Study On The Preparation And Separation Performance Of Fibrous Core-shell Silica

Separating material is the core part of the separation process.Due to its high mechanical strength,excellent stability,ease of surface modification,and biological compatibility,silica has become an irreplaceable separation material.In recent years,fibrous core-shell silica particles has drawn much attention owing to its large surface areas and tunable pore diameters.Two aspects of the work were launched with fibrous core-shell silica particles as the object of study in this paper.First,3-?m fibrous core-shell silica particles were synthesized and their chromatographic properties were further studied after modified by n-octadecyltrichlorosilane and 3-aminopropyltriethoxysilane.Second,nanosized phenylboric acid-modified magnetic fibrous core-shell porous silica was prepared.The adsorption properties were explored using cis-diol molecules as model compounds and successfully used to enrich adenosine from urine.This thesis mainly includes the following three parts:Chapter 1 ReviewThis chapter mainly reviews the types,main synthesis methods,new developments and applications of porous core-shell silicas in recent years.Chapter 2 Study on properties of fibrous core-shell silica stationary phaseUsing 3-?m non-pore silica as the core,the fibrous structured core-shell silica particles(FCSS)were successfully synthesized by one-step oil-water biphase microemulsion coating strategy.Environmental scanning electron microscope(ESEM)and transmission electron microscopy(TEM)showed that the particles had good monodispersion and the spherical silica cores were uniformly coated with a well-defined fibrous silica shell in all directions.N2 adsorption results show that FCSS has an pore size of 19.89 nm.FCSS-80-C18 column obtained by C18 functionalized post packing.Subsequently,the separation of small molecules and proteins by FCSS-80-C18 was studied.Compared with the commercial C18 column,the FCSS column exhibited faster baseline separation of all the analytes studied with similar column efficiency.Baseline separation of seven small molecules was achieved within 10 min and six proteins within 6 min.In addition,FCSS have high mechanical strength,good reproducibility,and stability,After using more than 500 hours and 450 injections,the fiber shell and column efficiency did not change significantly.Finally,the separation of three phenolic small molecules was successfully realized by the amino functional chromatographic column.The faster and more efficient separation with relatively low back pressure demonstrate that FCSS particles have great potential application for separation with HPLC in the future.Chapter 3 The synthesis and adsorption behavior study of magnetic fibrous core-shell silica.Using magnetic silica as the core,the magnetic fibrous structured core-shell silica particles(MFMS)were successfully synthesized by one-step oil-water biphase microemulsion coating strategy.After boric acid functionalization,the adsorption material phenylboric acid modified magnetic fibrous mesoporous silica(MFMS-P)was obtained.The subsequent particle was systematic characterized by environmental scanning electron microscope(ESEM),transmission electron microscopy(TEM),N2 adsorption,vibrating-sample magnetometer(VSM).The adsorption behavior including adsorption model and adsorption kinetics were systematically researched using catechol as model molecules.The result showed the particle composed of a Fe3O4 core,non-porous silica interlayer and fibrous shell,which the fibrous silica shell were uniformly coated in magnetic silica cores with a well-defined.MFMS-P have radial-like direct channels and ideal pore size(12.72nm)and strong magnetic response.The adsorption capacity of catechol was as high as 293.03 ?mol g-1 for MFMS-P.The adsorption equilibrium was reached within 10 min,and the adsorption capacity was increased with temperature increasing.Adsorption mechanism study showed that the adsorption of catechol by MFMS-P is more suitable for the Langmuir model,the adsorption proceeded by monolayer formation.At the same time,the adsorption process is more in line with the pseudo-second-order kinetics model.These findings indicate that chemisorption was the rate-controlling step over the adsorption.The rate constant reaches 0.50 g(?mol min)-1.In addition,MFMS-P has satisfactory reusability,the adsorption performance is not significantly reduced after 5 cycles.Furthermore,it was successfully used to separation and enrichment nucleoside from the urine.All the result proved the magnetic fibrous structured mesoporous silica have the advantages of fast and high efficiency,and have an excellent separation material in rapid separation field.