Fabrication of Nanosized Alumina Powders by a Simple Polymer Solution Route

2006 ◽  
Vol 6 (11) ◽  
pp. 3633-3636
Author(s):  
Sang-Jin Lee ◽  
Sung-Yong Chun ◽  
Choong-Hyo Lee ◽  
Young-Soo Yoon
Keyword(s):  
Particle Size ◽  
Polymer Solution ◽  
Gas Adsorption ◽  
Average Particle Size ◽  
High Specific Surface Area ◽  
Milling Process ◽  
Degree Of Polymerization ◽  
Average Particle ◽  
Porous Microstructure ◽  
Solution Route

Nanosized alumina (Al2O3) powders had been successfully fabricated by a simple polymer solution route employing polyvinyl alcohol (PVA) as an organic carrier. The fabricated alumina powders had an average particle size of 6.1 nm with a high specific surface area of 99.5 m2/g. As well, the alumina powders were fully crystallized to α phase at a relatively low temperature of 1000 °C. The PVA polymer contributed to a soft and porous microstructure of the calcined alumina powders, and ball-milling process with the porous powders was effective in making nanosized alumina powders. In addition, the content and degree of polymerization of the PVA affected the development of crystallization and powder properties. In this study, the simple polymer technique and milling process for the fabrication of nanosized alumina powders are introduced, and the effects of PVA on the property of the synthesized alumina powders are observed. For the study, the characterizations of the synthesized powders are conducted by using XRD, TEM, particle size analyzer, and nitrogen gas adsorption.

Kinetics of Structural Changes in Strontium Hexa-Ferrite Powder during Milling in Beater Mill

2020 ◽  
Vol 989 ◽  
pp. 199-203
Author(s):  
Ivan N. Egorov ◽  
Nikolay Ya. Egorov ◽  
Viktor P. Kryzhanovsky
Keyword(s):  
Particle Size ◽  
Structural Characteristics ◽  
Average Particle Size ◽  
Experimental Studies ◽  
Milling Process ◽  
Strontium Hexaferrite ◽  
Average Particle ◽  
Relative Deformation ◽  
Ferrite Powder ◽  
Electromagnetic Effect

The paper presents the results of experimental studies of strontium hexa-ferrite average particle size and structural characteristics changes during milling process. Coarse strontium hexaferrite was milled in beater mill, without and with electromagnetic effect. Electromagnetic effect was produced by constant and alternating gradient magnetic fields with mutually perpendicular induction lines. Particle sizes were measured by microscopic methods, and structural characteristics were calculated by processing of X-ray diffractograms. Diffraction studies showed that during milling process, both with and without electromagnetic effect, the most intensive changes of coherent scattering region (CSR) sizes, dislocation densities and relative deformation of particulate material occur at earlier stage of milling. At this stage the speed of average particle size decrease is maximal. At later stage both average particle size and structural characteristic changes correlate and have asymptotic character.

scholarly journals The Use of Inorganic Packing Materials during Methane Biofiltration

2010 ◽  
Vol 2010 ◽  
pp. 1-8 ◽  
Author(s):  
Josiane Nikiema ◽  
Michèle Heitz
Keyword(s):  
Particle Size ◽  
Gas Phase ◽  
Average Particle Size ◽  
High Specific Surface Area ◽  
Packing Material ◽  
Average Particle ◽  
Packing Materials ◽  
Clay Particles ◽  
Good Surface ◽  
Methane Elimination

The objective behind this study is to select a suitable inorganic packing material for methane biofiltration. Three packing materials are to be compared: two rock materials (average particles' sizes: 2 and 5 mm) and one porous clay particles (average particle size of 7 mm). The main parameter used to assess the efficiency of the packing material is the methane elimination capacity. The study reveals that the rock material having an average particle size around 2 mm is to be preferred. This result is probably due to its high specific surface area and to its good surface properties as compared to the other 2 tested porous materials. The influence of the nonirrigation with the nutrient solution of the biofilter is also investigated. It has been found that nonirrigation of biofilter causes the biofilter performance to decrease significantly (e.g., 45% decrease in 1 week) even with the humidification of the gas phase prior to its introduction into the biofilter.

scholarly journals Phase Transformation and Morphology Evolution of Ti50Cu25Ni20Sn5 during Mechanical Milling

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1769 ◽  
Author(s):  
Dora Janovszky ◽  
Ferenc Kristaly ◽  
Tamas Miko ◽  
Adam Racz ◽  
Maria Sveda ◽  
...  
Keyword(s):  
Particle Size ◽  
Phase Transformation ◽  
Ball Milling ◽  
Milling Time ◽  
Average Particle Size ◽  
Amorphous Powder ◽  
Xrd Analysis ◽  
Milling Process ◽  
Average Particle ◽  
Amorphous Content

