Study on Stability of AgI/TiO2 Visible Light Photocatalysts in Solutions of Various pH Values

2011 ◽  
Vol 399-401 ◽  
pp. 1272-1275
Author(s):  
Lu Feng ◽  
Ke Feng He ◽  
Wan Ping Chen
Keyword(s):  
Visible Light ◽  
Absorption Edge ◽  
Ph Value ◽  
Alkaline Treatment ◽  
Alkaline Solutions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Acidic Solutions ◽  
Ph Values ◽  
Vis Spectroscopy

Nanostructured AgI/TiO2 photocatalysts exhibit highly efficient visible light photocatalytic activity. Though there have been extensive investigations on AgI/TiO2 photocatalysts, study on their stablity is still very limited. So in this paper, such a study is designed and conducted. AgI/TiO2 nanostructured photocatalysts were prepared and separately immersed in HCl solutions, DI water and NaOH solutions with pH value of 0, 4, 7, 10 and 14, respectively. X-ray diffraction and diffusive reflectance UV-vis spectroscopy analyses reveal that the immersion in acidic solutions led to the formation of AgCl and a blue shifting to 450nm for the absorption edge of AgI/TiO2, while the alkaline treatment had no significant effect on the composite structure of AgI/TiO2 or on the UV-vis absorption edge. Photocatalytic tests show that immersion in acidic solutions had more significant influence on AgI/TiO2 photocatalytic degradation of methyl orange (MO). At pH = 4, photocatalytic efficiency was dropped nearly 30%. At pH = 10, no significant change was observed. AgI/TiO2 nanostructured photocatalysts have thus been found to display a higher stability in alkaline solutions than in acidic solutions.

Study on Influence of Silicate Morphology Based on pH Value

2012 ◽  
Vol 454 ◽  
pp. 324-328
Author(s):  
Yan He ◽  
Ya Jing Liu ◽  
Yong Lin Cao ◽  
Li Xia Zhou
Keyword(s):  
Silicic Acid ◽  
Ph Value ◽  
Colorimetric Method ◽  
Absorption Spectrometry ◽  
Degree Of Polymerization ◽  
Raw Material ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ph Values ◽  
The Stability

Infra-red absorption spectrometry, X-ray diffraction observations and characterization tests based on silicon molybdenum colorimetric method were used to investigate the optimal pH value controlling the stability of the silicic acid form. The experiment process was done by using sodium silicate as raw material. The results showed that the solution of silicate influenced the polymerization. The active silicic acid solution with a certain degree of polymerization was obtained by controlling the pH values.

Photocatalytic Activity of CuO/ZnO Heterostructure Nanocrystals under UV-Visible Light Irradiation

2014 ◽  
Vol 787 ◽  
pp. 35-40 ◽  
Author(s):  
Xiao Yan Zhou ◽  
Peng Wei Zhou ◽  
Hao Guo ◽  
Bo Yang ◽  
Ru Fei Ren
Keyword(s):  
Photocatalytic Activity ◽  
Visible Light ◽  
Visible Light Irradiation ◽  
Cuo Nanoparticles ◽  
Light Irradiation ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
X Ray ◽  
Vis Spectroscopy ◽  
Uv Visible

The p-n junction photocatalysts, p-CuO (at. 0-25%)/n-ZnO nanocomposite were prepared through hydrothermal method without using any organic solvent or surfactant. The as-prepared samples were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive X-Ray spectroscopy, and UV-vis spectroscopy. The results demonstrated that the CuO/ZnO nanocomposite presented a two-dimensional morphology composed of sheet-like ZnO nanostructures adorned with CuO nanoparticles. The photocatalytic activity of CuO/ZnO with different Cu/Zn molar rations and pure ZnO synthesized by the identical synthetic route were evaluated by degrading methylene blue (MB) dye under UV-visible light irradiation. The CuO/ZnO with Cu/Zn molar ratio of 4% exhibits the highest photocatalytic activity compared that of the other photocatalysts under the identical conditions. It is mainly attributed to the increased charge separation rate in the nanocomposite and the extended photo-responding range.

Influence of pH on the Morphology and Luminescence Properties of Europium-Doped Hydroxyapatite Nanoparticles

2011 ◽  
Vol 391-392 ◽  
pp. 1132-1137
Author(s):  
Su Ping Huang ◽  
Jun Zhu ◽  
Ke Chao Zhou
Keyword(s):  
Photoelectron Spectroscopy ◽  
Inductively Coupled Plasma ◽  
Doping Concentration ◽  
Ph Value ◽  
Luminescence Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
Inductively Coupled ◽  
Ph Values ◽  
Influence Of Ph

Luminescence behaviors and morphology of Eu3+doped hydroxyapatite synthesized under different pH values were well investigated by X-ray diffraction (XRD), scanning electronic microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Inductively Coupled Plasma (ICP) (ICP–PLASMA 1000), and photoluminescence (PL) spectroscopy. Results revealed that With pH values increased from 6.5 to 10.0, the morphology of nano-Eu:HA particles changes from rod particles to equiaxed particles. The actual doping concentration and aspect ratio of Eu3+-doped HA decreased with the increasing of pH value. At the same time, the fluorescence intensity also tends to weakly lower with the increasing of pH value, which indicated that the luminescence properties mainly depended on the actual Eu3+doping concentration, the influences of morphology on the luminescence properties were slight.

