scholarly journals Preparation of nano manganese oxides by H2O2 in-situ oxidation: effect of regulation mechanism on physical and chemical properties

2021 ◽  
Author(s):  
Mingdong Li ◽  
Jiawei Wang ◽  
Dejin Fu ◽  
Bibo Gou ◽  
Xiaoliang Chen ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Manganese Oxides ◽  
Ph Value ◽  
Chemical Properties ◽  
Manganese Sulfate ◽  
Physical And Chemical Properties ◽  
Physical And Chemical ◽  
And Chemical Properties

Abstract Manganese oxides showed many special physicochemical properties in many fields such as electrochemistry, adsorption and catalysis. They were widely used in cathode materials for lithium batteries, molecular sieves, catalytic materials and adsorbents. In this paper, in situ oxidation of manganese sulfate solution was conducted with H2O2 as oxidant, and the characterization means of XRD, SEM and BET were used. The purpose was to study the effects of different regulation mechanisms on the physical and chemical properties of manganese oxides such as morphology, phase composition, surface properties and specific surface area. The adsorption properties of γ-MnO2 for Co and Ni in manganese ore leaching solution were tested. The results showed as follows. Under alkaline conditions, the main product of manganese sulfate solution oxidized by H2O2 was Mn3O4 spherical particles with a radius of about 50 nm, these particles had micropores or mesopores, the oxidation reaction rate was rapid, and the specific surface area and N2 adsorption capacity changed with the change of reaction conditions.The temperature had a great influence on the micro morphology of the product.The micro morphology was slender nanorod when the temperature was 20℃. With the increase of temperature, the length of nanorod became shorter. When the temperature rises to 50℃, the rod became spherical. When the pH value decreased from 9 to 7, the diffraction peak of each crystal plane in the product Mn3O4 decreased gradually. The diffraction peak of γ-MnO2 appeared when the pH value decreased to 5. All the products were γ-MnO2 when the pH value decreased to 3. With the increase of Mn2+ concentration, the grain size decreased and agglomeration was easy to occur. The optimum conditions were obtained as follows: the temperature was 30℃, pH was 3, reaction time was 90 min, the mole ration of H2O2 to Mn2+ was 1:1, and Mn2+ concentration was 10g/L. Under the optimum conditions, γ-MnO2 with high specific surface area (172.41 m2/g) was prepared. This γ-MnO2 has a good adsorption effect on Co and Ni in manganese ore leaching solution, and the adsorption efficiency could be reached 94.75 % and 95.67 %. This study would provide a reference for the preparation of manganese oxides with different physical and chemical properties.

scholarly journals Influence of the Calcination Temperature on the properties of The Alumina as Catalyst Support for Catalysis

Paliva ◽  
2020 ◽  
pp. 155-161
Author(s):  
Tomáš Hlinčík ◽  
Veronika Šnajdrová ◽  
Veronika Kyselová
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Calcination Temperature ◽  
Specific Surface Area ◽  
Catalyst Support ◽  
Chemical Properties ◽  
Total Pore Volume ◽  
Temperature Range ◽  
Calcination Temperatures ◽  
Physical And Chemical

Alumina is commonly used in industrial practice as a catalyst support and it is made from boehmite. Depending on the calcination temperature, this mineral is transformed into various crystalline modifications which have different physical and chemical properties. For this reason, the following parameters were determined at different calcination temperatures: length, width, material hardness, specific surface area and total pore volume. The results show that with increasing calcination temperature there have been significant changes which may be important when using the material as a catalyst support, e.g. in the preparation of catalysts or in the design of cat-alytic reactors. The specific surface area, which decreases in the temperature range 450–800 °C, is an important parameter for the preparation of catalysts, so it is appropriate to choose a temperature of 600 °C, when the specific surface area is above 200 m2·g-1. The effect of calcination temperature on the structural transitions of boehmite was also monitored. The results showed that γ-Al2O3 has the most suitable properties as a catalyst sup-port in the temperature range 450–800 °C.

Some Physical, Chemical and Mineralogical Properties of Some Canadian Fly Ashes

1986 ◽  
Vol 86 ◽  
Author(s):  
R. C. Joshi ◽  
B. K. Marsh
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Chemical Properties ◽  
Water Soluble ◽  
Pozzolanic Activity ◽  
Unburned Carbon ◽  
Magnetic Fraction ◽  
Fly Ashes ◽  
Physical And Chemical

ABSTRACTThis paper gives physical and chemical properties of some Canadian fly ashes. Specific surface area, magnetic fraction, water soluble fraction and fraction finer than 45 μm were determined as part of the physical tests. Thermo-gravimetric analyses (TGA) in oxygen and nitrogen were conducted on raw ash samples. The change of pH with time in suspensions of the different ashes in water was also determined. Pozzolanic activity of the ashes with lime for all the ashes was evaluated to measure ash reactivity.The ash activity seems to be related to fineness of the ash measured by the Blaine air permeability method, but not to the fineness measured by nitrogen sorption. Generally the greater the specific surface area, the higher the reactivity of the ash. The correlation was, however, not strong and no other physical or chemical parameter measured in this investigation seems to be related to pozzolanic activity.The results of pH and TGA tests indicated that the ashes differ in many respects from each other. The TGA data suggest that loss on-ignition in many of the ashes is not entirely due to the presence of unburned carbon. Specific surface area determined by various methods seems to provide different values. No characterization parameter was found that was uniquely related to coal type.

