Preparation Of Magnetic MCM-41 Mesoporous Molecular Sieve And Study On Adsorption Of Rhodamine B

Molecular sieve is a kind of mesoporous material with porous structure,which belongs to the water-containing silicate compound.Because of its rich structure in the skeleton structure,it has the characteristics of large specific surface area,uniform pore volume and pore size distribution.Molecular sieves have been widely used in the field of catalysis,adsorption separation and ion exchange.Molecular sieves are generally powdered particles,in the course of the use of saturated adsorption is difficult to separate with the role of the object,which is not easy to be reused.In this paper,magnetic separation technology is applied.When molecular sieves are combined with magnetic materials,the molecular sieves can be separated from the reaction system under the external magnetic field,which solves the problem of solid-liquid separation and creates the conditions for the recycling.Therefore,Magnetic molecular sieves become one of the hotspots in the field of adsorption.In this experiment,Fe₃O₄ particles with different sizes and morphologies were prepared by coprecipitation method and solvothermal method respectively.The optimum conditions for the synthesis of Fe₃O₄ particles were investigated by influencing the addition of NaOH,PVP and reaction time in solvothermal method.It is found that the spherical Fe₃O₄ particles prepared by solvothermal method are highly controllable,the particle size is uniform and the magnetic properties are good.Therefore,we choose spherical Fe₃O₄ particles for the next application.In order to explore the magnetic properties of MCM-41 mesoporous molecular sieves,MCM-41 mesoporous molecular sieves were prepared by hydrothermal synthesis method.In the process of synthesizing MCM-41 mesoporous molecular sieves,different kinds of spherical Fe₃O₄ particles were added to the reaction mixture.Magnetic MCM-41 mesoporous molecular sieves containing different Fe₃O₄ particles.（FT-IR）,X-ray diffraction（XRD）,transmission electron microscopy（TEM）,scanning electron microscopy（SEM）,vibrating sample magneto-meter（VSM）,nitrogen adsorption-desorption（BET）And other means of the synthesis of different samples of performance and structural characterization.The adsorption properties of the composite MCM-41 mesoporous molecular sieve composites were measured by UV-Vis spectrophotometer.The experimental results show that the introduction of Fe₃O₄ particles does not destroy the skeletal structure of MCM-41 mesoporous molecular sieves and has little effect on the pore structure of mesoporous molecular sieves.With the increase of the addition of Fe₃O₄ particles,the magnetic properties of the prepared magnetic MCM-41 mesoporous molecular sieves were enhanced up to 29.26emu/g.The adsorption performance of magnetic MCM-41 mesoporous molecular sieves decreased slightly compared with pure MCM-41 mesoporous molecular sieves,but the magnetic MCM-41 mesoporous molecular sieves could be separated quickly under magnetic field.The adsorption model was studied by adsorption model.It was found that the adsorption process was closer to Langmuir model,indicating that the adsorption process was monomolecular adsorption.And the adsorption performance was influenced by the adsorption conditions.Under the condition of initial concentration of Rhodamine B of 100mg/L,temperature of 20℃and pH of solution 4.0,the optimum amount of adsorbent was 0.5g/L,120min,the removal rate of rhodamine B was 86.7%.The results show that the magnetic MCM-41 mesoporous molecular sieves still have high adsorption capacity and the adsorption capacity of the MCM-41 mesoporous molecular sieves can be maintained at about 70%.The reproducibility experiments showed that the prepared MCM-41 mesoporous molecular sieve adsorbents had good stability and could be reused several times.