Preparation Of Functional Composite Aerogel And Study On Their Cu(Ⅱ) Removal Properties And Mechanism

Aerogel has important research significance in water pollution treatment because of its properties of low density,high porosity and high specific surface area.In this thesis,Amino modified Si O₂ aerogel（APTES/TEOS aerogel）was prepared by atmospheric drying method,and amino modified sodium alginate aerogel（SA/PEI aerogel）and cellulose aerogel（Cell aerogel）were prepared by vacuum freeze-drying method.Three different feed gas gel were used as adsorbent,and heavy metal Cu（II）was used as target pollutant.SEM,XRD,FTIR,XPS and other characterization methods were used to explore the impact of p H,ionic strength,time,temperature and other environmental factors on the adsorption process,and to study the adsorption mechanism.（1）APTES/TEOS aerogel was prepared by atmospheric drying method with ethyl orthosilicate（TEOS）as raw material and 3-aminopropyl triethoxysilane（APTES）as amination modifier.APTES/TEOS aerogel was characterized by SEM,XRD,FTIR and XPS.Taking heavy metal Cu（II）as the target pollutant,kinetics,isothermal model and thermodynamics of adsorption process were studied.The results show that the adsorption of Cu（II）by APTES/TEOS aerogel conforms to Freundlich isothermal adsorption model and quasi-second-order kinetic model,and the adsorption process is boundary layer diffusion,intra-particle diffusion and chemisorption.Thermodynamic parametersΔG<0,ΔH>0,ΔS>0,that is,the adsorption process belongs to the spontaneous reaction of endothermic and entropic increase.（2）SA/PEI aerogel was synthesized by vacuum freeze-drying with sodium alginate（SA）as raw material and polyethylenimide（PEI）as amination reagent.The influence of environmental factors such as p H value of solution,ionic strength,adsorption time and adsorption temperature on Cu（II）adsorption performance was studied,and the SA/PEI aerogel was characterized by SEM,XRD,FTIR and XPS to explore its adsorption mechanism.The results show that the adsorption capacity of Cu（II）increases with the increase of p H and decreases with the increase of ionic strength.The adsorption process reached an equilibrium state at 60 min,which was consistent with the quasi-second-order kinetic model.Through XPS and FTIR characterization,surface complexation and electrostatic interaction were the main adsorption mechanisms.（3）Cell aerogel was prepared by vacuum freeze-drying technology using cellulose powder as raw material and epichlorohydrin as crosslinking agent.The adsorption process of Cu（II）in water by Cell aerogel was studied by using the quasi-first-order kinetic model,quasi-second-order kinetic model,intra-particle diffusion model and isothermal adsorption model.The results showed that the adsorption capacity of Cell aerogel for Cu（II）solution with a mass concentration of 140 mg/L was 132.mg/g at 318K.According to the site energy distribution theory,under the same q_e condition,the size order of E*is 298K<308K<318K.Under the same E*condition,the size order of F（E*）is 298K<308K<318K.