Factors Affecting Strength of Agglomerates Formed During Spray Drying of Nanophase Powders

1994 ◽  
Vol 346 ◽  
Author(s):  
A. Maskara ◽  
D.M. Smith
Keyword(s):  
Surface Tension ◽  
Particle Size ◽  
Spray Drying ◽  
Particle Surface ◽  
Strength Distribution ◽  
Particle Sizes ◽  
Factors Affecting ◽  
Surface Hydroxyl ◽  
Alcohol Water ◽  
Nanosized Silica

ABSTRACTNanosized silica particles dispersed in various solvents were spray dried and the change in size distribution, agglomerate strength, and strength distribution was determined. The effect of solvent surface tension, pH, and particle surface chemistry on strength of agglomerates formed during spray drying was studied for particle sizes between 15 and 500 nm. Alcohol/water mixtures having different surface tension, and water at different pH levels, were employed to separate the effects of capillary pressure and surface hydroxyl condensation reactions. The agglomerate strength was determined using an ultrasonic measurement technique. The particle size was determined using sedimentation. The strength and strength distribution of agglomerates was found to depend on the solvent surface tension, solubility (pH), and primary particle size.

scholarly journals On the contribution of Aitken mode particles to cloud droplet populations at continental background areas – a parametric sensitivity study

2007 ◽  
Vol 7 (3) ◽  
pp. 6077-6112
Author(s):  
T. Anttila ◽  
V.-M. Kerminen
Keyword(s):  
Surface Tension ◽  
Particle Size ◽  
Chemical Composition ◽  
Pure Water ◽  
Particle Surface ◽  
Chemical Properties ◽  
Sensitivity Study ◽  
Geometric Standard Deviation ◽  
Cloud Droplets ◽  
Aitken Mode

Abstract. Aitken mode particles are potentially an important source of cloud droplets in continental background areas. In order to find out which physico-chemical properties of Aitken mode particles are most important regarding their cloud-nucleating ability, we applied a global sensitivity method to an adiabatic air parcel model simulating the number of cloud droplets formed on Aitken mode particles, CD2. The technique propagates uncertainties in the parameters describing the properties of Aitken mode to CD2. The results show that if the Aitken mode particles do not contain molecules that are able to reduce the particle surface tension more than 30% and/or decrease the mass accommodation coefficient of water, α, below 10−2, the chemical composition and modal properties may have roughly an equal importance at low updraft velocities characterized by maximum supersaturations <0.1%. For larger updraft velocities, however, the particle size distribution is clearly more important than the chemical composition. In general, CD2 exhibits largest sensitivity to the particle number concentration, followed by the particle size. Also the shape of the particle mode, characterized by the geometric standard deviation (GSD), can be as important as the mode mean size at low updraft velocities. Finally, the performed sensitivity analysis revealed also that the chemistry may dominate the total sensitivity of CD2 to the considered parameters if: 1) the value of α varies at least one order of magnitude more than what is expected for pure water surfaces (10−2–1), or 2) the particle surface tension varies more than roughly 30% under conditions close to reaching supersaturation.

scholarly journals Ultrasonic application and spray drying during amorphous calcium phosphate synthesis

2019 ◽  
Vol 8 (4) ◽  
pp. 711-714
Keyword(s):  
Electron Microscopy ◽  
Particle Size ◽  
Calcium Phosphate ◽  
Spray Drying ◽  
Amorphous Calcium Phosphate ◽  
Calcium Phosphates ◽  
Calcium Content ◽  
Synthesis Process ◽  
Particle Sizes ◽  
Ultrasound Application

Hydroxyapatite, amorphous calcium phosphates, calcium triphosphate and calcium octaphosphate are the main components present in bones and teeth. Calcium phosphates are easily synthesized, playing an important role in regenerative medicine, being able to be used as bone implants. There are different ways of synthesizing phosphates, the most commonly used being wet chemical method. The objective of this work was to study the influence of the use of ultrasound and spray drying on the synthesis of amorphous calcium phosphate. Two synthetic variants were studied. One without ultrasound application and the other with ultrasound application. The samples obtained were characterized by X-ray diffraction, FTIR spectroscopy and scanning electron microscopy. The particle size by electron microscopy and the calcium content by atomic absorption was determined. The results showed that when spray drying is applied, particle sizes of less than 261 nm are obtained in the samples synthesized without ultrasound application, being less than 59 nm in the samples synthesized with ultrasound application. The statistical analysis by ANOVA showed significant differences between the particle sizes of the samples synthesized without ultrasound application and the samples synthesized by applying ultrasound. In both cases the particles were spherical. The results obtained show that the application of ultrasound during the synthesis process decreases the particle size, increasing the surface area, which favors the spray drying process.

