Preparation And Adsorption Properties Of Iron Ion Imprinted Materials

Ion imprinting technology is a new polymer technology based on specific ions,which have the properties of specific absorption and selective recognization of target ions.It is show a broad prospect of application of the fields of separation、purification、immunoassay、analogue enzyme catalyst and trace analysis.The technology of ion imprinting is used in trace and ultra trace analysis to make great breakthroughs in technology of chemical separation and preconcentration.This paper aims at developing an organic or inorganic material with excellent selectivity and provides new means and ideas for high efficiency separation of iron ions.According to the thought of molecular imprinting on the surface of silica gel,this paper proposes an ion imprinting technique based on the surface modification of silica gel.Using MPMS was grafted on the silica gel particles on the activation of hydrochloric acid,then the iron ion imprinting material IIP-MPMS/SiO₂ was prepared by the template ion Fe³⁺ of the participation of the role of coordination bond with the crosslinking agent epichlorohydrin.Examining the different reaction time,reaction temperature,the type of crosslinking agent,solvents and the addition order of template ions effects on the imprinting reaction.The IIP-MPMS/SiO₂ was successfully synthesized and was characterized by FTIR,Scanning electron microscope（SEM）and Thermogravimetric analyzer.The particle PMAA/SiO₂ was obtained by the methacrylic acid as functional monomer with the initiator ammonium persulfate was grafted on the surface of modified silica gel MPMS/SiO₂ with sulfhydryl group.Then,the iron ion imprinted material IIP-PMAA/SiO₂ was prepared by surface imprinting of the polymer chain PMAA on silica gel surface by using Fe³⁺ was used as template ion in aqueous solution and ethylene glycol two methacrylate as cross-linking agent.Moreover,to discussed the effects of different reaction temperature,reaction time and the ratio of PMAA to crosslinker on the reaction.The binding properties of the two imprinted materials to Fe³⁺ are studied by static method.The results showed that the prepared imprinted materials had strong selection and recognition ability for Fe³⁺,mainly in two aspects:（1）The binding capacity of Fe³⁺ is very large.The saturated adsorption capacity of IIP-MPMS/Si02 and IIP-PMAA/SiO₂ to Fe³⁺ is 11.20 mg/g and 26.80 mg/g,respectively.（2）The selectivity for Fe³⁺ is strong.When IIP-MPMS/Si02 is used as adsorbent,the relative selectivity coefficients of Fe³⁺ relative to Pb²⁺,Ni²⁺,Zn²⁺ and Cu²⁺ are 4.58,2.06,4.43,7.34 respectively.When IIP-PMAA/SiO₂ is the adsorbent,the relative selectivity of Fe³⁺ to Pb²⁺,Ni²⁺,Zn²⁺,and Cu²⁺ are 23.84,16.92,6.75 and 2.99 respectively.At the same time,the two kinds of imprinted materials were stable after regeneration by hydrochloric acid.The adsorption capacity of the imprinted materials.was still over 91%after repeated use of 10 times.The adsorption mechanism of two kinds of imprinted silica gel was studied by Scatchard analysis.The results showed that there was a single binding mode between IIP-MPMS/SiO₂ and Fe³⁺ in the selected concentration range,there were two different binding modes between IIP-PMAA/SiO₂ and Fe³⁺,which was related to the two binding sites.