scholarly journals Preparation and characterization of high specific surface area Mn3O4 from electrolytic manganese residue

2010 ◽  
Vol 8 (5) ◽  
pp. 1059-1068 ◽  
Author(s):  
Tiefeng Peng ◽  
Longjun Xu ◽  
Hongchong Chen
Keyword(s):  
Particle Size ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Magnetic Measurements ◽  
High Specific Surface Area ◽  
Surface Areas ◽  
Electrolytic Manganese ◽  
Electrolytic Manganese Residue ◽  
Specific Surface Areas

AbstractMn3O4 powders have been produced from Electrolytic Manganese Residue (EMR). After leaching of EMR in sulfuric acid, MnSO4 solution containing various ions was obtained. Purifying the solution obtained and then adding aqueous alkali to the purified MnSO4 solution, Mn(OH)2 was prepared. Two methods were employed to produce Mn3O4. One way was oxidation of Mn(OH)2 in aqueous phase under atmosphere pressure to obtain Mn3O4. The other way was roasting Mn(OH)2 precursors in the range of 500°C to 700°C. The prepared samples were investigated by using several techniques including X-ray powder diffraction (XRD), Fourier Transformation Infra-Red (FTIR) spectra, and Brunauer-Emmett-Teller (BET) specific surface area instrument. Particle distribution and magnetic measurements were carried out on laser particle size analyzer, vibrating sample magnetometer (VSM). Through XRD, FTIR and determination of total Mn content (TMC), the products prepared were confirmed to be a single phase Mn3O4. BET specific surface areas can reach to 32 m2 g−1. The results indicated that products synthesized by aqueous solution oxidation method had higher specific surface areas and smaller particle size than those prepared by means of roasting. However the products prepared using the above two methods showed no obvious differences in magnetic property.

scholarly journals The Effects of Various Parameters of the Microwave-Assisted Solvothermal Synthesis on the Specific Surface Area and Catalytic Performance of MgF2 Nanoparticles

Materials ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 3566
Author(s):  
Yawen Wang ◽  
Zahra Gohari Bajestani ◽  
Jérôme Lhoste ◽  
Sandy Auguste ◽  
Annie Hémon-Ribaud ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Solvothermal Synthesis ◽  
Catalytic Performance ◽  
High Specific Surface Area ◽  
Microwave Assisted ◽  
Surface Areas ◽  
Specific Surface Areas ◽  
Nanoparticle Sizes

High-specific-surface-area MgF2 was prepared by microwave-assisted solvothermal synthesis. The influences of the solvent and the magnesium precursors, and the calcination atmospheres, on the nanoparticle sizes and specific surface areas, estimated by X-Ray Powder Diffraction, N2 sorption and TEM analyses, were investigated. Nanocrystallized (~7 nm) magnesium partially hydroxylated fluorides (MgF2−x(OH)x) with significant specific surface areas between 290 and 330 m2∙g−1 were obtained. After activation under gaseous HF, MgF2−x(OH)x catalysts underwent a large decrease of both their surface area and their hydroxide, rates as shown by their 19F and 1H solid-state NMR spectra. Expect for MgF2 prepared from the acetate precursor, an activity of 30–32 mmol/h∙g was obtained which was about 40% higher compared with that of MgF2 prepared using Trifluoroacetate method (21.6 mmol/h∙g).

scholarly journals An eco-friendly route for template-free synthesis of high specific surface area mesoporous CeO2 powders and their adsorption for acid orange 7

RSC Advances ◽  
2019 ◽  
Vol 9 (39) ◽  
pp. 22366-22375 ◽  
Author(s):  
Yaohui Xu ◽  
Ruixing Li ◽  
Yang Zhou
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
High Specific Surface Area ◽  
Acid Orange 7 ◽  
Acid Orange ◽  
Surface Areas ◽  
Template Free ◽  
Specific Surface Areas ◽  
Mesoporous Ceo2

An eco-friendly route for template-free synthesis of mesoporous CeO2 powders with high specific surface areas.

