Preparation And Adsorption Properties Of Heavy Metal Ions And Dyes For Magnetic Modified Polyaniline Absorbent

In this paper,magnetic nanoparticles were synthesized by modified coprecipitation method,and then modified with silane coupling agent KH550 to prepare KH550-modified magnetic nanoparticles.At last KH550-modified magnetic nanoparticles were used to graft copolymerization with aniline and3,5-diaminobenzoic acid to synthesize magnetic modified polyaniline absorbent by chemical oxidation polymerization.Effects of synthesis parameters and absorption condition on heavy metal ions absorption capacity of magnetic polymer absorbent were investigated.The structure and morphologies of magnetic nanoparticles,KH550-modified magnetic nanoparticles and magnetic modified polyaniline absorbent were characterized by UV/Vis,TEM,SEM,FTIR,XRD.Magnetic properties of three substances were also investigated.Effects of polymerization parameters and adsorption condition on the adsorption properties of heavy metal ions and dyes for magnetic modified polyaniline absorbent were studied.Heavy metal ions and dyes adsorption kinetics and adsorption thermodynamics of magnetic modified polyaniline absorbent were investigated.The main experimental results were as follows:?1?TEM indicated that magnetic nanoparticles and KH550-modified magnetic nanoparticles had irregular shape with particle size between 15-25nm.Particle agglomeration decreased after KH550 modification of magnetic nanoparticles.SEM showed that magnetic modified polyaniline absorbent had rough surface with many unevenly sized micropores.?2?Magnetic nanoparticle had saturation magnetization of 67.8emu/g.KH550-modified magnetic nanoparticles had high saturation magnetization?57.7emu/g?.Magnetic modified polyaniline adsorbent still had certain magnetic responsiveness?10.2emu/g?.Both magnetic nanoparticle,KH550-modified magnetic nanoparticles and magnetic modified polyaniline adsorbent had near zero residual magnetism and coercivity.Both magnetic nanoparticles dispersion and KH550-modified magnetic nanoparticles dispersion had Tyndall phenomenon.?3?FTIR indicated that the prepared magnetic modified polyaniline adsorbent had the target structure.XRD showed that the polyaniline matrix had amorphous structure After graft-copolymerization of KH550-modified magnetic nanoparticles with aniline and 3,5-diaminobenzoic acid,the crystal type and structure of the magnetic nanoparticles did not change during oxidation polymerization.?4?Magnetic modified polyaniline absorbent had maximum absorption property of lead ion in the condition of ammonium persulfate amount of 1.6:1,KH550-modified magnetic nanoparticles amount of 10%,aniline/3,5-diaminobenzoic acid mass ratio of7:3,monomer concentration of 10%,and phytic acid amount of 2mL.Magnetic modified polyaniline absorbent had maximum absorption property of methylene blue dye in the condition of ammonium persulfate amount of 1.6:1,KH550-modified magnetic nanoparticles amount of 10%,aniline/3,5-diaminobenzoic acid mass ratio of7:3,monomer concentration of 12.5%,and phytic acid amount of 2.5mL.Magnetic modified polyaniline absorbent had maximum absorption property of methyl orange dye in the condition of ammonium persulfate amount of 1.6:1,KH550-modified magnetic nanoparticles amount of 10%,aniline/3,5-diaminobenzoic acid mass ratio of8:2,monomer concentration of 10%,and phytic acid amount of 2mL.?5?With the increase of pH,adsorption capacity of heavy metal ions such as Ni²⁺,Pb²⁺and Cd²⁺for magnetic modified polyaniline adsorbent increased firstly and then decreased secondly,and methylene blue adsorption capacity increased constantly,whereas adsorption capacity of methyl orange reduced gradually.Both adsorption of heavy metal ions,anionic and cationic dyes for magnetic modified polyaniline adsorbent increased rapidly at the initial absorption stage and then slowed down until reached equilibrium.Elevated temperature decreased the adsorption capacity of heavy metal ions and methyl orange but increases the adsorption capacity of methylene blue.With the increase of the initial concentration of heavy metal ions and dyes,the adsorption capacity of heavy metal ions and dyes increased constantly while the increase slowed down.?6?Adsorption of heavy ions for magnetic modified polyaniline absorbent accorded with Freundlich adsorption model and pseudo-second kinetic equations.Adsorption of methylene blue dye for magnetic modified polyaniline absorbent accorded with Freundlich adsorption model and pseudo-second kinetic equations.Adsorption of methyl orange dye for magnetic modified polyaniline absorbent accorded with Langmuir adsorption model and pseudo-second kinetic equations.?7?After 5 times recycling use,magnetic modified polyaniline absorbent had more than 94%and 93%desorption ratio of lead ion and methylene blue dye,respectively,and 84%and 82%compared with absorption capacity of the first time use for lead ion and methylene blue dye,respectively.This indicated that magnetic modified polyaniline adsorbent had good desorption and recycling properties.