scholarly journals Removal of Phosphate from Aqueous Solutions Using Chemically Synthesized Vaterite Polymorph of Porous Calcium Carbonate Nanoparticles under Optimized Conditions

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
D. D. T. T. Darshana Senarathna ◽  
K. H. D. Namal Abeysooriya ◽  
S. P. Dunuweera ◽  
B. P. K. Ekanayake ◽  
W. M. H. K. Wijenayake ◽  
...  
Keyword(s):  
Particle Size ◽  
Calcium Carbonate ◽  
Natural Water ◽  
Phosphate Removal ◽  
Water Bodies ◽  
Phosphate Solution ◽  
Average Particle ◽  
Order Kinetic ◽  
X Ray ◽  
Porous Calcium Carbonate

Eutrophication is one of the most adverse impacts of nutrient contamination of water bodies where the phosphate is considered to be the primary limiting factor. The vaterite polymorph of porous calcium carbonate nanoparticles (VPCCNPs) were synthesized and used to remove orthophosphate ions in water. In this study, the VPCCNPs were synthesized chemically, using calcium acetate and sodium bicarbonate in a water-ethylene glycol media, at a temperature of 100°C, in a reaction time of 24 hours. Synthesized nanoparticles were characterized by X-ray diffractometry to confirm that the crystalline phase of calcium carbonate formed is spherical vaterite polymorph. Scanning electron microscopy coupled with energy dispersive X-ray analysis further confirms the spherical shape of the vaterite nanoparticles and the presence of only calcium, carbon, and oxygen thus showing high purity of the synthesized calcium carbonate nanoparticles. The dynamic laser light scattering-based particle size analysis (DLS) shows the average particle size to be 25.5 nm. The Fourier transform infrared spectroscopy was used to find functional groups before and after the adsorption of phosphate by vaterite nanoparticles. The phosphate removal efficiency of synthesized nanoparticles was tested with different concentrations of phosphate solutions (2–80 mg/L), pH levels (5–12), adsorbent dosages (0.025–0.250 g), and contact times (5–120 min). Ion chromatography was used to analyse the phosphate concentrations in water samples. The maximum phosphate removal percentage of 100% was obtained with 50 mL of 2 mg/L phosphate solution and 0.15 g of the synthesized nanoparticle. Adsorption data were well fitted with the Langmuir adsorption isotherm model and the pseudo-second-order kinetic model with R2 of 0.99 and 0.98 (rate constant -0.083 g g-1 min-1), respectively. The presence of F−, NO3−, and SO42− has no effect on phosphate adsorption since 100% phosphate removal is obtained in the presence of these ions. Furthermore, the particle shows a 100% removal of orthophosphate ions available in eutrophic water regardless of the presence of many other ions in natural water bodies. The study presents a viable option for removing excess phosphate in natural water to desirable levels as a means for controlling eutrophication.

Morphology-Controlled CaCO3 Nanostructures by Modified Co-Precipitation in Pulsed Mode

2015 ◽  
Vol 752-753 ◽  
pp. 148-153
Author(s):  
M.M. Nassar ◽  
Taha Ebrahiem Farrag ◽  
M.S. Mahmoud ◽  
Sayed Abdelmonem
Keyword(s):  
Particle Size ◽  
Calcium Carbonate ◽  
Rotation Speed ◽  
Average Particle Size ◽  
Calcium Nitrate ◽  
Precipitation Method ◽  
Average Particle ◽  
X Ray ◽  
Co Precipitation ◽  
Pulsed Mixing

Calcium carbonate nanoparticles and nanorods were synthesized by precipitation from saturated sodium carbonate and calcium nitrate aqueous solutions through co precipitation method. A new rout of synthesis was done by both using pulsed mixing method and controlling the addition of calcium nitrate. The effect of the agitation speed, and the temperature on particle size and morphology were investigated. Particles were characterized using X-ray Microanalysis, X-ray analysis (XRD) and scanning electron microscopy (SEM). The results indicated that increasing the mixer rotation speed from 3425 to 15900 (rpm) decreases the average particle size to 64±7 nm. A rapid nucleation then aggregation induced by excessive shear force phenomena could explain this observation. Moreover, by increasing the reaction temperature, the products were converted from nanoparticle to nanorods. The maximum attainable aspect ratio was 6.23 at temperature of 75°C and rotation speed of 3425. Generally, temperature raise promoted a significant homoepitaxial growth in one direction toward the formation of calcite nanorods. Overall, this study can open new avenues to control the morphology of the calcium carbonate nanostructures.

