Study of Fibrous AlPO4-5 via Hydrothermal Conditions: Morphology Evolution and Growth Mechanism

Aluminophosphate molecular sieves (AlPO4-5s) with fibrous morphology were readily prepared via hydrothermal method at 180 °C with the initial molar ratio of Al(OiPr)3: H3PO4: TrPA: HF: H2O as 1: 0.83: 1: 0.8: 70. The morphology and structure of the prepared AlPO4-5s were characterized by XRD, SEM, TEM and nitrogen sorption measurement. The morphology development and structure evolution mechanism were proposed.

Download Full-text

Controlled Hydrothermal Growth of CuO-Based Nanostructures from Copper Alginate

Materials Science Forum ◽

10.4028/www.scientific.net/msf.688.19 ◽

2011 ◽

Vol 688 ◽

pp. 19-22 ◽

Cited By ~ 1

Author(s):

Bing Bing Wang ◽

Qing Shan Kong ◽

Jian Ping Sun ◽

Quan Feng Yu ◽

Quan Ji ◽

...

Keyword(s):

Hydrothermal Method ◽

Growth Mechanism ◽

Hydrothermal System ◽

Ph Value ◽

Structure Evolution ◽

Structure Directing Agent ◽

Aggregation State ◽

Air Atmosphere ◽

Morphology And Structure ◽

Different Temperatures

Schistose and aciculate CuO nanostructures have been synthesized by a novel ammonia assisted hydrothermal method of copper alginate. The conversion processes of copper alginate are investigated by thermogravimetrics (TG) analyses under N2and air atmosphere. The morphology, structure, and composition of the obtained CuO are investigated using SEM,TEM and XRD. It is found that different temperature and pH value resulted in the morphology and structure evolution of CuO. Ammonia was used as structure-directing agent in the hydrothermal system. The aggregation state of the nanostructures was controlled by the temperature. Dispersive schistose structures about 1μm in diameter were synthesized with 0.5mL ammonia at different temperatures. Dispersive microspheres of about 4 μm in diameter were also synthesized with 1 mL ammonia. Microspheres composed of nanoneedles and nanoplates were synthesized at 120°C and 160°C, respectively. Moreover, a possible growth mechanism governing the formation of such a nanomicrostructure was primarily discussed.

Download Full-text

Morphology Evolution and Luminescence Properties of YF3: Sm Nano-/Microcrystals

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.463-464.112 ◽

2012 ◽

Vol 463-464 ◽

pp. 112-118

Author(s):

Feng Tao ◽

Geng Zhu ◽

Zhi Jun Wang ◽

Feng Pan ◽

Yu Feng Sun ◽

...

Keyword(s):

Hydrothermal Method ◽

Growth Mechanism ◽

Room Temperature ◽

Red Light ◽

Environmentally Friendly ◽

Morphology Evolution ◽

Flat Panel Display ◽

Flat Panel ◽

Display Devices ◽

Potential Applications

Abstract. Recently, there has been increasting interest in the doping of nano-/microcrystal hosts with Sm3+. However, very few examples of Sm3+doped YF3-based nanophosphors have been reported. In this paper, a variety of uniform YF3:Sm nano-/microcrystals have been successfully prepared by a facile, effective, and environmentally friendly hydrothermal method. The morphology evolution process has been investigated by quenching the reaction at different time. Based on the results, a possible growth mechanism is presented in detail. The as-obtained YF3:Sm nano-/microcrystals show strong yellow and red light emissions under room temperature, which is quite different from those reported previously and might find potential applications in fields such as light phosphor powers and advanced flat panel display devices.

Download Full-text

Facile Synthesis, Morphology Evolution and Tunable Luminescence of NaGdF4:Yb,Er Nanorods with Various Aspect Ratios

NANO ◽

10.1142/s1793292018500935 ◽

2018 ◽

Vol 13 (08) ◽

pp. 1850093 ◽

Cited By ~ 1

Author(s):

Shasha Gai ◽

Jiqing Jiao ◽

Wei Wei ◽

Yao Li ◽

Lihua Liu ◽

...

