Modified graphene quantum dots-zinc oxide nanocomposites for photocatalytic degradation of organic dyes and commercial herbicide

The high crystallinity of graphene quantum dots-ZnO nanocomposites is considered to have a significant effect in improving the carrier lifetime for enhanced photocatalytic degradation. The graphene quantum dots-ZnO nanocomposites were synthesized by adding graphene quantum dots solution into starting precursors during the precipitation. Characterization was performed using various techniques. High crystallinity of graphene quantum dots-ZnO nanocomposites is obtained in terms of increased crystal size and decreased dislocation density. The improved crystallinity increases the carrier lifetime on the material surface for the functional improvement of photocatalytic material. Photocatalytic test of methylene blue and methyl orange was performed under UV irradiation. Degradation rate constant reaches the maximum value for both organic dyes for the appropriate preparing condition of graphene quantum dots-ZnO nanocomposites. The graphene quantum dots-ZnO nanocomposites were then applied to degrade commercial glyphosate herbicide contaminants for an agricultural wastewater treatment investigation. The investigation aims to demonstrate a facile useful way of herbicide contaminant reduction for the better health of farmers. The graphene quantum dots-ZnO nanocomposites show an enhancement of the photocatalytic process with improved degradation rate constant (23% increased) in comparison to pure ZnO. Therefore, this work demonstrates that graphene quantum dots-ZnO nanocomposites can be used as a photocatalytic material for degrading organic dyes and commercial herbicide contaminants owing to its low-cost and environmental-friendly properties.

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Enhanced photocatalytic degradation of N-doped TiO2-SiO2 composite for degradation of phenol under simulated natural light assisted by S2O8 2- anions

IOP Conference Series Earth and Environmental Science ◽

10.1088/1755-1315/947/1/012020 ◽

2021 ◽

Vol 947 (1) ◽

pp. 012020

Author(s):

Huu-Tai Huynh ◽

Minh-Vien Le ◽

Luan Van Hoang

Keyword(s):

Photocatalytic Degradation ◽

Band Gap ◽

Rate Constant ◽

Degradation Rate ◽

Band Gap Energy ◽

Natural Light ◽

Doped Tio2 ◽

Gap Energy ◽

Molar Ratios ◽

Degradation Rate Constant

Abstract In recent years, TiO2 photocatalyst has been studied to increase the overall efficiency in the degradation of organic pollutants in water. Several solutions have been proposed such as non-metal doping to reduce a high band gap energy (3.2 eV) of TiO2 to increase absorption in the visible region and synthesis of composite photocatalyst to improve the efficiency of electron-hole separation and the specific surface area. Herein, the N-doped TiO2-SiO2 photocatalysts were investigated. Powder samples with three molar ratios of TiO2/SiO2 (95/5-TS5, 85/15-TS15, 75/25-TS25) were successfully synthesized, characterized, and estimated their photocatalytic activity toward the phenol degradation (initial concentration to be 10 ppm) under simulated natural light. N-doped TiO2-SiO2 samples were prepared with molar ratios of N to designed TiO2 to be 3%, 5%, 7%. The 3N-TS5 photocatalyst (3 mol % N doped TS5) shows the highest phenol efficiency degradation, to be 95% in 4 h, photocatalytic degradation rate constant of 1.02}10−2 min−1 due to its narrower band gap energy (3.05 eV). Furthermore, the addition of S2O8 2- anions at a concentration of 1 mM is enhanced degradation efficiency and degradation rate. And phenol is almost completely degraded within 60 min and achieved a degradation rate constant of 7.65*10−2 min−1, 7.5 times higher than that without the presence of S2O8 2- anions. This attractive result is attributed to the generation of sulfate radical (SO4 *“) during photolysis. Finally, N-doped TiO2-SiO2 photocatalyst assisted by S2O8 2- anions shows potential to design and improve manufacturing processes to obtain photoreactors for organic degradation from waste-water under natural light degradation.

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Promoted photocatalytic degradation and detoxication performance for norfloxacin on Z-scheme phosphate-doped BiVO4/graphene quantum dots/P-doped g-C3N4

Separation and Purification Technology ◽

10.1016/j.seppur.2021.118692 ◽

2021 ◽

pp. 118692

Author(s):

Meiyang Wang ◽

Han Yu ◽

Pan Wang ◽

Zexu Chi ◽

Zhenzong Zhang ◽

...