Synthesis and Characterization of Calcium Carbonate Nanoparticles via Bacterial Mineralization in Steel Slag Comprising Cementitious Materials

2020 ◽  
Vol 12 (5) ◽  
pp. 760-768 ◽  
Author(s):  
Haihe Yi ◽  
Chun-Xiang Qian
Keyword(s):  
Electron Microscopy ◽  
Particle Size ◽  
Compressive Strength ◽  
Calcium Carbonate ◽  
Building Materials ◽  
Average Particle Size ◽  
Steel Slag ◽  
Average Particle ◽  
Calcium Carbonate Precipitate ◽  
X Ray

Bacteria-induced mineralization is a new technique to produce calcium carbonate in steel slag for the preparation of building materials. Calcium carbonate nanoparticles were precipitated as a result of the enzymatic activity of Bacillus mucilaginous subtilis in steel slag. The crystal structure and morphology of the calcium carbonate precipitate were studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), atomic force microscopy (AFM), while thermal properties were studied by thermogravimetric-differential scanning calorimetry (TG-DSC) analysis. The experimental results showed that the microstructure of calcium carbonate precipitate induced by the reproductive enzymes of Bacillus mucilaginous differs from the chemical precipitation in simulated pore solution of steel slag. Powder XRD patterns confirmed the formation of Bacillus mucilaginous subtilis-induced calcium carbonate with an average particle size of 42.1 nm, while the average particle size of the chemically synthesized calcium carbonate was 59.3 nm. Compared with the chemical synthesis, we found that the decomposition temperature of calcite by bacterial precipitation was higher than that for the chemically-precipitated calcite. The compressive strength improved with the amount of bacterial content. Bacterial mineralization could accelerate the rate of carbon sequestration in the mineralization process. The content of calcium carbonate in microbial mineralized steel slag increased obviously. The compressive strength of steel slag mortar with 1.5% bacterial reached up to 51.5 MPa, the compressive strength increased over 50% compared with the carbonized steel slag mortar. The micron-size calcite by bacterial mineralization resulted in a more compact structure. Our study suggests that microbial mineralization technology is a good method to utilize steel slag for building materials.

scholarly journals Thermal, Structural, and Physical Properties of Freeze Dried Tropical Fruit Powder

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
K. A. Athmaselvi ◽  
C. Kumar ◽  
M. Balasubramanian ◽  
Ishita Roy
Keyword(s):  
Particle Size ◽  
Physical Properties ◽  
Average Particle Size ◽  
Average Particle ◽  
X Ray Diffraction ◽  
Tropical Fruit ◽  
X Ray ◽  
Freeze Dried ◽  
Fruit Powder ◽  
Lcr Meter

This study evaluates the physical properties of freeze dried tropical (guava, sapota, and papaya) fruit powders. Thermal stability and weight loss were evaluated using TGA-DSC and IR, which showed pectin as the main solid constituent. LCR meter measured electrical conductivity, dielectric constant, and dielectric loss factor. Functional groups assessed by FTIR showed presence of chlorides, and O–H and N–H bonds in guava, chloride and C–H bond in papaya, and chlorides, and C=O and C–H bonds in sapota. Particle size and type of starch were evaluated by X-ray diffraction and microstructure through scanning electronic microscopy. A semicrystalline profile and average particle size of the fruit powders were evidenced by X-ray diffraction and lamellar/spherical morphologies by SEM. Presence of A-type starch was observed in all three fruits. Dependence of electric and dielectric properties on frequency and temperature was observed.

