scholarly journals Synthesis of Gd2O3 Nanoparticles and Their Photocatalytic Activity for Degradation of Azo Dyes

Catalysts ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 742
Author(s):  
Sugyeong Jeon ◽  
Jeong-Won Ko ◽  
Weon-Bae Ko
Keyword(s):  
Methyl Orange ◽  
Photocatalytic Degradation ◽  
Azo Dyes ◽  
Uv Light ◽  
Nitrate Hexahydrate ◽  
Acid Orange 7 ◽  
Pseudo First Order Reaction ◽  
Acid Orange ◽  
Vis Spectroscopy ◽  
Gd2o3 Nanoparticles

Gadolinium oxide (Gd2O3) nanoparticles were prepared via the reaction of gadolinium nitrate hexahydrate (Gd (NO3)3·6H2O) and ethylamine (C2H5NH2), and their surface morphology, particle size, and properties were examined by using scanning electron microscopy, X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, and ultraviolet visible (UV-vis) spectroscopy. The Gd2O3 nanoparticles were used as the photocatalyst for the degradation of various azo dyes, such as methyl orange (MO), acid orange 7 (AO7), and acid yellow 23 (AY23) under irradiation with UV light. The effect of the experimental parameters (initial concentration of azo dyes, dosage of catalyst, and wavelength of UV light) on the photocatalytic properties of the Gd2O3 nanoparticles were investigated. At a constant H2O2 concentration, the photocatalytic degradation efficiency of the Gd2O3 nanoparticles for various azo dyes was in the order: methyl orange > acid orange 7 > acid yellow 23. The kinetics study showed that the photocatalytic degradation of azo dyes was followed by a pseudo first-order reaction rate law.

Microbial conversion of selected azo dyes and their breakdown products

2006 ◽  
Vol 53 (11) ◽  
pp. 163-171 ◽  
Author(s):  
N. Yemashova ◽  
S. Kalyuzhnyi
Keyword(s):  
Methyl Orange ◽  
Activated Sludge ◽  
Azo Dyes ◽  
Anthranilic Acid ◽  
Methyl Red ◽  
Acid Orange 7 ◽  
Microbial Conversion ◽  
Aerobic Conditions ◽  
Acid Orange ◽  
Sulphanilic Acid

Four selected azo dyes (acid orange 6, acid orange 7, methyl orange and methyl red) were completely decolourised in the presence of anaerobic granular sludge, while only methyl red was degraded in aerobic conditions using a conventional activated sludge. Additional experiments with culture broth devoid of cells showed that anaerobic decolourisation of azo dyes was performed by extracellular reducing agents produced by anaerobic bacteria. This was further confirmed by abiotic experiments with sulphide and NADH. The presence of redox mediators such as riboflavin led to dramatic acceleration of the anaerobic biodecolourisation process. The azo dye reduction products were found to be sulphanilic acid and 4-aminoresorcinol for acid orange 6; sulphanilic acid and 1-amino-2-naphthol for acid orange 7; N,N-dimethyl-1,4-phenylenediamine and sulphanilic acid for methyl orange; and N,N-dimethyl-1,4-phenylenediamine and anthranilic acid for methyl red. Anaerobic toxicity assays showed that the azo dyes were more toxic than their breakdown products (aromatic amines), except 1-amino-2-naphthol. In the presence of activated sludge, only anthranilic acid was completely mineralised while sulphanilic acid was persistent. 4-aminoresorcinol, 1-amino-2-naphthol and N,N-dimethyl-1,4-phenylenediamine underwent autooxidation in aerobic conditions yielding coloured polymeric products. On the contrary, in the presence of granular methanogenic sludge, 4-aminoresorcinol, 1-amino-2-naphthol and anthranilic acid were quantitatively methanised, sulphanilic acid was partially (70%) mineralised while N,N-dimethyl-1,4-phenylenediamine was only demethylated producing 1,4-phenylenediamine as an end product.

scholarly journals Photocatalytic Degradation of Azo Dyes Using Microreactors: Mechanistic Study of its Effects on H2O2 Addition

2021 ◽  
Vol 01 (03) ◽  
pp. 1-1
Author(s):  
Minato Nakamura ◽  
◽  
Yoshinori Murakami ◽  
Keyword(s):  
Photocatalytic Degradation ◽  
Azo Dyes ◽  
Azo Dye ◽  
Glass Plate ◽  
Degradation Efficiency ◽  
Mechanistic Study ◽  
Photocatalytic Reaction ◽  
Acid Orange 7 ◽  
Acid Orange ◽  
H2o2 Addition