Keyword(s):

Energy Level ◽

Hydrothermal Method ◽

Growth Mechanism ◽

Morphology Evolution ◽

Schematic Diagram ◽

Facile Synthesis ◽

Reaction Conditions ◽

Facile Hydrothermal Method ◽

Aspect Ratios ◽

Lower Temperature

The well-defined NaGdF4:Yb,Er nanorods (NRs) with various aspect ratios were synthesized using a facile hydrothermal method. The morphology and crystal phase of NRs could be controlled by reaction conditions. NaGdF4:Yb,Er NRs with various aspect ratios could be synthesized and their upconversion (UC) luminescence was tuned. It is displayed that the NRs with aspect ratios about 5 exhibited the strongest UC luminescence among samples. The growth mechanism and morphology transition of NRs had been deduced by schematic diagram. And UC mechanism had been determined by energy level diagrams. Compared with previous reports, the work provided a facial method for UCNRs with various aspect ratios at lower temperature.

Download Full-text

Hollow Crystals of BiFeO3 Prepared via a Al3+-Assisted Hydrothermal Method

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.174-177.516 ◽

2012 ◽

Vol 174-177 ◽

pp. 516-519

Author(s):

Yong Gang Wang ◽

Lin Lin Yang ◽

Yu Jiang Wang ◽

Xiao Feng Wang

Keyword(s):

Electron Microscopy ◽

Scanning Electron Microscopy ◽

Hydrothermal Method ◽

Field Emission ◽

Growth Mechanism ◽

Irregular Shape ◽

Morphology Evolution ◽

X Ray Diffraction ◽

X Ray ◽

Scanning Electron

The BiFeO3 hollow crystals were successfully prepared at 200oC by a Al3+assisted hydrothermal method. The structures and morphologies of the as-obtained products were characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (SEM). A morphology evolution from irregular shape to square, hollow, and sphere-like was observed as the Al ions concentration varied from 0% to 1.5%. The possible growth mechanism of the BiFeO3hollow crystals was also discussed.

Download Full-text

The Effect of Molar Ratio of TiO2/WO3 Nanocomposites on Visible Light Prepared by Hydrothermal Method

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.488-489.572 ◽

2012 ◽

Vol 488-489 ◽

pp. 572-577 ◽

Cited By ~ 1

Author(s):

Siriphan Chainarong ◽

Sutham Niyomwas ◽

Lek Sikong ◽

Sorapong Pavasupree

Keyword(s):

Visible Light ◽

Hydrothermal Method ◽

Absorption Spectra ◽

Hydrothermal Condition ◽

Molar Ratio ◽

Visible Light Region ◽

Hydrothermal Conditions ◽

Transmission Electron ◽

Light Region ◽

Hydrogen Titanate

The coupled TiO2/WO3 nanocomposites were synthesized by hydrothermal method by using hydrogen titanate and ammonium metatungstate hydrate as the precursors of TiO2 and WO3, respectively. The effects of hydrothermal conditions to prepare hydrogen titanate powders were studied. It was found that the hydrothermal condition at 130 °C for 24h shown the best result. The TiO2/WO3 nanocomposites were carried out as a function of varied molar ratio of TiO2/WO3 for 1:1, 3:1 and 1:3. The coupled TiO2/WO3 nanocomposites are characterized by transmission electron microscopy, UV-vis absorption spectra by UV–VIS spectrometer and photocatalytic activity by degradation of MB solution under visible light. The results show that the absorption spectra of the coupled TiO2/WO3 nanocomposites can be seen in visible light region which higher than pure TiO2 (from hydrothermal method) and P25-Degussa.

Download Full-text

Enzymatic Synthesis of Isopropyl Acetate by Immobilized Bacillus cereus Lipase in Organic Medium

Enzyme Research ◽

10.4061/2011/919386 ◽

2011 ◽

Vol 2011 ◽

pp. 1-7 ◽

Cited By ~ 21

Author(s):

Madan Lal Verma ◽

Wamik Azmi ◽

Shamsher Singh Kanwar

Keyword(s):

