Surface Modification Of Magnetic Polymer Microspheres And Their Application In Adsorption And Catalysis

Magnetic polymer microspheres which can be separated from a mixture bysensitively response to magnetic field without physical contact to it are becomingmore and more popular as they can be designed to possess all kinds ofconfiguration and morphology. Modification of magnetic polymer microsphereshas been a hot research issue and their application prospect in environmentalengineering, biotechnical as well as supported catalyst were greatly promising.The research of this work focused on the application of magnetic polymermicrospheres in adsorption and catalysis based on the preparation and modificationof magnetic polymer microspheres. The main achievements of the work were asfollowing:（1） Oleic acid modified magnetic Fe₃O₄nanoparticles were prepared bychemical co-precipitation.（2） Magnetic PMMA microspheres were prepared via micro-suspensionpolymerization with methyl methacrylate as the main monomer and withdivinylbenzene as the crosslinking monomer. Furthermore, the magnetic PMMAmicrospheres were modified with ethanediamine thus magnetic PMMA-NH₂microspheres possessed amino groups were synthesized.（3） Magnetic PVBC microspheres were prepared via micro-suspensionpolymerization with Vinylbenzyl chloride as the main monomer and withdivinylbenzene as the crosslinking monomer. Furthermore, the magnetic PVBCmicrospheres were modified with ethanediamine thus magnetic PVBC-NH₂microspheres possessed amino groups were synthesized. Similarly, magneticPVBC-SH microspheres were prepared via the treatment of thiocarbamide.Magnetic PVBC-NH₂and PVBC-SH microspheres were further loaded with Au3+by adsorption, respectively. Furthermore, PVBC-NH₂-Au3+and PVBC-SH-Au3+turned to be PVBC-NH₂-nanoAu and PVBC-SH-nanoAu by reduction.The results of study in this paper were listed as following： The magnetic PMMA-NH₂microspheres performed excellent adsorption abilityfor Ag+and Zn²⁺in aqueous solution. The adsorption was exothermic fitted withpseudo-second kinetic model. The adsorption equilibrium of Ag+was fitted withLangmuir isotherm while the adsorption equilibrium of Zn²⁺was fitted withFreundlich isotherm. The maximum adsorption of Ag+and Zn²⁺were90.3mg/g（0.836mmol/g） and80.8mg/g（0.748mmol/g）, respectively. Theadsorption efficiency exceeds98%when the pH of the aqueous solution rangesfrom2to5. The Ag+or Zn²⁺loaded on the magnetic PMMA-NH₂microspherescan be desorbed by the treatment of strong acid solution（pH<3）. And adsorptionability of the magnetic PMMA-NH₂microspheres was recovered after soapingwith NaOH solution thus the magnetic PMMA-NH₂microspheres can be appliedin adsorption again. The adsorption of magnetic PMMA-NH₂microspheres forAg⁺or Zn²⁺maintain at99%after more than22rounds ofadsorption-desorption-regeneration.In the reduction of p-Nitrophenol, the PVBC-NH₂-nano-Au catalyzed thecomplete reduction of PNP in5min while it took25min for PVBC-SH-nanoAu tomake complete catalysis of the reduction when Au/PNP/NABH4=1/10/5300inmolar ratio.Magnetic polymer microspheres with amino groups on the surface have favorablebinding ability to heavy metals making them promising in waster treatment and thepreparation of microspheres supported catalyst.