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排序方式: 共有161条查询结果,搜索用时 15 毫秒
1.
《印度化学会志》2021,98(11):100191
Hydroxyapatite is a versatile compound resembling natural bone mineral. HAP insinuates feasibility with substitution ensuing in its application in various fields. The properties of calcium and strontium are cognate and pose as a bone-seeking trace-element that accumulates in new trabecular bone. Strontium substituted hydroxyapatite, Ca9.5Sr0.5(OH)2(PO4)6, was synthesized using citric acid as fuel and calcined 900 °C. The as-prepared product notably was characterized by powder X-ray diffraction, Fourier - Transform Infrared spectroscopy and Scanning Electron Microscope along with Energy Dispersive Spectroscopy. FT-IR analysis exhibited stretching and bending vibrations of (PO4)3- and OH− groups along without any signal of carbonate group. Studies showed that product formed is strontium substituted hydroxyapatite, and calcination temperature plays an essential role in the formation of hydroxyapatite phase. The precursors when calcined resulted in 46–50 nm of Sr substituted hydroxyapatite. 相似文献
2.
Nickel aluminate (NiAl2O4) and doped nickel aluminate (Ni1-xMxAl2O4; M = Mg, Zn, Cu; x = 0.1) were prepared by sol-gel method using citric acid. The synthesized compounds were analyzed by various techniques such as powder XRD, FTIR, SEM-EDAX and UV-DRS. The lattice parameter was found to increase with the copper, zinc and magnesium doping in nickel aluminate. The band gap was decreased from 3.0 eV (NiAl2O4) to 2.9 (zinc doped), 2.7 eV (magnesium doped) and increased to 3.1 eV in the case of copper doping. The catalytic study was carried out for a cationic (methylene blue) and an anionic dye (methyl orange). The percentage degradation of methyl orange using Zn0.1Ni0.9Al2O4 and Mg0.1Ni0.9Al2O4 was found to be 92% (180 min) and 96% (90 min). 93% (120 min) and 97% (120 min) degradation of methylene blue was observed using zinc doped and magnesium doped nickel aluminate respectively. These results are comparatively higher than its parent analogue (94% (180 min) degradation against methyl orange and 91% (120 min) against methylene blue). Whereas the percentage degradation was found to be less in the case of Cu0.1Ni0.9Al2O4 (83% (180 min) against methyl orange and 90% (120 min) against methylene blue). 相似文献
3.
Yingchao Han Xinyu Wang Shipu Li Xionghua Ma 《Journal of Sol-Gel Science and Technology》2009,49(1):125-129
Terbium doped calcium phosphate (Tb-doped CaP) nanocrystalline powders were synthesized by the citric acid sol–gel combustion
method. The phase composition, morphology and luminescent property of Tb-doped CaP nanocrystalline powders were characterized
by powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, fluorescence spectrophotometer
and fluorescence microscopy. At 700 °C, Tb-doped CaP nanocrystalline powders are composed of HAP (main phase) and β-TCP (minor
phase) with Tb doping content of 0.5–4%. SEM and TEM observations show that the 4% Tb-doped CaP nanocrystalline powders are
about 50–150 nm spherical particles. The 4% Tb-doped CaP nanocrystalline powders exhibit the strongest emission at 548 nm
(λexcitation = 240 nm) and show strong green fluorescence under fluorescence microscopy. 相似文献
4.
柠檬酸对Ru/AC氨合成催化剂结构和活性的影响 总被引:1,自引:0,他引:1
使用柠檬酸(CA)修饰石墨化活性炭(AC)和钌以改善Ru/AC催化剂中钌粒子的尺寸分布和催化剂的活性, 并通过透射电镜(TEM)、热重分析(TGA)、CO化学吸附和N2物理吸附等方法研究了柠檬酸对AC和Ru/AC催化剂织构、钌的分散度和催化剂的活性等性质的影响. 结果表明, 负载的柠檬酸优先吸附于活性炭微孔, 少量柠檬酸即可大幅度降低活性炭的比表面积, 增加活性炭表面含氧官能团的数量, 改善了钌粒子分布. 最佳负载顺序是柠檬酸和氯化钌依次负载. 在活性炭中添加适量的柠檬酸对催化剂的低温活性有显著影响. 柠檬酸处理后的Ru/AC催化剂活性最大提高幅度为21.4%. 相似文献
5.
Influence of citric acid on the morphology and magnetic properties of barium ferrite thin films 总被引:1,自引:0,他引:1
Wanli Zhang 《Applied Surface Science》2010,257(1):176-6964
Hexagonal barium ferrite (BaFe12O19) thin films were fabricated by spin coating of precursors from sol-gel methods. Different amount of citric acid was added. Weight loss and changes of chemical bonds during the heat treatment below 500 °C were recorded by thermogravity analyzer and Fourier transform infrared spectroscopy, respectively. The morphology of the films, i.e. the amount of acicular crystallites in the film, was controlled by adjusting the quantity of citric acid. The X-ray diffraction shows that the films are c-axis oriented, but the crystallization is less perfect with the increase of the citric acid. With the increase of the citric acid, the percentage of the acicular crystallites increased. At the same time, the coercivity force increased. The acicular crystallites were not exchange-coupled to the platelet crystallites. The citric acid was understood to form complex with iron ions and accelerate the exothermal auto-combustion. The c-axis oriented growth of the film was thus deteriorated. 相似文献
6.