Анализ параметров медицинского технологического оборудования, учитывающие факторы, влияющие на качество изготовления лекарств

2020 ◽  
pp. 90-95
Author(s):  
T.V. Karlova ◽  
◽  
D.O. Sv ◽  
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Particle Shape ◽  
Particle Surface ◽  
Technological Equipment ◽  
Factors Affecting ◽  
Particle Strength ◽  
The Web

The article is devoted to the analysis of parameters of medical technological equipment that take into account factors affecting the quality of manufacture of drugs. Factors such as particle size, particle size distribution, particle shape, particle surface properties, particle strength, which, based on the «Web» method, are used to analyze the «vibrosieve» technological equipment, are considered.

scholarly journals Study on the Influencing Factors of Ultrafine Spherical RDX during Spray Drying with Low Speed

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Wenzheng Xu ◽  
Jie Wang ◽  
Jinyu Peng ◽  
Xin Liang ◽  
Hao Li ◽  
...  
Keyword(s):  
Particle Size ◽  
Spray Drying ◽  
Mass Fraction ◽  
Raw Materials ◽  
Impact Sensitivity ◽  
Drying Temperature ◽  
Factors Affecting ◽  
Low Speed ◽  
Preparation Conditions ◽  
Size And Morphology

Cyclotrimethylene trinitramine (RDX, C3H6N6O6) with the size of 400 to 600 nm was prepared by low-speed spray-drying method. Meanwhile, the crystal morphology, particle size, crystal structure, thermal decomposition properties, and impact sensitivity properties of the raw materials of RDX and the prepared ultrafine spherical RDX were characterized by scanning electron microscope (SEM), laser particle size analyzer (LPSA), X-ray diffractometer (XRD), differential scanning calorimeter (DSC), and impact sensitivity instrument. The factors affecting experimental results were discussed; the size and morphology of RDX crystals were found to be affected by drying temperature, spray speed, and RDX mass fraction in solution. The optimal preparation conditions for the ultrafine spherical RDX were studied, and the results showed that the RDX particles with the best morphology and particle uniformity were prepared when the drying temperature was 90°C, spray speed was 1 ml/min, and the RDX mass fraction in solution was 4%. As a result, the activation energy (Ea) of the ultrafine spherical RDX was lower than that of raw RDX by 24.52 KJ·mol-1, and the characteristic drop (H50) of the ultrafine spherical RDX was higher by 35.3 cm.

Centrifuge Study on Influence of Particle Size, Compression and Substratum on Particle-Surface Adhesion Force

2008 ◽  
Vol 591-593 ◽  
pp. 347-351 ◽  
Author(s):  
M.A. Felicetti ◽  
José Renato Coury ◽  
M.L. Aguiar
Keyword(s):  
Particle Size ◽  
Phosphate Rock ◽  
Adhesion Force ◽  
Rotation Speed ◽  
Particle Surface ◽  
Particle Sizes ◽  
Adhesion Forces ◽  
Surface Adhesion ◽  
Log Normal ◽  
Log Normal Distribution

The centrifugal technique was used to investigate the influence of particle size, applied compression and substrate materials (stainless steel, glass, Teflon® and PVC) on particle-surface adhesion force. Phosphate rock and manioc starch particles were used in a microcentrifuge that contained specially designed centrifuge tubes and reached a maximum rotation speed of 14,000 rpm. The profile of adhesion force followed a log-normal distribution and adhesion force increased linearly with particle size and the increment of the compression force. The manioc starch particles presented adhesion forces greater than those for the phosphate rock particles for all particle sizes studied. The glass substrate showed a higher adherence than other materials, most probably due to its hardness and polishing.

scholarly journals The Selectivity of Different Sized Catalysts on DOM Fractional Removal during the Catalytic Ozonation of Municipal Sewage

Catalysts ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 14
Author(s):  
Cheng Wang ◽  
Ji Wu ◽  
Aimin Li ◽  
Chendong Shuang
Keyword(s):  
Particle Size ◽  
Catalyst Particle ◽  
Catalytic Ozonation ◽  
Municipal Sewage ◽  
Hydroxyl Groups ◽  
Particle Sizes ◽  
Surface Hydroxyl ◽  
Molecular Weights ◽  
Catalyst Particle Size ◽  
Advanced Treatments

