Electrochemical in-situ hydrogen peroxide generation in a packed-bed reactor for Fenton oxidation of p-nitrophenol in aqueous solution

2019 ◽  
Vol 123 ◽  
pp. 161-168 ◽  
Author(s):  
James I. Colades ◽  
Mark Daniel G. de Luna ◽  
Mona Freda N. Secondes ◽  
Chin-Pao Huang
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Peroxide ◽  
Packed Bed ◽  
Fenton Oxidation ◽  
Packed Bed Reactor ◽  
Hydrogen Peroxide Generation

scholarly journals Multienzymatic in situ hydrogen peroxide generation cascade for peroxygenase-catalysed oxyfunctionalisation reactions

2019 ◽  
Vol 74 (3-4) ◽  
pp. 101-104 ◽  
Author(s):  
Milja Pesic ◽  
Sébastien Jean-Paul Willot ◽  
Elena Fernández-Fueyo ◽  
Florian Tieves ◽  
Miguel Alcalde ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Formate Dehydrogenase ◽  
Flavin Mononucleotide ◽  
Candida Boidinii ◽  
Reaction Parameters ◽  
Old Yellow Enzyme ◽  
Hydroxylation Reaction ◽  
In Situ Generation ◽  
Hydrogen Peroxide Generation

Abstract There is an increasing interest in the application of peroxygenases in biocatalysis, because of their ability to catalyse the oxyfunctionalisation reaction in a stereoselective fashion and with high catalytic efficiencies, while using hydrogen peroxide or organic peroxides as oxidant. However, enzymes belonging to this class exhibit a very low stability in the presence of peroxides. With the aim of bypassing this fast and irreversible inactivation, we study the use of a gradual supply of hydrogen peroxide to maintain its concentration at stoichiometric levels. In this contribution, we report a multienzymatic cascade for in situ generation of hydrogen peroxide. In the first step, in the presence of NAD+ cofactor, formate dehydrogenase from Candida boidinii (FDH) catalysed the oxidation of formate yielding CO2. Reduced NADH was reoxidised by the reduction of the flavin mononucleotide cofactor bound to an old yellow enzyme homologue from Bacillus subtilis (YqjM), which subsequently reacts with molecular oxygen yielding hydrogen peroxide. Finally, this system was coupled to the hydroxylation of ethylbenzene reaction catalysed by an evolved peroxygenase from Agrocybe aegerita (rAaeUPO). Additionally, we studied the influence of different reaction parameters on the performance of the cascade with the aim of improving the turnover of the hydroxylation reaction.

scholarly journals Hydrogen Peroxide Generation of Copper/Ascorbate Formulations on Cotton: Effect on Antibacterial and Fibroblast Activity for Wound Healing Application

Molecules ◽  
2018 ◽  
Vol 23 (9) ◽  
pp. 2399 ◽  
Author(s):  
J. Edwards ◽  
Nicolette Prevost ◽  
Michael Santiago ◽  
Terri von Hoven ◽  
Brian Condon ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Wound Healing ◽  
Cotton Fiber ◽  
Cotton Effect ◽  
Aqueous Environment ◽  
Amplex Red ◽  
Low Levels ◽  
Icp Analysis ◽  
Hydrogen Peroxide Generation

Greige cotton (unbleached cotton) is an intact plant fiber that retains much of the outer cotton fiber layers. These layers contain pectin, peroxidases, and trace metals that are associated with hydrogen peroxide (H2O2) generation during cotton fiber development. When greige cotton is subjected to a nonwoven hydroentanglement process, components of the outer cotton fiber layers are retained. When hydrated, this fabric can generate H2O2 (5–50 micromolar). This range has been characterized as inducing accelerated wound healing associated with enhanced cell signaling and the proliferation of cells vital to wound restoration. On the other hand, H2O2 levels above 50 micromolar have been associated with bacteriostatic activity. Here, we report the preparation and hydrogen peroxide activity of copper/ascorbate formulations, both as adsorbed and in situ synthesized analogs on cotton. The cooper/ascorbate-cotton formulations were designed with the goal of modulating hydrogen peroxide levels within functional ranges beneficial to wound healing. The cotton/copper formulation analogs were prepared on nonwoven unbleached cotton and characterized with cotton impregnation titers of 3–14 mg copper per gram of cotton. The copper/ascorbate cotton analog formulations were characterized spectroscopically, and the copper titer was quantified with ICP analysis and probed for peroxide production through assessment with Amplex Red. All analogs demonstrated antibacterial activity. Notably, the treatment of unbleached cotton with low levels of ascorbate (~2 mg/g cotton) resulted in a 99 percent reduction in Klebsiella pneumoniae and Staphylococcus aureus. In situ synthesized copper/ascorbate nanoparticles retained activity and did not leach out upon prolonged suspension in an aqueous environment. An assessment of H2O2 effects on fibroblast proliferation are discussed in light of the copper/cotton analogs and wound healing.