Nanocrystalline/amorphous powder was produced by ball milling of Ti50Cu25Ni20Sn5 (at.%) master alloy. Both laser diffraction particle size analyzer and scanning electron microscope (SEM) were used to monitor the changes in the particle size as well as in the shape of particles as a function of milling time. During ball milling, the average particle size decreased with milling time from >320 µm to ~38 µm after 180 min of milling. The deformation-induced hardening and phase transformation caused the hardness value to increase from 506 to 779 HV. X-ray diffraction (XRD) analysis was used to observe the changes in the phases/amorphous content as a function of milling time. The amount of amorphous fraction increased continuously until 120 min milling (36 wt % amorphous content). The interval of crystallite size was between 1 and 10 nm after 180 min of milling with 25 wt % amorphous fractions. Cubic Cu(Ni,Cu)Ti2 structure was transformed into the orthorhombic structure owing to the shear/stress, dislocations, and Cu substitution during the milling process.

Characterization of Nano Scaled Mullite Powders Prepared by Organic-Inorganic Solution Technique

2007 ◽  
Vol 119 ◽  
pp. 43-46
Author(s):  
Sang Jin Lee ◽  
Choong Hwan Jung
Keyword(s):  
Particle Size ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Crystallization Behavior ◽  
Average Particle Size ◽  
Degree Of Polymerization ◽  
Solution Technique ◽  
Average Particle ◽  
Porous Powder

Nano scaled mullite (3Al2O3·2SiO2) powders had been fabricated by an organic-inorganic solution technique using a polyvinyl alcohol (PVA) as an organic carrier. PVA polymer contributed to a soft and porous powder microstructure, and ball milling with the porous powder was effective in making nano-sized mullite powders. In addition, the degree of polymerization of PVA affected the crystallization behavior. The fully crystallized and ball-milled mullite powders had an average particle size of 120 nm with a specific surface area of 67.0 m2/g. In this paper, the simple solution technique and milling process for the fabrication of nano scaled mullite powders are introduced. And the effects of PVA on the crystallization behavior and powder specific surface area are also studied. The characteristics of the synthesized powders are examined by using XRD, TEM, particle size analyzer and nitrogen gas adsorption.

Diagnostic of Structural Changes in Ferromagnetic Powders during Milling in Beater Mill

2021 ◽  
Vol 316 ◽  
pp. 187-192
Author(s):  
I.N. Egorov ◽  
S.I. Egorova ◽  
G.F. Lemeshko
Keyword(s):  
Particle Size ◽  
Fluidized Bed ◽  
Structural Changes ◽  
Structural Characteristics ◽  
Average Particle Size ◽  
Coherent Scattering ◽  
Milling Process ◽  
Average Particle ◽  
Ferrite Powder ◽  
Great Decrease

Problem of obtaining fine powders of strontium hexa-ferrite is actual because of its wide applications. The paper provides the results of studies of particle size distribution and structural characteristic changes of strontium hexa-ferrite powder (SrFe12O19) during milling in impact mill and after its consequent annealing. Mechanical processing of coarse particulate system was carried out in the mill for 120 minutes without electromagnetic effect and with creation of magneto fluidized bed, formed by perpendicular constant and alternating magnetic field with induction gradient of 210 mT/m, providing reciprocating motion of particles and aggregates with sizes of 3 – 4 mm. It was shown that milling of coarse strontium hexa-ferrite with average particle size 1558.5 μm and the most possible size 1500 μm in magneto fluidized bed allowed to intensify milling process and to provide a significant increase of powder particle sizes uniformity. It was found out, that milling in magneto fluidized bed leads to a great decrease of coherent scattering regions sizes and an increase of lattice micro-deformations and relative dislocation density. Consequent annealing of the powder for 2 hours at 850°C refined structural characteristics significantly. The carried out research allows to choose the optimal milling duration for solution of practical problems of powder metallurgy.

