scholarly journals Hierarchical TiO2 Layers Prepared by Plasma Jets

Nanomaterials ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3254
Author(s):  
Radek Zouzelka ◽  
Jiri Olejnicek ◽  
Petra Ksirova ◽  
Zdenek Hubicka ◽  
Jan Duchon ◽  
...  
Keyword(s):  
Environmental Remediation ◽  
Advanced Oxidation Processes ◽  
Reaction Rate ◽  
Photocatalytic Performance ◽  
Scale Up ◽  
Textural Properties ◽  
Heterogeneous Photocatalysis ◽  
Reaction Rate Constant ◽  
Plasma Jets ◽  
Physico Chemical

Heterogeneous photocatalysis of TiO2 is one of the most efficient advanced oxidation processes for water and air purification. Here, we prepared hierarchical TiO2 layers (Spikelets) by hollow-cathode discharge sputtering and tested their photocatalytic performance in the abatement of inorganic (NO, NO2) and organic (4-chlorophenol) pollutant dispersed in air and water, respectively. The structural-textural properties of the photocatalysts were determined via variety of physico-chemical techniques (XRD, Raman spectroscopy, SEM, FE-SEM. DF-TEM, EDAX and DC measurements). The photocatalysis was carried out under conditions similar to real environment conditions. Although the abatement of NO and NO2 was comparable with that of industrial benchmark Aeroxide® TiO2 P25, the formation of harmful nitrous acid (HONO) product on the Spikelet TiO2 layers was suppressed. Similarly, in the decontamination of water by organics, the mineralization of 4-chlorophenol on Spikelet layers was interestingly the same, although their reaction rate constant was three-times lower. The possible explanation may be the more than half-magnitude order higher external quantum efficacy (EQE) compared to that of the reference TiO2 P25 layer. Therefore, such favorable kinetics and reaction selectivity, together with feasible scale-up, make the hierarchical TiO2 layers very promising photocatalyst which can be used for environmental remediation.

scholarly journals Heterogeneous Photocatalysis Scalability for Environmental Remediation: Opportunities and Challenges

Catalysts ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1109 ◽  
Author(s):  
Sherif Younis ◽  
Ki-Hyun Kim
Keyword(s):  
Environmental Remediation ◽  
Scale Up ◽  
Pilot Scale ◽  
Heterogeneous Photocatalysis ◽  
Solar Irradiation ◽  
Practical Implementation ◽  
Feed Composition ◽  
Photocatalytic System ◽  
Environmental Treatment ◽  
Contemporary Perspective

Heterogeneous photocatalysis is an ecofriendly technique for purifying organic pollutants in environmental systems. While pilot-scale photoreactors have explored photocatalytic system upscalibility, their practical implementation is restricted for various reasons. These include feed composition alteration, complicated photoreactor designs, high operation and synthesis costs, photocatalyst poisoning, low quantum yield under solar irradiation, fast exciton recombination, and low reuse or regeneration capabilities. In this paper, we highlight the photocatalyst scalability challenges for real-world applications. We also provide an in-depth discussion on photocatalyst opportunities for effective air and water pollution control. Lastly, we offer a contemporary perspective on photocatalysis scale-up for the real environmental treatment.

scholarly journals Removal of Ampicillin by Heterogeneous Photocatalysis: Combined Experimental and DFT Study

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1992
Author(s):  
Lenka Belhacova ◽  
Hana Bibova ◽  
Tereza Marikova ◽  
Martin Kuchar ◽  
Radek Zouzelka ◽  
...  
Keyword(s):  
Degradation Mechanism ◽  
Textural Properties ◽  
Degradation Pathway ◽  
Heterogeneous Photocatalysis ◽  
Reaction Rate Constant ◽  
Radical Scavenger ◽  
Reaction Products ◽  
Degree Of Mineralization ◽  
Ampicillin Concentration ◽  
Nominal Size

A long-term exposition of antibiotics represents a serious problem for the environment, especially for human health. Heterogeneous photocatalysis opens a green way for their removal. Here, we correlated the structural-textural properties of TiO2 photocatalysts with their photocatalytic performance in ampicillin abatement. The tested nanoparticles included anatase and rutile and their defined mixtures. The nominal size range varied from 5 to 800 nm, Aeroxide P25 serving as an industrial benchmark reference. The degradation mechanism of photocatalytic ampicillin abatement was studied by employing both experimental (UPLC/MS/MS, hydroxyl radical scavenger) and theoretical (quantum calculations) approaches. Photocatalytic activity increased with the increasing particle size, generally, anatase being more active than rutile. Interestingly, in the dark, the ampicillin concentration decreased as well, especially in the presence of very small nanoparticles. Even if the photolysis of ampicillin was negligible, a very high degree of mineralization of antibiotic was achieved photocatalytically using the smallest nanoparticles of both allotropes and their mixtures. Furthermore, for anatase samples, the reaction rate constant increases with increasing crystallite size, while the degree of mineralization decreases. Importantly, the suggested degradation pathway mechanism determined by DFT modeling was in very good agreement with experimentally detected reaction products.

