scholarly journals Preparation of Hierarchical Structure Au/ZnO Composite for Enhanced Photocatalytic Performance: Characterization, Effects of Reaction Parameters, and Oxidizing Agent Investigations

2021 ◽  
Vol 2021 ◽  
pp. 1-19
Author(s):  
Anh-Tuan Vu ◽  
Thi Anh Tuyet Pham ◽  
Xuan Truong Do ◽  
Van Anh Tran ◽  
Van Duong Le ◽  
...  
Keyword(s):  
Hierarchical Structure ◽  
Photocatalytic Performance ◽  
Uv Light ◽  
Chemical Reduction ◽  
Bandgap Energy ◽  
Order Kinetic ◽  
Reaction Parameters ◽  
Paramagnetic Resonance ◽  
X Ray ◽  
Order Kinetic Model

Zinc oxide (ZnO) has been shown as a potential photocatalyst under ultraviolet (UV) light but its catalytic activity has a limitation under visible (Vis) light due to the wide bandgap energy and the rapid recombination of electrons and holes. Thus, hierarchical structure Au/ZnO composites were fabricated by the hydrothermal method and chemical reduction method for enhanced photocatalytic performance under visible light. As-prepared composites were characterized by UV-vis diffuse reflectance spectra (DR/UV-Vis), field emission scanning electron microscope (FESEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and electron paramagnetic resonance (EPR). The Au/ZnO-5 composite showed the highest adsorption among as-prepared samples in the range of 250-550 nm, having bandgap energy of 0.13 eV. Au nanoparticles of about 3-5 nm were well dispersed on hierarchical flower ZnO with approximately 10-15 μm. The EPR signal at g = 1.965 on both ZnO and Au/ZnO samples was attributed to oxygen vacancy Vo•, but the presence of Au led to a decrease in signal strength of Au/ZnO composite, showing the degradation efficiency (DE) and reaction rate of 99.2% and 0.109 min-1, respectively; these were larger than those of other samples. The effects of reaction parameters and oxidizing agents on photocatalytic performance were investigated and showed that the presence of H2O2 and O2 could improve the reaction of composite. In addition, the kinetic and photocatalytic mechanism of tartrazine (TA) on catalysts were studied by the first-order kinetic model and characterized analyses.

scholarly journals Photodecolourization of congo red dye in presence of Ni3+ layered double hydroxide

2021 ◽  
Vol 30 ◽  
pp. 02010
Author(s):  
Irina Ryltsova ◽  
Evgenia Tarasenko ◽  
Olga Lebedeva
Keyword(s):  
Layered Double Hydroxide ◽  
Congo Red ◽  
Uv Light ◽  
Order Kinetic ◽  
X Ray ◽  
Congo Red Dye ◽  
Order Kinetic Model ◽  
Co Precipitation ◽  
Red Dye ◽  
Double Hydroxide

Layered double hydroxide containing Ni3+ (Mg/AlNi-LDH) was successfully synthesized by co-precipitation in an oxidizing media. The resulted product was characterized using X-ray diffraction, wavelength dispersive X-ray fluorescence spectrometry. The activity of Mg/AlNi-LDH in the process of photodegradation of Congo red dye using UV light irradiation was evaluated. The initial rate of photodegradation of the dye in the presence of LDH is 1.6 times higher than that of UV irradiated solution. The kinetic data obtained for photodegradation process can be adequately described by pseudo-first-order kinetic model. The presence of Mg/AlNi – LDH leads to increased photodegradation yield compared to destruction only by UV irradiation.

Destruction of Pollutants and Microorganisms in Water by UV Light and Hydrogen Peroxide

1992 ◽  
Vol 27 (1) ◽  
pp. 57-68 ◽  
Author(s):  
D.W. Sundstrom ◽  
B.A. Weir ◽  
T. A. Barber ◽  
H. E. Klei
Keyword(s):  
Hydrogen Peroxide ◽  
Organic Compounds ◽  
Chemical Structure ◽  
Uv Light ◽  
Liquid Films ◽  
Strong Interactions ◽  
Order Kinetic ◽  
E Coli ◽  
Order Kinetic Model ◽  
Catalyzed Oxidation

