Preparation of Nanosize Anatase TiO2 Powders by Hydrothermal Synthesis

Nanosize anatase TiO2 powders have been synthesized by hydrothermal synthesis by using technical grade TiOSO4 as precursor and urea as precipitating agent. The initial pressure of the reaction system was set at 6 MPa. Stirring speed was fixed at 300r/min. The reaction system reacted at the temperature ranged from 110 to 150°C for holding 2hrs to 8hrs and the concentration of the precursor was ranged from 0.25M to1.5M. XRD patterns show that the synthesized powders are in the form of anatase phase. Calculated grain size is ranged from 6.7 to 8.9nm by Scherrer method from the line broadening of the (101) diffraction peak of anatase. The specific surface area of the powders synthesized under different conditions is ranged from 124 to 240m2/g. The grain size of the powders increases with the increase of the reaction temperature, holding time and precursor concentration, respectively. The specific surface area decreases with the increase of reaction temperature and holding time, and does not obviously change with the change of precursor concentration when the concentration of the precursor is less than 1M. However, when the concentration is higher than 1M, the specific surface area will decrease quickly with the increase of the precursor concentration. XRD and DSC-TG analysis shows that the synthesized anatase TiO2 will begin to transform to rutile TiO2 at about 840°C. When heated to 1000°C for holding 1h, the anatase powders will transform to rutile completely.

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The Experiment Study on Making Ultrafine Superfine Nickel Powder by N2H4–KHB Reduction and H2 Reduction

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.295-297.677 ◽

2011 ◽

Vol 295-297 ◽

pp. 677-680

Author(s):

Shu Juan Dai ◽

Yao Liu

Keyword(s):

Grain Size ◽

Reaction Time ◽

Specific Surface ◽

Surface Area ◽

Specific Surface Area ◽

Reaction Temperature ◽

Nickel Powder ◽

Nickel Content ◽

Nickel Sulfate ◽

Experiment Study

The N2H4–KHB reduction then CH3OH watering and H2 reduction system was used to make superfine nickel powder by using nickel sulfate as material.The superfine nickel powder of the specific surface area of the nickel powde being 4.24m2/g, spheric shape with grain size 0.5-0.9μm,nickel content being over 99.5%,The toll nichel recovery being over 99.5% was made on the condition of reaction temperature 60°C, reaction time 150-180min,pH 8.0-8.5,[Ni]=1.25M,N2H4/Ni=1.35（mol ratio）,sodium hexametaphosphate of 1.5‰ as additive，the dosage of KHB of 8.37×10-3g/g Ni and washing by carbinol,reducing by H2.

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Design of ZnMoO4 porous nanosheet with oxygen vacancy as better performance electrode material for supercapacitor

New Journal of Chemistry ◽

10.1039/d1nj01219c ◽

2021 ◽

Author(s):

Pengxi Li ◽

Jiepeng Wang ◽

Liming Li ◽

Shili Song ◽

Xianming Yuan ◽

...

Keyword(s):

Hydrothermal Synthesis ◽

Oxygen Vacancy ◽

Specific Surface ◽

Surface Area ◽

Specific Surface Area ◽

Electrode Material ◽

Reduction Method

ZnMoO4 with oxygen vacancy (ZnMoO4-OV) porous nanosheet was synthesized by hydrothermal synthesis and hydrogenation reduction method. The ZnMoO4-OV porous nan sheet delivers a higher specific surface area together with a...

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The referential grain size and effective porosity in the Kozeny–Carman model

10.5194/hess-2015-524 ◽

2016 ◽

Author(s):

K. Urumović ◽

K. Urumović Sr.

Keyword(s):

Grain Size ◽

Hydraulic Conductivity ◽

Specific Surface ◽

Surface Area ◽

Specific Surface Area ◽

Effective Porosity ◽

Critical Conditions ◽

Saturated Porous Media ◽

New Developments ◽

Mean Grain Size

Abstract. In this paper, the results of permeability and specific surface area analyses as functions of granulometric composition of various sediments (from silty clays to very well-graded gravels) are presented. The effective porosity and the referential grain size are presented as fundamental granulometric parameters expressing an effect of the forces operating on fluid movement through the saturated porous media. This paper suggests procedures for calculating referential grain size and determining effective (flow) porosity, which result in parameters that reliably determine the specific surface area and permeability. These procedures ensure the successful application of the Kozeny–Carman model up to the limits of validity of Darcy’s law. The value of effective porosity in the referential mean grain size function was calibrated within the range of 1.5 μm to 6.0 mm. The reliability of the parameters applied in the KC model was confirmed by a very high correlation between the predicted and tested hydraulic conductivity values (R2=0.99 for sandy and gravelly materials; R2=0.70 for clayey-silty materials). The group representation of hydraulic conductivity (ranging from 10–12 m/s up to 10–2 m/s) presents a coefficient of correlation of R2=0.97 for a total of 175 samples of various deposits. These results present new developments in the research of the effective porosity, the permeability and the specific surface area distributions of porous materials. This is important because these three parameters are critical conditions for successful groundwater flow modeling and contaminant transport. Additionally, from a practical viewpoint, it is very important to identify these parameters swiftly and very accurately.

