scholarly journals Spherical Ni 3 S 2 /Fe‐NiP x Magic Cube with Ultrahigh Water/Seawater Oxidation Efficiency

2022 ◽  
pp. 2104846
Author(s):  
Xu Luo ◽  
Pengxia Ji ◽  
Pengyan Wang ◽  
Xin Tan ◽  
Lei Chen ◽  
...  
Keyword(s):  
Magic Cube ◽  
Oxidation Efficiency

Multi-level Security Based On Dynamic Magic Cube And Chaotic Maps

2017 ◽  
pp. 106
Author(s):  
Dhaher Abass Redha ◽  
Marwa Mohamed ali Mohsen
Keyword(s):  
Chaotic Maps ◽  
Multi Level ◽  
Magic Cube

scholarly journals CO Oxidation Efficiency and Hysteresis Behavior over Mesoporous Pd/SiO2 Catalyst

Catalysts ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 131 ◽  
Author(s):  
Rola Mohammad Al Soubaihi ◽  
Khaled Mohammad Saoud ◽  
Myo Tay Zar Myint ◽  
Mats A. Göthelid ◽  
Joydeep Dutta
Keyword(s):  
Carbon Monoxide ◽  
Catalytic Activity ◽  
Co Oxidation ◽  
Active Sites ◽  
Bond Activation ◽  
Dissociative Adsorption ◽  
High Catalytic Activity ◽  
Good Catalytic Activity ◽  
Pretreatment Conditions ◽  
Oxidation Efficiency

Carbon monoxide (CO) oxidation is considered an important reaction in heterogeneous industrial catalysis and has been extensively studied. Pd supported on SiO2 aerogel catalysts exhibit good catalytic activity toward this reaction owing to their CO bond activation capability and thermal stability. Pd/SiO2 catalysts were investigated using carbon monoxide (CO) oxidation as a model reaction. The catalyst becomes active, and the conversion increases after the temperature reaches the ignition temperature (Tig). A normal hysteresis in carbon monoxide (CO) oxidation has been observed, where the catalysts continue to exhibit high catalytic activity (CO conversion remains at 100%) during the extinction even at temperatures lower than Tig. The catalyst was characterized using BET, TEM, XPS, TGA-DSC, and FTIR. In this work, the influence of pretreatment conditions and stability of the active sites on the catalytic activity and hysteresis is presented. The CO oxidation on the Pd/SiO2 catalyst has been attributed to the dissociative adsorption of molecular oxygen and the activation of the C-O bond, followed by diffusion of adsorbates at Tig to form CO2. Whereas, the hysteresis has been explained by the enhanced stability of the active site caused by thermal effects, pretreatment conditions, Pd-SiO2 support interaction, and PdO formation and decomposition.

scholarly journals UV/Vis-Based Persulphate Activation for p-Nitrophenol Degradation

Catalysts ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 480
Author(s):  
Valentin Dubois ◽  
Carmen S. D. Rodrigues ◽  
Ana S. P. Alves ◽  
Luis M. Madeira
Keyword(s):  
Reaction Time ◽  
Oxidation Process ◽  
Activation Process ◽  
Direct Photolysis ◽  
Simulated Solar Light ◽  
Uv Visible ◽  
Oxidation Efficiency ◽  
Nitrophenol Degradation ◽  
Persulphate Oxidation ◽  
Radiation Type

In the present work, the degradation of p-nitrophenol (PNP) and its mineralization by a UV/Vis-based persulphate activation process was investigated. Firstly, a screening of processes as direct photolysis, persulphate alone and persulphate activated by radiation was performed. The incidence of radiation demonstrated to have an important role in the oxidant activation, allowing to achieve the highest PNP and total organic carbon (TOC) removals. The maximum PNP oxidation (100%) and mineralization (61.6%)—both after 2 h of reaction time—were reached when using T = 70 °C, (S2O82−) = 6.4 g/L and I = 500 W/m2. The influence of radiation type (ultraviolet/visible, visible or simulated solar light) was also evaluated, being found that the source with the highest emission of ultraviolet radiation (UV/visible) allowed to achieve the best oxidation efficiency; however, solar radiation also reached very-good performance. According to quenching experiments, the sulphate radical is key in the activated persulphate oxidation process, but the hydroxyl radical also plays an important role.

scholarly journals Ether Oxidation by an Evolved Fungal Heme-Peroxygenase: Insights into Substrate Recognition and Reactivity

2021 ◽  
Vol 7 (8) ◽  
pp. 608
Author(s):  
Raul Mireles ◽  
Joaquin Ramirez-Ramirez ◽  
Miguel Alcalde ◽  
Marcela Ayala
Keyword(s):  
Molecular Weight ◽  
Environmental Conditions ◽  
Substrate Recognition ◽  
Enzyme Inactivation ◽  
Biochemical Reaction ◽  
Low Molecular Weight ◽  
Factors Influencing ◽  
Secondary Reactions ◽  
Oxidation Efficiency ◽  
Favorable Conditions

Ethers can be found in the environment as structural, active or even pollutant molecules, although their degradation is not efficient under environmental conditions. Fungal unspecific heme-peroxygenases (UPO were reported to degrade low-molecular-weight ethers through an H2O2-dependent oxidative cleavage mechanism. Here, we report the oxidation of a series of structurally related aromatic ethers, catalyzed by a laboratory-evolved UPO (PaDa-I) aimed at elucidating the factors influencing this unusual biochemical reaction. Although some of the studied ethers were substrates of the enzyme, they were not efficiently transformed and, as a consequence, secondary reactions (such as the dismutation of H2O2 through catalase-like activity and suicide enzyme inactivation) became significant, affecting the oxidation efficiency. The set of reactions that compete during UPO-catalyzed ether oxidation were identified and quantified, in order to find favorable conditions that promote ether oxidation over the secondary reactions.