Acetic Acid ◽

Bacillus Cereus ◽

Water Activity ◽

Molecular Sieves ◽

Immobilized Lipase ◽

Molar Ratio ◽

Ester Synthesis ◽

Initial Water ◽

Isopropyl Acetate ◽

Mg Addition

Selective production of fragrance fatty acid ester from isopropanol and acetic acid has been achieved using silica-immobilized lipase of Bacillus cereus MTCC 8372. A purified thermoalkalophilic extracellular lipase was immobilized by adsorption onto the silica. The effects of various parameters like molar ratio of substrates (isopropanol and acetic acid; 25 to 100 mM), concentration of biocatalyst (25–125 mg/mL), reaction time, reaction temperature, organic solvents, molecular sieves, and initial water activity were studied for optimal ester synthesis. Under optimized conditions, 66.0 mM of isopropyl acetate was produced when isopropanol and acetic acid were used at 100 mM: 75 mM in 9 h at 55°C in n-heptane under continuous shaking (160 rpm) using bound lipase (25 mg). Addition of molecular sieves (3 Å × 1.5 mm) resulted in a marked increase in ester synthesis (73.0 mM). Ester synthesis was enhanced by water activity associated with pre-equilibrated saturated salt solution of LiCl. The immobilized lipase retained more than 50% of its activity after the 6th cycle of reuse.

Download Full-text

Cetyltrimethylammonium bromide- and ethylene glycol-assisted preparation of mono-dispersed indium oxide nanoparticles using hydrothermal method

Chemical Papers ◽

10.2478/s11696-014-0543-9 ◽

2014 ◽

Vol 68 (8) ◽

Cited By ~ 5

Author(s):

Selvakumar Dhanasingh ◽

Dharmaraj Nallasamy ◽

Saravanan Padmanapan ◽

Vinod Padaki

Keyword(s):

Ethylene Glycol ◽

Hydrothermal Method ◽

Indium Oxide ◽

Cetyltrimethylammonium Bromide ◽

Oxide Nanoparticles ◽

X Ray Diffraction ◽

Hydrothermal Conditions ◽

X Ray ◽

Transmission Electron ◽

Diffraction Patterns

AbstractThe influence of cetyltrimethylammonium bromide and ethylene glycol on the size and dispersion of indium oxide nanoparticles prepared under hydrothermal conditions was investigated. The precursor compound, indium hydroxide, obtained by the hydrothermal method in the absence as well as the presence of cetyltrimethylammonium bromide, was converted to indium oxide by sintering at 400°C. The formation of nanoscale indium oxide upon sintering was ascertained by the characteristic infrared adsorption bands and X-ray diffraction patterns of indium oxide. Transmission electron microscopy and band gap values confirmed that the cetyltrimethylammonium bromide facilitated the formation of indium oxide nanoparticles smaller in size and narrower in distribution than those prepared without the assistance of cetyltrimethylammonium bromide.

Download Full-text

Lipase-Catalyzed Acyl-L-Carnitines Synthesis in [Bmim]PF6 Ionic Liquid

International Journal of Food Engineering ◽

10.2202/1556-3758.1631 ◽

2009 ◽

Vol 5 (1) ◽

Author(s):

Jin-qiang Tian ◽

Qiang Wang ◽

Zhong-yuan Zhang

Keyword(s):

Ionic Liquid ◽

Lipase Activity ◽

Molecular Sieves ◽

Reaction Medium ◽

Molar Ratio ◽

Reaction Conditions ◽

Optimal Reaction ◽

Better Than

In order to significantly improve the biosynthesis of acyl-L-carnitines catalyzed by lipase, there must be an efficient and suitable reaction medium that is not only polar but also hydrophobic. [Bmim]PF6, which satisfies the above two requirements, was applied as the medium. The optimal reaction conditions were: for isovaleryl-L-carnitine, 0.22aW, 200mg molecular sieves, 60ºC, 4:1 of molar ratio (fatty acid:L-carnitine), 150rpm and 60h; for octanoyl-L-carnitine and palmitoyl-L-carnitine, 0.22aW, 250 mg molecular sieves, 5:1 of molar ratio (fatty acid:L-carnitine), 200rpm, 48h, 60ºC (octanoyl-L-carnitine) and 65ºC (palmitoyl-L-carnitine). Their overall yields could reach 59.14%, 90.79% and 98.03%, respectively. The yields of isovaleryl-L-carnitine, octanoyl-L-carnitine and palmitoyl-L-carnitine in [Bmim]PF6 were 16.21%, 73.67% and 44.22 % more than those in acetonitrile, respectively. [Bmim]PF6 as the medium was better than acetonitrile. It could not only enhance the yields of acyl-L-carnitines, but also protect the lipase activity.

Download Full-text