scholarly journals Characterization of Samarium Doped Ceria Powders Having High Specific Surface Area Synthesized by Carbon-Assisted Spray Pyrolysis

2011 ◽  
Vol 485 ◽  
pp. 137-140 ◽  
Author(s):  
Kenichi Myoujin ◽  
Hiroki Ichiboshi ◽  
Takayuki Kodera ◽  
Takashi Ogihara
Keyword(s):  
Specific Surface ◽  
Relative Density ◽  
Spray Pyrolysis ◽  
Surface Area ◽  
Specific Surface Area ◽  
Carbon Sources ◽  
Chemical Properties ◽  
High Specific Surface Area ◽  
Doped Ceria ◽  
Physical And Chemical

Spherical samarium doped ceria (Ce0.8Sm0.2O1.9, SDC) powders having high specific surface area (SSA) were successfully synthesized by carbon-assisted spray pyrolysis (CASP). Saccharides, such as monosaccharides and disaccharides, or organic acids were used as carbon sources. The physical and chemical properties of these powders were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), Thermo gravimetry-Differential Thermal Analysis (TG-DTA), and BET. Decarbonized powders obtained by this method exhibit spherical morphologies and nano- and submicron-sizes. The SSA of SDC obtained from CASP was more than seven times higher than that obtained from conventional spray pyrolysis (CSP). The SSA of the decarbonized SDC powders obtained by calcination at 900 °C was estimated to be approximately 70 m2/g by using the BET method. The relative density of SDC obtained from CASP was higher than that obtained from CSP. The relative density of the SDC pellet was highest (96 %) when it was sintered at 1400 °C.

scholarly journals Effects of Continuous Cropping of Dictyophora on Soil Physical and Chemical Properties, Microbial Biomass and Enzyme Activity

2021 ◽  
Vol 8 (7) ◽  
pp. 214-220
Author(s):  
Long Tong ◽  
◽  
Hongyan Li ◽  
Xiaoming Liu ◽  
Bin Li ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Ph Value ◽  
Chemical Properties ◽  
Available Phosphorus ◽  
Continuous Cropping ◽  
Physical And Chemical Properties ◽  
Factors Affecting ◽  
The One ◽  
Physical And Chemical ◽  
And Chemical Properties

The continuous obstacle of Dictyophora indusiata has become the one of the main factors affecting the healthy development of D. indusiata industry. In order to study the effects of continuous cropping of D. indusiata on the soil environment, four treatments were used in this study: no planted (CK), planted for 1 years (1Y), continuous cropping for 2 years (2Y) and continuous cropping for 3 years (3Y), to determined of the yield of D. indusiata, soil physical and chemical properties, microbial content and enzyme activity. The results showed that the yield and soil pH value decreased with the increase of continuous cropping years, and the contents of organic matter, total nitrogen, total phosphorus and total potassium, C/N and C/P also increased with the increase of continuous cropping years. Soil availability decreased with the increase of continuous cropping years, the content of alkaline nitrogen, available phosphorus and available potassium decreased by 12.25%, 28.91% and 24.86% at 3Y compared with 1Y, respectively. The biomass of bacteria, actinomycetes and fungi and the total amount of microorganism in soil increased at 1Y compared with CK, but with the increase of continuous cropping years, the biomass of bacteria and actinomycetes and the total amount of microorganism decreased significantly, while the biomass of fungi increased significantly; the continuous cropping of D. indusiata also decreased the value of bacteria/fungi in soil. The enzyme activities of the soil were higher than those of the unplanted plots, however, the activities of urease, catalase, peroxidase, sucrase, phosphatase and protease decreased with the increase of continuous cropping years. In a word, with the increase of continuous cropping, the acidity of rhizosphere soil increased, the availability of soil nutrients and the activity of soil enzymes decreased, the biomass of soil microorganisms, bacteria and actinomycetes decreased. However, the increase of fungal biomass led to the decline of soil texture.

scholarly journals Influence of the Addition of Calcium Hydroxide Powder on Some Physical and Chemical Properties of the Sealer MTA Fillapex

2012 ◽  
Vol 3 (2) ◽  
pp. 180-183
Author(s):  
Marcelo Ferrarezi de Andrade ◽  
Renato de Toledo Leonardo ◽  
Edson Alves de Campos ◽  
Milton Carlos Kuga ◽  
Marco Antonio Hungaro Duarte ◽  
...  
Keyword(s):  
Calcium Hydroxide ◽  
Calcium Release ◽  
Ph Value ◽  
Chemical Properties ◽  
Physical And Chemical Properties ◽  
Ph Values ◽  
The One ◽  
Physical And Chemical ◽  
The Impact ◽  
And Chemical Properties