scholarly journals Silica Monolith for the Removal of Pollutants from Gas and Aqueous Phases

Molecules ◽  
2021 ◽  
Vol 26 (5) ◽  
pp. 1316
Author(s):  
Vanessa Miglio ◽  
Chiara Zaccone ◽  
Chiara Vittoni ◽  
Ilaria Braschi ◽  
Enrico Buscaroli ◽  
...  
Keyword(s):  
Rhodamine B ◽  
Water Solution ◽  
Synthesis Method ◽  
Textural Properties ◽  
Adsorption Properties ◽  
Water Soluble ◽  
Silica Monoliths ◽  
Physico Chemical ◽  
Gaseous Toluene ◽  
Mcm 41

This study focused on the application of mesoporous silica monoliths for the removal of organic pollutants. The physico-chemical textural and surface properties of the monoliths were investigated. The homogeneity of the textural properties along the entire length of the monoliths was assessed, as well as the reproducibility of the synthesis method. The adsorption properties of the monoliths for gaseous toluene, as a model of Volatile Organic Compounds (VOCs), were evaluated and compared to those of a reference meso-structured silica powder (MCM-41) of commercial origin. Silica monoliths adsorbed comparable amounts of toluene with respect to MCM-41, with better performances at low pressure. Finally, considering their potential application in water phase, the adsorption properties of monoliths toward Rhodamine B, selected as a model molecule of water soluble pollutants, were studied together with their stability in water. After 24 h of contact, the silica monoliths were able to adsorb up to the 70% of 1.5 × 10−2 mM Rhodamine B in water solution.

scholarly journals Valorisation of Coffee Roasting By-Products: Recovery of Silverskin Fat By Supercritical CO2 Extraction

2021 ◽  
Author(s):  
Rita Nasti ◽  
Andrea Galeazzi ◽  
Stefania Marzorati ◽  
Federica Zaccheria ◽  
Nicoletta Ravasio ◽  
...  
Keyword(s):  
Scale Up ◽  
Added Value ◽  
Supercritical Co2 Extraction ◽  
Green Technologies ◽  
Coffee Silverskin ◽  
New Concepts ◽  
Physico Chemical ◽  
High Investment ◽  
Fat Yield ◽  
By Products

AbstractRecovery of agro and food-industrial waste and their valorisation via green technologies can help to outline new concepts of industrial strategies. In this contest, a fat enriched of added-value components was extracted from coffee silverskin by applying a supercritical fluid extraction technique (sc-CO2). An appropriate modulation of process parameters like temperature (T = 35, 50, 60 °C) and pressure (p = 200–300 bar) influences the fat yield and the chemical composition, opening the way for targeted extraction. The extraction time, the organic solvent use and the energy consume were reduced compared to Soxhlet. Moreover, a mathematical model was constructed based on the experimental data collected, employed apparatus, and physico-chemical characteristics of biomass, pointing to a possible industrial scale-up. The experimental results are accompanied by a preliminary cost of manufacturing (COM), highlighting how the high investment for the apparatus is compensated by several benefits. Graphic Abstract

ZIF-8 calcination derived Cu2O-ZnO* material for enhanced visible-light photocatalytic performance

2021 ◽  
Author(s):  
YiLin Yin ◽  
Jingchao Liu ◽  
Zengnan Wu ◽  
Ting Zhang ◽  
Zenghe Li
Keyword(s):  
Solar Cells ◽  
Visible Light ◽  
Environmental Remediation ◽  
Photocatalytic Performance ◽  
Morphology Control ◽  
Visible Light Photocatalytic

As one of the most essential semiconductors, ZnO has been widely used for solar cells, photocatalysis, environmental remediation, etc. Doping and morphology control of ZnO can significantly improve the efficiency...

