Study On The Adsorption Of Hg²⁺ By Sulfhydryl Modified Salix Psammophila Powder

Salix psammophila powder（SPP）,as a natural polymer material,has many superior properties and certain adsorption capacity.However,the compact structure leads to the small adsorption capacity of SPP,which limits its application.In this thesis,sulfhydryl modified Salix psammophila powder（TSPP）was synthesized from SPP.Salix psammophila powder（SPPM）and sulfhydryl modified Salix psammophila powder（TSPPM）were prepared by wet spinning to solve the problem of small adsorption capacity.The prepared membrane material for the treatment of Hg²⁺pollution in water has the advantages of high adsorption efficiency,environmental protection of reagents,simple operation and easy recovery.The effects of preparation conditions and adsorption conditions on the adsorption capacity of SPPM,TSPP and TSPPM on the adsorption of Hg²⁺were studied,and the adsorption kinetic model and adsorption isotherm model were analyzed.SEM,FTIR,XRD,TG,EDS and XPS were used to characterize the three materials to explore the adsorption mechanism.The effects of desorption conditions on the three materials were investigated and the cycle times of the materials were determined.The main results of this thesis are as follows:（1）Swelling experiment of SPPMSPPM has good swelling properties,and the maximum swelling degree is 21.8 g/g when pH is 5,temperature is 75℃and ionic strength is 0.02 mol/L,for 20 min.The swelling process is mainly affected by osmotic pressure.The swelling kinetics of SPPM is studied.The initial stage of swelling is well fitted with Fickian diffusion model,and the whole process of water absorption swelling is well fitted with Schott model.It shows that the swelling process of SPPM is mainly affected by the diffusion of water molecules,and it can be kept intact for a long time at high temperature,which provides the possibility for the sustainability of SPPM.（2）Study on the adsorption/desorption properties of Hg²⁺on SPPMWhen the initial concentration of Hg²⁺is 500 mg/L,the pH value is 1,the adsorption time is 60min and the solution temperature is 35℃,the adsorption capacity of Hg²⁺is 436 mg/g.The adsorption data of SPPM fit well with the pseudo-second-order kinetics and Freundlich model.The adsorption process is a spontaneous process in which the degree of exothermic chaos decreases.The adsorption process is mainly the interaction of-COOH and-NH₂with Hg²⁺.After 4cycles of adsorption and desorption,the adsorption capacity is still 375 mg/g and can be recycled for more than 4 times.（3）Study on the adsorption/desorption properties of Hg²⁺on TSPPWhen the initial concentration of Hg²⁺solution is 700 mg/L,the adsorption time is 60 min,the adsorption temperature is 45℃,and the pH value is 2,the adsorption capacity of TSPP to Hg²⁺is the maximum,which is 1659.1 mg/g.The adsorption data of TSPP to Hg²⁺fit well with the pseudo-second-order kinetic model and Langmuir isotherm model.The adsorption process of TSPP to Hg²⁺is a process of spontaneity,endotherm and confusion.The desorption rate of TSPP can reach 100%,and the adsorption capacity is 1547.5 mg/g after 4 cycles.（4）Study on the adsorption/desorption properties of Hg²⁺on TSPPMThe adsorption capacity of TSPPM under the optimum adsorption conditions is1715 mg/g.The pseudo-second-order kinetic model and Langmuir model fit well with the adsorption data of TSPPM.Adsorption is a process of increasing confusion and spontaneity.The higher the temperature,the greater the trend of spontaneous reaction.TSPPM still has good adsorption capacity after several cycles,and the adsorption capacity is 1682 mg/g.