Synthesis Of Acrylonitrile-itaconic Acid Copolymers And Their Adsorption Properties For Metal Ions After Modification

Acrylonitrile-itaconic copolymers were synthesized by using the high internal phaseemulsion as templates with acrylonitrile and itaconic acid as monomers, the effects of variousreaction conditions on the pore structure and specific surface area of the polymers wereinvestigated systematically; On this basis, acrylonitrile-itaconic copolymers were modifiedwith hydroxylamine and a new typed of chelating resin containing amidoxime and carboxylgroups was achieved. The structures of the chelating resins were characterized by Fouriertransform-infrared spectra (FTIR), scanning electron microscopy (SEM) and porous structureanalysis. Adsorption properties of amidoxime modified acrylonitrile-itaconic copolymers forPb(II)、Cd(II)、Hg(II) in aqueous were investigated in details, including static saturatedadsorption capacities, adsorption kinetics, the influence of pH, thermodynamics, andenrichment performance.1. With acrylonitrile and itaconic acid as monomers, azobisisobutyronitrile (AIBN) asinitiator, span80as emulsifier, cyclohexane as porogen, CaCl2as a stabilizer, using the highinternal phase emulsion as templates, acrylonitrile-itaconic acid copolymers were synthesized.Studied the effects of reaction conditions (including AIBN content, AN/IA molar ratio,Span80content, temperature, aqueous phase volume, reaction time)on the pore size, pore sizedistribution and specific surface area of the porous materials. Those chelating resins werecharacterized by Fourier transform-infrared spectra (FTIR), scanning electron microscopy(SEM) and porous structure analysis. The results showed that when the reaction conditionswere as follows: AN/IA molar ratio,10:1; AIBN content,7wt%; Span80content,38wt%;temperature was70℃; volume content of aqueous phase,80%; reaction time was7hours; theaverage pore size distributions of the resulting copolymers were in between10-70nm, andspecific surface area was15.78m2g-1. The resins were of loose and porous morphology andof mesoporous structure.2. Acrylonitrile-itaconic copolymers were modified with hydroxylamine and then theachieved chelating resins were characterized by FTIR and SEM. The adsorption properties ofthe resin for Pb(II)、Cd(II) and Hg(II) ions in aqueous were investigated in details.Experimental results showed that the modified polyacrylonitrile-itaconic acid copolymer hada high metal ion adsorption capacity. The static adsorption capacities for Pb(II), Cd(II) and Hg(II) were0.44、0.38、0.42mmol/g, respectively. The adsorption kinetics experimentsshowed that: The t1/2of the resins for Pb(II), Cd(II) and Hg(II) were about10min, exhibitedexcellent adsorption rate for heavy metal ions; The adsorption mechanism is liquid filmdiffusion and the adsorption process can be well described by the pseudo-second-order kineticmodel. Adsorption thermodynamics experiments showed that: the equilibrium adsorptionisotherm was closely fitted with the Freundlich model, and the temperature conducive to theincrease of the adsorption rate and adsorption amount. For trace metal ion enrichmentexperiments showed that if Pb (II), Cd (II), and Hg (II) ion concentration were0.1,0.01and2mg/L, respectively, the recovery rate of metal ions can reach more than85%. Pb(II), Cd(II)and Hg(II) sorption efficiency is not affected by the presence of interfering ions like Ca(II),and Na(I) in solution.