion and other selected metal ion using IIP microspheres and non-IIP microspheres were determined. The Hg( II )-IIP/Cd( II )-IIP microspheres show excellent selectivity for the target metal ion(Hg( II )/Cd( II )).The process of adsorption kinetic and isothermal adsorption of Hg( II )-IIP/Cd( II )-IIP microspheres were investigated. Experimental results show that the adsorption of Hg( II )-IIP/Cd( II )-IIP microspheres of Hg( II )/Cd( II) accords with the Langmuir equation and Freundlich equation.3. Anew Schiff basic complexantN-(2-hydroxybenzyliden)acrylohydrazine was prepared by the reaction of acrylohydrazine with salicyladehyde .Two kinds of new polymerizable complexes were prepared by using Zn( II ),Ni( II) (ionic template) and N-(2-hydroxybenzyliden)acrylohydrazine . The IIP microspheres were prepared with suspension polymerization by EGDMA and polymerizable complexes with AIBN as initiator, toluene as poregen. Zn( II )-IIP/Ni( II )-IIP microspheres were obtained by leaching with 0.1M EDTA.The polymerizable complexes, the IIP microspheres(before and after leaching) and non-IIP microspheres were characterized by EA, IR,DSC, XRD, SEM, NSA and IPC-AES studies. These leached IIP microspheres could pick up Zn( II )/Ni( II) ions from dilute aqueous solution. Percent enrichment, distribution ratio andselectivity coefficients of the target metal ion and other selected metal ion using IIP microspheres were determined. The Zn( II )-IIP/Ni( II )-IIP microspheres showed excellent selectivity for the target metal ion(Zn( II )/Ni( II )).The process of adsorption kinetic and isothermal adsorption of Zn( II )-IIP/Ni( II )-IIP microspheres were investigated. Experimental results show that the adsorption of Zn( II )-IIP/Ni( II )-IIP microspheres of Zn( II )/Ni( II ) fits the Langmuir equation and Freundlich equation.