Abstract This project investigated the destruction of organic compounds and microorganisms in water by ultraviolet catalyzed oxidation using hydrogen peroxide as the oxidizing agent. The combination of UV light and hydrogen peroxide was effective in decomposing all of the organic compounds studied. The rates of destruction increased with increasing peroxide concentration and UV light intensity, and were highly dependent on chemical structure. The destruction of mixtures of organic compounds showed strong interactions between reacting components. The inactivation of E. coli and B. subtilis spores by UV light and/or hydrogen peroxide was studied in flat plate reactors. By using thin liquid films, the combination of UV light and peroxide greatly increased the rates of inactivation of both microorganisms. The results were correlated by a mixed second order kinetic model.

scholarly journals The Removal of Uranium and Thorium from Their Aqueous Solutions by 8-Hydroxyquinoline Immobilized Bentonite

Minerals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 626 ◽  
Author(s):  
Salah ◽  
Gaber ◽  
Kandil
Keyword(s):  
Aqueous Solutions ◽  
Metal Ions ◽  
Langmuir Isotherm ◽  
Freundlich Isotherm ◽  
Order Kinetic ◽  
X Ray Diffraction ◽  
Solution Ph ◽  
X Ray ◽  
Order Kinetic Model ◽  
Pseudo Second Order

The sorption of uranium and thorium from their aqueous solutions by using 8-hydroxyquinoline modified Na-bentonite (HQ-bentonite) was investigated by the batch technique. Na-bentonite and HQ-bentonite were characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier Transform Infrared (FTIR) spectroscopy. Factors that influence the sorption of uranium and thorium onto HQ-bentonite such as solution pH, contact time, initial metal ions concentration, HQ-bentonite mass, and temperature were tested. Sorption experiments were expressed by Freundlich and Langmuir isotherms and the sorption results demonstrated that the sorption of uranium and thorium onto HQ-bentonite correlated better with the Langmuir isotherm than the Freundlich isotherm. Kinetics studies showed that the sorption followed the pseudo-second-order kinetic model. Thermodynamic parameters such as ΔH°, ΔS°, and ΔG° indicated that the sorption of uranium and thorium onto HQ-bentonite was endothermic, feasible, spontaneous, and physical in nature. The maximum adsorption capacities of HQ-bentonite were calculated from the Langmuir isotherm at 303 K and were found to be 63.90 and 65.44 for U(VI) and Th(IV) metal ions, respectively.

scholarly journals Conversion of fisheries waste as magnetic hydroxyapatite bionanocomposite for the removal of heavy metals from groundwater

2017 ◽  
Vol 18 (4) ◽  
pp. 1406-1419
Author(s):  
F. Elmi ◽  
R. Chenarian Nakhaei ◽  
H. Alinezhad
Keyword(s):  
Heavy Metals ◽  
Freundlich Isotherm ◽  
Spectroscopic Techniques ◽  
Order Kinetic ◽  
Fish Scale ◽  
X Ray Diffraction ◽  
X Ray ◽  
Removal Of Heavy Metals ◽  
Order Kinetic Model ◽  
Ir Spectroscopic

Abstract This study is the first report of its type demonstrating the synthesis of mHAP on the basis of magnetic functionalization with nHAP, which were synthesized using Rutilus frisii kutum fish scale as a benign fishery waste by-product. The mHAP was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray diffraction (EDX), and Fourier transform infrared (FT-IR) spectroscopic techniques. The XRD pattern confirmed the formation of a single-phase nHAP without any extra steady phases. It was also found that the pseudo-second-order kinetic model gave a satisfactory fit to the experimental data (R2 = 0.99). The maximum removal percentages of Cu and Zn ions in optimal conditions (adsorbent dosage at 0.1 g, 30 min contact time at 25 ± 1 °C and pH = 5 ± 0.1) by mHAP were 97.1% and 93.8%, respectively. Results also demonstrated that mHAP could be recycled for up to five cycles in the case of copper and zinc. The Langmuir isotherm was proved to have a better correlation compared with that of the Freundlich isotherm. The thermodynamic parameters indicated that it was a spontaneously endothermic reaction. In conclusion, mHAP could be regarded as a powerful candidate for efficient biosorbent, capable of adsorbing heavy metals from aqueous solutions.

