Preparation Of Functionalized Mesoporous Alumina Materials And Their Adsorption Properties

Mesoporous alumina is widely used in adsorption,catalysis,medicine and energy fields because of its many excellent properties.At present,porous alumina is mainly produced by aluminate carbonization method,but the product has low purity and heterogeneity,which is restricted in many applications.So far,the high-end commoditized porous alumina is represented by SB powder produced of Sasol,Germany,which is made of easy-to-purified aluminum alkoxide.In recent years,Chinese researchers have conducted research on the production of high quality mesoporous alumina with aluminum alkoxide,but some problems need to be solved compared with SB powder,for example,the gelation speed of the synthetic pseudo-boehmite is slower than that of SB powder.The pore diameter of mesoporous alumina is relatively smaller compared with the alumina after SB powder roasting.In addition,it's difficult to recover when recycling with mesoporous alumina as adsorbent.In this paper,the gelation properties and pore structure were controlled by adding additives in the aging process with isopropanol aluminum as the source of aluminium.The adsorption properties of mesoporous alumina with different pore structures were studied.On this basis,mesoporous alumina was functionalized and the magnetic mesoporous alumina was obtained with ZnFe₂O₄,and its adsorption performance was studied.?1?The study on the gelation properties of pseudo-boehmite.The gelation properties were controlled by different additives and amount?additive and isopropanol aluminum quality ratio?.The results show that the B₂ additive was more suitable to regulate the gelation properties and the optimum additive amount was 0.0375.Compared with SB powder,the gelation properties of pseudo-boehmite is basically the same,which can be changed from sol to gel in about 1 h.?2?The study on the pore structure of mesoporous alumina.The pore structure of mesoporous alumina was controlled by adding different kinds of organic solvents(A_1-A₈)in the process of aging.It was found that mesoporous alumina obtained with the addition of A₅with 0.5?the mass ratio of A5 to isopropanol aluminum.?has the greatest specific surface area of 313.2 m²/g,the highest pore volume of 0.82 mL/g,the largest average pore diameter of10.4 nm,higher than the mesoporous alumina obtained by imported SB powder.Mesoporous alumina obtained with 0.5A5 has the maximum adsorption capacity of 317 mg/g.The adsorption conforms to the pseudo-second-order reaction kinetics model and the Langmuir thermodynamic model,and has better cyclic adsorption performance.Its adsorption performance is obviously higher than that of SB.?3?The study on functionalization of mesoporous alumina.?-Al₂O₃/ZnFe₂O₄ having different magnetism and structure were obtained by regulating the addition of zinc ferrite nanoparticles ZnFe₂O₄?the mass ratio of ZnFe₂O₄ and?-Al₂O₃?in the preparation process of porous alumina.The samples were all bowl-shaped after spray drying.When the addition of ZnFe₂O₄ was 0.06,the specific surface area was 316.6 m²/g and the saturation magnetic induction intensity?1.96 emu/g?was suitable.?-Al₂O₃/0.06 ZnFe₂O₄ has a high adsorption efficiency for Congo red and the maximum adsorption capacity is 413 mg/g.What's more,it has excellent cyclic adsorption performance,after six adsorption cycles,the adsorption capacity has hardly changed.In the process of cyclic adsorption,the rapid separation of adsorbents and solutions can be achieved through the external magnetic field.