Preparation Of Functional Mesoporous Materials And Its Application In Selective Separation Of Metal Pollutants And Biosensing

Mesoporous materials are inorganic porous material with regular pore structure and narrow pore size distributions between 2 and 50 nm. Mesoporous materials have been gradually applied in separation due to their large surface area, homogeneous transfer and high adsorption capacity. Especially the long-range ordered mesoporous structure and well modified surface properties with abundant Si-OH active bonds inside and outside of the pore walls which provide advantageous conditions for functionalization assembling.In this study, mesoporous structure sorbents of high selectivity, large adsorption capacity and good regeneration capability were synthesized by molecular imprinted technology which has specified recognition capability towards target compound. New targeted separation/pre-enrichment system has been developed. Meanwhile, appropriate immobilization technology of protein by metal doping modification mesoporous materials has been studied. The electrocatalysis activity of metal containing mesoporous material and the immobilized enzyme were investigated. The main conclusion included the following items:1. The preparation of surface imprinting modified mesoporous materialsSurface imprinting modified mesoporous materials applied in selective adsorption of Co(II), Pb(II) and Cr(III) were prepared by graft polymerization and sol-gel reaction with the surface imprinting technique on the support of silica mesoporous material. The prepared polymer was characterized by FT-IR, SEM, XRD,TEM and N2 adsorption-desorption isotherm. The results showed that the polymer possessed high ordered mesoporous structure.2. The application of surface imprinting modified mesoporous materials in selective separation/enrichment of environmental metal pollutants(1) It was found that the pseudo-second-order model best correlated the kinetic data of Co(II) adsorption onto Co(II)-IIP. The adsorption process was controlled by the intraparticle diffusion mechanism. Langmuir model fitted the experiment data well and the maximum calculated capacity of Co(II) reached 39.26 mg/g. Co(II)-IIP showed high affinity and selectivity for template ion compared with NIP. Co(II) adsorbed to the adsorbent could be eluted quantitatively. Co(II)-IIP is a regenerable SPE adsorbent of good selectivity.(2) Pb(II)-IIP showed fast kinetics, high selectivity and satisfied adsorption capacity for adsorption of Pb(II). Pb(II) adsorption process over Pb(II)-IIP followed pseudo-second-order reaction kinetics and the Langmuir adsorption model. The adsorption process was controlled by intraparticle diffusion mechanism together with external mass transfer and the pore diffusion was more dominant than film diffusion. The sorbent was applied to the selective separation and determination of Pb(II) in water and sediment samples with satisfactory results.(3) A new SPE method for the speciation, separation, preconcentration and determination of Cr(III) and Cr(VI) by ICP-AES and UV on mesoporous imprinted polymer adsorbent was developed. The adsorption kinetics, thermodynamics behavior and recognizing ability towards Cr(III) on imprinted and non imprinted polymer were compared. The results showed that Cr(III)-IIP had higher selectivity and larger Langmuir adsorption capacity of 38.50 mg/g. The proposed method has been successfully applied in the determination and speciation of chromium in natural water samples with satisfactory results.3. The preparation of metal ion doping modified mesoporous materials and research of application in biosensing(1) Nano CoMCM-41 modified glassy carbon electrode has been fabricated by polymer imbedded method and characterized by SEM. The modified electrode exhibited significant sensitization and electro-separation effect towards AA and DA. With potential difference of 310 mV, it was possible to obtain potentiometric sensor for determination of AA and DA simultaneously.(2) Nano NiMCM-41 film modified electrode has been fabricated by coelectrodeposition method to immobilize horseradish peroxidase (HRP). HRP could maintain its bioactivity and showed linear response to hydrogen peroxide in the range of 3.52×10-6～1.31×10-3mol/L in the presence of hydroquinone with detection limit of 1.17×10-6mol/L (S/N=3). The Michaelis constant was 1.47 mmol/L. The biosensor showed good stability and reproducibility(3) TiSBA-15 was synthesized under normal pressure by microwave irradiation. Composites of TiSBA-15, CTS and AChE were immobilized on Au electrode by one-step electrodeposition method. Stable electrochemical response of acetylthiocholine was obtained on modified electrode which showed that AChE retained good catalytic activity. The carbaryl inhibition ratio was proportional to its concentration in two ranges from 0.005 to 0.1μg/mL and 0.5 to 5μg/mL with the detection limit of 0.003μg/mL. The biosensor showed good reproducibility and stability.(4) One-step electrodeposition method has been applied for preparation of TiSBA-15/CTS/GOD composites film modified electrode. The uniform pores of TiSBA-15 allowed to controlling the adsorption of enzyme molecules on the basis of size. Direct electrochemistry was investigated on the film and the immobilized GOD displayed an excellent electrochemical response towards the electrocatalytic oxidation of glucose in the presence of oxygen. The linear range was 0.02-10 mmol/L and the Michaelis constant was 2.2 mmol/L. A new method for fabricating reagentless glucose biosensor has been developed.