scholarly journals A Novel Process for the Synthesis of NaV2O5 Mesocrystals from Alkaline-Stripped Vanadium Solution via the Hydrothermal Hydrogen Reduction Method

Minerals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 271
Author(s):  
Guobin Zhang ◽  
Yimin Zhang ◽  
Shenxu Bao ◽  
Liuhong Zhang
Keyword(s):  
Electron Microscopy ◽  
Hydrogen Reduction ◽  
Ph Value ◽  
Hydrothermal Process ◽  
Reduction Process ◽  
Oriented Attachment ◽  
Synthesis Process ◽  
Synthesis Mechanism ◽  
Time Saving ◽  
Synthesis Time

NaV2O5 mesocrystals were successfully synthesized from an alkaline-stripped pentavalent vanadium solution through a novel hydrothermal hydrogen reduction process. The optimal conditions for the hydrogen partial pressure, reaction temperature, initial solution pH value, and reaction time for the pure-phase NaV2O5 synthesis were ascertained to be 4 MPa, 200 °C, 4.0, and 2 h, respectively. The synthesis time (only 2 h) was greatly shortened, by nine times, compared with the most time-saving (18 h) hydrothermal process at present. X-ray diffraction (XRD) analysis revealed that the as-prepared powders demonstrated a typical layered orthorhombic structure of NaV2O5. The purity of the as-prepared NaV2O5 reached up to 99.98%. An electrochemical test showed that the as-prepared NaV2O5 has a potential application in sodium ion batteries. According to scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses, the as-prepared NaV2O5 powders were identified to have rod-like mesocrystals consisting of small rods which preferentially grow along the (010) direction. Furthermore, the phase transformation mechanism and crystal growth mechanism in NaV2O5 preparation were discussed systematically, based on which the synthesis mechanism of NaV2O5 was proposed as pentavalent vanadates pre-sedimentation, hydrogen reduction with dehydration, sodium ions insertion, and finally self-assembly oriented attachment. The synthesis process is characterized as time-saving and low-cost, and thus it may have great application prospects.

scholarly journals The nanostructure of barium dititanate prepared by hydrothermal method

2019 ◽  
Vol 09 (02) ◽  
pp. 1950011
Author(s):  
Sarah L. Rasheed ◽  
Emad K. Al-Shakarchi
Keyword(s):  
Electron Microscopy ◽  
Reaction Time ◽  
Hydrothermal Method ◽  
Ph Value ◽  
Hydrothermal Process ◽  
Dielectric Ceramic ◽  
Lattice Constants ◽  
Preparation Conditions ◽  
Transmission Electron ◽  
Lcr Meter

The dielectric ceramic of barium dititanate compound BaTi2O5 had been prepared through the hydrothermal process by applying different parameters, such as pH-value, reaction time, temperature and pressure. The prepared powders were examined by X-ray diffraction (XRD). The predominant phase was a monoclinic phase with lattice constants ([Formula: see text], [Formula: see text], [Formula: see text] Å), ([Formula: see text], [Formula: see text]), and the unit cell volume (527 Å3). The surface morphology was demonstrated by Scanning Electron Microscopy (SEM). It exhibited the grains in spherical and elliptical shapes with high homogeneity. The shapes of nanostructure were analyzed by Transmission Electron Microscopy (TEM). The appearance of nanostructures like the nanoparticles and nano rods were found. The size of nanoparticles was in the range of 9–31[Formula: see text]nm, and size of nanorods was 32–37[Formula: see text]nm. The dielectric measurements were done by using LCR meter at different temperature and frequencies (10, 50 and 100[Formula: see text]kHz). It was clear that the Curie temperature had a high value up to (485∘C). The relative permittivity was partially changed for two prepared samples regarding high pressure and long reaction time, which were the main preparation conditions of hydrothermal method.

