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采用吸附法处理染料废水需要合适的吸附剂。利用溶剂蒸发自组装法,以甲阶酚醛树脂为碳源、介孔SiO2粉体为载体制备介孔C/SiO2粉体,表征所制C/SiO2粉体的结构,研究C/SiO2粉体对阳离子型染料亚甲基蓝和阳离子红X-GRL的吸附性能,并与相同条件下制备的非负载的多孔C粉体以及介孔SiO2载体进行比较。结果表明,介孔C/SiO2粉体的孔窗口为11~18 nm,比表面积为303 m2.g-1,比孔容为1.11 cm3.g-1;C/SiO2粉体对这两种染料吸附量均高于C粉体和SiO2载体;在pH≤10的范围内,吸附量随pH值增大而显著提高。 相似文献
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以EDTA2-、SO42-作为反离子分别合成了具有管状和圆盘状结构的介孔SiO2,并测定了2种介孔SiO2焙烧至不同温度时的表面积、孔体积参数,及其等电点;通过752分光光度计在550nm处测定纤维素内切酶的吸光度,研究了2种形貌的介孔SiO2对纤维素内切酶的吸附性能,同时测定了固定酶的活性。结果表明,管状和圆盘状结构的介孔SiO2对纤维素内切酶的吸附等温线分别为Ⅱ和Ⅰ型;介孔SiO2焙烧至700℃时,两者皆为Ⅱ型;至850℃时,前者转化为Ⅰ型,而后者转化为Ⅴ型。吸附等温线类型与介孔SiO2的结构、等电点以及酶分子尺寸与介孔尺寸的相匹配有关。酶经过介孔SiO2吸附固定后,稳定性明显提高;其中,管状结构的介孔SiO2对酶具有最大的负载量,但固定酶的活性却较低。 相似文献
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微孔-介孔复合SiO2-Al2O3分子筛的水热合成研究 总被引:7,自引:2,他引:5
结合介孔和微孔分子筛的合成,采用十六烷基三甲基溴化铵(CTAB)和ZSM-5引导剂分别作为介孔和微孔结构的导向剂,在水热条件下合成了具有微孔-中孔复合结构的SiO2-Al2O3分子筛,并采用XRD和N2吸附对分子筛的结构进行了表征.结果表明,分子筛的XRD图谱在大角度区和小角度区同时出现较强的衍射峰,分别对应于四方晶型和MCM-41的结构.样品的N2吸附曲线亦在P/P0<0.1和P/P0=0.25~0.4出现两个突跃,其DFT孔径则主要集中在1.2nm和3.4nm. 相似文献
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采用十六烷基三甲基溴化铵(CTAB)为模板剂,四乙氧基硅烷(正硅酸乙酯,TEOS)为硅源,硝酸为催化剂来制备介孔SiO2,并采用后嫁接法对介孔SiO2进行氨基化改性。利用红外光谱(IR),X射线粉末衍射(XRD),差热-热重分析(DTA-TG),扫描电镜(SEM),元素分析,微电泳法及N2吸附-脱附方法对改性前后的产物进行表征。结果表明氨基已成功嫁接到介孔SiO2孔道中,改性后的介孔SiO2有序度有所下降,但仍为介孔材料;改性之后介孔材料的孔径、比表面积、孔体积均变小。等电点由原来的2.74变为4.75。本文还以氨基修饰的介孔SiO2为载体,通过交联剂戊二醛固定诺维信(Novozymes)工业级漆酶,并采用正交设计法对固定化条件进行了优化。研究表明漆酶经固定化后,其操作稳定性比游离酶高。 相似文献
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利用酸化法在磁性Fe3O4纳米粒子表面包覆SiO2膜,制备了Fe3O4/SiO2复合粒子。然后将该复合粒子超声分散在尿素和铝盐的混合溶液中,利用油中成型法制备出球形纳米磁性Al2O3复合材料,通过水热焙烧等工序处理得γ-Al2O3。实验中采用XRD、TEM、BET、AGM等方法对复合粒子的性能进行了表征,探讨了制备过程对产物晶型的影响、产物的孔结构变化和磁学性能。另外添加的SiO2膜阻止了磁性Fe3O4纳米粒子的进一步团聚,使得Fe3O4纳米粒子保持较小尺寸并均匀分散在产物中,复合材料表现出超顺磁性;同时SiO2膜防止了磁核部分与Al2O3包覆层在高温焙烧时发生反应;还起到加强粘结的作用,使得Al2O3在使用过程中不容易脱落。 相似文献
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合成了手性阳离子型两亲性小分子化合物,利用圆二色谱分析了其在水中形成的自组装体的结构;以该化合物的自组装体为模板,在正丙醇和氨水的混合溶剂中制备得到了介孔二氧化硅空心球;利用扫描电镜、透射电镜、X射线衍射仪以及氮气吸附-脱附试验装置分析了二氧化硅空心球的形貌及孔结构.结果表明,两亲性小分子在水中形成的自组装体呈现手性堆积;合成的介孔二氧化硅空心球的直径约为600~800nm,壁厚约为100~150nm,其孔道垂直于球的表面,孔径约为3.0nm,比表面积约为306m2·g-1.正丙醇作为模板控制二氧化硅空心球的空腔尺寸和形貌,而两亲性小分子的自组装体作为模板控制放射状孔道的形貌和尺寸. 相似文献
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以二甲基二乙氧基硅烷为硅源,在水溶液中成功制备了SiO2修饰纳米ZrO2颗粒;利用透射电子显微镜、热重分析仪、X射线衍射仪、红外光谱仪分析了样品的形貌和结构;将SiO2/ZrO2与α-Al2O3制成陶瓷材料,考察了其机械性能.结果表明,所制备的SiO2/ZrO2晶粒均一,直径约为10nm,硅原子在SiO2/ZrO2中以Si―O―Zr键合形式存在,SiO2不影响ZrO2的晶型.引入SiO2使得ZrO2晶粒细化、尺寸均匀性提高;SiO2/ZrO2/Al2O3陶瓷气孔率小,具有致密的显微结构和优异的机械性能. 相似文献
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Magnetic mesoporous silica nanoparticles (M-MSNs) are emerging as one of the most appealing candidates for theranostic carriers. Herein, a simple synthesis method of M-MSNs with a single Fe(3)O(4) nanocrystal core and a mesoporous shell with radially aligned pores was elaborated using tetraethyl orthosilicate (TEOS) as silica source, cationic surfactant CTAB as template, and 1,3,5-triisopropylbenzene (TMB)/decane as pore swelling agents. Due to the special localization of TMB during the synthesis process, the pore size was increased with added TMB amount within a limited range, while further employment of TMB lead to severe particle coalescence and not well-developed pore structure. On the other hand, when a proper amount of decane was jointly incorporated with limited amounts of TMB, effective pore expansion of M-MSNs similar to that of analogous mesoporous silica nanoparticles was realized. The resultant M-MSN materials possessed smaller particle size (about 40-70 nm in diameter), tunable pore sizes (3.8-6.1 nm), high surface areas (700-1100 m(2)/g), and large pore volumes (0.44-1.54 cm(3)/g). We also demonstrate their high potential in conventional DNA loading. Maximum loading capacity of salmon sperm DNA (375 mg/g) was obtained by the use of the M-MSN sample with the largest pore size of 6.1 nm. 相似文献