Effects of Rotation Speeds and Media Density on Ground Calcium Carbonate during Ultrafine Grinding Process in Planetary Mill

2014 ◽  
Vol 997 ◽  
pp. 542-545
Author(s):  
Yan Ru Chen ◽  
Yi Chen Lu ◽  
Xiao Min Lian ◽  
Chao Yang Li ◽  
Shui Lin Zheng
Keyword(s):  
Particle Size ◽  
Calcium Carbonate ◽  
Rotational Speed ◽  
Planetary Mill ◽  
X Ray Diffraction ◽  
X Ray ◽  
Dry Grinding ◽  
Ultrafine Grinding ◽  
Effects Of Rotation ◽  
Ground Calcium Carbonate

Superfine ground calcium carbonate (GCC) produced by carbonate minerals is a widely used inorganic powder material. In order to get a finer GCC powder with narrow distribution span, the effect of rotational speed and media density on ground GCC were studied by dry grinding GCC in a planetary ball mill under different rotational speed and various media density. The grinding limit-particle size and distribution of grinding calcium carbonate were measured by centrifugal sedimentation granulometer. The structure of GCC was measured by X-ray diffraction. The result shows that low rotational speed and high-density media is conducive to get a product with smaller particle size and narrow size distribution; crystal plane (012) and (122) are more stable than (018) and (116).

scholarly journals Preparation, Characterization and Performance Properties of Polydodecylmethylsilsesquioxane Nanoparticles

Coatings ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1045
Author(s):  
Fuquan Deng ◽  
Hua Jin ◽  
Wei Xu
Keyword(s):  
Thermal Stability ◽  
Particle Size ◽  
Electron Microscope ◽  
Contact Angles ◽  
Process Conditions ◽  
Average Particle ◽  
Gravimetric Analysis ◽  
Laser Scattering ◽  
Excellent Thermal Stability ◽  
X Ray

A series of polydodecylmethylsilsesquioxane (PDMSQ) nanocomposite latexes were prepared via emulsion polymerization of methyltriethoxysilane (MTES) and dodecyltrimethoxysilane (DTMS) and sodium hydroxide as the catalyst, and sodium dodecyl benzene sulfonate/Tween 80 as the mixed emulsifiers. Effects of the emulsifier doses, the reaction temperature, the catalyst concentration and the oil/water ratio on the particle size and distribution of the PDMSQ nanoparticles were discussed. Particle size and micromorphology, structure, thermal stability, crystallinity and hydrophobicity of PDMSQ nanoparticles (PDMSQ NPs) were investigated by dynamic laser scattering (DLS), Fourier transform infrared spectroscopy (FTIR), silicon-nuclear magnetic resonance (28Si-NMR), X-ray photoelectron spectroscope (XPS), scanning electron microscope (SEM), transmission electron microscope (TEM), atomic force microscope (AFM), thermo gravimetric analysis (TGA), X-ray diffraction (XRD) and contact angle tester. Results showed that a series of PDMSQ NPs could be obtained with an average particle size of less than 80 nm and narrow distribution as well as spherical structure under the optimal process conditions. PDMSQ NPs exhibited excellent thermal stability and were mainly amorphous but also contained some crystal structures. Importantly, the static water contact angles (WCAs) on its latex films were larger than 150° and the WCAs hysteresis were less than 10°, thus those PDMSQ nanocomposite latexes show potential in the field of superhydrophobic coatings.

Rapid defluoridation of drinking water by calcium carbonate nanoadsorbent: characterization, adsorption studies and application to real samples’ treatment

2019 ◽  
Vol 20 (2) ◽  
pp. 667-678
Author(s):  
Masooma Zawar ◽  
Rabia Nazir ◽  
Almas Hamid ◽  
Eder C. Lima ◽  
Muhammad Raza Shah
Keyword(s):  
Drinking Water ◽  
Calcium Carbonate ◽  
Average Particle Size ◽  
Particle Diffusion ◽  
Average Particle ◽  
Batch Mode ◽  
X Ray ◽  
Global Issue ◽  
Effective Removal ◽  
Intra Particle Diffusion