Effects of Alkaline Treatment on Corrosion Behavior of Biodegradable Magnesium

2015 ◽  
Vol 1125 ◽  
pp. 441-444 ◽  
Author(s):  
Mahtab Assadian ◽  
Mohd Hasbullah Idris ◽  
Mohammad Mahdi Taheri ◽  
Mostafa Rezazadeh Shirdar ◽  
Davood Almasi
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Behavior ◽  
Barrier Layer ◽  
Room Temperature ◽  
Ph Value ◽  
Alkaline Treatment ◽  
X Ray Diffraction ◽  
X Ray ◽  
Biomaterial Application ◽  
Biodegradable Magnesium

Corrosion behavior of Magnesium substrate were investigated after NaOH treatment in different concentrations (1, 5, and 10 Molar) and duration of (10 min, 30 min, 1 h, 3 h, 6 h and 24 h) at room temperature to be utilized in biomaterial application. Creation of Mg(OH)2 barrier layer after treatment enhanced corrosion resistance. X-Ray diffraction (XRD) was conducted to detect the existence of barrier layer. Potentiodynamic polarization and immersion tests were evaluated the corrosion behavior of Magnesium in Kokubo simulated body fluid (SBF). It is found that Magnesium treated by 1M NaOH for 30 min reveals higher corrosion resistance. In addition this investigation indicates that pH value of Kokubo SBF, strongly influenced by different time and concentration of alkaline treatment

Effects of pH Values on the Structure, Composition and Luminescence of CaWO4:Tb3+ Thin Films

2012 ◽  
Vol 531-532 ◽  
pp. 204-207
Author(s):  
Lian Ping Chen ◽  
Yuan Hong Gao
Keyword(s):  
Thin Films ◽  
Ph Value ◽  
Electrochemical Techniques ◽  
Luminescent Properties ◽  
X Ray Diffraction ◽  
Step Method ◽  
X Ray ◽  
Ph Values ◽  
Effects Of Ph ◽  
Rare Earth Doped

It is hardly possible to obtain rare earth doped CaWO4thin films directly through electrochemical techniques. A two-step method has been proposed to synthesize Tb3+-doped CaWO4thin films. X-ray diffraction, energy dispersive X-ray analysis, spectrophotometer were used to characterize their phase, composition and luminescent properties. Results reveal that Tb3+-doped CaWO4films have a tetragonal phase. The ratio of n(Tb)/[n(Ca)+n(Tb)+n(Na)] decreases with the increase of pH value of TbCl3solutions. When the pH value (adjusted by NaOH) is higher than 5, Na element has been detected in CaWO4:Tb3+thin films. Based on the analysis on the composition and luminescence, it can be concluded that the pH value of TbCl3solutions must be no higher than 9.1, otherwise, no Tb3+-doped CaWO4thin films can be obtained. Under the excitation of 237 nm, sharp emission peaks at 543 and 489 nm have been observed for Tb3+-doped CaWO4:Tb3+thin films.

EFFECT OF pH ON ZnS NANOCRYSTALLINE THIN FILM EMBEDDED IN A POLYVINYL ALCOHOL MATRIX

2010 ◽  
Vol 24 (29) ◽  
pp. 5663-5673 ◽  
Author(s):  
J. P. BORAH ◽  
J. BARMAN ◽  
K. C. SARMA
Keyword(s):  
Electron Microscopy ◽  
Polyvinyl Alcohol ◽  
Ph Value ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ph Values ◽  
Nanocrystalline Thin Film ◽  
Transmission Electron ◽  
Uv Visible ◽  
Compositional Characterization

Polyvinyl alcohol (PVA) has been used as a matrix to synthesize ZnS / PVA nanocomposite film on glass substrate by chemical method. Transmission electron microscopy (TEM), X-ray diffraction (XRD), Scanning electron microscopy (SEM) has been used for structural, morphological and compositional characterization. Optical properties have been studied by UV-Visible spectrophotometry and photoluminescence (PL) spectroscopy. Changing pH value from 4.8 to 0.8 decreases the particle size and correspondingly increases the band gap. The PL emission intensity also increases by decreasing the pH values.

