Functionalization Of Two Forms Of Mesoporous Silica And The Preparation Of Calcium Carbonate With Different Morphologies

Mesoporous silica materials with special pore structure, high specific surfacearea and pore volume, good thermal stability and hydrothermal stability, controllablemorphology, easy functionalization and a series of excellent performances, haveattracted more and more attentions due to the special performances. Due to theseadvantages, it shows great potential application in adsorption, separation, catalysis,chemical sensors, and biological medical science and so on. The mesoporous silicamonolithic with good absorbability, reproducibility, eroding resistion and easy-handleof operation may have significant applicability as a regenerated adsorbent, which canreduce the labor intensity and improve the efficiency of the researching. Mesoporoushollow silica nanospheres （MHSNS） with lower apparent density, higher specificsurface area, unique chemical and optical properties, larger drug loading, andsustained release, can be used in extensive application in biomedical. The preparationof CaCO₃with different morphologies and polymorphs, is a hot topic for scientistsdue to its wide application in various fields such as rubbers, plastics, paper andpainting ink industries. Therefore, it is very important to seek new strageties ofpreparation of the CaCO₃materials.In this paper, in the second and third chapters, we investigated the preparationand functionalization of the different morphological mesoporous silica; in the fouthand fifth chapters, the preparation and characterization of CaCO₃with differentmorphologies were explored. Main contents are described in the following aspects:1. The worm-like mesoporous silica monolithic （WMSM） was firstly prepared bysolvent evaporation method. Then, the WMSM was further modified with aminoagent （3-Aminopropyltriethoxysilane, APTES） by a co-precipitation method andnoted as （WMSM-NH₂）. Thirdly, we used WMSM-NH₂as an adsorbent for the adsorption of Cu²⁺ions and the regeneration of adsorbent was investigated. Theexperiment results show the WMSM-NH₂materials present high adsorption efficiencyof99.3%for Cu²⁺ions. Importantly, the adsorption efficiency of89.0%was remainedand only8.0%of the mass was lost after seven adsorption-desorption cycles wereexecuted on the products. The low mass loss is more favorable to the recyclingoperations, such as easy multiple washing, fast filtration and extraction, which canreduce the labor intensity and improve the efficiency of the researching. In summary,the modified mesoporous silica monolithic with good absorbability, reproducibility,eroding resistion and easy-handle of operation may have significant applicability as areusable adsorbent in the area of environment field.2. Calcium carbonate （CaCO₃）, as a cheap and abundant material, is easilyprepared and removed by acid, and synthesized with different morphologies byadjusting the experiment conditions. Therefore, the synthesis of hollow silica usingcalcium carbonate as hard template has become a research hotspot. However, in mostof the reported methods, the shell materials was coated on the pre-synthesized coretemplate, CaCO₃, which had to be prepared firstly, followed by the centrifugation,separation and washing. The procedure is costly, time consuming, and complicated. Inthis doctor thesis, we present a simple and environmental friendly pathway tofabricate mesoporous hollow silica nanospheres （MHSNS） via core-shell structure ofCaCO₃@SiO2from Ca（CH3COO）2and NaHCO₃in the mixed solvent of H₂O/EG bya one-pot route. A great of-OH were maintained after the core template was removedby acid. The MHSNS exhibits the characteristics of the mesostructure and sphericalmorphology with an average diameter of100nm and a silica shell of around10nm.The CaCO₃@SiO2material provides a good platform for the adsorption of drugmolecules, IBU, with drug loading of750mg/g and exhibits good sustained release.3. Hollow calcium carbonate （CaCO₃） represents an important class ofbiodegradable materials, which have been of great attentions. According to theliteratures, the hollow CaCO₃particles were mostly prepared with the aid of templates,which lead to costly, complicated procedures, time consuming, stringent conditionsand pollutants generated from the elimination of the templates. Therefore, we seek asimple and environmentally friendly template-free synthetic route for fabricatinghollow vaterite CaCO₃microspheres with an average diameter of800nm and a shellof around150nm from precipitation reaction of Ca（CH3COO）2and NaHCO₃in the mixed solvent of H₂O/EG without any templates at room temperature. In addition,hollow CaCO₃, as a container, can be used in the carry of large drug molecules owingto its large hollow structure and biocompatibility, which has the potential andpromising application in biomedicine.4. CaCO₃with different morphologies and polymorphs was prepared by a facileadditive-free method between Ca（CH3COO）2and NaHCO₃in H₂O/EG mixed solvent.Interesting morphologies of spherical, elliptoid, spindle-like, petal-like, cricoid, cubic,plate-like and rod-like products were obtained by adjusting the concentration ofNaHCO₃and Ca（CH3COO）2,the volume ratio of H₂O/EG and the rection temperature.The structures of the products were studied. The results showed that lowconcentration of Ca²⁺（HCO₃^-） and high temperature were in favor of the formationof vaterite and aragonite, respectively. This method is a simple, easily handled andenvironmentally friendly, which provide new insights into the morphosynthesis andcrystalline phase control of other inorganic materials.