Abstract Groundwater contamination of fluoride is a serious global issue leading to its excessive intake and subsequently numerous adverse health issues. This research was designed to assess the efficiency of nanoadsorbent for removal of fluoride levels from water. For this purpose, calcium carbonate nanoparticles (average particle size 14.6 nm) were prepared and later applied for effective removal of fluoride from simulated as well as real drinking water (DW) samples collected from different areas of Lahore, Pakistan. The particles were characterized by powder X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy/energy-dispersive X-ray spectroscopy, and atomic force microscopy. Physico-chemical parameters were studied in batch mode which revealed high adsorption capacity (i.e. 754.36 mg g−1) at room temperature and neutral pH within 10 min. The kinetic isotherms (general, pseudo-first, and pseudo-second order), diffusion studies (intra-particle diffusion and particle diffusion models), and adsorption models (Langmuir, Freundlich, Liu, and Redlich–Peterson) were also applied to evaluate the suitability of adsorption process. The applicability of nanoadsorbent to fluoride-contaminated real DW samples led to 98–100% efficacy of defluoridation.

scholarly journals Preparation of ultrafine iron phosphate micro-powder from phosphate slag

2018 ◽  
Vol 238 ◽  
pp. 02002
Author(s):  
Fangjing Sun ◽  
Yi Zhang ◽  
Jiawei Zhang ◽  
Xixi Yan ◽  
Xiaoyu Liu ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Particle Size ◽  
Electron Microscope ◽  
Average Particle Size ◽  
Iron Phosphate ◽  
Average Particle ◽  
X Ray ◽  
Particle Size Analyzer ◽  
Phosphate Slag ◽  
Scanning Electron

In this experiment, ultrafine iron phosphate micro-powder was prepared by hydrothermal method which used phosphate slag as an iron source. The effects of reaction temperature, surfactants type and amount on its particle size were explored. The samples were characterized by using Malvern Laser Particle Size Analyzer (MS2000), X-Ray Diffractometer (XRD), Scanning Electron Microscope (SEM) and Energy Dispersive X-Ray Spectroscopy (EDX).The results showed that at 160 °C, 1 wt%CTAB, monoclinic iron phosphate micro-powder was obtained with an average particle size about 0.4 μm which also has a good dispersion in aqueous solution.

Fabrication and Characterization of Nanospinel ZnCr2O4 Using Thermal Treatement Method

2015 ◽  
Vol 1107 ◽  
pp. 301-307 ◽  
Author(s):  
Salahudeen A. Gene ◽  
Elias B. Saion ◽  
Abdul Halim Shaari ◽  
Mazliana A. Kamarudeen ◽  
Naif Mohammed Al-Hada
Keyword(s):  
Particle Size ◽  
Calcination Temperature ◽  
Average Particle Size ◽  
Treatment Method ◽  
Esr Spectra ◽  
Resonance Spectroscopy ◽  
Average Particle ◽  
Face Centered Cubic ◽  
X Ray ◽  
Xrd Patterns

The fabrication of nanospinel zinc chromite (ZnCr2O4) crystals by the means of thermal treatment method from an aqueous solution containing metal nitrates, polyvinyl pyrrolidone (PVP), and deionized water was described in this study. The samples were calcined at various temperatures ranging from 773 to 973 K for the decomposition of the organic compounds and crystallization of the nanocrystals. PVP was used as capping agent to control the agglomeration of the particles. The characterization studies of the fabricated samples were carried out by X-ray diffraction spectroscopy (XRD), transmission electron microscopy (TEM), energy dispersed X-ray spectroscopy (EDX) and electron spin resonance spectroscopy (ESR). The corresponding peaks of Zn, Cr and O were observed in the EDX spectrum of the sample which confirms the formation of ZnCr2O4. The XRD patterns also confirmed the formation of the single faced nanocrystallines of spinel ZnCr2O4 with a face-centered cubic structure. The average particle size of the synthesized crystals was also determined from the XRD patterns using the Scherers formula which shows that the crystallite sizes increases with increase in calcination temperature and was in good agreement with the TEM images which shows cubical ZnCr2O4 nanocrystals with uniform morphology and particle size distributions. The ESR spectra confirmed the existence of unpaired electron in the fabricated samples and the increase in g-factor and decreases in resonant magnetic field (Hr) were observed as the calcination temperature increases.