Keyword(s):

Quantum Dots ◽

Photocatalytic Degradation ◽

Graphene Quantum Dots

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Enhanced solar photocatalytic degradation of nitric oxide using graphene quantum dots/bismuth tungstate composite catalysts

Chemical Engineering Journal ◽

10.1016/j.cej.2021.129595 ◽

2021 ◽

Vol 420 ◽

pp. 129595

Author(s):

Yunpei Cui ◽

Teng Wang ◽

Jiayou Liu ◽

Lizhen Hu ◽

Qianqian Nie ◽

...

Keyword(s):

Nitric Oxide ◽

Quantum Dots ◽

Photocatalytic Degradation ◽

Graphene Quantum Dots ◽

Bismuth Tungstate ◽

Composite Catalysts

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Sensitivity analysis using a diffuse pollution hydrologic model to assess factors affecting pesticide concentrations in river water

Water Science & Technology ◽

10.2166/wst.2010.540 ◽

2010 ◽

Vol 62 (11) ◽

pp. 2579-2589 ◽

Cited By ~ 3

Author(s):

Koji Tani ◽

Yoshihiko Matsui ◽

Kentaro Narita ◽

Koichi Ohno ◽

Taku Matsushita

Keyword(s):

Sensitivity Analysis ◽

River Water ◽

Rate Constant ◽

Degradation Rate ◽

Hydrologic Model ◽

Adsorption Coefficient ◽

Pesticide Concentration ◽

Artificial Drainage ◽

Degradation Rate Constant ◽

Intermittent Irrigation

We quantitatively evaluated the factors that affect the concentrations of rice-farming pesticides (an herbicide and a fungicide) in river water by a sensitivity analysis using a diffuse pollution hydrologic model. Pesticide degradation and adsorption in paddy soil affected concentrations of the herbicide pretilachlor but did not affect concentrations of the fungicide isoprothiolane. We attributed this difference to the timing of pesticide application in relation to irrigation and drainage of the rice paddy fields. The herbicide was applied more than a month before water drainage of the fields and runoff was gradual over a long period of time, whereas the fungicide was applied shortly before drainage and runoff was rapid. However, the effects of degradability-in-water on the herbicide and fungicide concentrations were similar, with concentrations decreasing only when the rate constant of degradation in water was large. We also evaluated the effects of intermittent irrigation methods (irrigation/artificial drainage or irrigation/percolation) on pesticide concentrations in river water. The runoff of the fungicide, which is applied near or in the period of intermittent irrigation, notably decreased when the method of irrigation/artificial drainage was changed to irrigation/percolation. In a sensitivity analysis evaluating the synergy effect of degradation and adsorbability in soil, the degradation rate constant in soil greatly affected pesticide concentration when the adsorption coefficient was small but did not affect pesticide concentration when the adsorption coefficient was large. The pesticide concentration in the river water substantially decreased when either or both the degradation rate constant in soil and adsorption coefficient was large.

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Gamma ray assisted modification of carbon quantum dot/polyurethane nanocomposites: structural, mechanical and photocatalytic study

RSC Advances ◽

10.1039/c9ra00500e ◽

2019 ◽

Vol 9 (11) ◽

pp. 6278-6286 ◽

Cited By ~ 4

Author(s):

Milica Budimir ◽

Zoran Marković ◽

Dragana Jovanović ◽

Miloš Vujisić ◽

Matej Mičušík ◽

...

Keyword(s):

Quantum Dots ◽

Quantum Dot ◽

Photocatalytic Degradation ◽

Gamma Ray ◽

Organic Dyes ◽

Carbon Quantum Dots ◽

Carbon Quantum Dot ◽

Polyurethane Nanocomposites

The present study reports the results of the gamma ray-assisted modification of hydrophobic carbon quantum dots (hCQDs)/polyurethane nanocomposites for photocatalytic degradation of organic dyes.

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pH effect on stability and kinetics degradation of nitazoxanide in solution

Drug Analytical Research ◽

10.22456/2527-2616.101465 ◽

2020 ◽

Vol 4 (1) ◽

pp. 12-17

Author(s):

Fábio Barbosa ◽

Leonardo Pezzi ◽

Julia Sorrentino ◽

Martin Steppe ◽

Nadia Volpato ◽

...