Dissolved organic matter (DOM) is a typical kind of pollutant with a complex composition, and different advanced treatments demonstrate different abilities toward its fractional removal. Hence, it is necessary to analyze the fraction of DOM that remains when using advanced treatments. In this paper, ozonation was used to deal with the biological effluents and comparisons of the catalytic ozonation with different particle sizes of γ-Al2O3 were made. The results of these comparisons indicated that the catalysts were active in improving the removal of DOM and γ-Al2O3 with different particle sizes can selectively remove DOM. The result of fluorescence showed that a decrease in the catalyst particle size contributes to a significant decrease in the fluorescence intensity, except for tryptophan-like substances. Meanwhile, DOM fractions with large molecular weights could be decomposed into small molecules by ozonation, resulting in increased hydrophilicity. However, the use of a catalyst in ozonation increased the removal of hydrophilic components. Additionally, a smaller catalyst particle size increased the removal of hydrophilic components. The results of catalyst analysis implied that the surface hydroxyl groups of catalyst γ-Al2O3 and the diffusion of DOM in the catalyst γ-Al2O3 played important roles in the ozonation catalytic process for the removal of DOM.

The Effect of Particle Sizes on the Concentration Dependence of the Surface Tension of Aqueous Suspensions of Bentonite

2021 ◽  
Vol 1022 ◽  
pp. 212-217
Author(s):  
R.Kh. Dadashev ◽  
R.S. Dzhambulatov ◽  
Z.S. Khasbulatova ◽  
Kh.S. Talkhigova
Keyword(s):  
Surface Tension ◽  
Solid Phase ◽  
Aqueous Suspension ◽  
Average Particle Size ◽  
Average Particle ◽  
Particle Sizes ◽  
Coarse Particles ◽  
Factors Affecting ◽  
Aqueous Suspensions ◽  
Surface Tension Isotherms

The paper presents experimental results on the dependence of surface tension on the concentration of a suspension of bentonite (0 - 10% by weight). The isotherms σ of aqueous suspensions of bentonite are characterized by local minima in the concentration range of 3-4 mass% of the solid phase. It has been established that a decrease in the average particle size leads to the disappearance of the extremum on the surface tension isotherms. The data obtained led to the conclusion that the most important factors affecting the nature of the isotherms of the surface tension of bentonite suspensions are the degree of dispersion and the presence in the aqueous suspension of bentonite, both colloidal and coarse particles.

Surface energy of cellulosic materials: The effect of particle morphology, particle size, and hydroxyl number

TAPPI Journal ◽  
2015 ◽  
Vol 14 (9) ◽  
pp. 565-576 ◽  
Author(s):  
YUCHENG PENG ◽  
DOUGLAS J. GARDNER
Keyword(s):  
Particle Size ◽  
Surface Energy ◽  
Particle Morphology ◽  
Nanofibrillated Cellulose ◽  
Particle Sizes ◽  
Hydroxyl Number ◽  
Small Individual ◽  
Dispersion Component ◽  
Commercial Applications ◽  
Lower Temperature

Understanding the surface properties of cellulose materials is important for proper commercial applications. The effect of particle size, particle morphology, and hydroxyl number on the surface energy of three microcrystalline cellulose (MCC) preparations and one nanofibrillated cellulose (NFC) preparation were investigated using inverse gas chromatography at column temperatures ranging from 30ºC to 60ºC. The mean particle sizes for the three MCC samples and the NFC sample were 120.1, 62.3, 13.9, and 9.3 μm. The corresponding dispersion components of surface energy at 30°C were 55.7 ± 0.1, 59.7 ± 1.3, 71.7 ± 1.0, and 57.4 ± 0.3 mJ/m2. MCC samples are agglomerates of small individual cellulose particles. The different particle sizes and morphologies of the three MCC samples resulted in various hydroxyl numbers, which in turn affected their dispersion component of surface energy. Cellulose samples exhibiting a higher hydroxyl number have a higher dispersion component of surface energy. The dispersion component of surface energy of all the cellulose samples decreased linearly with increasing temperature. MCC samples with larger agglomerates had a lower temperature coefficient of dispersion component of surface energy.

Moxifloxacin Hydrochloride-Loaded Eudragit® RL 100 and Kollidon® SR Based Nanoparticles: Formulation, In vitro Characterization and Cytotoxicity.

