Preparation And Property Studyof Fly Ash@chitosan Magnetic Copper Ion Adsorbent

To realize the deep and high value-added utilization of the coal by-product fly ash and other industrial wastes has a great significance on eliminating environmental pollution,alleviating the shortage of resources and realizing sustainable development of the society.The magnetic microspheres of fly ash have important potential application in the field of cheap magnetic cores and magnetic adsorbents due to their high content of iron,strong magnetism and abundant pores.Insides,it is one of the important research hotpots to treat heavy metal wastewater by fly ash magnetic microspheres.The adsorption method is one of the most commonly used heavy metal wastewater treatment,but the current adsorbents generally are hard to separate from liquid due to their fine grains and good suspension,which has become one of the factors restricting the application of adsorption method.We can solve the problem of difficult separation with the help of external magnetic field if we introduce the magnetic separation technology to sewage disposal process.But the current magnetic adsorbents prepared by chemical synthesis of nanomagnetic cores have the disadvantages of high cost,heavy environmental load and high requirement of storage and utilization.It can not only meet the requirements of magnetic separation,but also reduce the cost of the medicament if we compound magnetic adsorbents by magneticspheres.In view of this,this paper selects carefully chosen processed fly ash magneticspheres as magnetic cores and chitosan as heavy metal ion adsorbent to synthesize magneticspheres@chitosan magnetic adsorbents for adsorption treatment of low concentration copper ion wastewater.The specific research work is as follows:Firstly,use the magnetic tube device to separate magnetic minerals from the fly ash,in order to get strong magnetic materials-magneticspheres.And then the finer magneticspheres were obtained by ball milling.Finally,adopt magneticspheres as magnetic cores and employ precipitation method,carbodiimide(EDAC)method and reverse microemulsion method these three methods respectively to prepare three types magneticspheres@chitosan composite microspheres adsorbents.Characterize their structures and material composition by SEM,EDS,FTIR,XRD and VSM,draw the standard curve of Cu2+ ions by UV-Vis spectrophotometry,and test the adsorption properties of magneticspheres@chitosan adsorbents.1.Magneticspheres@chitosan gel beads prepared by precipitation method have large size(500-800?m).XRD study showed that the diffraction peaks of magneticspheres and chitosan were both in the patterns,which illustrated that chitosan and magneticspheres were composed successfully;VSM characterization showed that the magneticspheres had poor magnetism,its saturation magnetization was just 2.02emu/g,which illustrated that there was a small proportion of magneticspheres in gel beads.The study of Cu2+ ion adsorption showed that the hydrogel had good adsorption and decolorization effect on the Cu2+ ion in the simulated copper containing wastewater,the adsorption capacity was above 4.5mg/g,and the gel became blue after adsorption.Through the experimental study on the isothermal adsorption model,we found that the adsorption on Cu2+ ions of magneticspheres@chitosan gel beads had a good compliance with Freundlich adsorption model.2.Magneticspheres@CMCS magnetic composite materials prepared by carbodiimide(EDAC)method possess well dispersed particles(average diameter was about 10?m).The characterization of VSM showed that the samples had strong magnetism,its saturation magnetization could reach 20.09 emu/g.The adsorption capacity of Cu2+ ions was studied and the adsorption capacity of low concentration copper ion was 10.33mg/g.3.Magneticspheres@Si02@CS microspheres were prepared by reverse microemulsion method.FTIR analysis showed that SiO2 was coated on the outside of the magneticspheres to form the core-shell structure,making it easier to combine with CS.The results of EDS showed that the beads were evenly distributed in the chitosan matrix.VSM detection showed that the doping amount of magneticspheres was about 32%.The adsorption of Cu2+ ions showed that the adsorbent had a good adsorption effect on the lower concentration of copper containing wastewater,and the adsorption capacity of 10mg/L and 20mg/L for the Cu2+ ion wastewater was 8.63mg/g and 11.08mg/g respectively.Through the study on the adsorption kinetics of three kinds of synthetic materials,it is found that these three all have a good fitting relationship with pseudo-second order kinetics,which indicating that the chemical adsorption is the main adsorption approach on Cu2+ ions.The fitting results of the isothermal adsorption indicate that the remaining two had a better compliance with the model of Langmuir adsorption isothermal while Freundlich adsorption model is the main precipitation method of the one in precipitation method.The studies on the best adsorption pH value of these three show that the best pH range is about 5-5.5.Peracid has inhibitory effect on ionization adsorption,however,while the copper ions precipitate directly under the conditions of relative alkaline.