scholarly journals TEMPO-Functionalized Nanoporous Au Nanocomposite for the Electrochemical Detection of H2O2

2018 ◽  
Vol 2018 ◽  
pp. 1-11
Author(s):  
Dongxiao Wen ◽  
Qianrui Liu ◽  
Ying Cui ◽  
Huaixia Yang ◽  
Jinming Kong
Keyword(s):  
Electrochemical Detection ◽  
Nanoporous Gold ◽  
Carboxyl Groups ◽  
Time Interval ◽  
Optimal Conditions ◽  
Sem Images ◽  
One Step ◽  
Ph Range ◽  
Synthesis Approach ◽  
Higher Sensitivity

A novel nanocomposite of nanoporous gold nanoparticles (np-AuNPs) functionalized with 2,2,6,6-tetramethyl-1-piperidinyloxy radical (TEMPO) was prepared; assembled carboxyl groups on gold nanoporous nanoparticles surface were combined with TEMPO by the “bridge” of carboxylate-zirconium-carboxylate chemistry. SEM images and UV-Vis spectroscopies of np-AuNPs indicated that a safe, sustainable, and simplified one-step dealloying synthesis approach is successful. The TEMPO-np-AuNPs exhibited a good performance for the electrochemical detection of H2O2 due to its higher number of electrochemical activity sites and surface area of 7.49 m2g-1 for load bigger amount of TEMPO radicals. The TEMPO-functionalized np-AuNPs have a broad pH range and shorter response time for H2O2 catalysis verified by the response of amperometric signal under different pH and time interval. A wide linear range with a detection limit of 7.8 × 10-7 M and a higher sensitivity of 110.403 μA mM-1cm-2 were obtained for detecting H2O2 at optimal conditions.

scholarly journals Electrochemical Detection of 4-Nitrophenol on a Nanoporous Gold Electrode Prepared by One-Step Anode Potential Step Method

2021 ◽  
pp. 12-19
Author(s):  
Dongsheng Lai ◽  
Lin Chen ◽  
Yuqing Liu ◽  
Wei Huang
Keyword(s):  
Electrochemical Detection ◽  
Differential Pulse ◽  
Nanoporous Gold ◽  
Current Response ◽  
Step Method ◽  
Detection Range ◽  
Potential Step ◽  
One Step ◽  
Optimized Conditions ◽  
Nanoporous Gold Electrode

The wastewater containing nitrophenol compounds is discharged into the water and soil environment, causing severe environmental pollution problems. In this paper, a one-step anodic potential step method involving Au(I) disproportionation was used to prepare nanoporous gold (D-NPG) electrodes for the electrochemical detection of 4-nitrophenol (4-NP) by differential pulse voltammetry (DPV). The D-NPG electrode has a high current response to the oxidation peak of 4-hydroxylaminophenol, a product of 4-NP electroreduction. This peak is used in the 4-NP detection. Under the optimized conditions, the resulting detection range is wide (0.01~20 µM) and the detection limit is low (3.5 nM), and its anti-interference ability is good. It can be used for the electrochemical detection of 4-NP in real water samples.

Fabrication of dendritic nanoporous gold via a two-step amperometric approach: Application for electrochemical detection of methyl parathion in river water samples

Talanta ◽  
2021 ◽  
Vol 226 ◽  
pp. 122130
Author(s):  
Gilberto J. Silva Junior ◽  
Jéssica Soares Guimarães Selva ◽  
Anandhakumar Sukeri ◽  
Josué M. Gonçalves ◽  
Matias Regiart ◽  
...  
Keyword(s):  
River Water ◽  
Electrochemical Detection ◽  
Water Samples ◽  
Methyl Parathion ◽  
Nanoporous Gold ◽  
River Water Samples

scholarly journals Optimization of pH, temperature and carbon source for bioleaching of heavy metals by Aspergillus flavus isolated from contaminated soil

2019 ◽  
Vol 42 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Sadia Qayyum ◽  
Ke Meng ◽  
Sidra Pervez ◽  
Faiza Nawaz ◽  
Changsheng Peng
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Aspergillus Flavus ◽  
Contaminated Soil ◽  
Ph Value ◽  
Optimal Conditions ◽  
Batch Experiments ◽  
Molecular Biological Analysis ◽  
One Step ◽  
Industrial Mining

