Preparation And Property Of Polyethyleneimine-tannin Based Adsorption Resin

Tannins,as a kind of polyphenolic compounds with abundant content in nature,can be biodegraded and have good biocompatibility.The structure of tannins is rich in phenolic hydroxyl groups,which makes it have special chemical properties.It is widely used in medical,food and cosmetics and other fields.Metal ions can be adsorbed by the complexation or electrostatic action of phenolic hydroxyl group in tannins.However,tannins are highly hydrophilic and easily soluble in water,and cannot be used directly for the adsorption of metal ions.Tannins can be cross-linked into water-insoluble polymer by crosslinking agent to improve the adsorption performance of tannins to metal ions.In this paper,the polyethyleneimine-tannin based adsorption resin was formed by the cross-linking of polyethyleneimine and chlorinated tannins prepared by the reaction of bayberry tannins and thionyl chloride.The adsorption resin for metal ions was investigated.The specific contents are as follows:1.Chlorinated tannins were prepared by the reaction of bayberry tannins with thionyl chloride,and then cross-linked with polyethylenimine to prepare polyethyleneimine-tannin based adsorption resin.The content of functional groups was increased as the amino group was introduced into the tannins structure,which effectively improved the adsorption performance of the adsorption resin for metal ions.2.The adsorption performance of polyethylenimine-tannin based adsorption resin for Cr(?)was investigated in this study.The maximum adsorption capacity of polyethylenimine-tannin based adsorption resin for Cr(?)was 364.46 mg/g at a temperature of 318 K and a p H of 2.0,and the initial concentration of Cr(?)was500mg/L.When the initial concentration of Cr(?)was lower than 20 mg/L,the adsorption rate of Cr(?)reached more than 95%.The adsorption of Cr(?)by polyethyleneimine-tannin based adsorption resin conforms to the Langmuir adsorption model and the pseudo-second-order kinetic equation.Thermodynamic parameters show that the adsorption process was endothermic.The resins had good reusability for the adsorption of Cr(?).3.The adsorption performance of polyethylenimine-tannin based adsorption resin for Cu(?)was investigated in this study.Under the conditions of temperature 318 K,p H5.0 and initial concentration of Cu(?)200 mg/L,the maximum adsorption capacity of the resin for Cu(?)was 129.52 mg/g.When the initial concentration of Cu(?)was lower than 20 mg/L,the adsorption rate of Cu(?)reached more than 94%.The adsorption of Cu(?)by polyethylenimine-tannin based adsorption resin conforms to the Langmuir adsorption model and the quasi-second-order kinetic equation.Thermodynamic parameters show that the adsorption process was endothermic.The resins had good reusability for the adsorption of Cu(?).4.The adsorption performance of polyethylenimine-tannin based adsorption resin for Nd(?)was investigated in this study.When the temperature was 318 K,p H was 5.0and Nd(?)concentration was 160 mg/L,the maximum adsorption capacity of Nd(?)was 81.32mg/g.When the initial concentration of Nd(?)was lower than 10mg/L,the adsorption rate of Nd(?)reached more than 91%.The adsorption of Nd(?)by polyethylenimine-tannin based adsorption resin conforms to the Langmuir adsorption model and the quasi-second-order kinetic equation.Thermodynamic parameters show that the adsorption process was endothermic.The resins had good reusability for the adsorption of Nd(?).In summary,the polyethylenimine-tannin based adsorption resin had good adsorption properties for Cr(?),Cu(?)and Nd(?),and was expected to achieve efficient enrichment and separation of metal ions in metal wastewater.