Effect of Microwave with Ultrasonic on the Morphology and Particle Size of (Y,Eu)2 O3 Precursor

2011 ◽  
Vol 347-353 ◽  
pp. 3981-3984
Author(s):  
Qing Yun Zeng ◽  
Qing Qing Chang ◽  
Xin Yu Ye
Keyword(s):  
Particle Size ◽  
Reaction Time ◽  
Reaction Temperature ◽  
Ageing Time ◽  
Preparation Conditions ◽  
Ultrasonic Assisted ◽  
The One ◽  
Co Precipitation ◽  
Average Size ◽  
The Ideal

The (Y,Eu)2O3 precursor prepared by microwave with ultrasonic-assisted co-precipitation is superior to the one prepared by co-precipitation of conventional approach as well as co-precipitation assisted by microwave. The effect of preparation conditions on the morphology and particle size of (Y,Eu)2O3 precursor was completely investigated in this study. The ideal conditions were optimized as 0.25M Ln3+ ions concentration, 80°C reaction temperature, 90 minutes reaction time and 0 minute ageing time. Consequently, the (Y,Eu)2O3 precursor in the needle-like shape with average size of 0.25μm in diameter was obtained. The possible mechanism was also presented.

Taguchi Approach and ANOVA in Optimization of the Dissolution of Colemanite in CO2 and SO2- Water Systems

2020 ◽  
Vol 10 (2) ◽  
pp. 88-97
Author(s):  
Zafer Ekinci ◽  
Esref Kurdal ◽  
Meltem Kizilca Coruh
Keyword(s):  
Particle Size ◽  
Reaction Time ◽  
Reaction Temperature ◽  
Gas Flow ◽  
Operating Conditions ◽  
Optimum Operating ◽  
Process Conditions ◽  
Liquid Ratio ◽  
Positive Effects ◽  
Controllable Factors

Background: Turkey is approximately 72% of the world’s boron sources. Colemanite, tincal, ulexite and pandermite are among the most significant in Turkey. Boron compounds and minerals are widely used in many industrial fields. Objective: The main purpose of this study was to investigate the control of impurities in the boric acid production process using colemanite by carrying out the reaction with a mixture of CO2 and SO2 - water, and determining the appropriate process conditions to develop a new process as an alternative to the use of sulfuric acid. Due to worrying environmental problems, intensive studies are being carried out globally to reduce the amount of CO2 and SO2 gases released to the atmosphere. Methods: The Taguchi method is an experimental design method that minimizes the product and process variability by selecting the most appropriate combination of the levels of controllable factors compared to uncontrollable factors. Results: It was evaluated the effects of parameters such as reaction temperature, solid-to liquid ratio, SO2/CO2 gas flow rate, particle size, stirring speed and reaction time. The optimum conditions determined to be reaction temperature of 45°C; a solid–liquid ratio of 0.083 g.mL−1; an SO2/CO2 ratio of 2/2 mL.s−1; a particle size of -0.354+0 .210 mm; a mixing speed of 750 rpm and a reaction time of 20 min. Conclusion: Under optimum operating conditions, 96.8% of colemanite was dissolved. It is thought that the industrial application of this study will have positive effects on the greenhouse effect by contributing to the reduction of CO2 and SO2 emissions that cause global warming.

Reactive Adsorption Desulfurization of Thiophene in n-hexane over Oxides Adsorbent of NiO-ZnO/Al2O3-SiO2

2013 ◽  
Vol 455 ◽  
pp. 43-47 ◽  
Author(s):  
Xiao Ming Hou ◽  
Ben Xian Shen ◽  
Ji Gang Zhao
Keyword(s):  
Reaction Time ◽  
Structural Properties ◽  
Reaction Temperature ◽  
Chemical Process ◽  
Removal Rate ◽  
Precipitation Method ◽  
Initial Concentration ◽  
Reactive Adsorption ◽  
Adsorption Desulfurization ◽  
Co Precipitation

The oxides adsorbent of NiO-ZnO/-Al2O3-SiO2 was prepared by co-precipitation method. SEM, XRD and BET studies were performed to understand the structural properties of the adsorbent. And the adsorbent can be used for the desulfurization of thiophene in n-hexane as model gasoline. Removal rate of thiophene increased with increasing reaction time. Removal rate of thiophene in equilibrium decreases with increasing the initial concentration of thiophene. The extent of adsorption in adsorbent increased with increasing the initial concentration of thiophene. The removal rate of thiophene increases with increasing reaction temperature, it showed that the desulfurization is a chemical process not a physical process.