Abstract Soil contamination with heavy metal content is a growing concern throughout the world as a result of industrial, mining, agricultural and domestic activities. Fungi are the most common and efficient group of heavy metal resistant microbe family which have potential for metal bioleaching. The use of filamentous fungi in bioleaching of heavy metals from contaminated soil has been developed recently. The current study intends to isolate a strain with the ability to degrade the pH value of the liquid medium. Identification results based on morphological and molecular biological analysis gave a 98% match to Aspergillus flavus. Batch experiments were conducted to select the optimal conditions for bioleaching process which indicated that 130 mg/ L sucrose, neutral pH and temperature of 30°C were more suitable during 15-day bioleaching experiments using A. flavus. In one-step bioleaching, the bioleaching efficiencies were 18.16% for Pb, 39.77% for Cd and 58.22% for Zn+2, while two-step bioleaching showed efficiencies of 16.91% for Pb, 49.66% for Cd and 65.73% for Zn+2. Overall, this study indicates that bioleaching of heavy metals in contaminated soil using A. flavus has the potential for contaminated soil remediation.

Succinate Functionalization of Hyperbranched Polyglycerol-Coated Magnetic Nanoparticles as a Draw Solute During Forward Osmosis

2015 ◽  
Vol 15 (10) ◽  
pp. 8279-8284 ◽  
Author(s):  
Hee-Man Yang ◽  
Hye Min Choi ◽  
Sung-Chan Jang ◽  
Myeong Jin Han ◽  
Bum-Kyoung Seo ◽  
...  
Keyword(s):  
Magnetic Nanoparticles ◽  
Succinic Anhydride ◽  
Water Flux ◽  
Forward Osmosis ◽  
Feed Solution ◽  
Carboxyl Groups ◽  
Solute Leakage ◽  
One Step ◽  
Hyperbranched Polyglycerol ◽  
The One

Hyperbranched polyglycerol-coated magnetic nanoparticles (SHPG-MNPs) were functionalized with succinate groups to form a draw solute for use in a forward osmosis (FO). After the one-step synthesis of hyperbranched polyglycerol-coated magnetic nanoparticles (HPG-MNPs), the polyglycerol groups on the surfaces of the HPG-MNPs were functionalized with succinic anhydride moieties. The resulting SHPG-MNPs showed no change of size and magnetic property compared with HPGMNPs and displayed excellent dispersibility in water up to the concentration of 400 g/L. SHPG-MNPs solution showed higher osmotic pressure than that of HPG-MNPs solution due to the presence of surface carboxyl groups in SHPG-MNPs and could draw water from a feed solution across an FO membrane without any reverse draw solute leakage during FO process. Moreover, the water flux remained nearly constant over several SHPG-MNP darw solute regeneration cycles applied to the ultrafiltration (UF) process. The SHPG-MNPs demonstrate strong potential for use as a draw solute in FO processes.

Optimal conditions for induction of competence in nitrogen-fixing Azotobacter vinelandii

1982 ◽  
Vol 28 (4) ◽  
pp. 389-397 ◽  
Author(s):  
William J. Page
Keyword(s):  
Dissolved Oxygen ◽  
Sodium Acetate ◽  
Azotobacter Vinelandii ◽  
Nitrogenase Activity ◽  
Cell Mass ◽  
Apparent Competition ◽  
Competence Development ◽  
Optimal Conditions ◽  
Nitrogen Fixing ◽  
Ph Range

Competence development in nitrogen-fixing Azotobacter vinelandii cells was optimal at pH 7.2–7.4 which necessitated additional buffering of the iron-limited nitrogen-free competence medium or the addition of a suitable organic acid salt, e.g., sodium acetate. An autolysin was active in this pH range and competent cells were more susceptible to autolysis than the general cell population. Competence development also required restricted aeration of the culture, and only those cultures that attained zero dissolved oxygen became competent. Restricted aeration served to protect the iron-limited cell nitrogenase from oxygen inactivation thus allowing the culture to reach zero dissolved oxygen. The inclusion of additional sources of reductant, e.g., malate, in buffered competence medium resulted in increased respiration and protection of nitrogenase, increased cell mass, and poly-β-hydroxybutyrate synthesis, but decreased competence. A possible explanation for the apparent competition between competence development and nitrogenase activity is discussed.

scholarly journals Influence of hydrotalcite preparation conditions on its physico-chemical properties

