scholarly journals Hydrated-electron-based short chain perfluorosulfonic acid decomposition in VUV/sulfite system

2020 ◽  
Vol 20 (8) ◽  
pp. 3615-3624
Author(s):  
Yurong Gu ◽  
Zijun Dong ◽  
Xi Zhang ◽  
Qi Han ◽  
Yongbing Li
Keyword(s):  
Hydrated Electron ◽  
Short Chain ◽  
Organic Substances ◽  
Acid Decomposition ◽  
Solution Ph ◽  
High Chemical ◽  
Perfluorocarboxylic Acids ◽  
Perfluoroalkyl Radical ◽  
Photo Decomposition ◽  
High Chemical Stability

Abstract Perfluorosulfonic acids (PFSAs) have attracted increasing attention due to their global distribution, high chemical stability and persistence. As a powerful reductant, hydrated electron () shows extraordinary reactivity towards halogenated organic substances like PFSAs. In this study, -based photo-decomposition of perfluorohexane sulfonate (PFHxS) in a VUV/sulfite system was investigated. The kobs of PFHxS decomposition in the studied system was 0.0049 ± 0.0005 min−1, which was 24.5-fold faster than that in a sole VUV system. It was demonstrated that was the main reactive species responsible for PFHxS decomposition. PFHxS decomposition kinetics were accelerated at higher initial solution pH and sulfite dosage, but were restrained when higher initial PFHxS concentration was introduced. Co-existence of chloride showed slight enhancement of PFHxS decomposition, whereas nitrate and bicarbonate suppressed PFHxS decomposition. Accompanying PFHxS decomposition, short chain perfluorocarboxylic acids (PFCAs) were detected as main intermediate products. PFHxS decomposition started with C-S bond fracture, followed by perfluoroalkyl radical hydrolysis reactions and perfluorohexanoic acid (PFHxA) formation. Afterwards, PFHxA was defluorinated by stepwise loss of CF2 units to generate other short chain PFCAs.

COMPRESSIVE STRENGTH AND EXPLOSIVE CHARACTERISTICS OF POLYMER-BONDED EXPLOSIVES BASED ON HEXOGEN AND FLUOROELASTOMERS

2020 ◽  
pp. 76-83
Author(s):  
Nguyen Trung Toan
Keyword(s):  
Compressive Strength ◽  
Vinylidene Fluoride ◽  
High Energy ◽  
High Chemical ◽  
Energy Characteristics ◽  
Coating Method ◽  
Polymer Bonded Explosives ◽  
Friction Sensitivity ◽  
The Impact ◽  
High Chemical Stability

This paper describes the formulation of two polymer-bonded explosives based on RDX (hexahydro-1,3,5- trinitro-1,3,5-triazine) and fluoroelastomer binders by the water-slurry coating method. The fluoroelastomers are poly(VDF-HFP) (vinylidene fluoride-hexafluoropropene copolymer) and poly(VDF-CTFE) (vinylidene fluoride-chlorotrifluoroethylene copolymer). It has been observed that the impact sensitivity and the friction sensitivity of PBX samples were significantly lower than that of the single RDX. Results also showed that two PBX formulations have high chemical stability, high energy characteristics, and equivalent to some PBX in the world. Finally, the compressive strength of these PBX compositions was found in the range of 8-12 MPa.

scholarly journals TiO2-Coated ZnO Nanowire Arrays: A Photocatalyst with Enhanced Chemical Corrosion Resistance

Catalysts ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1289
Author(s):  
Lan Gao ◽  
Elyes Nefzaoui ◽  
Frédéric Marty ◽  
Mazen Erfan ◽  
Stéphane Bastide ◽  
...  
Keyword(s):  
Chemical Stability ◽  
Large Scale ◽  
Organic Dyes ◽  
Synthesis Method ◽  
Atomic Layer ◽  
Strong Acid ◽  
Tio2 Coating ◽  
High Chemical ◽  
Chemical Corrosion ◽  
High Chemical Stability

Photocatalysis is proven to be the most efficient and environmentally friendly method for the degradation of organic pollutants in water purification. To meet the requirement of large-scale water treatment, there are two important points: One is the lifetime and chemical stability of the photocatalyst material, especially in the complex and harsh aqueous conditions. The other is the ease of synthesis of such photocatalysts with specific nano-morphology. In this work, two common photocatalyst materials, zinc oxide (ZnO) and titanium dioxide (TiO2), are selected to form more sustainable photocatalysts with high chemical stability. This involves the combination of both TiO2 and ZnO in a two-step simple synthesis method. It appears advantageous to exploit the conformal deposition of atomic layer deposition (ALD) to achieve nanometer-thick TiO2 coating on ZnO nanowires (NWs) with a high aspect ratio, which are firmly anchored to a substrate and exhibit a large specific surface area. The high chemical stability of the ALD TiO2 coating has been investigated in detail and proven to be effective under both strong acid and strong alkaline aqueous solutions. In addition, photocatalysis experiments with organic dyes show that via this simple two-step synthesis method, the produced ZnO/TiO2 tandem does indeed exhibit improved chemical stability in a harsh environment, while allowing efficient photodegradation.