Enhanced Photocatalytic Performance and Mechanism of Ag3PO4 Particles Synthesized via a Sonochemical Process

2018 ◽  
Vol 10 (3) ◽  
pp. 337-345 ◽  
Author(s):  
Chengxiang Zheng ◽  
Hua Yang ◽  
Yang Yang ◽  
Haimin Zhang
Keyword(s):  
Particle Size ◽  
Photocatalytic Activity ◽  
Reaction Time ◽  
Reaction Temperature ◽  
Ph Value ◽  
Dye Degradation ◽  
Sonochemical Method ◽  
Simulated Sunlight ◽  
Spherical Nanoparticles ◽  
Direct Oxidation

A facile sonochemical method was used to synthesize Ag3PO4 particles and the effect of pH value, reaction temperature and reaction time on the products was investigated. It is found that the samples prepared at neutral (pH = 7) and alkaline (pH = 11) environments exhibit a similar particle morphology and size. The particles are shaped like spheres with a size distribution majorly focusing on a range of 200–450 nm, and the average particle size is about 300 nm. The sample prepared at acidic environment (pH = 3) is composed of polyhedral microparticles with size of 5–8 μm. At relatively low temperatures of 20–50 °C, the spherical nanoparticles do not undergo obvious morphology/size changes; however, when the temperature is increased up to 80 °C, the nanoparticles are aggregated to form large-sized polyhedral microparticles in the size range of 4–7 μm. Compared to the pH value and reaction temperature, the reaction time has a minor effect on the morphology of Ag3PO4 particles. RhB was chosen as the target pollutant to evaluate the photocatalytic activity of the as-prepared Ag3PO4 samples under simulated-sunlight irradiation. It is shown that the samples consisting of spherical nanoparticles exhibit an extremely high photocatalytic activity, and the degradation percentage of RhB after reaction for 50 min reaches over 90%. The samples of polyhedral microparticles have a relatively low photocatalytic activity, which is possibly due to their large particle size. Hydroxyl (.OH) radical was detected by spectrofluorimetry using terephthalic acid as a .OH scavenger and was not found to be produced over the simulated-sunlight-irradiated Ag3PO4 catalyst. The effect of ethanol, benzoquinone and ammonium oxalate on dye degradation was also investigated. Based on experimental results, the direct oxidation by h+ is suggested to the dominant mechanism toward the dye degradation.

scholarly journals One-Step Synthesis of Spherical γ-Fe2O3 Nanopowders and the Evaluation of Their Photocatalytic Activity for Orange I Degradation

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Chunhua Liang ◽  
Hui Liu ◽  
Jianmin Zhou ◽  
Xiaochun Peng ◽  
Haizhou Zhang
Keyword(s):  
Particle Size ◽  
Reaction Time ◽  
Synthesis Method ◽  
Total Pore Volume ◽  
Xrd Analysis ◽  
Bet Surface Area ◽  
Particle Sizes ◽  
Aqueous Synthesis ◽  
One Step ◽  
The One

Maghemite (γ-Fe2O3) nanopowders were synthesized under aeration (oxidizing) conditions by aqueous synthesis in this study. The microstructures of the prepared powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and BET-BJH. The XRD analysis and the chemical experiments showed that well-crystallized γ-Fe2O3 nanoparticles were successfully obtained with a mean particle size of approximately 17 nm. The prepared γ-Fe2O3 was spherical with a BET surface area of 14.357 m2/g and a total pore volume of 0.050 cm3/g. Varying the reaction conditions, such as pH, temperature, and reaction time, we obtained crystallized γ-Fe2O3 powders with different crystallization extent and different particle sizes. When the pH of the reaction suspension was increased, the reaction time was prolonged, and the reaction temperature was increased, the γ-Fe2O3 powders underwent superior crystallization and had larger particle sizes. All the obtained γ-Fe2O3 powders had significant photocatalytic activities under both UV and visible light irradiation for Orange I degradation, and the powders with better crystallization and larger particle size had relatively lower activities for Orange I photocatalytic degradation. The one-step aqueous synthesis method presented in this paper may provide an advantageous pathway to synthesize large quantities of this important iron oxide.