Graphitization and particle size analysis of pyrolyzed cobalt phthalocyanine/carbon catalysts for oxygen reduction in fuel cells

1994 ◽  
Vol 9 (12) ◽  
pp. 3203-3209 ◽  
Author(s):  
L. Dignard-Bailey ◽  
M.L. Trudeau ◽  
A. Joly ◽  
R. Schulz ◽  
G. Lalande ◽  
...  
Keyword(s):  
Particle Size ◽  
Fuel Cells ◽  
Size Distribution ◽  
Amorphous Carbon ◽  
Pyrolysis Temperature ◽  
Carbon Support ◽  
Solid Polymer ◽  
Average Particle ◽  
Cobalt Phthalocyanine ◽  
X Ray

Cobalt phthalocyanine (CoPc) adsorbed on a carbon black support (Vulcan XC-72) and pyrolyzed at various temperatures is a potential catalyst for the reduction of oxygen in solid polymer electrolyte fuel cells. This paper reports the results of the microstructural characterization of β-Co particles that are formed after pyrolysis at temperatures of 700, 900, and 1050 °C. Transmission electron microscopy (TEM) indicated that (i) for a pyrolysis temperature of 700 °C, the size distribution of the Co particles is bell-shaped with an average value of 4 nm and mean deviation of 1 nm; (ii) for a pyrolysis temperature of 900 °C, the Co particle size distribution skews toward larger particle sizes. The most probable particle size is about 6 nm, and the average particle size is 13 nm. By comparison with the TEM results, the particle size estimated from a spectroscopic method like x-ray absorption is underestimated, while from x-ray diffraction is overestimated. The TEM images show that Co particles act as heterogeneous nucleation sites for the graphitization of amorphous carbon. It is shown that (i), at least for pyrolysis temperature of 900 °C and above, most of the β-Co particles are surrounded by a shell of graphitic carbon layers that appears to protect the particles from corrosion in acidic media; (ii) for pyrolysis temperature of 1050 °C, graphite strings also appear throughout the amorphous carbon support in areas where Co particles are not detected. This behavior was not observed after pyrolysis of as-received carbon support at 1050 °C. These results allow for a better understanding of the behavior of the pyrolyzed catalysts immersed in an acidic solution or in a solid polymer fuel cell.

scholarly journals Studies on Black Iron Oxide Pigment. Part-II: Effect of Preparation Parameter on Particle Size and Microstructure of Ferrosoferric Oxide

1970 ◽  
Vol 44 (1) ◽  
pp. 31-40 ◽  
Author(s):  
AJM Tahuran Neger ◽  
Aftabuddin Ahmed ◽  
Sufia Parvin ◽  
AM Shafiqul Alam
Keyword(s):  
Particle Size ◽  
Iron Oxide ◽  
Standard Sample ◽  
Average Particle ◽  
X Ray Diffraction ◽  
Sample Number ◽  
X Ray ◽  
Iron Oxide Pigment ◽  
Oxide Pigment ◽  
Preparation Parameter

This paper deals with the effect of preparation parameter on particle size and microstructure of the prepared ferrosoferric oxide. 10 prepared samples (from 23 samples) and one standard sample (Bayferrox 318 standard 88) collected from BAYER, Germany was selected for this study. X-ray diffraction, petrographic microscopy, scanning electron microscope and particle size analyzer were used to characterize the phase present, particle size and shape of the particle. It is observed from X-ray diffraction that all these samples mainly contain Fe3O4 phase. The shape of the particle is found to be round and agglomerated. The average particle diameter of highest portion of pigment in the peak region is ranged from 12.25μ to 17.32μ, which is very similar to the standard sample (17.32μ). Sample number 9, which was prepared with ferrous sulphate, hydrochloric acid, sodium nitrate and ammonium hydroxide at a molar ratio 1:1.74:0.16:4.07 and standard sample contain narrow high peak in their particle size distribution curve. Another observation is that, experimental parameter, though have some effect on particle size but have no effect on microstructure. Key words: Black iron oxide, Pigment, Particle size, Microstructure, Ferrosoferric oxide.     doi: 10.3329/bjsir.v44i1.2711 Bangladesh J. Sci. Ind. Res. 44(1), 31-40, 2009

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