Metal-free carbon nitride photocatalysis with in situ hydrogen peroxide generation for the degradation of aromatic compounds

2019 ◽  
Vol 252 ◽  
pp. 128-137 ◽  
Author(s):  
André Torres-Pinto ◽  
Maria J. Sampaio ◽  
Cláudia G. Silva ◽  
Joaquim L. Faria ◽  
Adrián M.T. Silva
Keyword(s):  
Hydrogen Peroxide ◽  
Aromatic Compounds ◽  
Carbon Nitride ◽  
Free Carbon ◽  
Metal Free ◽  
Hydrogen Peroxide Generation

Epoxidation of Olefins Catalyzed by Polyoxomolybdates Formed in-situ in Ionic Liquids

2013 ◽  
Vol 68 (10) ◽  
pp. 1138-1142 ◽  
Author(s):  
Lilian R. Graser ◽  
Sophie Jürgens ◽  
Michael E. Wilhelm ◽  
Mirza Cokoja ◽  
Wolfgang A. Herrmann ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Peroxide ◽  
Ionic Liquid ◽  
Catalyst Concentration ◽  
Sodium Molybdate ◽  
Significant Loss ◽  
Catalytic Epoxidation ◽  
Epoxidation Reaction ◽  
Epoxidation Of Olefins

Polyoxomolybdates were generated in situ by treating a carboxylic acid-functionalized ionic liquid with an aqueous solution of sodium molybdate. This reaction mixture was applied in the catalytic epoxidation of olefins using hydrogen peroxide as oxidant. The influence of acid and catalyst concentration as well as of the reaction temperature was investigated. The system showed a good performance for the epoxidation reaction and can be reused several times without a significant loss of activity. We present an easy, cheap and environmentally friendly catalytic system for the epoxidation of cis-cyclooctene.

scholarly journals Model Capabilities for In-Situ Oil Shale Recovery

1981 ◽  
Vol 103 (2) ◽  
pp. 138-146 ◽  
Author(s):  
P. J. Hommert ◽  
C. E. Tyner
Keyword(s):  
Oil Shale ◽  
Maximum Yield ◽  
Packed Bed ◽  
The United States ◽  
Packed Bed Reactor ◽  
One Dimensional ◽  
Operating Strategies ◽  
Dimensional Simulation ◽  
Shale Recovery

The extensive oil shale reserves of the United States are now under development as an energy source. One of the approaches for extracting oil from shale is the so-called modified in-situ retort. The operation of such retorts for maximum yield requires an understanding of oil loss mechanisms so that operating strategies that minimize these losses can be developed. The present modeling capabilities for describing the behavior and yield from a modified in-situ retort are discussed. Two models that have been subject to comparison with laboratory retorts are described. The first is a one-dimensional model that treats the retort as a packed bed reactor; the second is a quasi-two-dimensional examination of block retorting. Both models are capable of predicting retorting rates, off-gas composition and oil yield losses to coking and combustion. The major need for modeling now is expansion to multi-dimensional simulation.

scholarly journals Continuous Bioinspired Oxidation of Sulfides

Molecules ◽  
2020 ◽  
Vol 25 (11) ◽  
pp. 2711
Author(s):  
Francesca Mangiavacchi ◽  
Letizia Crociani ◽  
Luca Sancineto ◽  
Francesca Marini ◽  
Claudio Santi
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Peroxide ◽  
Selective Oxidation ◽  
Flow Conditions ◽  
Oxidation Of Sulfides ◽  
Vinyl Sulfides ◽  
Scale Preparation ◽  
Dialkyl Sulfides

A simple, efficient, and selective oxidation under flow conditions of sulfides into their corresponding sulfoxides and sulfones is reported herein, using as a catalyst perselenic acid generated in situ by the oxidation of selenium (IV) oxide in a diluted aqueous solution of hydrogen peroxide as the final oxidant. The scope of the proposed methodology was investigated using aryl alkyl sulfides, aryl vinyl sulfides, and dialkyl sulfides as substrates, evidencing, in general, a good applicability. The scaled-up synthesis of (methylsulfonyl)benzene was also demonstrated, leading to its gram-scale preparation.

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