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A Simple Hydrothermal Synthesis of Cadmium Sulfide Wrapped on Graphene Nanocomposite for Supercapacitor Applications

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2021.19503 ◽

2021 ◽

Vol 21 (12) ◽

pp. 5835-5845

Author(s):

Ranjith Balu ◽

Arivuoli Dakshanamoorthy

Keyword(s):

Hydrothermal Synthesis ◽

Specific Surface ◽

Cadmium Sulfide ◽

Specific Capacitance ◽

Surface Area ◽

Specific Surface Area ◽

High Current Density ◽

Specific Capacity ◽

Cds Nanoparticles ◽

Electrochemical Characteristics

Supercapacitor with high specific capacity is desirable for various energy storage and high powerdensity applications. Though Graphene has been the preferred material for high current density, nanocomposites have been attempted to increase the specific capacitance. Hydrothermal synthesis of cadmium sulfide/graphene (CdS/G) nanocomposite with CdS nanoparticles anchored/decorated over the graphene sheets is reported. The structural studies reveal the hexagonal phase of the prepared materials. The specific surface area (BET) and porosity is found to increase upon nanocomposite formation. The electrochemical characteristics such as cyclic voltammetry (CV), GCD and EIS of the CdS/G nanocomposite have been investigated. The capacitance of CdS/G nanocomposite almost doubled to 248 Fg−1 indicating the enhanced performance of the nanocomposite system and in addition it also showed excellent cycling stability of 74.8 percent after 1000 cycles. The supercapacitor investigated retained the initial energy density after charge-discharge, at 0.5 A/g for 1000 cycles. The graphene nanosheets increased the specific surface area and interfacial electron transfer of the composite material. It enhances the specific capacitance and cyclic stability of the supercapacitor device.

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Study on Adsorption Mechanism and Failure Characteristics of CO2 Adsorption by Potassium-Based Adsorbents with Different Supports

Materials ◽

10.3390/ma11122424 ◽

2018 ◽

Vol 11 (12) ◽

pp. 2424 ◽

Cited By ~ 3

Author(s):

Bao-guo Fan ◽

Li Jia ◽

Yan-lin Wang ◽

Rui Zhao ◽

Xue-song Mei ◽

...

Keyword(s):

Fly Ash ◽

Specific Surface ◽

Surface Area ◽

Specific Surface Area ◽

Reaction Temperature ◽

Adsorption Mechanism ◽

Co2 Adsorption ◽

Carbonation Reaction ◽

Failure Characteristics ◽

Boiler Fly Ash

In order to obtain the adsorption mechanism and failure characteristics of CO2 adsorption by potassium-based adsorbents with different supports, five types of supports (circulating fluidized bed boiler fly ash, pulverized coal boiler fly ash, activated carbon, molecular sieve, and alumina) and three kinds of adsorbents under the modified conditions of K2CO3 theoretical loading (10%, 30%, and 50%) were studied. The effect of the reaction temperature (50 °C, 60 °C, 70 °C, 80 °C, and 90 °C) and CO2 concentration (5%, 7.5%, 10%, 12.5%, and 15%) on the adsorption of CO2 by the adsorbent after loading and the effect of flue gas composition on the failure characteristics of adsorbents were obtained. At the same time, the microscopic characteristics of the adsorbents before and after loading and the reaction were studied by using a specific surface area and porosity analyzer as well as a scanning electron microscope and X-ray diffractometer. Combining its reaction and adsorption kinetics process, the mechanism of influence was explored. The results show that the optimal theoretical loading of the five adsorbents is 30% and the reaction temperature of 70 °C and the concentration of 12.5% CO2 are the best reaction conditions. The actual loading and CO2 adsorption performance of the K2CO3/AC adsorbent are the best while the K2CO3/Al2O3 adsorbent is the worst. During the carbonation reaction of the adsorbent, the cumulative pore volume plays a more important role in the adsorption process than the specific surface area. As the reaction temperature increases, the internal diffusion resistance increases remarkably. K2CO3/AC has the lowest activation energy and the carbonation reaction is the easiest to carry out. SO2 and HCl react with K2CO3 to produce new substances, which leads to the gradual failure of the adsorbents and K2CO3/AC has the best cycle failure performance.

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Retrieval of Snow Properties from the Sentinel-3 Ocean and Land Colour Instrument

Remote Sensing ◽

10.3390/rs11192280 ◽

2019 ◽

Vol 11 (19) ◽

pp. 2280 ◽

Cited By ~ 14

Author(s):

Alexander Kokhanovsky ◽

Maxim Lamare ◽

Olaf Danne ◽

Carsten Brockmann ◽

Marie Dumont ◽

...