Determination of grinding parameters of fenugreek seed

1970 ◽  
Vol 26 (1) ◽  
pp. 16 ◽  
Author(s):  
S Balasubramanian ◽  
Rajkumar Rajkumar ◽  
K K Singh
Keyword(s):  
Particle Size ◽  
Energy Consumption ◽  
Moisture Content ◽  
Specific Energy ◽  
Feed Rate ◽  
Average Particle Size ◽  
Specific Energy Consumption ◽  
Average Particle ◽  
Fenugreek Seeds ◽  
Fenugreek Seed

Experiment to identify ambient grinding conditions and energy consumed was conducted for fenugreek. Fenugreek seeds at three moisture content (5.1%, 11.5% and 17.3%, d.b.) were ground using a micro pulverizer hammer mill with different grinding screen openings (0.5, 1.0 and 1.5 mm) and feed rate (8, 16 and 24 kg h-1) at 3000 rpm. Physical properties of fenugreek seeds were also determined. Specific energy consumptions were found to decrease from 204.67 to 23.09 kJ kg-1 for increasing levels of feed rate and grinder screen openings. On the other hand specific energy consumption increased with increasing moisture content. The highest specific energy consumption was recorded for 17.3% moisture content and 8 kg h-1 feed rate with 0.5 mm screen opening. Average particle size decreased from 1.06 to 0.39 mm with increase of moisture content and grinder screen opening. It has been observed that the average particle size was minimum at 0.5 mm screen opening and 8 kg h-1 feed rate at lower moisture content. Bond’s work index and Kick’s constant were found to increase from 8.97 to 950.92 kWh kg-1 and 0.932 to 78.851 kWh kg-1 with the increase of moisture content, feed rate and grinder screen opening, respectively. Size reduction ratio and grinding effectiveness of fenugreek seed were found to decrease from 4.11 to 1.61 and 0.0118 to 0.0018 with the increase of moisture content, feed rate and grinder screen opening, respectively. The loose and compact bulk densities varied from 219.2 to 719.4 kg m-3 and 137.3 to 736.2 kg m-3, respectively.  

Formulating SLN and NLC as Innovative Drug Delivery Systems for Non-Invasive Routes of Drug Administration

2020 ◽  
Vol 27 (22) ◽  
pp. 3623-3656 ◽  
Author(s):  
Bruno Fonseca-Santos ◽  
Patrícia Bento Silva ◽  
Roberta Balansin Rigon ◽  
Mariana Rillo Sato ◽  
Marlus Chorilli
Keyword(s):  
Drug Delivery ◽  
Particle Size ◽  
Drug Release ◽  
Drug Loading ◽  
Average Particle Size ◽  
Delivery Systems ◽  
Average Particle ◽  
Minor Importance ◽  
Routes Of Administration ◽  
Non Invasive

Colloidal carriers diverge depending on their composition, ability to incorporate drugs and applicability, but the common feature is the small average particle size. Among the carriers with the potential nanostructured drug delivery application there are SLN and NLC. These nanostructured systems consist of complex lipids and highly purified mixtures of glycerides having varying particle size. Also, these systems have shown physical stability, protection capacity of unstable drugs, release control ability, excellent tolerability, possibility of vectorization, and no reported production problems related to large-scale. Several production procedures can be applied to achieve high association efficiency between the bioactive and the carrier, depending on the physicochemical properties of both, as well as on the production procedure applied. The whole set of unique advantages such as enhanced drug loading capacity, prevention of drug expulsion, leads to more flexibility for modulation of drug release and makes Lipid-based nanocarriers (LNCs) versatile delivery system for various routes of administration. The route of administration has a significant impact on the therapeutic outcome of a drug. Thus, the non-invasive routes, which were of minor importance as parts of drug delivery in the past, have assumed added importance drugs, proteins, peptides and biopharmaceuticals drug delivery and these include nasal, buccal, vaginal and transdermal routes. The objective of this paper is to present the state of the art concerning the application of the lipid nanocarriers designated for non-invasive routes of administration. In this manner, this review presents an innovative technological platform to develop nanostructured delivery systems with great versatility of application in non-invasive routes of administration and targeting drug release.

Azithromycin nanosuspension preparation using evaporative precipitation into aqueous solution (EPAS) method and its comparative dissolution study

2020 ◽  
Vol 17 ◽  
Author(s):  
Mohammad Hossain Shariare ◽  
Tonmoy Kumar Mondal ◽  
Hani Alothaid ◽  
Md. Didaruzzaman Sohel ◽  
MD Wadud ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Particle Size ◽  
Dissolution Rate ◽  
Average Particle Size ◽  
Scale Up ◽  
Average Particle ◽  
Total Drug ◽  
Residual Solvent ◽  
Dissolution Study ◽  
Drug Content