Study on Hydrothermal Process Variables Correlation to WO3 Nanostructure through Design of Experiments (DOE) Approach

2014 ◽  
Vol 607 ◽  
pp. 47-50
Author(s):  
Amirul Abd Rashid ◽  
Nor Hayati Saad ◽  
Daniel Bien Chia Sheng ◽  
Kah Yaw Lee ◽  
Wai Yee Lee ◽  
...  
Keyword(s):  
Hydrothermal Synthesis ◽  
Design Of Experiments ◽  
Tungsten Trioxide ◽  
Ph Value ◽  
Hydrothermal Process ◽  
Synthesis Temperature ◽  
Synthesis Process ◽  
Process Variables ◽  
Material Source ◽  
Experimental Procedure

There are few known parameters which govern tungsten trioxide (WO3) hydrothermal synthesis process which includes material source concentration, synthesis temperature, duration, pH value and additive level. Using design of experiments (DOE) approach, a systematic experimental procedure was conducted to investigate the effect of each parameter to the final morphology of the synthesized nanostructure. Despite the response obtained from this study is in qulitative form, the analysis still can be done to identify the combination of variables that most likely can produce either 1-D, 2-D or 3-D nanostructure. This insight is essential before further optimization of the process can be done in order to predict the behavior of the WO3 hydrothermal synthesis process.

scholarly journals Montmorillonite immobilized Fe/Ni bimetallic prepared by dry in-situ hydrogen reduction for the degradation of 4-Chlorophenlo

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Shuo-Shuo Zhang ◽  
Ning Yang ◽  
Xuming Zhuang ◽  
Liying Ren ◽  
Vinothkumar Natarajan ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Bimetallic Nanoparticles ◽  
Hydrogen Reduction ◽  
Maximum Activity ◽  
Synthesis Process ◽  
Reduction Temperature ◽  
Liquid Environment ◽  
X Ray ◽  
Ni Content

Abstract This study puts forward a new way to produce montmorillonite immobilized bimetallic nickel-iron nanoparticles by dry in-situ hydrogen reduction method in the non-liquid environment, which effectively inhibits the oxidation of iron and nickel during the synthesis process and improves the reactivity of the material. The degradation of 4-Chlorophenol (4-CP) was investigated to examine the catalytic activity of the material. The morphology and crystal properties of the montmorillonite-templated Fe/Ni bimetallic particles were explored by using scanning electron microscopy, transmission electron microscopy, X-ray diffraction studies, and energy dispersive X-ray spectroscopy analysis. Results suggest that Fe and Ni particles were homogeneously dispersed on the montmorillonite. The optimization of Ni content and reduction temperature over the degradation of 4-CP was also studied. The introduction of Ni intensely improved the degradation of 4-CP and reached over 90% when Ni content was 28.5%. The degradation rate increased significantly with the increase of reduction temperature and showed maximum activity at the reduction tempreature of 800 °C. This study offers a new method to fabricate montmorillonite immobilized Fe/Ni bimetallic nanoparticles in the non-liquid environment and the composites exhibited high degradation activity to chlorinated organic compounds.

Synthesis, Characterization and Optical Property of Uniform Bi2S3 Nanorods

2011 ◽  
Vol 412 ◽  
pp. 211-214 ◽  
Author(s):  
Shu Ling Liu ◽  
Qiang Qiang Shi ◽  
Jian Bo Tong ◽  
Shu Li ◽  
Miao Miao Liu
Keyword(s):  
Electron Microscopy ◽  
Ph Value ◽  
Hydrothermal Process ◽  
High Yield ◽  
Shape Evolution ◽  
X Ray ◽  
Experimental Parameters ◽  
Two Parameters ◽  
Simple Hydrothermal Process ◽  
Scanning Electron

Uniform rod-like Bi2S3 nanostructures were successfully synthesized by a simple hydrothermal process in a high yield. X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and UV-vis absorption spectroscopy were used to characterize the obtained products. It was found that the morphologies of the as-obtained Bi2S3 were highly dependent on the experimental parameters, including the pH value and the solvent. The adjustments of two parameters could lead to an obvious shape evolution of products. Then based on the discussion of the experimental parameters and the captive intermediate, the possible growth mechanism was proposed.

scholarly journals Further Exploration of Sucrose-Citric Acid Adhesive: Synthesis and Application on Plywood

Polymers ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 1875 ◽  
Author(s):  
Shijing Sun ◽  
Zhongyuan Zhao ◽  
Kenji Umemura
Keyword(s):  
Citric Acid ◽  
Research Direction ◽  
Synthesis Temperature ◽  
Solid Content ◽  
National Standard ◽  
Synthesis Process ◽  
Synthesis Mechanism ◽  
Synthesis Time ◽  
Synthesis Conditions ◽  
Bond Performance