A Comparison of Methods for Determining Surface Areas of Carbon Black

1973 ◽  
Vol 46 (1) ◽  
pp. 192-203 ◽  
Author(s):  
R. A. Klyne ◽  
B. D. Simpson ◽  
M. L. Studebaker
Keyword(s):  
Carbon Black ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Surface Areas ◽  
Furnace Black ◽  
Area Increase ◽  
Experimental Errors ◽  
Specific Surface Areas ◽  
Surface Area Increase

Abstract 1. The various tint tests correlate with each other—it does not make much difference which of the three procedures is used. The discrimination between similar blacks is comparable. Specific surface areas obtained by the three methods are comparable and differences appear to be due to experimental errors. (Compare Figures 5–7). 2. Surface areas larger than some 90 to 100 m2/g cannot be reliably determined from tint strength measurements alone. 3. Structure exerts a pronounced effect on tint strength of furnace blacks, especially above 90 to 100 m2/g. Porosity and/or composition are apparently also variables which affect tinting strength. 4. Densichron reflectance on the dry carbon black can be used to estimate specific surface areas up to about 140 m2/g; but, since theabsoluteerrorincreases as the specific surface area increases, this method loses some of its reliability at values above about 110 m2/g. The relative error in reflectance determinations does not vary greatly over the furnace-black range. Densichron reflectance is influenced by composition, evidently due to composition-related differences in optical properties of the carbons. 5. In CTAB adsorption measurements, titration errors and handling errors tend to be rather constant for blacks of different surface area. Hence, CTAB permits better discrimination among blacks of small particle size. 6. The errors in Densichron reflectance surface area increase with specific surface area. Hence, the deviations between CTAB and reflectance surface area which are due to experimental error increase with the surface area of the sample.

Gold Cementation by Dendritic Zinc Powders in Percolation Mode

2020 ◽  
Vol 989 ◽  
pp. 543-547
Author(s):  
K.D. Naumov ◽  
Vladimir G. Lobanov
Keyword(s):  
Particle Size ◽  
Physical Properties ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
High Specific Surface Area ◽  
Alkaline Solutions ◽  
Wide Range ◽  
Zinc Powders ◽  
Cyanide Solutions

In present article gold cementation features from cyanide solutions using dendritic zinc powders are studied. The powders were obtained by electroextraction from alkaline solutions. Powders with different physical properties were obtained by means of change in current density (from 0.5 to 2 A/m2) and NaOH concentration in solution (from 100 to 400 g/dm3) at the constant zinc concentration (10 g/dm3). The physical properties of mentioned powders were studied using SEM (Jeol JSM-6390LA), BET (Gemini VII 2390) and laser diffraction (Sympatec HELOS & RODOS). It is shown that electrolytic powders have high specific surface area, which is 1.8–2.6 times larger than the surface area of ​​the zinc powder currently used for cementation. At that electrolytic powders particle size is 8-22 times larger than the particle size of powder currently used for cementation. The reason of high specific surface area is the electrolytic zinc powders dendritic structure. It was found that the obtained powders precipitate gold from cyanide solutions with a greater efficiency in a wide range of productivity. Laboratory unit simulating Merrill-Crow technology was used for cementation. Immediately ahead conducting the experiments, Na2SO3 was added to the solution in excess to remove dissolved oxygen. Zinc powders were plated by dendritic lead before loading into the laboratory setup by cementation. Lead was added as acetate (Pb (CH3COO)2). The consumption of lead acetate was 10% by weight of zinc. Correlation between the powders physical properties and the gold extraction is shown.