Catalytic Synthesis of Ethyl Acetate Using Ti2SnC

2013 ◽  
Vol 634-638 ◽  
pp. 628-631
Author(s):  
Yun Hui Long ◽  
Jun Ming Guo ◽  
Du Shu Huang ◽  
Gui Yang Liu
Keyword(s):  
Acetic Acid ◽  
Reaction Time ◽  
Ethyl Acetate ◽  
Reaction Temperature ◽  
Conversion Rate ◽  
Reaction System ◽  
Catalytic Performance ◽  
Catalytic Synthesis ◽  
Molar Ratio ◽  
The Ideal

The catalytic synthesis of ethyl acetate from ethanol and acetic acid using Ti2SnC in liquid phase under the atmospheric pressure was studied. The influences of some factors such as catalyst usage, initial reactant molar ratio, reaction temperature and reaction time on acetic acid conversion rate of this reaction system were investigated. The acetic acid conversion rate of 88.12% is achieved while the molar ratio of alcohol and acid is 1:3.6, the amount of catalyst is 0.2000 g, the reaction temperature is 80 °C and the reaction time is 30min. The catalyst Ti2SnC is the ideal catalyst for synthesis of ethyl acetate for good catalytic performance, non-corrosive to equipment, easily separated from product and used repeatedly.

Preparation and Characterization of Nanocrystalline CaO-ZrO2 Powders by Microwave Pyrolysis

2014 ◽  
Vol 602-603 ◽  
pp. 97-100
Author(s):  
Bing Bing Fan ◽  
Ke Ke Guan ◽  
Hao Chen ◽  
Xiao Xuan Pian ◽  
Chen Yang Wang ◽  
...  
Keyword(s):  
Phase Transition ◽  
Reaction Temperature ◽  
Pyrolysis Temperature ◽  
Precipitation Method ◽  
Microwave Pyrolysis ◽  
Model Chamber ◽  
Co Precipitation ◽  
Average Size

CaO(15%)-ZrO2nano-powders were prepared by microwave pyrolysis in a multi-model chamber at the temperature ranging from 650°C to 800°C, with the precursor processed at different reaction temperature from 0°C to 80°C by chemical co-precipitation method. XRD and SEM techniques were used to characterize the phase transition and micrograph of powders. It is found that the content of m-ZrO2phase decreased with the increasing of reaction temperature and pyrolysis temperature. The high dispersed and superfine nano-powders were obtained at the pyrolysis temperature of 750°C for 20 min at 80°C. And only cubic ZrO2phase were detected in CaO (15%)-ZrO2powders and the average size of the powders is about 41 nm.

Removal of silicon from green liquor with carbon dioxide in the chemical recovery process of wheat straw soda pulping

TAPPI Journal ◽  
2013 ◽  
Vol 12 (3) ◽  
pp. 35-40 ◽  
Author(s):  
XINXING XIA ◽  
MINGZHU DU ◽  
XIUJUAN GENG
Keyword(s):  
Carbon Dioxide ◽  
Particle Size ◽  
Wheat Straw ◽  
Reaction Temperature ◽  
Recovery Process ◽  
Chemical Recovery ◽  
Step Process ◽  
Green Liquor ◽  
One Step ◽  
The One

Green liquor in the chemical recovery process of wheat straw pulping was treated with carbon dioxide to precipitate silicon by a one-step process and a seeding process to address problems caused by high silicon content. The total silicon removal, the particle size, and the sedimentation performance of silica were investigated. The results showed that the pH of green liquor decreased with increasing amounts of carbon dioxide, becoming stable after the pH decreased to 8.2. Reaction temperature had no significant effect on the removal of silicon. About 99% of silicon removal was achieved at a pH of 9.2 at room temperature. In the one-step process, the particle size increased and the silica sedimentation performance improved with decreasing pH. The particle size decreased and the sedimentation performance improved with increasing reaction temperature. At a pH of 9.5 and reaction temperature of 80°C, the particle size was 10.43 μm. In the seeding process, 40% green liquor was treated with carbon dioxide at 80°C until the pH was about 10.5, then the 40% treated green liquor was mixed with the remaining 60% of green liquor. The mixture was then treated with carbon dioxide at a reaction temperature of 80°C until the pH reached 9.5. In that situation, the particle size reached 14.11 μm. Compared with the one-step process, the particle size of silica generated by the seeding process was bigger and the sedimentation performance was improved.

