Synthesis And Study Of Metal Ion And Dye Absorption Performance Of Magnetic Straw Cellulose/Polyethyleneimine

In this paper,magnetic nanoparticles were synthesized by modified coprecipitation method,and then modified with silane coupling agent?KH550?.Finally KH550-modified magnetic nanoparticles was used to react with straw cellulose containing aldehyde,polyethyleneimine?PEI?and glutaraldehyde to preparemagnetic straw cellulose/polyethyleneimine used for metal ion and dye absorption.Effects of synthesis condition and absorption condition on absorption performance of heavy metal ions,cationic dye methylene blue and anionic dye methyl orange of magnetic straw cellulose/ polyethyleneimine were investigated.Heavy metal ion and dyeadsorption kinetics and adsorption thermodynamics for themagnetic straw cellulose/ polyethyleneiminewere studied.Heavy metal ion and dyedesorption and recycling performance of magnetic straw cellulose/ polyethyleneimine were also discussed.The structure of magnetic straw cellulose/ polyethyleneimine were characterized by a variety of advanced characterization methods.Possible adsorption mechanism of heavy metal ion and dye for the magnetic straw cellulose/ polyethyleneimine was preliminarily discussed.The main experimental results were as follows:1.Both magnetic nanoparticles and KH550-modified magnetic nanoparticles have high mangnetic responsiveness.Magnetic Fe₃O₄ nanoparticles,KH550 modifiedmagnetic nanoparticles and magnetic straw cellulose/ polyethyleneimine have nearly zero remanence and coercivity,indicating their superparamagnetism.Magnetic nanoparticles has saturation magnetization intensity as high as 67.76 emu/g.In comparison,KH550 modified-magnetic nanoparticleshas slight decreased saturation magnetization.Magnetic straw cellulose/ polyethyleneiminehas much lower saturation magnetization than magnetic nanoparticles but still has some saturation magnetization.2.Magnetic straw cellulose/ polyethyleneimine has relatively maximum absorption performance of copper ion in the condition of 2.5% straw cellulose containing aldehyde,1% KH550 modified magnetic nanoparticles,1.5% PEI,and 0.8% glutaraldehyde.3.With increasing pH,absorption capacities of copper ion,lead ion and cadmium ion for magnetic straw cellulose/ polyethyleneimine increased firstly and then decreased secondly,whereas absorption capacity of methylene blue increased constantly and absorption capacity of methyl orange decreased slowly.Absoption rates of heavy ions,cationic and anionic dyes for magnetic straw cellulose/ polyethyleneimine increased rapidly firstly and then slowly with increasing absorption time.With increasing temperatures,absorption capacities of heavy metal ions and methyl orange dereased,whereas absorption capacity of methylene blue increased.With increasing initial concentration of heavy metal ions and dyes,absorption capacities of heavy metal ions and dyes for magnetic straw cellulose/ polyethyleneimine increasedrapidly firstly and then slowly.4.Heavy metal ion adsorption of themagnetic straw cellulose/ polyethyleneimine is spontaneous,exothermicand entropy reduction process,and accorded with Freundlich adsorption model and pseudo-second kinetic equation.Absorption of methylene blue of themagnetic straw cellulose/ polyethyleneimine is spontaneous,and entropy increase process,and accorded with Freundlich adsorption model and pseudo-second kinetic equation.Absorption of methyl orange of themagnetic straw cellulose/ polyethyleneimineis spontaneous,exothermicand entropy reduction process,and accorded with Freundlich adsorption models and pseudo-second kinetic equation.5.After 5 times recycling use,magnetic straw cellulose/ polyethyleneiminehas 78% copper ion adsorption capacity and 73% methylene blue adsorption capacity compared with those of the first time use,accompanied with desorption ratio above 90% and 94% for copper ion and methylene blue,respectively,indicating good desorption and recycling performance of magnetic straw cellulose/ polyethyleneimine.6.XRD showed that the crystallization of the pretreated straw cellulose increased whereas the crystallinity of the aldehyde-containing straw cellulose reduced.Both magnetic Fe₃O₄ nanoparticles,KH550 modified magnetic nanoparticles and magnetic straw cellulose/ polyethyleneimine have certain crystallinity.