Study On The Adsorption Properties Of Modified Magnetic Chitosan Beads For U(Ⅵ)

The development of society and the advancement of industry have brought a lot of pollution that is difficult to be handled.The nuclear power industry,as a hot energy industry in recent years,has developed rapidly and provided convenience to people.At the same time,it has also produced a huge number of uranium-containing wastewater that pose serious threats to human health and the environment.At present,the most commonly used method for wastewater treatment is the adsorption method.This method is widely used in factories,power plants,and other industries because of its high efficiency,simple operation,and low cost.Therefore,it is the research focus of many researchers to explore and fabricate an economical,green and efficient adsorbent.In this paper,based on chitosan(CS),magnetic chitosan was fabricated through a co-precipitation method,which was simultaneously cross-linked and modified with sodium citrate or phytic acid/glutaraldehyde,respectively.Two functionalized magnetic chitosan materials,sodium citrate-modified magnetic chitosan beads(CMC)and phytic acid-modified magnetic chitosan beads(PMC),were prepared.Characterization and analysis of modified chitosan materials were performed by means of SEM,TEM,VSM,FTIR.XRD,XPS and other characterization methods.Adsorption experiments were carried out using simulated low-concentration uranium-containing wastewater,and the adsorption performance and mechanism of U(VI)in water by CMC and PMC were studied.The following results were obtained:(1)In situ co-precipitation method can be used to prepare magnetic chitosan with mixed structure,and a variety of modified chitosan materials can be prepared according to different cross-linking methods,reagent ratios.In these chitosan beads,Fe3O4 is uniformly distributed inside the material.The finally obtained magnetic chitosan beads had superparamagnetism.Modification can also improve the thermal stability of the adsorbent.This paper also discussed the factors affecting the structure and adsorption performance of modified chitosan beads.(2)The adsorption experiments were carried out using the two adsorbents prepared.The effects of pH,initial concentration,reaction time,and reaction temperature on the adsorption of U(VI)by CMC and PMC were investigated.The optimal adsorption pH of CMC and PMC is 6.0,and the adsorption equilibrium time is about 120～180 min.The maximum adsorption capacity of CMC is 245.10 mg/g,and the maximum adsorption capacity of PMC is 342.18 mg/g.The adsorption process fits well with Langmuir adsorption isotherm model and Quasi-second-order kinetic equation.In terms of reusability,CMC and PMC can maintain 79.37%and 90.27%adsorption efficiency after four cycles.