Keyword(s):

Grain Size ◽

Specific Surface ◽

Surface Area ◽

Specific Surface Area ◽

Environmental Changes ◽

Ice Sheet ◽

Greenland Ice Sheet ◽

The Arctic ◽

Observation Data ◽

Snow Properties

The Sentinel Application Platform (SNAP) architecture facilitates Earth Observation data processing. In this work, we present results from a new Snow Processor for SNAP. We also describe physical principles behind the developed snow property retrieval technique based on the analysis of Ocean and Land Colour Instrument (OLCI) onboard Sentinel-3A/B measurements over clean and polluted snow fields. Using OLCI spectral reflectance measurements in the range 400–1020 nm, we derived important snow properties such as spectral and broadband albedo, snow specific surface area, snow extent and grain size on a spatial grid of 300 m. The algorithm also incorporated cloud screening and atmospheric correction procedures over snow surfaces. We present validation results using ground measurements from Antarctica, the Greenland ice sheet and the French Alps. We find the spectral albedo retrieved with accuracy of better than 3% on average, making our retrievals sufficient for a variety of applications. Broadband albedo is retrieved with the average accuracy of about 5% over snow. Therefore, the uncertainties of satellite retrievals are close to experimental errors of ground measurements. The retrieved surface grain size shows good agreement with ground observations. Snow specific surface area observations are also consistent with our OLCI retrievals. We present snow albedo and grain size mapping over the inland ice sheet of Greenland for areas including dry snow, melted/melting snow and impurity rich bare ice. The algorithm can be applied to OLCI Sentinel-3 measurements providing an opportunity for creation of long-term snow property records essential for climate monitoring and data assimilation studies—especially in the Arctic region, where we face rapid environmental changes including reduction of snow/ice extent and, therefore, planetary albedo.

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Preparation of Porous Wollastonite Ceramics for Filtration

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.336-338.1102 ◽

2007 ◽

Vol 336-338 ◽

pp. 1102-1104 ◽

Cited By ~ 1

Author(s):

Ming Sheng He ◽

Jian Bao Li ◽

Bo Wen Li ◽

Hong Lin ◽

Xiao Zhan Yang ◽

...

Keyword(s):

Specific Surface ◽

Pore Size ◽

Surface Area ◽

Specific Surface Area ◽

Sintering Temperature ◽

Porous Ceramics ◽

Holding Time ◽

Starting Material ◽

Sintering Method

Wollastonite powder was selected as a starting material with carbonate as pore-forming agent and binder added. The porous ceramics were prepared at different temperature by sintering method. The process includes batching, granulating, pressing molding, drying and sintering. It is discussed the influence of sintering temperature, dosage of binder, dosage of pore-forming agent, pressure of molding and holding time on the performance of porous ceramics. According to the principle of particles stack, the porous wollastonite ceramics for filtration with various diameters, shapes and porosity were fabricated by serial experiments. These products have 1 to 10 microns in pore size, 30.04 to 66.15% in porosity, 2.82 m2/g in specific surface area.

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Property of Nanoporous Metal-Organic Frameworks at Different Synthesis Temperature

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.427.123 ◽

2012 ◽

Vol 427 ◽

pp. 123-127

Author(s):

Yuan Hui Ma ◽

Lei Zhang ◽

Cheng Chun Tang

Keyword(s):

Specific Surface ◽

Surface Area ◽

Specific Surface Area ◽

Reaction Temperature ◽

Metal Organic Frameworks ◽

Synthesis Temperature ◽

Structure Stability ◽

Nanoporous Metal ◽

Metal Organic ◽

Ft Ir

The nanoporous metal-organic frameworks were synthesized under solvothermal conditions using organic solvent dimethylformamide. The samples were characterized by XRD, SEM, TGA, FT-IR and specific surface area for their properties difference. When the reaction temperature rises, the particle size becomes larger. All TGA curves are the basically same, the framework structure begins to be destroyed from 500°C up to around 600°C. The metal-organic frameworks accepted at reaction temperature 190°C have larger specific surface area and better structure stability.

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Study on Nano-Hydroxyapatite Assisted Preparing by Ionic Liquids

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1015.501 ◽

2014 ◽

Vol 1015 ◽

pp. 501-504 ◽

Cited By ~ 1

Author(s):

Yong Guang Bi ◽

Xu Si Xu

Keyword(s):

Grain Size ◽

Ionic Liquids ◽

Specific Surface ◽

Surface Area ◽

Specific Surface Area ◽

Large Scale ◽

Preparation Method ◽

Raw Material ◽

Large Scale Preparation ◽

Scale Preparation

Papers with Ca (NO3)2• 4H2O and (NH4)2HPO4as raw material, prepared by ionic liquids assisted nanoHAP, resulting hexagonal nanoHAP are crystal grain size are 10-20nm level, are smaller nanometer range ; specific surface area, the findings show that ionic liquids have the technology to promote the significance of the preparation method can provide a reference for large-scale preparation of biomedical nanomaterials.

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