Effect of pH Values on Conversion of Calcite Crystals into Calcium Phosphate Phases in Buffer Solutions

2007 ◽  
Vol 353-358 ◽  
pp. 2183-2186 ◽  
Author(s):  
Ya Ping Guo ◽  
Bao Qiang Li ◽  
Yu Zhou ◽  
De Chang Jia
Keyword(s):  
Calcium Phosphate ◽  
Ph Value ◽  
Octacalcium Phosphate ◽  
Precipitation Reaction ◽  
X Ray Diffraction ◽  
Buffer Solution ◽  
Effect Of Ph ◽  
X Ray ◽  
Buffer Solutions ◽  
Ph Values

Calcium phosphate phases with laminar-plate structure were converted from calcite powders after soaking in phosphate buffer solutions of pH’s 6.0-8.0 at 37 °C for 9 days. The effect of pH values on the conversion of calcite crystals was investigated by X-ray diffraction, scanning electron microscopy and Fourier-transform infrared spectroscopy. If the pH value of a buffer solution is kept at 6.0, calcite powders are converted mainly to dicalcium phosphate dehydrate (DCPD) or octacalcium phosphate (OCP). If the pH value is kept at 6.4 or 7.0, calcite powders are converted mainly to OCP. Hydroxyapatite (HAP) with poorly crystalline can be obtained from calcite powders both by treatment of a basic buffer solution, and by treatment of an acid buffer solution without regulating its pH value during the reaction. The conversion mechanism of calcite crystals is a dissolution-precipitation reaction.

scholarly journals Synthesis and Characterization of CdS/TiO2-Montmorillonite Nanocomposite with Enhanced Visible-Light Absorption

2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
Feng-shan Zhou ◽  
Dai-mei Chen ◽  
Bao-lin Cui ◽  
Wei-heng Wang
Keyword(s):  
Visible Light ◽  
Light Absorption ◽  
Photoelectron Spectroscopy ◽  
Synthesis Method ◽  
Cds Nanoparticles ◽  
X Ray Diffraction ◽  
Visible Light Absorption ◽  
X Ray ◽  
Vis Spectroscopy ◽  
Adsorption Desorption

Sodium montmorillonite (MMT) was chosen as the carrier; a serial of CdS/TiO2-MMT nanocomposites with enhanced visible-light absorption ability was prepared by hydrothermal synthesis method combination with semiconductor compound modification method. The samples are characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and ultraviolet visible (UV-Vis) spectroscopy; the results showed that TiO2and CdS nanoparticles were loaded on the surface of montmorillonite uniformly. N2adsorption-desorption experiment showed that the specific surface area of TiO2/montmorillonite nanocomposite made by this method can reach 200 m2/g and pore-size distribution was from 4 to 6 nm; UV-Vis showed that the recombination of CdS and TiO2enhanced visible-light absorption ability of samples of TiO2/montmorillonite and visible-light absorption ability increase with the increased of the adsorption of CdS.

scholarly journals Study on synthesizing Mg/Al layered double hydroxides at different pHs

2014 ◽  
Vol 15 ◽  
pp. 36-39 ◽  
Author(s):  
E Otgonjargal ◽  
G Burmaa ◽  
B Enkhmaa ◽  
M Enkhtuul ◽  
L Nyam-Ochir ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Ph Value ◽  
Infrared Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ph Values ◽  
Double Hydroxide ◽  
Double Hydroxides ◽  
Influence Of Ph ◽  
Scanning Electron

Mg/Al layered double hydroxide (LDH) was successfully synthesized at different pHs values. The Mg/AL LDH was well characterized by X-Ray diffraction and Fourier transform infrared analysis. The morphology of the LDH was observed using Scanning electron microscopy with energy dispersive X-ray spectroscopy. The influence of pH values on the morphology of the Mg/Al LDHs were studied. The result showed that the well-synthesized Mg/Al LDHs could be obtained when the pH value was about 10.0 at room temperature.DOI: http://doi.dx.org/10.5564/mjc.v15i0.319 Mongolian Journal of Chemistry 15 (41), 2014, p36-39

scholarly journals Enhanced Visible Light Photocatalytic Degradation of Fe-Doped ZnO Nanoparticles For Organic Dyes

2021 ◽  
Author(s):  
Senthilkumar M ◽  
C. Arunagiri
Keyword(s):  
Photocatalytic Activity ◽  
Visible Light ◽  
Organic Dyes ◽  
Chemical Precipitation ◽  
Precipitation Method ◽  
Photocatalytic Efficiency ◽  
X Ray Diffraction ◽  
X Ray ◽  
Vis Spectroscopy ◽  
Visible Light Photocatalytic

Abstract FexZn1-xO (x = 0, 0.05, 0.075, 0.1 M) nanoparticles based photocatalysts were synthesized by a chemical precipitation method and characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive X-ray emission (EDX) and UV–Vis spectroscopy. The photocatalytic efficiency of FexZn1-xO catalysts was assessed under visible light irradiation using the degradation of methylene blue (MB) and methyl orange (MO) dye in aqueous solution. The present investigation shows that the effect of optimized parameters (pH, catalyst dosage and initial dye concentration) and doping concentrations plays significant role in photocatalytic activity. The detailed photocatalytic mechanism for the enhancement of photocatalytic activity has also been proposed.

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