ABSTRACT Objective This study evaluated the flow, pH and calcium release of MTA Fillapex (G1) or Fillapex plus 10% in weight of calcium hydroxide powder (G2), compared to AH Plus (G3) and Sealapex (G4). Materials and methods The flow test was performed according to ISO 6876:2001 requirements. The sealers were placed into plastic tubes and immersed in deionized water. After 24 hours, 7, 14 and 28 days, the water of each tube was removed and tested to evaluate the pH values and the level of released calcium. Calcium release values were analyzed statistically by Kruskal Wallis and Dunn tests and pH values analyzed by ANOVA and Tukey tests (α = 5%). Results G1 presented higher flow among all sealers. The addition of 10% calcium hydroxide into MTA Fillapex reduced the flow (p < 0.05) but, in a level, that is lower than the one recommended for ISO norms. G2 and G4 presented pH values and calcium release higher than G3 (p < 0.05) in all periods. G1 presented pH value higher than G3 (p < 0.05), except in 7 days period (p > 0.05). G4 presented higher pH values than G1 and G2, but the calcium release was similar for all periods (p > 0.05). G3 presented lower calcium release among all groups (p < 0.05). Conclusion The addition of 10% calcium hydroxide in MTA Fillapex caused reduction in flow and no negative interference in pH and/or calcium release. However, the obtained flow is different from ISO requirements. Clinical relevance MTA Fillapex presents levels of flow above the ISO norms. The addition of calcium hydroxide is a suggestion for solving this problem, but the impact of these procedures should be carefully evaluated. How to cite this article Keine KC, Guiotti FA, Leonardo RT, Kuga MC, Duarte MAH, de Campos EA, de Andrade MF. Influence of the Addition of Calcium Hydroxide Powder on Some Physical and Chemical Properties of the Sealer MTA Fillapex. World J Dent 2012;3(2):180-183.

Relationship Between Particle Size Distribution and Specific Surface Area of Urban Roadway Stormwater Solids

1997 ◽  
Vol 1601 (1) ◽  
pp. 95-108 ◽  
Author(s):  
John J. Sansalone ◽  
Steven G. Buchberger ◽  
Joseph M. Koran ◽  
Joseph A. Smithson
Keyword(s):  
Particle Size ◽  
Specific Surface ◽  
Surface Area ◽  
Particle Surface ◽  
Chemical Properties ◽  
Spherical Particles ◽  
Particle Surface Area ◽  
Surface Areas ◽  
Physical And Chemical ◽  
And Chemical Properties

Surface area is a primary factor in determining many physical and chemical properties of solids, especially particles. In urban and highway runoff, solids can mediate the partitioning between the dissolved and particulate-bound phases of metal elements and organic compounds. Solids are also capable of adversely affecting roadway drainage appurtenances through sedimentation and clogging. Solids characteristics of primary importance for both solute adsorption and clogging and sedimentation are particle size distributions (PSDs), specific surface areas (SSAs), and mass loadings. PSD and SSA results are presented for rainfall and snowmelt solids from a heavily traveled urban roadway in Cincinnati. Integration of the PSD and SSA results indicates that particle surface area is greatest for the midrange (> 100 μm) to the coarser end (<2000 μm) of the gradation. SSA results determined using the assumption of smooth spherical particles are indicated to grossly underestimate actual SSA values.

Novel Rice Gel for Ultrasound Applications: Physical and Chemical Properties

2018 ◽  
Vol 773 ◽  
pp. 344-348 ◽  
Author(s):  
Sittiporn Punyanitya ◽  
Rungsarit Koonawoot ◽  
Sakdiphon Thiensem ◽  
Warangkul Punyanitya
Keyword(s):  
Moisture Content ◽  
Ph Value ◽  
Chemical Properties ◽  
High Viscosity ◽  
Rice Starch ◽  
Physical And Chemical Properties ◽  
Ultrasound Applications ◽  
Physical And Chemical ◽  
Aqueous Solution Method ◽  
And Chemical Properties

Novel rice gels were prepared with different compositions of rice starch (RS) powder and solution of additives. The formulations of gels were composed of RS powder, liquid glycerol, and additives by aqueous solution method. Five solution with different concentration of RS powder (0.5 g, 1 g, 1.5 g, 2 g and 2.5 g). These solutions were dried in electric oven at 65°C for 4 hours. The physical and chemical properties of rice gel characterized were: turbidity, viscosity, smell, irritation, cleaning, pH and moisture content of these gels have been monitored. Results showed that 2 g of RS powder was optimized formulation which had turbidity, high viscosity, pleasant smell, non-irritation and easy to clean. The pH value of this gel was 6.92 ± 0.01 and the moisture content was 0.21 ± 0.07 % which was equivalent to commercial standard of ultrasound gel. These results concluded that the application of RS in gel ultrasound was safe and effective for replacement commercial gel ultrasound. This gel should be studied on image quality in ultrasound examination next step.

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