scholarly journals Modified-TiO2 Photocatalyst Supported on β-SiC Foams for the Elimination of Gaseous Diethyl Sulfide as an Analog for Chemical Warfare Agent: Towards the Development of a Photoreactor Prototype

Catalysts ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 403
Author(s):  
Armelle Sengele ◽  
Didier Robert ◽  
Nicolas Keller ◽  
Valérie Keller
Keyword(s):  
Photocatalytic Oxidation ◽  
Chemical Warfare Agents ◽  
Chemical Warfare Agent ◽  
Chemical Warfare ◽  
Diethyl Sulfide ◽  
Tio2 Photocatalysts ◽  
Doped Tio2 ◽  
Model Molecule ◽  
Warfare Agents ◽  
Oxidation Efficiency

In the context of the increase in chemical threat due to warfare agents, the development of efficient methods for destruction of Chemical Warfare Agents (CWAs) are of first importance both for civilian and military purposes. Amongst possible methods for destruction of CWAs, photocatalytic oxidation is an alternative one. The present paper reports on the preparation of Ta and Sn doped TiO2 photocatalysts immobilized on β-SiC foams for the elimination of diethyl sulfide (DES) used as a model molecule mimicking Yperite (Mustard Gas) in gaseous phase. Photo-oxidation efficiency of doped TiO2 catalyst has been compared with TiO2-P25. Here, we demonstrate that the Sn doped-TiO2 with a Polyethylene glycol (PEG)/TiO2 ratio of 7 exhibits the best initial activity (up to 90%) but is deactivates more quickly than Ta doped-TiO2 (40% after 800 min). The activity of the catalysts is strongly influenced by the adsorption properties of the support, as β-SiC foams adsorb DES and other sulfur compounds. This adsorption makes it possible to limit the poisoning of the catalysts and to maintain an acceptable conversion rate even after ten hours under continuous DES flow. Washing with NaOH completely regenerates the catalyst after a firs treatment and even seems to “wash” it by removing impurities initially present on the foams.

Comparison study of TEMPO and phthalimide-N-oxyl (PINO) radicals on oxidation efficiency toward cellulose

2013 ◽  
Vol 91 (2) ◽  
pp. 502-507 ◽  
Author(s):  
Gabriela Biliuta ◽  
Lidija Fras ◽  
Mioara Drobota ◽  
Zdenka Persin ◽  
Tatjana Kreze ◽  
...  
Keyword(s):  
Comparison Study ◽  
Oxidation Efficiency

scholarly journals Multiple-Image Encryption Algorithm Based on the 3D Permutation Model and Chaotic System

Symmetry ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 660 ◽  
Author(s):  
Xiaoqiang Zhang ◽  
Xuesong Wang
Keyword(s):  
Image Encryption ◽  
Chaotic System ◽  
Three Dimensional ◽  
Multiple Image ◽  
External Mode ◽  
Large Numbers ◽  
Permutation Model ◽  
Magic Cube ◽  
Exclusive Or ◽  
Image Encryption Algorithm

Large numbers of images are produced in many fields every day. The content security of digital images becomes an important issue for scientists and engineers. Inspired by the magic cube game, a three-dimensional (3D) permutation model is established to permute images, which includes three permutation modes, i.e., internal-row mode, internal-column mode, and external mode. To protect the image content on the Internet, a novel multiple-image encryption symmetric algorithm (block cipher) with the 3D permutation model and the chaotic system is proposed. First, the chaotic sequences and chaotic images are generated by chaotic systems. Second, the sender permutes the plain images by the 3D permutation model. Lastly, the sender performs the exclusive OR operation on permuted images. The simulation and algorithm comparisons display that the proposed algorithm possesses desirable encryption images, high security, and efficiency.

Modeling and prediction for the oxidation efficiency of magnesium sulfite in aeration tank of magnesium-based seawater exhaust gas clean system

2017 ◽  
Vol 233 (1) ◽  
pp. 164-173
Author(s):  
Quan Liu ◽  
Yimin Zhu ◽  
Tie Li ◽  
Xiaojia Tang ◽  
Weifeng Liu ◽  
...  
Keyword(s):  
Flow Field ◽  
Initial Conditions ◽  
Negative Impact ◽  
Fluid Model ◽  
Aeration Tank ◽  
Exhaust Gas ◽  
Clean System ◽  
Physics Modeling ◽  
Set Up ◽  
Oxidation Efficiency

In magnesium-based seawater exhaust gas clean system, the desulfurization by-product, magnesium sulfite (MgSO3), has a negative impact on the ecological environment, which needs to be treated to make harmless. Due to the limited space on board, the aeration oxidation method is used to convert it to magnesium sulfate. Because of the variable size, shape and flow field of aeration tank, it is difficult and expensive to design and verify the oxidation efficiency of the aeration tank by experimental method. In this work, in order to predict the oxidation efficiency accurately, RFlow, a computational fluid dynamics software, was used to analyze the flow field and MgSO3 oxidation reaction in aeration tank. The subdomain technology was adopted for physics modeling and mesh generation of the aeration tank, and the total number of meshes was 285,000. The multi-phase flow field model was set up using the multi-fluid model and dispersive k-ε turbulence model. Under the given initial conditions, the predicted oxidation efficiency was 94.2%. Compared with the results of the actual ship test, the prediction model for MgSO3 oxidation efficiency of the aeration tank is reliable.

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