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Suteewong T Sai H Cohen R Wang S Bradbury M Baird B Gruner SM Wiesner U 《Journal of the American Chemical Society》2011,133(2):172-175
Mesoporous silica with cubic symmetry has attracted interest from researchers for some time. Here, we present the room temperature synthesis of mesoporous silica nanoparticles possessing cubic Pm3?n symmetry with very high molar ratios (>50%) of 3-aminopropyl triethoxysilane. The synthesis is robust allowing, for example, co-condensation of organic dyes without loss of structure. By means of pore expander molecules, the pore size can be enlarged from 2.7 to 5 nm, while particle size decreases. Adding pore expander and co-condensing fluorescent dyes in the same synthesis reduces average particle size further down to 100 nm. After PEGylation, such fluorescent aminated mesoporous silica nanoparticles are spontaneously taken up by cells as demonstrated by fluorescence microscopy. 相似文献
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A series of hierarchically mesostructured silica nanoparticles (MSNs) less than 100 nm in size were fabricated by means of a one-step synthesis using dodecanethiol (C(12)-SH) and cetyltrimethylammonium bromide (CTAB) as the dual template, and trimethylbenzene (TMB) as the swelling agent. Silica nanoparticles with varied morphologies and structures, including mesoporous silica nanoparticles with tunable pore size, mesoporous silica nanoparticles with a thin solid shell, hollow mesoporous silica nanoparticles with tunable cavity size, and hollow mesoporous silica nanoparticles with a thin solid shell, were obtained by regulating the TMB/CTAB molar ratio and the stirring rate with the assistance of C(12)-SH. Silica particulate coatings were successfully fabricated by using MSNs with varied morphologies and structures as building block through layer-by-layer dip-coating on glass substrates. The thickness and roughness of the silica particulate coatings could be tailored by regulating the deposition cycles of nanoparticles. The silica particulate coatings composed of hollow mesoporous silica nanoparticles with a thin shell (S2) increased the maximum transmittance of slide glass from 90 to 96%, whereas they reduced its minimum reflection from 8 to 2% at the optimized wavelength region that could be adjusted from visible to near-IR with a growing number of deposition cycles. The coatings also exhibited excellent superhydrophilic and antifogging properties. These mesostructured silica nanoparticles are also expected to serve as ideal scaffolds for biological, medical, and catalytic applications. 相似文献
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Wang L Shi J Zhu Y He Q Xing H Zhou J Chen F Chen Y 《Langmuir : the ACS journal of surfaces and colloids》2012,28(11):4920-4925
A multi-nanoparticle-embedded amorphous aluminum/magnesium oxides (AAMO) core/mesoporous silica (mSiO(2)) shell structure has been successfully synthesized by calcining the presynthesized catalyst precursor-containing layered double hydroxide (LDH) core/mesoporous silica shell composite. The well-dispersed catalytic nanoparticles were fixed at the interface between AAMO core and mesoporous SiO(2) shell, i.e., at the inner pore mouths of the mesoporous SiO(2) shell, which could effectively prevent nanoparticles from growth and/or aggregation with each other and in the meantime allow efficient access of reactants to the catalytic NPs. The final core/shell composite was found to be an efficient and highly recyclable heterogeneous catalyst. 相似文献