The development of eco-friendly adhesives is a major research direction in the wood-based material industry. Previous research has already demonstrated the mixture of sucrose and citric acid could be utilized as an adhesive for the manufacture of particleboard. Herein, based on the chemical characteristics of sucrose, a synthesized sucrose-citric acid (SC) adhesive was prepared, featuring suitable viscosity and high solid content. The investigation of synthesis conditions on the bond performance showed that the optimal mass proportion between sucrose and citric acid was 25/75, the synthesis temperature was 100 °C, and the synthesis time was 2 h. The wet shear strength of the plywood bonded with SC adhesive, which was synthesized at optimal conditions and satisfied the China National Standard GB/T 9846-2015. The synthesis mechanism was studied by both 13C NMR analysis and HPLC, and the chemical composition manifesting caramelization reaction occurred during the synthesis process. The results of ATR FT-IR indicated the formation of a furan ring, carbonyl, and ether groups in the cured insoluble matter of the SC adhesive, which indicated dehydration condensation as the reaction mechanism between sucrose and citric acid.

Preparation and Characterization of Cu Nano-Powders by Hydrothermal Decomposition and Hydrogen Reduction Process

2010 ◽  
Vol 160-162 ◽  
pp. 456-459 ◽  
Author(s):  
Zai Yuan Li ◽  
Yun Gao ◽  
Duo Jin ◽  
Jie Liu ◽  
Yu Chun Zhai
Keyword(s):  
Hydrogen Reduction ◽  
Ph Value ◽  
Raw Materials ◽  
Reduction Process ◽  
Powder Size ◽  
Reaction Conditions ◽  
Nano Powder ◽  
Circular System ◽  
Reaction Speed

In this paper, Cu nano-powder was used to reduce CuO nano-powder by hydrogen reduction process, which was prepared by hydrothermal decomposition method taken CuSO4•5H2O and NaOH as raw materials. The reaction conditions of CuO nano-stick were that concentration of CuSO4 liquor was 0.1mol•L-1, concentration of NaOH liquor was 5mol•L-1, dropping speed was 50ml•min-1, pH value of reacting terminal was 12, stirring speed was 1200 r•min-1, reacting temperature was 60°C, reacting time was 30min. The CuO stick longness was 200nm, diameter was 30nm. The reaction conditions of CuO nano-boll were that dropping speed was 50ml•min-1, pH value of reacting terminal was 7, stirring speed 100 r•min-1, reacting temperature was 80°C, reacting time 30min. The diameter of CuO nano-ball was 50~100 nm. The Cu powder was prepared with materials CuO tick by hydrogen reduction in closed circular system. The higher the temperature, the reaction speed is faster. Hydrogen reduction time was 400s in reacting temperature 240°C. The Cu powder’ size was less than 100nm.

Morphology Control of PbS Nanocrystals by a Novel Hydrothermal Process

2004 ◽  
Vol 99-100 ◽  
pp. 197-202 ◽  
Author(s):  
Yujie Ji ◽  
De Ren Yang ◽  
Hui Zhang ◽  
Xiang Yang Ma ◽  
Jin Xu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Ph Value ◽  
Critical Role ◽  
Hydrothermal Process ◽  
X Ray Diffraction ◽  
Pbs Nanocrystals ◽  
Transmission Electron ◽  
Salt Structure ◽  
Lead Source

Star-shaped and rod-like PbS crystals have been successfully prepared by a novel thioglycolic acid (TGA) assisted hydrothermal method. X-ray diffraction (XRD) reveals that the PbS crystals are of the cubic rock-salt structure and well formed. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) observations show that the morphology of PbS nanocrystals is easily controlled according to sulphur source, lead source, and pH value. Furthermore, the paper gives a preliminary presntation of the mechanism and the critical role of the TGA-assisted hydrothermal synthesis of PbS nanorods

Adsorption of safranine T from aqueous medium by nano mesoporous MCM-41: adsorption equilibrium, kinetics, and thermodynamics

