scholarly journals Photo-Luminescence study of Ba3Gd1-x(BO3)3 : X Ce3+ phosphor

YMER Digital ◽  
2021 ◽  
Vol 20 (11) ◽  
pp. 75-82
Author(s):  
V. R Panse ◽  
Keyword(s):  
Blue Light ◽  
Uv Light ◽  
Average Particle Size ◽  
Photo Luminescence ◽  
Average Particle ◽  
Solution Combustion ◽  
Excitation Peak ◽  
Broad Absorption Band ◽  
Sem Image ◽  
Light Excitation

The polycrystalline powder sample of Ce3+ activated barium gadolinium borate phosphors Ba3Gd1-x(BO3)3 : X Ce3+(0.01 ≤ X ≤ 0.06 ) are prepared by solution combustion. Formation of phosphor in desired crystalline phase confirmed by powder XRD characterization & FTIR. A SEM image shows the irregular grains with average particle size 2.5μm. The excitation spectrum consists of a single broad absorption band from 200 to 400 nm with the prominent excitation peak at 343 nm [2F5/2 to 5D1 of Ce3+ ions]. Strongest emission peak of 488nm [5D1→ 2F5/2] and weak of 501nm [5D1→ 2F7/2] wavelength which is of blue light is observed at 343nm UV light excitation. Ba3Gd1-x(BO3)3 : X Ce3+ phosphor emits blue light under UV excitation. Maximum PL emission takes place at 3 mole percentage of Ce3+. Concentration quenching for Ce3+ ions is studied. Hence Ba3Gd1-x(BO3)3 : X Ce3+ is new UV excited blue emitting phosphor useful for UV/Blue chip WLEDs.

Photocatalytically Active Cotton Fabrics Produced with Anatase Synthesized Using a Low-Temperature Sol-Gel Process

2018 ◽  
Vol 762 ◽  
pp. 408-412
Author(s):  
Raivis Eglītis ◽  
Gundars Mežinskis
Keyword(s):  
Photocatalytic Activity ◽  
Uv Light ◽  
Sol Gel ◽  
Average Particle Size ◽  
Synthesis Method ◽  
Average Particle ◽  
X Ray Diffraction ◽  
Sol Gel Process ◽  
Anatase Nanoparticles ◽  
Pre Treatment

In this work two different hydrosols were used to impregnate a commercially available cotton fabric with anatase nanoparticles to give it photocatalytic activity. To increase the activity, different pre-treatment methods were applied. The nanoparticle size was determined using dynamic light scattering and x-ray diffraction and the fabrics were examined using scanning electron microscopy. Photocatalytic activity was measured using the degradation of methyl-orange while irradiating the samples with UV light. The synthesis method allowed to produce anatase with an average particle size of 32 to 37 nm depending on the synthesis method used.

Effects of Dissolving Agents on Particle Size Reduction of Titanium Dioxide Synthesized by Solution Combustion Technique

2016 ◽  
Vol 690 ◽  
pp. 236-239
Author(s):  
Oratai Jongprateep ◽  
Rachata Puranasamriddhi
Keyword(s):  
Particle Size ◽  
Titanium Dioxide ◽  
Sulfuric Acid ◽  
Nitric Acid ◽  
Average Particle Size ◽  
Average Particle ◽  
Particle Sizes ◽  
Solution Combustion ◽  
Initial Reagent ◽  
Combustion Technique

High photocatalytic activity of nanoparticulate titanium dioxide has attracted worldwide attention. Synthesis techniques of the nanoparticles, however, often require high energy supply or costly initial reagents. Solution combustion technique is an energy-effective technique capable of synthesizing nanosized titanium powders. This research aimed at utilizing a less expensive initial reagent in synthesis of nanoparticulate titanium dioxide by the solution combustion technique. The research also examined effects of dissolving agents on chemical composition and particle sizes of the synthesized powders. A low-cost initial reagent, titanium dioxide with average particle size of 154 nanometers, was dissolved in sulfuric acid or dispersed in nitric acid prior to the combustion. Experimental results revealed that the pure anatase phase titanium dioxide was successfully obtained in powders prepared from both sulfuric acid and nitric acid. The average particle size of the powder prepared from sulfuric acid was 77 nanometers, while that of the powder prepared from nitric acid was 117 nanometers. The difference in particle sizes was attributed to solubility of the initial reagent in the acid. Complete solution of initial reagent in sulfuric acid was the main factor attributed to finer particle size.