The photocatalytic reaction involved in TiO<sub>2</sub> photocatalysis was investigated using a microreactor coated with TiO<sub>2</sub> film on the glass plate attached on one side of the microreactor. It was confirmed that the effect of H<sub>2</sub>O<sub>2</sub> on the photocatalytic degradation efficiency of azo dyes (acid orange 7, acid red 151, and acid yellow 23) was dependent on the polymorphs (anatase and rutile) of TiO<sub>2</sub> coated on the glass plate of the UV-irradiated microreactor. Scavengers of holes (KI) and electrons (p-benzoquinone) were added to the solution of azo dyes, and their effects on the degradation efficiencies of the azo dye (acid orange 7) in the microreactor system were investigated. It was found that the electron scavengers of p-benzoquinone showed much larger effects on the photocatalytic degradation efficiency than the hole scavengers of KI. Based on these results, the mechanism of the photocatalytic degradation of the azo dyes in the presence of H<sub>2</sub>O<sub>2</sub> was proposed.

scholarly journals Ultrasound Assisted Synthesis of Gadolinium Oxide-Zeolitic Imidazolate Framework-8 Nanocomposites and Their Optimization for Photocatalytic Degradation of Methyl Orange Using Response Surface Methodology

Catalysts ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1022
Author(s):  
Su-Gyeong Jeon ◽  
Jeong-Won Ko ◽  
Weon-Bae Ko
Keyword(s):  
Response Surface Methodology ◽  
Methyl Orange ◽  
Photocatalytic Degradation ◽  
Response Surface ◽  
Uv Light ◽  
Gadolinium Oxide ◽  
Experimental Conditions ◽  
Zeolitic Imidazolate Framework ◽  
Vis Spectroscopy ◽  
Ultrasound Assisted

An ultrasound-assisted method was used to prepare gadolinium oxide (Gd2O3)-zeolitic imidazolate framework (ZIF)-8 nanocomposites. The surface morphology, particle size, and properties of the Gd2O3-ZIF-8 nanocomposites were examined using scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, and ultraviolet-visible (UV-vis) spectroscopy. The synthesized Gd2O3-ZIF-8 nanocomposites were used as a catalyst to degrade methyl orange (MO) under UV light irradiation at 254 nm. The color of the aqueous MO dye solution during photocatalytic degradation was examined using color spectroscopy. Response surface methodology (RSM) using a four-factor Box-Behnken design (BBD) was used to design the experiments and optimize the photocatalytic degradation of MO. The significance of the experimental factors and their interactions were determined using analysis of variance (ANOVA). The efficiency of Gd2O3-ZIF-8 nanocomposites for the photocatalytic degradation of MO reached 98.05% within 40 min under UV irradiation at 254 nm under the experimental conditions of pH 3.3, 0.4 g/L catalyst dose, 0.0630 mM MO concentration, and 431.79 mg/L H2O2 concentration. The kinetics study showed that the MO photocatalytic degradation followed a pseudo-first-order reaction rate law.

Phase-controlled synthesis of bismuth oxide polymorphs for photocatalytic applications

2018 ◽  
Vol 2 (9) ◽  
pp. 1664-1673 ◽  
Author(s):  
Thangavel Selvamani ◽  
Sambandam Anandan ◽  
Luis Granone ◽  
Detlef W. Bahnemann ◽  
Muthupandian Ashokkumar
Keyword(s):  
Methylene Blue ◽  
Methyl Orange ◽  
Bismuth Oxide ◽  
Rhodamine B ◽  
Controlled Synthesis ◽  
Acid Orange 7 ◽  
Acid Orange ◽  
Photocatalytic Applications

Bismuth oxide polymorphs (β-Bi2O3 nanoparticles and α-Bi2O3 coral-like morphology) were synthesized and they show an enhanced efficacy for the degradation of rhodamine B and acid orange 7 as compared to that of methylene blue and methyl orange under simulated solar illumination.

Two-fold 2D + 2D → 2D interweaved rhombus (4,4) grid: synthesis, structure, and dye removal properties in darkness and in daylight

2019 ◽  
Vol 48 (3) ◽  
pp. 1095-1107 ◽  
Author(s):  
Meng-Jung Tsai ◽  
Jheng-Hua Luo ◽  
Jing-Yun Wu
Keyword(s):  
Methylene Blue ◽  
Methyl Orange ◽  
Malachite Green ◽  
Dye Removal ◽  
Acid Orange 7 ◽  
High Adsorption ◽  
Acid Orange ◽  
Adsorption Capacities

A rhombus (4,4) grid showing two-fold 2D + 2D → 2D interweaved nets appeared to be a good adsorbent to selectively adsorb and separate anionic methyl orange (MO) and acid orange 7 (AO7) dyes over cationic methylene blue (MB) and malachite green (MG) from water with high adsorption capacities in both darkness and daylight.

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