Chromate sorption and reduction kinetics onto an aminated biosorbent

2006 ◽  
Vol 54 (10) ◽  
pp. 1-8 ◽  
Author(s):  
S. Deng ◽  
Y.P. Ting ◽  
G. Yu
Keyword(s):  
Photoelectron Spectroscopy ◽  
Penicillium Chrysogenum ◽  
Sorption Process ◽  
Sorption Kinetics ◽  
Order Kinetic ◽  
Chromium Species ◽  
X Ray ◽  
Order Kinetic Model ◽  
Pseudo Second Order ◽  
Amine Groups

A novel biosorbent was prepared by chemically grafting of polyethylenimine (PEI) onto the fungal biomass of Penicillium chrysogenum through a two-step reaction. The modified biosorbent is favorable for the removal of anionic Cr(VI) species from aqueous solution due to the protonation of amine groups on the biomass surface. The sorption capacity for Cr(VI) increased by 7.2-fold after surface modification. Sorption kinetics results show that the pseudo-second-order kinetic model described the experimental data well. During the sorption process, X-ray photoelectron spectroscopy (XPS) was used to analyze the chromium species on the biosorbent surface and the results indicate that part of the Cr(VI) ions were reduced to Cr(III) ions which can be chelated with the amine groups on the biomass surface. The reduced Cr(III) ions formed some aggregates on the surface at higher solution pHs.

Solvothermal Synthesis of Novel 3D Peony-Like TiO2 Microstructures and its Enhanced Photocatalytic Activity

NANO ◽  
2018 ◽  
Vol 13 (05) ◽  
pp. 1850056 ◽  
Author(s):  
Yugan He ◽  
Qi Yan ◽  
Xiaoyu Chang ◽  
Meiying Zhu ◽  
Weiwei Wang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Reaction Time ◽  
Uv Light ◽  
X Ray Diffraction ◽  
Reaction Parameters ◽  
X Ray ◽  
Uv Light Irradiation ◽  
Transmission Electron ◽  
Irradiation Power ◽  
Degussa P25

A TiO2 photocatalyst with peony-like microstructures and a large percentage of exposed {001} facets was synthesized using a facile solvethermal method. The peony-like TiO2 was obtained using HF as a capping agent, TiCl4 as the precursor and ethanol as the solvothermal agent. The parameters which influence the mophology and formation mechanism of the products including the HF concentration, the reaction time and temperature and the solvothermal solvent, were investigated. The samples were characterized using field emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction and N2 adsorption and desorption analysis. As the reaction time or reaction temperature increased, the morphology TiO2 changed from hexagonally assembled microspheres to peony-like microflowers which were composed of stacks of ultrathin nanosheets. The other reaction parameters also play a crucial role in the formation of the TiO2 microstuctures. Photocatalytic experiments showed that the synthesized TiO2 outperformed Degussa P25 in the photodegradation of methelene blue under a very weak UV light irradiation (power: 8[Formula: see text]W, light intensity: 0.4[Formula: see text]mW[Formula: see text]cm[Formula: see text]).

Photocatalytic Performance of Polyoxometallate Intercalated Layered Double Hydroxide

2010 ◽  
Vol 663-665 ◽  
pp. 187-190 ◽  
Author(s):  
Yu Hui Zhang ◽  
Ji Xin Su ◽  
Xiao Peng Wang ◽  
Qi Pan ◽  
Wen Qu
Keyword(s):  
Methyl Orange ◽  
Ir Spectra ◽  
Photocatalytic Performance ◽  
Uv Light ◽  
X Ray Diffraction ◽  
X Ray ◽  
Uv Light Irradiation ◽  
Ft Ir ◽  
Double Hydroxide ◽  
Degradation Of Methyl Orange

Based on X-ray diffraction results, the gallery height of modified Mg3Al-LDH was expanded to 9.6Å from the original 4.8Å, indicating that the H3PW12O40 was indeed inserted into the hydroxide layers. Moreover, the results of FT-IR spectra proved the Keggin structure of PW11O397- species. The resulting material showed a high activity of degradation of methyl orange in the presence of H2O2 and UV light irradiation.

scholarly journals Use of Aluminosilicate Residue from Insulators of High Voltage Transformers for the Adsorption of Basic Dyes

2021 ◽  
Author(s):  
Fernando Murga ◽  
José de Campos ◽  
Roberta Signini
Keyword(s):  
High Voltage ◽  
Physical Adsorption ◽  
Fluorescence Analysis ◽  
Point Of Zero Charge ◽  
Isotherm Models ◽  
Order Kinetic ◽  
Solution Ph ◽  
X Ray ◽  
Basic Dyes ◽  
Order Kinetic Model