Green Route Synthesis of MgO Nanoparticles Using Murraya Koenigii Leaf Extract: An Efficient Photo Catalyst for Malachite Green

2018 ◽  
Vol 24 (8) ◽  
pp. 5801-5804
Author(s):  
K. N. Shravana Kumara ◽  
H. P Nagaswarupa ◽  
K. R. Vishnu Mahesh ◽  
M Mylarappa ◽  
S. C Prashantha ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Average Particle Size ◽  
Diffraction Method ◽  
Combustion Method ◽  
Average Particle ◽  
Murraya Koenigii ◽  
Solution Combustion ◽  
Efficient Catalyst ◽  
Mgo Nanoparticles ◽  
Average Size

The objective of this work is mainly focused on green synthesis and characterization of MgO nanoparticles by low temperature solution combustion method. The Murraya koenigii (Curry leaves) was used as a reducing agent (as fuel). The average size and crystallinity of nano MgO particles are analyzed by X-ray Diffraction method (PXRD) and accurate morphology was studied using Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM). From XRD, shows that average particle size of MgO is 40 nm. The synthesized MgO particles used as an efficient catalyst shows rapid color removal and reduction in the concentration of dyes.

DEVELOPMENT OF A NON-CONTINUOUS MICRO-FLOW OPTO-WETTING DROPLET MANIPULATION TECHNOLOGY

2005 ◽  
Vol 17 (06) ◽  
pp. 293-299 ◽  
Author(s):  
MING-YIH LEE ◽  
HUNG-CHIA LIN ◽  
HUNG-WEI CHIANG ◽  
WEI-XUN LEE ◽  
XIAN-DONG HUANG
Keyword(s):  
Surface Tension ◽  
Uv Light ◽  
Liquid Droplet ◽  
Average Particle Size ◽  
Base Material ◽  
Material Surface ◽  
Average Particle ◽  
Hydrophilic Property ◽  
Manipulation System ◽  
Droplet Manipulation

The aim of this study is to develop a non-continuous droplet manipulation technology in contrast to conventional continuous flow micro-fluidic systems. The droplets were manipulated based on the proposed opto-wetting effect. In addition, an experimental ultraviolet (UV) light actuated droplet manipulation system was developed for verifying the opto-wetting droplet manipulation. The proposed opto-wetting effect was achieved by utilizing ultraviolet to activate oxidation-reduction mechanism of nano-TiO2 photo catalyst coated base material. The water-affinity of the base material will changed due to the decreased free-energy of the material surface. Therefore, the contact angle between the liquid droplet and base material will also be changed which facilitates droplet manipulability. The main components of the proposed ultraviolet (UV) light actuated droplet manipulation system include ultraviolet masking device, moving platform and main frame structure. System software and user interface were designed by using Microsoft Visual Basic 6.0 toolkit. Upon completion of the proposed system, experiments were carried out to verify system functionalities. Follow by the controlled variable optimization using Taguchi method and liquid droplet manipulation experiments. The experiment results indicate that by exposure to 6.8mW UV light, the surface tension and hydrophilic property of nano-TiO2 (anatase type, 3.5% concentration, PH 1.5, and with average particle size of 69 nm) coated base material will changed. The change of surface tension and hydrophilic property were critical for droplet manipulation. The moving speed of the liquid droplet was measured as 3.33mm/sec. The results suggest that the opto-wetting system may be effective to overcome the shortcoming of traditional opto-electrowetting technique. The proposed opto-wetting droplet manipulation system could potentially applied for manipulating biomedical or pathological test specimens in the future.

scholarly journals Volatile Organic Compound (VOC) Removal via Photocatalytic Oxidation Using TiO2 Coated Nanofilms

2017 ◽  
Vol 15 (7) ◽  
pp. 491-501
Author(s):  
Sunun KHAMI ◽  
Wipawee KHAMWICHIT ◽  
Ratthapol RANGKUPAN ◽  
Kowit SUWANNAHONG
Keyword(s):  
Bacterial Cellulose ◽  
Photocatalytic Oxidation ◽  
Uv Light ◽  
Average Particle Size ◽  
Average Particle ◽  
Experimental Conditions ◽  
Electrospinning Technique ◽  
Photocatalytic Reactor ◽  
Toluene Concentration ◽  
Spinning Process