2019 ◽  
Vol 12 (1) ◽  
pp. 119-126
Author(s):  
Miroslava Mališová ◽  
Michal Horňáček ◽  
Pavol Hudec ◽  
Jozef Mikulec ◽  
Vladimír Jorík ◽  
...  
Keyword(s):  
Catalytic Properties ◽  
Chemical Properties ◽  
Synthesis Temperature ◽  
Optimal Synthesis ◽  
Preparation Process ◽  
Optimal Conditions ◽  
Temperature Range ◽  
Preparation Conditions ◽  
Physico Chemical ◽  
Ph Range

Abstract The aim of the research was to prepare and characterize hydrotalcite synthesized under different preparation conditions. The most common hydrotalcite preparation is the co-precipiaton method. The preparation process strongly influences the catalytic properties of hydrotalcite; therefore, optimal conditions have to be determined. During the study, seven samples of the catalyst were prepared in the pH range from 8 to 12 and the synthesis temperature range from 25 to 55 °C. Based on several catalyst properties, optimal synthesis pH 10 was found. Ideal temperature of the preparation was determined to be 35 °C, but the temperature does not have a significant effect on the catalyst properties.

scholarly journals The Use of Calcium Lactate to Enhance the Durability and Engineering Properties of Bioconcrete

2021 ◽  
Vol 13 (16) ◽  
pp. 9269
Author(s):  
Saddam Hussein Abo Sabah ◽  
Luis Hii Anneza ◽  
Mohd Irwan Juki ◽  
Hisham Alabduljabbar ◽  
Norzila Othman ◽  
...  
Keyword(s):  
Calcium Lactate ◽  
Engineering Properties ◽  
Optimal Conditions ◽  
Scanning Electronic Microscopy ◽  
Electronic Microscopy ◽  
Sem Images ◽  
X Ray ◽  
Predicted Values ◽  
Potential Option ◽  
Scanning Electron

This study investigated the optimization of the bioconcrete engineering properties and durability as a response of the calcium lactate (CL) content (0.22–2.18 g/L) and curing duration (7–28 days) using the response surface methodology (RSM). Scanning electronic microscopy (SEM) was conducted to evaluate the microstructure of calcium precipitated inside the bioconcrete. The results indicated that the optimal conditions for the engineering properties of concrete and durability were determined at 2.18 g/L of CL content after 23.4 days. The actual and predicted values of the compressive strength, splitting tensile strength, flexural strength, and water absorption were 43.51 vs. 43.43, 3.19 vs. 3.19, 6.93 vs. 5.50, and 7.55 vs. 7.55, respectively, with a level of confidence exceeding 95%. The scanning electron microscope (SEM) images and energy-dispersive X-ray spectroscopy (EDX) proved that the amount of calcium increased with the increase in CL content up to 2.81 g/L at 23.4 days, reducing the pores inside the concrete and making it a great potential option for healing of concrete structures.

scholarly journals Studies on Highly Dense Pure YIG Polycrystalline Ceramics Fabricated by Tape-casting Method

2020 ◽  
Author(s):  
Chong Zhao ◽  
Yingkui Li ◽  
Xiaofei Shen ◽  
Zhijun Cao ◽  
Zhiquan Cao ◽  
...  
Keyword(s):  
Tape Casting ◽  
Solid State Reaction Method ◽  
Grain Structure ◽  
Casting Method ◽  
Forming Process ◽  
Sem Images ◽  
Polycrystalline Ceramics ◽  
Pure Phase ◽  
One Step ◽  
Xrd Patterns

Abstract Pure phase Y3Fe5O12 (YIG) ceramics was successfully produced by tape-casting forming process and one-step solid-state reaction method. With the sintering temperature above 1100 ºC, the pure phase YIG ceramics was synthesized with no YIP or Fe2O3 phase in XRD patterns. YIG ceramic sintering at 1400 ºC for 10 h showed a clear grain structure with an obvious grain boundary, and no pores were observed in the SEM images. YIG ceramics in this paper has a high relative density which was 99.8% and the saturation magnetization was 28.2 emu/g at room temperature. The hysteresis loss at temperatures of 230-360 K was smaller than 10 mJ/kg. The tan Se was nearly zero at 6~7 GHz and 11~12 GHz, showing that it can be used as a good material for microwave applications. In addition, the low values of tan and tan indicates that it may have a good electromagnetic wave absorption ability.

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