Preparating Arsenic Trioxide with Sulfuric Acid Wet Oxidation

2013 ◽  
Vol 662 ◽  
pp. 437-440
Author(s):  
Lin Zhuan Ma ◽  
Jun Ming Guo ◽  
Qiong Fang Cui ◽  
Man Hong Liu ◽  
Ying Jie Zhang
Keyword(s):  
Particle Size ◽  
Sulfuric Acid ◽  
Reaction Time ◽  
Arsenic Trioxide ◽  
Reaction Temperature ◽  
Extraction Yield ◽  
Wet Oxidation ◽  
Optimal Conditions ◽  
Concentrated Sulfuric Acid

The technology of the acidification is adopted to prepare arsenic trioxide (As2O3). With a concentration of 98% of concentrated sulfuric acid and Orpiment made into a certain ratio of the slurry suspension. Arsenic trioxide’s content is 99.94%, extraction yield can reach to 98.92%. The optimal conditions is reaction temperature at 120°Cand the reaction time in 2.5 h; the slurry ratio is less than 1/6 and particle size is less than 0.080 mm.

Study of the preparation and properties of CeO2single/multiwall hollow microspheres

2007 ◽  
Vol 22 (6) ◽  
pp. 1472-1478 ◽  
Author(s):  
Youjin Zhang ◽  
Tao Cheng ◽  
Qixiu Hu ◽  
Zhiyong Fang ◽  
Kaidong Han
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Reaction Time ◽  
Reaction Temperature ◽  
Hollow Microspheres ◽  
X Ray ◽  
Molar Ratios ◽  
Preparation Conditions ◽  
Transmission Electron ◽  
Absorption Edges

Novel slight yellow CeO2single/multiwall hollow microspheres were synthesized by the hydrothermal method without any surfactant and characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), field-emission scanning electron microscopy (FESEM), and x-ray photoelectron spectra (XPS). The results showed that the products were CeO2single/multiwall hollow microspheres, the shells of which were composed of CeO2nanoparticles with a mean size of 70 nm. The effect of the preparation conditions, the reaction temperature, the reaction time, and the molar ratios of urea to Ce(NO3)3·6H2O on the morphology of the products, was investigated. The optimal preparation conditions are determined as follows: the reaction temperature of 230 °C, the reaction time of 6 to 10 h, and the molar ratios of urea to Ce(NO3)3·6H2O of 3:1 to 6:1. The formation mechanism of CeO2single/multiwall hollow microspheres was proposed. The ultraviolet-visible (UV-VIS) diffuse reflectance spectra of the samples were measured. The results showed that the absorption edges of the samples were red-shifted compared with that of bulk CeO2, and that the red-shift of the absorption edges and the yellow of the samples enhanced with increasing the yield of CeO2single/multiwall hollow microspheres. The catalytic activity and the recycling performance of the sample on CO oxidation were tested and theT100%(the temperature at which CO 100% conversion) was 230 °C in the first run and decreased by 270 and 205 °C compared with that of bulk CeO2and CeO2nanocrystal, respectively.

A Novel Method of Leaching Vanadium from Extracted Vanadium Residue Using Sodium Sub-Molten Salt Medium

2011 ◽  
Vol 402 ◽  
pp. 253-260
Author(s):  
Lan Jie Li ◽  
Shi Li Zheng ◽  
Dong Hui Chen ◽  
Shao Na Wang ◽  
Hao Du ◽  
...  
Keyword(s):  
Particle Size ◽  
Reaction Time ◽  
Molten Salt ◽  
Reaction Temperature ◽  
Orthogonal Experiment ◽  
Salt Medium ◽  
Leaching Process ◽  
Novel Method ◽  
The Impact ◽  
Leaching Efficiency

Leaching of an extracted vanadium residue in sodium sub-molten salt medium was investigated. The significant effects of reaction temperature, particle size of residue, reaction time and NaOH-to-residue mass ratio on vanadium extraction were studied. By the orthogonal experiment study, it can be concluded that the impact order of factors is Tr> t>R according to the significance to the leaching process. Under conditions of reaction temperature 170°C, NaOH-to-residue 4:1, stirring speed 700 rpm, particle size -74 µm and reaction time around 180 min, leaching efficiency of vanadium obtained is higher than 90%. And, the leaching process of vanadium, with activation energy 27.69 kJ•mol-1, is controlled by the chemical reaction-controlled as the following rate equation. ln(1-x)=-kt

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