In this paper, toluene removal via photocatalytic oxidation using TiO2 dip coated nanofilms is presented. Nanofilms were synthesized from bacterial cellulose using the electrospinning technique. The physical properties of the nanofilms were analyzed by scanning electron microscopy (SEM). The ratio of bacterial cellulose/nylon used in the spinning process was 0.165:1. The results from SEM showed that the structure of the TiO2 composite nanofilms was rutile crystalline with an average particle size of 20 nm, and synthesized nanofilms had an average size of 20 - 30 nm. The band gap energies of TiO2-dip coated nanofilms ranged from 3.18 - 3.21 eV. SEM results of TiO2 coated nanofilms suggested that the TiO2 was rather uniformly distributed onto the surface of the nanofilms. The actual amount of TiO2 coated on the nanofilms was estimated using thermogravimetric analysis (TGA) for 1x1 cm2 surface area. It was found that 0.1852, 0.2897 and 0.7275 mg of TiO2 were coated on the surface of the nanofilms for 1, 2.5 and 5 % (weight) TiO2 dosage, respectively. The photocatalytic activity of the nanofilms was tested for the removal of gaseous toluene in a photocatalytic reactor. Experimental conditions were set as follows: UV light intensity of approximately 2.7 mW.cm-2, flow rate of 0.2 L.min-1, and an initial toluene concentration of about 200±20 ppm, and a retention time at 200 min. The degradation rate of toluene increased with increasing dosage of TiO2 from 1, 2.5 and 5 %. The nanofilms at a 5 % dosage yielded the highest removal efficiency of 92.71 %, followed by the 2.5 and 1 % dosage, respectively.

scholarly journals Photocatalytic Degradation of Rhodamine B and Malachite Green by Cobalt Sulfide Nanoparticles

2022 ◽  
Vol 34 (2) ◽  
pp. 331-341
Author(s):  
Gunjan Chauhan ◽  
Manjeet Sharma
Keyword(s):  
Malachite Green ◽  
Rhodamine B ◽  
Degradation Rate ◽  
Uv Light ◽  
Average Particle Size ◽  
Single Step ◽  
Cobalt Sulfide ◽  
Cds Nanoparticles ◽  
Average Particle ◽  
Cobalt Sulphide

Present study reports the simple and cost effective thermolytic method for the synthesis of cobalt sulphide nanoparticles (CoS NPs). The PXRD spectrum of cobalt sulphide (CdS) nanoparticles exhibited four peaks indexed to (100), (101), (102) and (110) crystal planes. The average particle size observed from DLS and PXRD was in the range 4.81-12.20 nm. A blue shift in band gap was observed from UV-visible spectra. The FESEM and TEM studies revealed that cobalt sulfide nanoparticles are of cubic and rectangle shapes. FTIR spectra of hexadecylamine (HDA) capped CoS NPs exhibited ν(N-H) absorption around 3350-3240 cm–1. The stretching frequency due to ν(Co-S) appeared in the region 334-332 cm–1. Proton NMR (1H) spectra of CoS NPs showed signals at nearly same positions as in case of capping agent, suggesting its capping nature. ESI-MS analyses of cobalt sulphide nanoparticles displayed peak at m/z = 124.93 corresponding to the [CoS2]+ ion. Thermogravimetric curves showed single step decomposition corresponding to 84.28% weight loss and 15.72% as final residue due to cobalt oxide. The degradation rate of rhodamine B and malachite green dyes after irradiating with sunlight showed 92-94% degradation while irradiated with UV-light of 4.8 eV show much slower degradation rate.

scholarly journals Methylene Blue Dye Photocatalytic Degradation over Synthesised Fe3O4/AC/TiO2 Nano-Catalyst: Degradation and Reusability Studies

Nanomaterials ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 2360
Author(s):  
Seyedehmaryam Moosavi ◽  
Rita Yi Man Li ◽  
Chin Wei Lai ◽  
Yusliza Yusof ◽  
Sinyee Gan ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Uv Light ◽  
Agricultural Waste ◽  
Average Particle Size ◽  
Blue Dye ◽  
Average Particle ◽  
Step Procedure ◽  
Nano Catalyst ◽  
One Step ◽  
The Stability

In this study, activated carbon (AC) from coconut shell, as a widely available agricultural waste, was synthesised in a simple one-step procedure and used to produce a magnetic Fe3O4/AC/TiO2 nano-catalyst for the degradation of methylene blue (MB) dye under UV light. Scanning electron microscopy revealed that TiO2 nanoparticles, with an average particle size of 45 to 62 nm, covered the surface of the AC porous structure without a reunion of its structure, which according to the TGA results enhanced the stability of the photocatalyst at high temperatures. The photocatalytic activities of synthesised AC, commercial TiO2, Fe3O4/AC, and Fe3O4/AC/TiO2 were compared, with Fe3O4/AC/TiO2 (1:2) exhibiting the highest catalytic activity (98%). Furthermore, evaluation of the recovery and reusability of the photocatalysts after treatment revealed that seven treatment cycles were possible without a significant reduction in the removal efficiency.