2020 ◽  
Vol 10 ◽  
Author(s):  
Xiao-Dong Li ◽  
Qing-Zhou Zhai
Keyword(s):  
Electron Microscopy ◽  
Ph Value ◽  
Particle Diameter ◽  
Spherical Particles ◽  
Practical Significance ◽  
Average Particle ◽  
Average Pore ◽  
Kinetics And Thermodynamics ◽  
Safranine T ◽  
Mcm 41

Introduction: In industrial production, a small amount of saffron T emissions will cause increase of water color and increase of chemical oxygen consumption, so study of the decolorization of saffron T wastewater has an important practical significance. Methods: MCM (Mobil Composition of Matter)-41 molecular sieve was synthesized by hydrothermal method. Power Xray diffraction and scanning electron microscopy were used to characterize the sample. Safranine T dye was adsorbed from water by the MCM-41 prepared. Kinetics and thermodynamics of the adsorption were studied. Results: The MCM-41 sample presented spherical particles and regular. The BET (Brunner-Emmett-Teller) specific surface area of the sample determined by 77 K low temperature nitrogen adsorption-desorption isotherm was 932 m2 /g. Its average particle diameter was 110 nm. TEM (transmission electron microscopy) results showed that the sample structure presented a honeycomb pore structure and the average pore diameter was 3.0 nm. The results showed that when room temperature was 20 ± 1 ℃, adsorbate safranine T: adsorbent MCM-41 = 20 : 1，the optimum pH value of adsorption was 4.0 and contact time was 20 min, the adsorption rate reached 98.29% and the adsorption capacity was 19.66 mg/g. The entropy change and enthalpy change of the adsorption system are respectively ΔS0 = 157.5 J/(mol·K); ΔH0 = 21.544 kJ/mol. When temperature was 277.15, 293.15, 303.15 K，the free energy change was respectively △G1 0 = -22.107 kJ/mol, △G2 0 = -24.627 kJ/mol, △G3 0 = -26.202 kJ/mol. Conclusion: The adsorption of safranine T by MCM-41 belongs to a pseudo-second-order adsorption. This adsorption accords with the Freundlich equation and belongs to a heterogeneous adsorption. The adsorption is an endothermic reaction of entropy increase, being spontaneous.

Effect of synthesis and activation methods on the character of CoMo/ultrastable Y-zeolite catalysts

2021 ◽  
Vol 19 (1) ◽  
pp. 745-754
Author(s):  
Khoirina Dwi Nugrahaningtyas ◽  
Eddy Heraldy ◽  
Rachmadani ◽  
Yuniawan Hidayat ◽  
Indriana Kartini
Keyword(s):  
Electron Microscopy ◽  
Reduction Process ◽  
Particle Morphology ◽  
Zeolite Catalysts ◽  
X Ray Diffraction ◽  
Y Zeolite ◽  
X Ray ◽  
Irregular Particle ◽  
Transmission Electron ◽  
Pure Metals

Abstract The properties of three types of CoMo/USY catalysts with different synthesized methods have been studied. The sequential and co-impregnation methods followed by activation using calcination and reduction process have been conducted. The properties of the catalysts were examined using Fourier-transform-infrared (FTIR) spectroscopy, X-ray diffraction (XRD) with refinement, and surface area analyzer (SAA). The FTIR spectrum study revealed the enhanced intensity of its Bronsted acid site, and the XRD diffractogram pattern verified the composition of pure metals, oxides, and alloys in the catalyst. The SAA demonstrated the mesoporous features of the catalyst. Scanning electron microscopy showed an irregular particle morphology. Additional analysis using the transmission electron microscopy indicated that the metal has successfully impregnated without damaging the USY structure.

Recasting Ni-foam into NiF2 nanorod arrays via a hydrothermal process for hydrogen evolution reaction application

2021 ◽  
Author(s):  
Nanasaheb M. Shinde ◽  
Siddheshwar D. Raut ◽  
Balaji G. Ghule ◽  
Krishna Chaitanya Gunturu ◽  
James J. Pak ◽  
...  
Keyword(s):  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Nickel Foam ◽  
Hydrothermal Process ◽  
Reduction Process ◽  
Nanorod Arrays ◽  
Ni Foam

A promising electrode for hydrogen evolution reaction (HER) has been prepared via a reduction process to form NiF2 nanorod arrays directly grown on a 3D nickel foam.

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