Single-atom catalysis in advanced oxidation processes for environmental remediation

2021 ◽  
Author(s):  
Yanan Shang ◽  
Xing Xu ◽  
Baoyu Gao ◽  
Shaobin Wang ◽  
Xiaoguang Duan
Keyword(s):  
Environmental Remediation ◽  
Advanced Oxidation Processes ◽  
Advanced Oxidation ◽  
Single Atom ◽  
Oxidation Processes ◽  
Recent Advances ◽  
Carbon Based ◽  
Advanced Oxidation Technologies

This review presents the recent advances in synthetic strategies, characterisation, and computations of carbon-based single-atom catalysts, as well as their innovative applications and mechanisms in advanced oxidation technologies.

scholarly journals Determination of exothermic batch reactor specific model parameters

2019 ◽  
Vol 292 ◽  
pp. 01063
Author(s):  
Lubomír Macků
Keyword(s):  
Rate Constant ◽  
Reaction Rate ◽  
Batch Reactor ◽  
Specific Model ◽  
Reaction Rate Constant ◽  
Order Reaction ◽  
First Order Reaction ◽  
Model Parameters ◽  
Reactor Model ◽  
First Order

An alternative method of determining exothermic reactor model parameters which include first order reaction rate constant is described in this paper. The method is based on known in reactor temperature development and is suitable for processes with changing quality of input substances. This method allows us to evaluate the reaction substances composition change and is also capable of the reaction rate constant (parameters of the Arrhenius equation) determination. Method can be used in exothermic batch or semi- batch reactors running processes based on the first order reaction. An example of such process is given here and the problem is shown on its mathematical model with the help of simulations.

Performance of Photocatalytic Microfiltration with Hollow Fiber Membrane

2007 ◽  
Vol 544-545 ◽  
pp. 95-98 ◽  
Author(s):  
Jong Tae Jung ◽  
Jong Oh Kim ◽  
Won Youl Choi
Keyword(s):  
Heavy Metals ◽  
Humic Acid ◽  
Rate Constant ◽  
Hollow Fiber ◽  
Reaction Rate ◽  
Hollow Fiber Membrane ◽  
Membrane Surface ◽  
Reaction Rate Constant ◽  
Operational Parameters ◽  
Tio2 Particles

The purpose of this study is to investigate the effect of the operational parameters of the UV intensity and TiO2 dosage for the removal of humic acid and heavy metals. It also evaluated the applicability of hollow fiber microfiltration for the separation of TiO2 particles in photocatalytic microfiltration systems. TiO2 powder P-25 Degussa and hollow fiber microfiltration with a 0.4 μm nominal pore size were used for experiments. Under the conditions of pH 7 and a TiO2 dosage 0.3 g/L, the reaction rate constant (k) for humic acid and heavy metals increased with an increase of the UV intensity in each process. For the UV/TiO2/MF process, the reaction rate constant (k) for humic acid and Cu, with the exception of Cr in a low range of UV intensity, was higher compared to that of UV/TiO2 due to the adsorption of the membrane surface. The reaction rate constant (k) increased as the TiO2 dosage increased in the range of 0.1~0.3 g/L. However it decreased for a concentration over 0.3 g/L of TiO2. For the UV/TiO2/MF process, TiO2 particles could be effectively separated from treated water via membrane rejection. The average removal efficiency for humic acid and heavy metals during the operational time was over 90 %. Therefore, photocatalysis with a membrane is believed to be a viable process for humic acid and heavy metals removal.

Reaction rate constant of SO3+ NH3in the gas phase

1990 ◽  
Vol 95 (D9) ◽  
pp. 13981 ◽  
Author(s):  
Gaunlin Shen ◽  
Masako Suto ◽  
L. C. Lee
Keyword(s):  
Gas Phase ◽  
Rate Constant ◽  
Reaction Rate ◽  
Reaction Rate Constant

Photocatalytic Degradation of Methyl Orange by TiO2/Schorl Photocatalyst: Kinetics and Thermodynamics

2015 ◽  
Vol 713-715 ◽  
pp. 2789-2792
Author(s):  
Huan Yan Xu ◽  
Xue Li ◽  
Yan Li ◽  
Ping Li ◽  
Wei Chao Liu
Keyword(s):  
Methyl Orange ◽  
Reaction Rate ◽  
Reaction Kinetic ◽  
Kinetic Studies ◽  
Reaction Rate Constant ◽  
Order Reaction ◽  
Solution Ph ◽  
Kinetics And Thermodynamics ◽  
Hoff Equation ◽  
Degradation Of Methyl Orange

An active dye, Methyl Orange (MO) was employed as the target pollutant to evaluate the photocatalytic activity of TiO2/schorl composite and the kinetics and thermodynamics of this process was emphasized in this work. Langmuir–Hinshelwood kinetic model was employed for the kinetic studies and the results revealed that the process of MO photocatalytic discoloration by TiO2/schorl composite followed one order reaction kinetic equation under different conditions. The reaction rate constant (k) increased with initial MO concentration decreasing. When the catalyst dosage or solution pH increased,kvalues increased and then decreased. The possible reasons for these phenomena were discussed. Finally, the thermodynamic parameters ΔG, ΔH, ΔSwere obtained by the classical Van't Hoff equation.

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