PREPARATION AND CHARACTERIZATION OF SiO2 NANOPARTICLE AND MESOPOROUS SILICATE MOLECULAR SIEVE MCM-48

2002 ◽  
Vol 01 (05n06) ◽  
pp. 539-543
Author(s):  
KYUNG WON SEO ◽  
SUNG DU MOON ◽  
YOUNG SOO KANG ◽  
YONG JOO KIM
Keyword(s):  
Particle Size ◽  
Molecular Sieve ◽  
Pore Diameter ◽  
Average Particle Size ◽  
Mesoporous Molecular Sieve ◽  
Average Particle ◽  
Narrow Size Distribution ◽  
Sem Image ◽  
Mesoporous Silicate

Nanosize SiO 2 particles with narrow size distribution were produced by modified Stober–Fink–Bohn method. Average particle size was determined as 170 nm by SEM image. Organosilica mesoporous molecular sieve (MCM-48) was synthesized. The calcined MCM-48 has pore diameter of 26.8 Å and a surface area of 1024 m 2 g -1 by BET (Brunauer–Emmet–Teller) measurement.

NITRITE REMOVAL FROM AQUEOUS SOLUTION USING SURFACE MODIFIED MAGHEMITE NANOPARTICLES

NANO ◽  
2014 ◽  
Vol 09 (02) ◽  
pp. 1450013 ◽  
Author(s):  
BEHRUZ MIRZAYI ◽  
ALI NEMATOLLAHZADEH ◽  
FOROUGH FIROUZNIA ◽  
SIMA HEYDARI
Keyword(s):  
Aqueous Solution ◽  
Average Particle Size ◽  
Sodium Dodecyl ◽  
Sodium Dodecyl Benzene Sulfonate ◽  
Xrd Analysis ◽  
Type Model ◽  
Average Particle ◽  
Maghemite Nanoparticles ◽  
Adsorbent Dosage ◽  
Sem Image

In the present work, maghemite nanoparticles (MNP) was synthesized by a simplified method and then modified by sodium dodecyl benzene sulfonate (NaDBS) for the removal of nitrite from aqueous solution. The prepared nanoparticles were characterized by Scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). The SEM image and XRD analysis showed that the average particle size and crystallite of the maghemite nanopaticles are ca. 32.7 nm and 33.5 nm, respectively. Different parameters namely, pH of the adsorption solution, adsorbent dosage and spectrophotometric reagents were optimized. Spectrophotometric determination of nitrite in an optimized condition showed that the MNP is able to deplete over 88% of nitrite from the initial solution. Moreover, dynamic adsorption study per se confirmed the shortest necessary contact time (ca. 6 min) in the adsorption process of nitrite which is quite encouraging from a practical and industrial point of view. The kinematic study revealed that the nitrite adsorption is a pseudo-first-order process. In addition, two different models (Freundlich- and kinetic-type model) were developed for the adsorbent dosage effect on nitrite adsorption. A Freundlich-type model manifested high coefficients of regression, indicating its robustness.

Nucleate Boiling Heat Transfer on Plain and Microporous Surfaces in Subcooled Water

2017 ◽  
Vol 139 (8) ◽  
Author(s):  
Seongchul Juna ◽  
Jinsub Kima ◽  
Hwan Yeol Kimb ◽  
Seung M. Youa
Keyword(s):  
Heat Transfer ◽  
High Speed ◽  
Average Particle Size ◽  
Nucleate Boiling ◽  
Average Particle ◽  
Transfer Coefficients ◽  
Sem Image ◽  
Subcooled Water ◽  
Plain Surface ◽  
Bubble Sizes

The growth of hovering bubbles on Copper, High-Temperature Thermally-Conductive Microporous Coating (Cu-HTCMC) and plain surface were compared at 1,000 kW/m2 in nucleate boiling with different subcoolings. Images obtained by a high speed camera operating at 2,000 frames per second were used. The Cu-HTCMC was created by sintering copper powders with the average particle size of 67 μm and ∼300 μm thickness, which showed the optimized nucleate boiling and critical heat flux enhancement. The hovering bubble size became smaller as subcooling increased for both Cu-HTCMC and plain surface due to condensation by surrounding subcooled water. At 30 K subcooling, big hovering bubbles disappeared on both surfaces. Small bubbles were shown on plain surface and mists were shown on Cu-HTCMC surface. The hovering bubble sizes were close and the growth times were comparable for both surfaces in saturated and 10 K subcooling cases. However, the bubbles on Cu-HTCMC surface were smaller than those of plain surface at 20 K and 30 K subcoolings. This is believed to be due to the microporous structures shown in the SEM image (top left figure). The heat transfer coefficients of Cu-HTCMC were ∼300 kW/m2K for various subcoolings, about 6 times higher than those of plain surface (top right figure). The figure indicates slightly increasing trend of the heat transfer coefficient with subcooling. This is believed to be the result of the disappearance of relatively big size bubbles in Cu-HTCMC case.

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