Preparation And Heavy Metal Ions Absorption Property Of Magnetic Polymer Absorbents

In this paper,magnetic nanoparticles were synthesized by modified coprecipitation method,and then modified with silane coupling agent?KH570?.Finally KH570-modified magnetic nanoparticles were used to graft copolymerization with functional monomers and polyvinylpyrrolidone?PVP?to prepare magnetic polymer absorbent used for heavy metal ion absorption with semi-interpenetrating network structure.Effects of synthesis parameters and absorption condition on heavy metal ion absorption capacity of magnetic polymer absorbent were investigated.The structure of magnetic polymer absorbent was characterized by various advanced characterization methods.Heavy metal ion adsorption kinetics and adsorption thermodynamics of magnetic polymer absorbent were investigated.Heavy metal ion desorption and recycling performance of magnetic polymer absorbent were studied.Possible adsorption mechanism of heavy metal ion for the magnetic polymer absorbent was preliminarily discussed.The main experimental results were as follows:1.SEM showed that the magnetic polymer had a three-dimensional network structure with a large number of meshes and gully.VSM results showed that the magnetization strength of KH570 modified magnetic nanoparticles and magnetic polymer adsorbent were lower than that of magnetic Fe₃O₄ nanoparticles,but they still had high magnetic properties and exhibited superparamagnetisms.Both magnetic nanoparticles dispersion and KH570 modified-magnetic nanoparticles dispersion have obvious Tyndall phenomenon and rapid magnetic responsiveness.2.XRD the results showed that the crystal structure of magnetic nanoparticles did not change after KH570 surface decoration and graft-copolymerization.FTIR spectra showed that KH570 was successful grafted onto the surface of magnetic nanoparticles,and the magnetic polymer adsorbent had targeted structure.TGA indicated the magnetic polymer adsorbents had high magnetic content and thermostability.3.Magnetic polymer adsorbent had maximum copper ion absorption performance in the condition of initiator amount of 0.8%,crosslinker amount of 0.2%,AA/ AM mass ratio of 60:40,AA neutralization degree of 70%,PVP content of 12%,and KH570 modified magnetic nanoparticles amount of 20%.4.With the increase of absorption time,adsorption capacity of heavy metal ions for magnetic polymer absorbent increased firstly and then slowly,approaching equilibrium at 60 min.With the increase of pH,adsorption capacity of heavy metal ions for magnetic polymer absorbent increased firstly and then decreased secondly.With the increase of heavy metal ion concentration,adsorption capacity of heavy metal ions for magnetic polymer absorbent increased rapidly and then slowly.Adsorption capacity of heavy metal ions for magnetic polymer absorbent decreased with increasing temperatures.5.Adsorption process of heavy metal ions such as copper,cadmium and lead ions for magnetic polymer absorbent was accorded with Langmuir adsorption models and pseudo-second kinetic equation.6.Magnetic polymer absorbent had rapid desorption rate for heavy metal ions,approaching equilibrium at 60 min.Desorption ratio of copper,cadmium and lead ions for magnetic polymer absorbent were above 99%,98% and 95%,respectively,indicating its good heavy metal ion desorption performance.After 5 times recycling use,magnetic polymer absorbent had absorption capacity of copper,cadmium and lead ions of 123.2 mg/g,90.2 mg/g and 333.5 mg/g,respectively,accounting for 75.6%,74.1% and 71% compared with those of the first time use,indicating its good recycling use performance.