2020 ◽  
Vol 23 ◽  
Author(s):  
Gülsel Yurtdaş Kırımlıoğlu ◽  
Sinan Özer ◽  
Gülay Büyükköroğlu ◽  
Yasemin Yazan
Keyword(s):  
Particle Size ◽  
Zeta Potential ◽  
Spray Drying ◽  
Prolonged Release ◽  
Ocular Delivery ◽  
Corneal Permeability ◽  
Release Pattern ◽  
In Vitro Characterization ◽  
Ocular Bioavailability

Background: Considering the low ocular bioavailability of conventional formulations used for ocular bacterial infection treatment, there’s a need for designing efficient novel drug delivery systems that may enhance of precorneal retention time and corneal permeability. Aim and Objective: The current research focuses on developing nanosized and non-toxic Eudragit® RL 100 and Kollidon® SR nanoparticles loaded with moxifloxacin hydrochloride (MOX) for its prolonged release to be promising for effective ocular delivery. Methods: In this study, MOX was incorporation was carried out by spray drying method aiming ocular delivery. In vitro characteristics were evaluated in detail with different methods. Results: MOX was successfully incorporated into Eudragit® RL 100 and Kollidon® SR polymeric nanoparticles by spray-drying process. Particle size, zeta potential, entrapment efficiency, particle morphology, thermal, FTIR, XRD and NMR analyses and MOX quantification using HPLC method were carried out to evaluate the nanoparticles prepared. MOX loaded nanoparticles demonstrated nanosized and spherical shape while in vitro release studies demonstrated modified release pattern which followed Korsmeyer-Peppas kinetic model. Following successful incorporation of MOX into the nanoparticles, the formulation (MOX: Eudragit® RL 100, 1:5) (ERL-MOX 2) was selected for further studies by the reason of its better characteristics like cationic zeta potential, smaller particle size, narrow size distribution and more uniform prolonged release pattern. Moreover, ERL-MOX 2 formulation remained stable for 3 months and demonstrated higher cell viability values for MOX. Conclusion: In vitro characterization analyses showed that non-toxic, nano-sized and cationic ERLMOX 2 formulation has the potential of enhancing ocular bioavailability.

scholarly journals Effect of particle size on phytochemical composition and antioxidant properties of Sargassum cristaefolium ethanol extract

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
E. S. Prasedya ◽  
A. Frediansyah ◽  
N. W. R. Martyasari ◽  
B. K. Ilhami ◽  
A. S. Abidin ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
Particle Size ◽  
Antioxidant Activities ◽  
Antioxidant Properties ◽  
Ethanol Extract ◽  
Total Phenolic ◽  
Particle Sizes ◽  
Epicatechin Gallate ◽  
Particle Size Reduction ◽  
Phytochemical Composition

AbstractSample particle size is an important parameter in the solid–liquid extraction system of natural products for obtaining their bioactive compounds. This study evaluates the effect of sample particle size on the phytochemical composition and antioxidant activity of brown macroalgae Sargassum cristaefolium. The crude ethanol extract was extracted from dried powders of S.cristeafolium with various particle sizes (> 4000 µm, > 250 µm, > 125 µm, > 45 µm, and < 45 µm). The ethanolic extracts of S.cristaefolium were analysed for Total Phenolic Content (TPC), Total Flavonoid Content (TFC), phenolic compound concentration and antioxidant activities. The extract yield and phytochemical composition were more abundant in smaller particle sizes. Furthermore, the TPC (14.19 ± 2.08 mg GAE/g extract to 43.27 ± 2.56 mg GAE/g extract) and TFC (9.6 ± 1.8 mg QE/g extract to 70.27 ± 3.59 mg QE/g extract) values also significantly increased as particle sizes decreased. In addition, phenolic compounds epicatechin (EC), epicatechin gallate (ECG), epigallocatechin (EGC), and Epigallocatechin gallate (EGCG) concentration were frequently increased in samples of smaller particle sizes based on two-way ANOVA and Tukey’s multiple comparison analysis. These results correlate with the significantly stronger antioxidant activity in samples with smaller particle sizes. The smallest particle size (< 45 µm) demonstrated the strongest antioxidant activity based on DPPH, ABTS, hydroxyl assay and FRAP. In addition, ramp function graph evaluates the desired particle size for maximum phytochemical composition and antioxidant activity is 44 µm. In conclusion, current results show the importance of particle size reduction of macroalgae samples to increase the effectivity of its biological activity.

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