Experimental Studies of Carbon Electrodes With Various Surface Area for Li–O2 Batteries

2019 ◽  
Vol 16 (4) ◽  
Author(s):  
Fangzhou Wang ◽  
P. K. Kahol ◽  
Ram Gupta ◽  
Xianglin Li
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Discharge Capacity ◽  
Carbon Materials ◽  
High Specific Surface Area ◽  
Acetylene Black ◽  
Carbon Electrodes ◽  
Tea Leaves ◽  
Surface Areas

Li−O2 batteries with carbon electrodes made from three commercial carbons and carbon made from waste tea leaves are investigated in this study. The waste tea leaves are recycled from household tea leaves and activated using KOH. The carbon materials have various specific surface areas, and porous structures are characterized by the N2 adsorption/desorption. Vulcan XC 72 carbon shows a higher specific surface area (264.1 m2/g) than the acetylene black (76.5 m2/g) and Super P (60.9 m2/g). The activated tea leaves have an extremely high specific surface area of 2868.4 m2/g. First, we find that the commercial carbons achieve similar discharge capacities of ∼2.50 Ah/g at 0.5 mA/cm2. The micropores in carbon materials result in a high specific surface area but cannot help to achieve higher discharge capacity because it cannot accommodate the solid discharge product (Li2O2). Mixing the acetylene black and the Vulcan XC 72 improves the discharge capacity due to the optimized porous structure. The discharge capacity increases by 42% (from 2.73 ± 0.46 to 3.88 ± 0.22 Ah/g) at 0.5 mA/cm2 when the mass fraction of Vulcan XC 72 changes from 0 to 0.3. Second, the electrode made from activated tea leaves is demonstrated for the first time in Li−O2 batteries. Mixtures of activated tea leaves and acetylene black confirm that mixtures of carbon material with different specific surface areas can increase the discharge capacity. Moreover, carbon made from recycled tea leaves can reduce the cost of the electrode, making electrodes more economically achievable. This study practically enhances the discharge capacity of Li−O2 batteries using mixed carbons and provides a method for fabricating carbon electrodes with lower cost and better environmental friendliness.

scholarly journals Adsorption of water vapour and the specific surface area of arctic zone soils (Spitsbergen)

2018 ◽  
Vol 32 (1) ◽  
pp. 19-27 ◽  
Author(s):  
Jolanta Cieśla ◽  
Zofia Sokołowska ◽  
Barbara Witkowska-Walczak ◽  
Kamil Skic
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Water Vapour ◽  
Specific Surface Area ◽  
Nitrogen Adsorption ◽  
Total Carbon ◽  
Arctic Zone ◽  
Surface Areas ◽  
Arctic Soils ◽  
Specific Surface Areas

AbstractWater vapour/nitrogen adsorption were investigated and calculated the specific surface areas of arctic-zone soil samples (Turbic Cryosols) originating from different micro-relief forms (mud boils, cell forms and sorted circles) and from different depths. For the characterisation of the isotherms obtained for arctic soils, the Brunauer-Emmet-Teller model was then compared with the two other models (Aranovich-Donohue and Guggenheim-Anderson-de Boer) which were developed from Brunauer-Emmet-Teller. Specific surface area was calculated using the Brunauer-Emmet-Teller model at p p0−1range of 0.05-0.35 for the water vapour desorption and nitrogen adsorption isotherms. The values of total specific surface area were the highest in Cryosols on mud boils, lower on cell forms, and the lowest on sorted circles. Such tendency was observed for the results obtained by both the water vapour and nitrogen adsorption. The differences in the values of specific surface area at two investigated layers were small. High determination coefficients were obtained for relationships between the specific surface areas and contents of clay and silt fraction in Cryosols. No statistically significant correlation between the total carbon amount and the values of specific surface area in Cryosols has been found.

OBTAINING OF VATERITE MICROPARTICLES WITH AN IMMOBILIZED ENZYME – CATALASE BY CO- SYNTHESIS

2020 ◽  
pp. 84-86
Author(s):  
N. Balabushevich ◽  
D. Volodkin ◽  
N. Eremeev ◽  
N. Klyachko
Keyword(s):  
Particle Size ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Immobilized Enzyme ◽  
High Specific Surface Area ◽  
Polymorphic Modifications

Among the polymorphic modifications of CaCO3, vaterite attracts much attention due to its unique properties such as a high specific surface area, controlled particle size [1], and it is also one of the most popular carriers for the manufacture of microparticles in biotechnology and medicine [2].