Precipitation and Coagulation of Organic Substances in Bleachery Effluents of Pulp Mills

1993 ◽  
Vol 27 (11) ◽  
pp. 193-199 ◽  
Author(s):  
S. Beulker ◽  
M. Jekel
Keyword(s):  
Organic Matter ◽  
Magnesium Hydroxide ◽  
Chemical Treatment ◽  
Organic Substances ◽  
Soluble Organic Matter ◽  
Pulp Mills ◽  
High Chemical ◽  
Physico Chemical ◽  
Chlorinated Organic ◽  
High Concentrations

The formation of chlorinated organic substances in bleachery effluents of pulp mills is avoided by changing the bleaching processes to nonchlorinating agents. However, high concentrations of poorly biodegradable and colored lignins are remaining. Precipitation can be one option in physico-chemical treatment of these waters. The influence of alum, lime and magnesium hydroxide as precipitation agents for two different bleachery wastewaters was investigated under various conditions. Alum prove to be the most effective precipitant. Application at an Al/DOC-ratio of 0.5 (g/g) yields a reduction of about 60 % of the soluble organic matter in chlorine-bleachery effluents at the pH = 5.5. Oxygen-bleachery effluents require only half of this specific dosage. Lime precipitation also causes low residual concentrations, but the high chemical demand leads to problems in application. The precipitation with magnesium hydroxide cannot be applied, because remaining concentrations of organic materials are quite high. The changes in bleaching processes are responsible for a new kind of wastewater, which has a significantly lower demand of precipitant

scholarly journals Annulated Dialkoxybenzenes as Catholyte Materials for Non-aqueous Redox Flow Batteries: Achieving High Chemical Stability through Bicyclic Substitution

2017 ◽  
Vol 7 (21) ◽  
pp. 1701272 ◽  
Author(s):  
Jingjing Zhang ◽  
Zheng Yang ◽  
Ilya A. Shkrob ◽  
Rajeev S. Assary ◽  
Siu on Tung ◽  
...  
Keyword(s):  
Chemical Stability ◽  
High Chemical ◽  
Redox Flow Batteries ◽  
Flow Batteries ◽  
High Chemical Stability

Thermal Energy Storage and Control

1975 ◽  
Vol 97 (3) ◽  
pp. 893-896 ◽  
Author(s):  
J. Schro¨der
Keyword(s):  
Heat Supply ◽  
Alkaline Earth ◽  
Heat Pipes ◽  
Alkaline Earth Metals ◽  
Melting Points ◽  
High Chemical ◽  
Heat Engines ◽  
High Level ◽  
And Control ◽  
High Chemical Stability

Eutectic fluoride mixtures of alkali and alkaline earth metals posses extremely high thermal storage capacities, and are therefore suitable for space heating as well as for powering heat engines. Their melting points ranging from 449 to 832° C are well adapted to any high level heat supply. The compounds are of high chemical stability and show no corrosive action with stainless steel. In order to make efficient use of the stored heat, good thermal insulation and controllable heat transfer are achieved by a multifoil insulation jacket with a controllable hydrogen filling. For powering engines energy transfer is realized by heat pipes.

Novel enantiomorphic Pb-coordination polymers dictated by the corresponding chiral ligands, [Pb((R,R)-TBA)(H2O)]·1.7H2O and [Pb((S,S)-TBA)(H2O)]·1.7H2O [TBA = 1,3,5-triazin-2(1H)-one-4,6-bis(alanyl)]

2021 ◽  
Author(s):  
Yunseung Kuk ◽  
Kang Min Ok
Keyword(s):  
Hydrogen Bonds ◽  
Coordination Polymers ◽  
Chemical Stability ◽  
Congo Red ◽  
Chiral Ligands ◽  
High Chemical ◽  
Selective Uptake ◽  
Congo Red Dye ◽  
Red Dye ◽  
High Chemical Stability

Two enantiomorphic Pb-coordination polymers dictated by the corresponding chiral ligands reveal high chemical stability and a selective uptake of Congo red dye through the hydrogen bonds.

Intramolecular hydrogen bond-induced high chemical stability of metal–organic frameworks

2020 ◽  
Vol 7 (19) ◽  
pp. 3548-3554
Author(s):  
Keke Wang ◽  
Qunmin Wang ◽  
Xiong Wang ◽  
Mei Wang ◽  
Qin Wang ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Intramolecular Hydrogen Bond ◽  
Chemical Stability ◽  
Metal Organic Frameworks ◽  
Carboxyl Groups ◽  
High Chemical ◽  
Metal Organic ◽  
Intramolecular Hydrogen ◽  
High Chemical Stability

Intramolecular hydrogen bonds in ligands restrict the rotation of carboxyl groups and consequently enhance the chemical stability of MOFs.

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