物质的相间分配对吸附相技术制备Ag/SiO_2反应过程的影响  

Effect of Interphase Distribution of Reactants in Binary Liquids on Preparation of Silver Nanoparticles on Silica Particles

作　　者：毛从文[1] 蒋新[1] 

机构地区：[1]浙江大学化学工程与生物工程学系,浙江杭州310027

出　　处：《高校化学工程学报》2007年第2期328-333,共6页Journal of Chemical Engineering of Chinese Universities

基　　金：国家自然科学基金资助项目(20476088);浙江科技计划项目(2005C31027)。

摘　　要：选择两个实验体系,分别研究了抗坏血酸和NaOH两种吸附质在SiO2表面富含水的吸附层与乙醇体相中的分配对在SiO2表面原位制备Ag的影响。结果表明,吸附质在SiO2表面吸附层和乙醇体相中的分配决定了Ag粒子的生成场所和形貌:抗坏血酸主要分配在乙醇体相中,导致Ag粒子的生成反应主要发生在乙醇体相中,生成的Ag粒子粒径较大;NaOH主要分配在吸附层中,导致Ag粒子的生成反应主要发生在吸附层中,生成的Ag粒子粒径较小。在不同NaOH浓度的实验中,随着NaOH浓度由0.0170g·L-1增至0.404g·L-1,吸附层和乙醇体相中的NaOH浓度分配比先增加后减小,导致反应的主要场所先由乙醇体相转移到吸附层,再由吸附层转移到乙醇体相,造成Ag晶粒粒径先减少后增加。当NaOH浓度为0.135g·L-1时,Ag粒子粒径达到最小(约5nm),且均匀分散在SiO2表面。Two kinds of adsorbates - L-ascorbic acid and NaOH were used separately to investigate the effects of adsorbate distribution between ethanol bulk phase and the phase of water-rich layer adsorbed by the surface of SiO2 particles on the preparation of silver nanoparticles on SiO2 particles. When the adsorbate L-ascorbic acid was used, L-ascorbic distributes mainly in the ethanol bulk phase and thus the Ag particle generating reaction will take place in the ethanol bulk phase with the generated Ag particle size of about 18 nm. When the adsorbate NaOH was used, NaOH distributes mainly in the phase of water-rich layer adsorbed on the surface of SiO2 particles and thus the Ag particles generate in the water-rich adsorption layer with particle size of only about 5.4 nm. Since the NaOH concentration effects its distribution between the two phases of ethanol bulk phase and water-rich adsorption layer, the further experiments with changing NaOH concentration in the reaction system from 0.0170 to 0.404 g·L^-1 were conducted. Results show that when concentration of NaOH in the system was increased from 0.0170 to 0.135 g·L^-1, the NaOH concentration in the water-rich adsorption layer increases with the increase of NaOH concentration in the system gradually, which causes the generation of Ag grains gradually centralizes in the adsorption layer with the grain size decreases from 8 nm to 5 nm, and the Ag particles generated cover the SiO2 more uniformly. When NaOH concentration in the system was increased from 0.135 to 0.404 g·L^-1, the amount of NaOH in the system is over the maximum NaOH capacity that can be contained in the water-rich adsorption layer and thus the NaOH concentration in ethanol bulk phase will increase to the limit, above which, the Ag generating reaction rate in it will accelerate more quickly than that in the water-rich adsorption layer, which causes the main generation zone of silver nanoparticles moves from water-rich adsorption layer to ethanol bulk phase gradually, and at the same time, the generated

关 键 词：相间分配 Ag/SiO2 反应场所 吸附层 

分 类 号：TQ026.5[化学工程] O647.314[理学—物理化学]