Aim: EPAS (evaporative precipitation into aqueous solution) was used in the current studies to prepare azithromycin nanosuspensions and investigate the physicochemical characteristics for the nanosuspension batches with the aim of enhancing the dissolution rate of the nanopreparation to improve bioavailability. Methods: EPAS method used in this study for preparing azithromycin nanosuspension was achieved through developing an in-house instrumentation method. Particle size distribution was measured using Zetasizer Nano S without sample dilution. Dissolved azithromycin nanosuspensions were also compared with raw azithromycin powder and commercially available products. Total drug content of nanosuspension batches were measured using an Ultra-Performance Liquid Chromatography (UPLC) system with Photodiode Array (PDA) detector while residual solvent was measured using gas chromatography (GC). Results: The average particle size of azithromycin nanosuspension was 447.2 nm and total drug content was measured to be 97.81% upon recovery. Dissolution study data showed significant increase in dissolution rate for nanosuspension batch when compared to raw azithromycin and commercial version (microsuspension). The residual solvent found for azithromycin nanosuspension is 0.000098023 mg/ mL or 98.023 ppb. Conclusion: EPAS was successfully used to prepare azithromycin nanoparticles that exhibited significantly enhanced dissolution rate. Further studies are required to scale up the process and determine long term stability of the nanoparticles.

scholarly journals Evaluation of the Effects of Filler Fineness on the Properties of an Epoxy Asphalt Mixture

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2003
Author(s):  
Wei Xu ◽  
Jintao Wei ◽  
Zhengxiong Chen ◽  
Feng Wang ◽  
Jian Zhao
Keyword(s):  
Particle Size ◽  
Average Particle Size ◽  
Asphalt Mixture ◽  
Average Particle ◽  
Fine Dust ◽  
Bonding Structure ◽  
Epoxy Asphalt ◽  
Mineral Powder ◽  
Marshall Stability ◽  
Mixture Sample

The type and fineness of a filler significantly affect the performance of an asphalt mixture. There is a lack of specific research on the effects of filler fineness and dust from aggregates on the properties of epoxy asphalt (EA) mixtures. The effects of aggregate dust and mineral powder on the properties of an EA mixture were evaluated. These filler were tested to determine their fineness, specific surface area and mineral composition. The effects of these fillers on the EA mastic sample and mixture were evaluated. The morphology of the EA mastic samples was analyzed using scanning electron microscopy (SEM). The effects of the fillers on the Marshall stability, tensile strength and fatigue performance of the EA mixture were evaluated. The dust from the aggregates exhibited an even particle size distribution, and its average particle size was approximately 20% of that of the mineral powder. The SEM microanalysis showed that the EA mastic sample containing relatively fine dust formed a tight and dense interfacial bonding structure with the aggregate. The EA mixture sample containing filler composed of dust from aggregate had a significantly higher strength and longer fatigue life than that of the EA sample containing filler composed of mineral powder.

scholarly journals Surface Activity of Humic Acid and Its Sub-Fractions from Forest Soil

2021 ◽  
Vol 13 (15) ◽  
pp. 8122
Author(s):  
Shijie Tian ◽  
Weiqiang Tan ◽  
Xinyuan Wang ◽  
Tingting Li ◽  
Fanhao Song ◽  
...  
Keyword(s):  
Surface Tension ◽  
Particle Size ◽  
Humic Acid ◽  
Forest Soil ◽  
Surface Activity ◽  
Self Assembly ◽  
Average Particle Size ◽  
Gaussian Model ◽  
Exponential Model ◽  
Average Particle

Surface activity of humic acid (HA) and its six sub-fractions isolated from forest soil were characterized by surface tension measurements, dynamic light scattering, and laser doppler electrophoresis. The surface tension of HA and its sub-fractions reduced from 72.4 mN·m−1 to 36.8 mN·m−1 in exponential model with the increasing concentration from 0 to 2000 mg·L−1. The critical micelle concentration (CMC) and Z-average particle size ranged from 216–1024 mg·L−1 and 108.2–186.9 nm for HA and its sub-fractions, respectively. The CMC have related with alkyl C, O-alkyl C, aromatic C, and carbonyl C (p < 0.05), respectively, and could be predicted with the multiple linear regression equation of CMC, CMC = 18896 − 6.9 × C-296 × alkyl C-331 × aromatic C-17019 × H/C + 4054 × HB/HI (p < 0.05). The maximum particle size was 5000 nm after filtered by a membrane with pore size of 450 nm, indicating HA and its sub-fractions could progressed self-assembly at pH 6.86. The aggregate sizes of number-base particle size distributions were mainly in six clusters including 2 ± 1 nm, 5 ± 2 nm, 10 ± 3 nm, 21 ± 8 nm, 40 ± 10 nm, and >50 nm analyzed by Gaussian model that maybe due to the inconsistency of the components and structures of the HA sub-fractions, requiring further study. It is significance to explore the surface activity of HA and its sub-fractions, which is helpful to clarify the environmental behavior of HA.

Sign in / Sign up

Export Citation Format

Share Document