Keyword(s):

Rate Constant ◽

Degradation Product ◽

Degradation Rate ◽

Degradation Kinetics ◽

Ph Effect ◽

Degradation Rate Constant ◽

Main Degradation Product ◽

Wide Ph Range ◽

The Stability ◽

Ph Range

Stability studies correspond to a set of tests designed to assess changes in the quality of a given drug over time and under the influence of a number of factors. Among these factors, pH plays an important role, due to the catalytic effect that hydronium and hydroxide ions can play in several reactions. In the present study, the degradation kinetics of nitazoxanide was evaluated over a wide pH range, and the main degradation product generated was identified by LC-MS/MS. Nitazoxanide showed first-order degradation kinetics in the pH range of 0.01 to 10.0 showing greater stability between pH 1.0 and 4.0. The degradation rate constant calculated for these pH was 0.0885 x 10-2 min-1 and 0.0689 x 10-2 min-1, respectively. The highest degradation rate constant value was observed at pH 10.0 (0.7418 x 10-2 min-1) followed by pH 0.01 (0.5882 x 10-2 min-1). A major degradation product (DP-1) was observed in all conditions tested. Through LC-MS/MS analysis, DP-1 was identified as a product of nitazoxanide deacetylation. The effect of pH on the stability of nitazoxanide and the kinetic data obtained contribute to a better understanding of the intrinsic stability characteristics of nitazoxanide.

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Removal of methyl orange (MO) using carbon quantum dots (CQDs) derived from watermelon rinds

International Journal of Engineering Technology and Sciences ◽

10.15282/ijets.v6i1.2226 ◽

2019 ◽

Vol 6 (1) ◽

pp. 91-99

Author(s):

Azrina Abd Aziz ◽

U.R. Ramzilah

Keyword(s):

Quantum Dots ◽

Methyl Orange ◽

Photocatalytic Degradation ◽

Degradation Rate ◽

Photocatalytic Performance ◽

Carbon Quantum Dots ◽

Facile Hydrothermal Method ◽

X Ray ◽

Degradation Activity ◽

Scanning Electron

In this study, carbon quantum dots (CQDs) was prepared via a facile hydrothermal method. The objective for this study is to assess the performance of CQDs in photocatalytic degradation activity of methyl orange (MO) under artificial visible light source. For that reason, the prepared photocatalyst undergo further characterization by scanning electron microscope (SEM), energy dispersive X-ray spectroscope (EDX) and UV- Vis spectrophotometer (UV-VIS) to verify the morphology structure of the photocatalyst, elemental composition as well as the absorbance intensity, respectively. The results indicates that the prepared photocatalyst possess irregular porous shape with nanometre (nm) dimensions that can escalate the surface area for photocatalytic degradation activity. The elements of the photocatalyst mainly consist of carbon and oxygen as the major constituents in which necessary for photocatalytic activity with intense peak of absorbance intensity. The prepared CQDs also shows an excellent photocatalytic performance over the MO with degradation rate of 68.9% within 120 minutes.

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Preparation of Bi/Bi2MoO6 Plasmonic Photocatalyst with High Photocatalytic Activity Under Visible Light Irradiation

NANO ◽

10.1142/s1793292018501278 ◽

2018 ◽

Vol 13 (11) ◽

pp. 1850127 ◽

Cited By ~ 6

Author(s):

Chentao Zou ◽

Zhiyuan Yang ◽

Mengjun Liang ◽

Yunpeng He ◽

Yun Yang ◽

...

Keyword(s):

Photocatalytic Activity ◽

Visible Light ◽

Photocatalytic Degradation ◽

Rate Constant ◽

Active Species ◽

High Photocatalytic Activity ◽

Composite Photocatalysts ◽

Degradation Rate Constant ◽

Degradation Activity ◽

Spr Effect

Bi metal deposited on Bi2MoO6 composite photocatalysts have been successfully synthesized via a simple reduction method at room temperature with using NaBH4 as the reducing agent. The photocatalytic activity of the composite was evaluated by degradation of rhodamine B (RhB) and bisphenol A (BPA) solution under visible light. The rate constant of Bi/Bi2MoO6 composite to RhB is 10.8 times that of Bi2MoO6, and the degradation rate constant of BPA is 6.9 times of that of Bi2MoO6. Nitrogen absorption–desorption isotherm proved that the increase of specific surface area is one of the reasons for the improvement of photocatalytic degradation activity of Bi/Bi2MoO6 composites. The higher charge transfer efficiency of Bi/Bi2MoO6 is found through the characterization of the photocurrent and impedance, which are attributed to the surface plasmon resonance (SPR) effect produced by the introduction of the metal Bi monomer in the composite. Free radical capture experiments proved that cavitation is the main active species. Based on the above conclusions, a possible mechanism of photocatalytic degradation is proposed.

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