scholarly journals Inhibition of tetrachloroethene and trichloroethene on methanogenesis in anaerobic sludges from various origins

2020 ◽  
Vol 81 (3) ◽  
pp. 544-549
Author(s):  
A. M. Wang ◽  
C. S. Hwu ◽  
C. H. Wu
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Physical Factor ◽  
Anaerobic Treatment ◽  
Contaminated Groundwater ◽  
Biological Factors ◽  
Methanogenic Activity ◽  
Surface Areas ◽  
Specific Surface Areas

Abstract Nine anaerobic sludges were screened to obtain the most effective methanogenic inoculum for the anaerobic treatment of groundwater that is contaminated with tetrachloroethene (PCE) or trichloroethene (TCE). The selection was based on the toxicity of PCE or TCE to acetoclastic methanogens in different sludges. The effects of two biological factors, sludge origin and specific acetoclastic methanogenic activity, and a physical factor, specific surface area of sludge, on the degree of inhibition were examined and compared. The fifty percent inhibition concentrations (IC50) of PCE and TCE that were obtained from 30 °C batch inhibition tests ranged from 0.18 to 0.41 and 1.71 to 3.31 mM, respectively, for the examined sludges. The toxicity of the contaminants to anaerobic sludges did not depend on the two biological factors but was closely correlated with the specific surface area of sludge. Suspended sludges, which have higher specific surface areas than granular sludges, suffered much greater inhibition. This paper suggests the use of anaerobic granular sludges as inocula in bioreactors for treating PCE- and TCE-contaminated groundwater to reduce the effect of their inhibition.

Organometallic precursor induced defect-enriched mesoporous CeO2 with high specific surface area: preparation and catalytic performance

2020 ◽  
Vol 8 (28) ◽  
pp. 14006-14014 ◽  
Author(s):  
Shaowei Yang ◽  
Haidong Shen ◽  
Fang Cheng ◽  
Chen Wu ◽  
Yueling Cao ◽  
...  
Keyword(s):  
Physicochemical Properties ◽  
Specific Surface ◽  
Porous Structure ◽  
Surface Area ◽  
Catalytic Performance ◽  
High Specific Surface Area ◽  
Surface Areas ◽  
Organometallic Precursor ◽  
Specific Surface Areas ◽  
Mesoporous Ceo2

CeO2 with special physicochemical properties including high specific surface areas, suitable porous structure and surface enriched defects has been prepared by an organometallic precursor induced method.

scholarly journals Towards Macroporous α-Al2O3—Routes, Possibilities and Limitations

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1787
Author(s):  
Simon Carstens ◽  
Ralf Meyer ◽  
Dirk Enke
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Sol Gel ◽  
Surface Areas ◽  
Alumina Membranes ◽  
Sol Gel Process ◽  
Specific Surface Areas ◽  
Α Al2o3 ◽  
Sol Gel Synthesis

This article combines a systematic literature review on the fabrication of macroporous α-Al2O3 with increased specific surface area with recent results from our group. Publications claiming the fabrication of α-Al2O3 with high specific surface areas (HSSA) are comprehensively assessed and critically reviewed. An account of all major routes towards HSSA α-Al2O3 is given, including hydrothermal methods, pore protection approaches, dopants, anodically oxidized alumina membranes, and sol-gel syntheses. Furthermore, limitations of these routes are disclosed, as thermodynamic calculations suggest that γ-Al2O3 may be the more stable alumina modification for ABET > 175 m2/g. In fact, the highest specific surface area unobjectionably reported to date for α-Al2O3 amounts to 16–24 m2/g and was attained via a sol-gel process. In a second part, we report on some of our own results, including a novel sol-gel synthesis, designated as mutual cross-hydrolysis. Besides, the Mn-assisted α-transition appears to be a promising approach for some alumina materials, whereas pore protection by carbon filling kinetically inhibits the formation of α-Al2O3 seeds. These experimental results are substantiated by attempts to theoretically calculate and predict the specific surface areas of both porous materials and nanopowders.

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