《高分子科学杂志,A辑:纯化学与应用化学》2013,50(11):1105-1121
Citric acid (CAc) moieties containing acrylamide (AAm) hydrogels were prepared by gamma irradiation of their aqueous solutions. A possible polymerization and crosslinking mechanism for acrylamide/citric acid (AAm/CAc) hydrogels is proposed. The effects of irradiation dose and citric acid content on swelling behavior were investigated. Swelling took place in water at 25°C and was followed gravimetrically. Incorporation of a relatively low amount of citric acid to acrylamide hydrogel increased its swelling up to 950% from 700%. The diffusion of water into AAm/CAc hydrogels was found to be a non-Fickian type. Diffusion coefficients of AAm/CAc hydrogels found as 5 × 10?7? 10 × 10?7 cm2 sec?1. It has also been found that the number average molar mass between crosslinks is increased with the CAc content and decreased with irradiation dose. 相似文献
7.
石墨烯量子点(GQDs)是一种新型碳基准零维材料,不但具有石墨烯的独特平面结构,同时具备碳点的量子限制效应和边界效应。GQDs具有独特的光学性质、低毒性、高荧光稳定性和高生物相容性,被广泛应用于检测、传感、催化、细胞成像、药物递送和污染治理等领域。GQDs的合成分为自上而下法和自下而上法,前者将大尺寸的石墨烯、石墨、碳材料切割成纳米级的量子点,后者使用不同的前驱体,通过水热法、热裂解法等方法合成石墨烯量子点。柠檬酸(CA)是一种重要的有机酸,室温下是白色结晶状粉末,是自下而上法合成GQDs的一种常用前驱体,近年来有许多关于以CA为前驱体合成不同GQDs的研究,以CA为前驱体合成的GQDs(CA-GQDs)在生物医药、荧光检测、成像等领域均有应用,具有较好的应用前景。对近年来基于CA的合成方法和具体应用进行了总结和回顾,旨在将现有CA-GQDs的相关成果尽可能汇总和展现,以对相关领域研究工作者提供一定参考,并对未来CA-GQDs较有前景的研究方向进行了展望。 相似文献
8.
柠檬酸试剂中痕量无机阴阳离子的离子色谱法测定 总被引:5,自引:0,他引:5
选用柱容量较高、亲水性较强的阴离子分析柱IonPac AS18,以30mmol/L KOH为淋洗液,等度淋洗分析了高浓度柠檬酸中的痕量无机阴离子。选用柱容量较高的阳离子分析柱IonPac CS12A,以H2SO4作淋洗液分析了柠檬酸试剂中的痕量阳离子。在所选色谱条件下,无需样品前处理,直接进样,电导检测,高浓度柠檬酸不影响痕量阴离子或阳离子的测定。方法具有良好的线性(r=0.9941~1.000),样品中所测离子峰面积的相对标准偏差(RSD)均在9.0%以下(n=7),回收率在82.7%~110%之间,检出限低于3.7μg/L。 相似文献
9.
Pure calcite crystal with different morphologies such as wood-block and spherical aggregates were prepared by a precipitation reaction in the presence of citric acid. The as-prepared products were characterized with scanning electron microscope (SEM) and X-ray diffraction (XRD). The results showed that citric acid obviously influenced the formation of precipitates and the morphology of final products. The formation mechanism of wood-block-like particles was proposed according to theoretical deduction and the proposed growth mode. 相似文献
10.
SYNTHESIS OF MESOPOROUS POLY(STYRENE-co-MALEIC ANHYDRIDE)/SILICA HYBRID MATERIALS VIA A NONSURFACTANT-TEMPLATED SOL-GEL PROCESS* 总被引:1,自引:0,他引:1
Jie-bin Pang Kun-yuan Qiu Yen Wei Department of Polymer Science Engineering College of Chemistry Molecular Engineering Peking University Beijing China. Department of Chemistry Drexel University Philadelphia Pennsylvania USA. 《高分子科学》2000,(5):469-472
Mesoporous poly (styrene-co-maleic anhydride)/silica hybrid materials have been prepared. The synthesis wasachieved by the HCl-catalyzed sol-gel reactions of tetraethyl orthosilicate (TEOS) and styrene-maleic anhydride copolymerin the presence of 3-aminopropyl triethoxysilane (APTES) as a coupling agent and citric acid as a nonsurfactant template orpore-forming agent, followed by ethanol extraction. Characterization results from nitrogen sorption isotherms and powder X-ray diffraction indicate that polymer-modified mesoporous materials with large specific surface areas (e.g. 900 m~2/g) andpore volumes (e.g. 0.6 cm~3/g) could be prepared. As the citric acid concentration is increased, the specific surface areas, porevolumes and pore diameters of the hybrid materials increase. 相似文献