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The role of pore size and structure on the thermal stability of gold nanoparticles within mesoporous silica 总被引:4,自引:0,他引:4
Bore MT Pham HN Switzer EE Ward TL Fukuoka A Datye AK 《The journal of physical chemistry. B》2005,109(7):2873-2880
Highly dispersed gold particles (<2 nm) were synthesized within the pores of mesoporous silica with pore sizes ranging from 2.2 to 6.5 nm and different pore structures (2D-hexagonal, 3D-hexagonal, and cubic). The catalysts were reduced in flowing H2 at 200 degrees C and then used for CO oxidation at temperatures ranging from 25 to 400 degrees C. The objective of this study was to investigate the role of pore size and structure in controlling the thermal sintering of Au nanoparticles. Our study shows that sintering of Au particles is dependent on pore size, pore wall thickness (strength of pores), and pore connectivity. A combination of high-resolution TEM/STEM and SEM was used to measure the particle size distribution and to determine whether the Au particles were located within the pores or had migrated to the external silica surface. 相似文献
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The incorporation of CdS nanoparticles, prepared in reverse micellar systems, into thiol-modified mesoporous silica, such as FM41 (functionalized MCM-41) and FM48 (functionalized MCM-48), has been investigated. The nanoparticles were immobilized in the mesopores via the incorporation of water droplets of the reverse micelles. A particle-sieving effect for FM41 having large (L-FM41, 3.8 nm) and medium (M-FM41, 3.6 nm) pore size was observed, in that the incorporation of the CdS nanoparticles was decreased with increasing particle size and with decreasing pore size of the FM41. Chemical vapor deposition treatment employed to narrow the mesopores of the CdS-FM41 enhanced the stability of CdS nanoparticles against heat treatment. The CdS-FM41 composites demonstrated photocatalytic activity for H(2) generation from 2-propanol aqueous solution, the better photocatalytic activity being obtained with the larger pore size for CdS-L-FM41. Copyright 2001 Academic Press. 相似文献
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Sun Z Zhang H Zhao Y Huang C Tao R Liu Z Wu Z 《Langmuir : the ACS journal of surfaces and colloids》2011,27(10):6244-6251
A universal strategy was developed for the preparation of high-temperature-stable carbon nanotube (CNT) -supported metal nanocatalysts by encapsulation with a mesoporous silica coating. Specifically, we first showed the design of one novel catalyst, Pt(@)CNT/SiO(2), with a controllable mesoporous silica coating in the range 11-39 nm containing pores ≈3 nm in diameter. The hollow porous silica shell offers a physical barrier to separate Pt nanoparticles from contact with each other, and at the same time the access of reactant species to Pt was not much affected. As a result, the catalyst showed high thermal stability against metal particle agglomeration or sintering even after being subjected to harsh treatments up to 500 °C. In addition, degradation in catalytic activity was minimized for the hydrogenation of nitrobenzene over the catalyst treated at 300 °C for 2 h. The scheme was also extended to coat porous silica onto the surfaces of CuRu(@)CNT and the resultant catalyst thereby can be reusable at least four times without loss of activity for the hydrogenolysis of glycerol. These results suggest that the as-prepared nanostructured CNT-supported catalysts may find promising applications, especially in those processes requiring rigorous conditions. 相似文献