Study On The Adsorption Properties Of Pb²⁺ By Salix Psammophila Powder Membranes

In recent years,environmental issues have received more and more attention.With the increasing global environmental problems,in the wastewater treatment,adsorbents prepared with natural polymer materials as raw materials have received more and more attention due to their environmental friendliness.However,since most of the adsorbents are in the form of powder,it is difficult to separate from the wastewater after adsorption,resulting in a low recovery rate.Salix psammophila powder membranes(SPPM)and carboxylation salix psammophila powder membranes(CSPM)were prepared using salix psammophila powder(SPP)and citric acid modified carboxylation salix psammophila powder(CSP)as raw materials.The effects of various experimental factors on the adsorption capacity of SPPM and CSPM were analyzed by orthogonal experimental analysis,and the optimal preparation conditions of SPPM and CSPM were determined.The microstructures of SPPM and CSPM were analyzed by Fourier transform infrared spectroscopy(FT-IR),X-ray diffraction(XRD)and scanning electron microscopy(SEM).Based on the optimal preparation conditions,the effects of adsorption conditions(initial concentration of Pb2+ solution,adsorption time,solution pH,adsorption temperature)on the adsorption of Pb2+ on SPPM and CSPM were studied,and the optimal adsorption conditions and maximum adsorption capacity were determined.The adsorption isotherms,adsorption kinetics models and adsorption thermodynamics of SPPM and CSPM were further determined.The microstructures of SPPM and CSPM after adsorption were analyzed by X-ray photoelectron spectroscopy(XPS),SEM and energy dispersive X-ray energy spectroscopy(EDX).The main research results of the thesis are as follows:1.Preparation of SPPM and it study on the adsorption properties of Pb2+:The optimum preparation conditions are:reaction time 2 h,reaction temperature 95?,pretreatment time 4h,NaOH pretreatment concentration 25%,pretreatment temperature 40?.The maximum adsorption capacity of SPPM for Pb2+ is 760 mg/g.The results of the adsorption experiment show that when the initial concentration of Pb2+ solution is 1600 mg/L,the adsorption time is 0.5 h,the pH is 5,and the adsorption temperature is 30?,the adsorption capacity reached the maximum,which is 760 mg/g.The adsorption process of Pb2+ by SPPM accords with the pseudo-secondary kinetics and the Freundlich adsorption isotherm model,which belongs to the chemical adsorption of multi-molecular layers.2.Preparation of CSPM and study of adsorption properties of Pb2+by CSPM:CSPM to Pb2+from strong to weak is:modification temperature,modification time,reaction temperature,citric acid concentration and reaction time.The optimum preparation conditions of CSPM are:modification temperature 110?,modification time 90 min,reaction temperature 85?,citric acid concentration 1.5 mol/L,reaction time 2 h.The maximum adsorption capacity of CSPM for Pb2+ is 950 mg/g.The results of the adsorption experiments show that when the initial concentration of Pb2+ solution is 2000 mg/L,the adsorption time is 0.5 h,the pH value is 4,and the adsorption temperature is 30?,the adsorption amount of Pb2+ by CSPM reached the maximum,which is 950 mg/g.The adsorption of Pb2+ by CSPM conforms to the Freundlich adsorption isotherm and pseudo-second-kinetic model,which is a heterogeneous chemical adsorption.