In this study, an aluminosilicate residue from insulators of high voltage transformers was used for the adsorption of basic dyes. The absorbent was characterized by X-ray fluorescence analysis, X-ray diffraction analysis, scanning electron microscopy, multimolecular adsorption theory (Branauer-Emmet-Teller (BET)) and determination of the point of zero charge (pHPZC). The effect of solution pH and adsorbent mass, the kinetic and thermodynamic behavior at different temperatures and the application of non-linear isotherm models of Langmuir, Freundlich, Temkin and Dubinin-Radushevich were investigated. The pHPZC value for the aluminosilicate was 3.7. The best conditions for adsorption of methylene blue and crystal violet dyes were pH 8.0 and adsorbent mass of 1100 mg in 25 mL. The best fit for the experimental data was obtained applying the pseudo-second-order kinetic model, with an equilibrium time of 480 to 720 min, and the activation energy suggests a physical adsorption mechanism. Isothermal parameters suggest a heterogeneous, favorable and predominantly physical surface adsorption. The thermodynamic studies indicated that the adsorption process is not spontaneous and is exothermic and the Gibbs energy values (ΔGº) suggest physisorption.

scholarly journals Physicochemical Characterization of Moroccan Natural Clays and the Study of their Adsorption Capacity for the Methyl Orange and Methylene

2020 ◽  
Vol 8 (4) ◽  
pp. 1258-1267
Keyword(s):  
Methyl Orange ◽  
Physicochemical Characterization ◽  
Order Kinetic ◽  
X Ray Diffraction ◽  
Calcined Clay ◽  
X Ray ◽  
Equilibrium Data ◽  
Order Kinetic Model ◽  
Natural Clays

The objective of this work was the physicochemical characterization of a Moroccan natural clay from the Jorf Arfoud region (Lampert Coodinates: x = 595610, y = 101578) and its valorization in the elimination of organic pollutants (methyl orange MO and methylene blue MB) from aqueous solutions, with the adsorption technique on raw and calcined clay at 500°C. The clay was characterized by chemical analysis such as X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Scanning electron microscopy (SEM). Crude and purified clays, consisting essentially of silica and alumina, are a characteristic property of phyllosilicates and also contain amounts of quartz, kaolinite and calcite as associated minerals. The experiments were performed after optimization of the parameters influencing the system, such as pH, adsorbent mass, initial dye concentration and temperature. The clays used absorb better the MB than MO, for an initial concentration of 10 mg/L and 20 mg/L respectively. Langmuir and Freundlich models of adsorption isotherms were applied to fit experimental equilibrium data. Results have showed that the adsorption of MB and MO followed very well the second order kinetic model on raw clay. The adsorption process was found to be exothermic in the case of MB. However, the adsorption of MO was endothermic.

scholarly journals Removal of Sulfamethoxazole, Sulfathiazole and Sulfamethazine in their Mixed Solution by UV/H2O2 Process

2019 ◽  
Vol 16 (10) ◽  
pp. 1797 ◽  
Author(s):  
Guangcan Zhu ◽  
Qi Sun ◽  
Chuya Wang ◽  
Zhonglian Yang ◽  
Qi Xue
Keyword(s):  
Uv Light ◽  
Degradation Pathway ◽  
Photochemical Oxidation ◽  
Order Kinetic ◽  
Mixed Solution ◽  
Initial Concentration ◽  
Aqueous Environments ◽  
Initial Ph ◽  
Order Kinetic Model ◽  
Acidic Conditions

Sulfamethoxazole (SMZ), sulfathiazole (STZ) and sulfamethazine (SMT) are typical sulfonamides, which are widespread in aqueous environments and have aroused great concern in recent years. In this study, the photochemical oxidation of SMZ, STZ and SMT in their mixed solution using UV/H2O2 process was innovatively investigated. The result showed that the sulfonamides could be completely decomposed in the UV/H2O2 system, and each contaminant in the co-existence system fitted the pseudo-first-order kinetic model. The removal of sulfonamides was influenced by the initial concentration of the mixed solution, the intensity of UV light irradiation, the dosage of H2O2 and the initial pH of the solution. The increase of UV light intensity and H2O2 dosage substantially enhanced the decomposition efficiency, while a higher initial concentration of mixed solution heavily suppressed the decomposition rate. The decomposition of SMZ and SMT during the UV/H2O2 process was favorable under neutral and acidic conditions. Moreover, the generated intermediates of SMZ, STZ and SMT during the UV/H2O2 process were identified in depth, and a corresponding degradation pathway was proposed.

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