The oxidation of toluene sorbed on activated carbon in the presence of H2O2 and manganese oxide

2012 ◽  
Vol 66 (11) ◽  
pp. 2349-2354 ◽  
Author(s):  
Si-Hyun Do ◽  
Sung-Ho Kong
Keyword(s):  
Hydrogen Peroxide ◽  
Electron Transfer ◽  
Activated Carbon ◽  
Control System ◽  
Hydroxyl Radical ◽  
Manganese Oxide ◽  
Superoxide Anion ◽  
Gas Flow ◽  
Pure Water ◽  
Gas Purging

We investigated the oxidation of toluene sorbed on activated carbon (AC) in the presence of hydrogen peroxide (H2O2) and pyrolusite (MnO2). Sorbed toluene was prepared by reacting a toluene-saturated solution and AC. The amounts of sorbed toluene (mg of toluene/g of AC) decreased as the amounts of AC were increased. The reaction was conducted in a gas-purging (GP) reactor and the gas flow at the outlet of a GP reactor was carefully maintained. As a result, the percentage of toluene captured by ORBO tube was 28% in the control system with pure water. When H2O2 was catalyzed by AC (i.e. this forms a hydroxyl radical by electron transfer), approximately 17% of the desorbed toluene was oxidized and 68% of toluene remained on AC which was similar to the control system. However, when pyrolusite (650 mg/L) was added together with H2O2 (10,000 mg/L), only 5% of toluene was captured by the ORBO tube and 55% of toluene remained on AC, which indicated that both desorbed and sorbed toluene was oxidized. Moreover, toluene oxidation increased when concentrations of pyrolusite and H2O2 were increased. It was suggested that superoxide anion, which is generated by the reaction of H2O2 and pyrolusite, might stimulate toluene desorption and then toluene in the aqueous phase could be oxidized by hydroxyl radical.

Removal of Tributyltin in Shipyard Waters: Characterization and Treatment to Meet Low Parts per Trillion Levels

2003 ◽  
Vol 19 (03) ◽  
pp. 179-186
Author(s):  
Gary C. Schafran ◽  
R. Prasad ◽  
F. H. Thorn ◽  
R. Michael Ewing ◽  
J. Soles
Keyword(s):  
Hydrogen Peroxide ◽  
Activated Carbon ◽  
Hydroxyl Radical ◽  
Ultraviolet Irradiation ◽  
Treatment Plant ◽  
Full Scale ◽  
Radical Formation ◽  
Estuarine Waters ◽  
Treatment Conditions ◽  
Made In

Removal of tributyltin (TBT) from shipyard waters has been conducted in Virginia shipyards for over 2.5 years and has resulted in a 99% reduction of TBT discharged to coastal-estuarine waters. This has been achieved by conventional coagulation clarification for particulate TBT removal and removal of dissolved TBT using activated carbon. Although advances have been made in the understanding of TBT removal under various treatment conditions, TBT removal with the existing full-scale treatment plant to levels that would comply with a 50 parts per trillion (pptr) discharge limit are not possible. Results from study efforts that are currently ongoing suggest that the 50 pptr limit might be reached using ultraviolet irradiation or ozonation and that both processes would be substantially improved with the addition of hydrogen peroxide to promote hydroxyl radical formation.

Evaluation of antioxidant activity of Melothria maderaspatana in vitro

2010 ◽  
Vol 5 (2) ◽  
pp. 224-230 ◽  
Author(s):  
Boobalan Raja ◽  
Kodukkur Pugalendi
Keyword(s):  
Hydrogen Peroxide ◽  
Antioxidant Activity ◽  
Free Radical ◽  
Hydroxyl Radical ◽  
Superoxide Anion ◽  
Radical Scavenging ◽  
Reducing Power ◽  
Free Radical Scavenging ◽  
Melothria Maderaspatana

AbstractIn this study, an aqueous extract of leaves from Melothria maderaspatana was tested for in vitro antioxidant activity. Free radical scavenging assays, such as hydroxyl radical, hydrogen peroxide, superoxide anion radical and 2,2-diphenyl-1-picryl hydrazyl (DPPH), 2,2’-azinobis-(3-ethyl-enzothiazoline-6-sulfonic acid) (ABTS) radical scavenging, and reducing power assay, were studied. The extract effectively scavenged hydroxyl radical, hydrogen peroxide and superoxide anion radicals. It also scavenged DPPH and ABTS radicals. Furthermore, it was found to have reducing power. All concentrations of leaf extract exhibited free radical scavenging and antioxidant power, and the preventive effects were in a dose-dependent manner. The antioxidant activities of the above were compared to standard antioxidants such as butylated hydroxytoluene (BHT), ascorbic acid, and α-tocopherol. The results obtained in the present study indicate that the M. maderaspatana extract could be considered a potential source of natural antioxidant.

scholarly journals Spontaneous generation of hydrogen peroxide from aqueous microdroplets

2019 ◽  
Vol 116 (39) ◽  
pp. 19294-19298 ◽  
Author(s):  
Jae Kyoo Lee ◽  
Katherine L. Walker ◽  
Hyun Soo Han ◽  
Jooyoun Kang ◽  
Fritz B. Prinz ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Hydroxyl Radical ◽  
Pure Water ◽  
Phenylboronic Acid ◽  
Production Method ◽  
Bulk Water ◽  
Spontaneous Generation ◽  
Production Of Hydrogen ◽  
Fluorescence Dye ◽  
Green Production

We show H2O2 is spontaneously produced from pure water by atomizing bulk water into microdroplets (1 μm to 20 µm in diameter). Production of H2O2, as assayed by H2O2-sensitve fluorescence dye peroxyfluor-1, increased with decreasing microdroplet size. Cleavage of 4-carboxyphenylboronic acid and conversion of phenylboronic acid to phenols in microdroplets further confirmed the generation of H2O2. The generated H2O2 concentration was ∼30 µM (∼1 part per million) as determined by titration with potassium titanium oxalate. Changing the spray gas to O2 or bubbling O2 decreased the yield of H2O2 in microdroplets, indicating that pure water microdroplets directly generate H2O2 without help from O2 either in air surrounding the droplet or dissolved in water. We consider various possible mechanisms for H2O2 formation and report a number of different experiments exploring this issue. We suggest that hydroxyl radical (OH) recombination is the most likely source, in which OH is generated by loss of an electron from OH− at or near the surface of the water microdroplet. This catalyst-free and voltage-free H2O2 production method provides innovative opportunities for green production of hydrogen peroxide.

Beta-2-Agonists Have Antioxidant Function in vitro. 1. Inhibition of Superoxide Anion, Hydrogen Peroxide, Hypochlorous Acid and Hydroxyl Radical

Respiration ◽  
1997 ◽  
Vol 64 (1) ◽  
pp. 16-22 ◽  
Author(s):  
Adrian Gillissen ◽  
Malgorzata Jaworska ◽  
Birgit Schärling ◽  
Dominique van Zwoll ◽  
Gerhard Schultze-Werninghaus
Keyword(s):  
Hydrogen Peroxide ◽  
Hydroxyl Radical ◽  
Superoxide Anion ◽  
Hypochlorous Acid ◽  
Antioxidant Function ◽  
Beta 2

scholarly journals Rhodanese Rdl2 produces reactive sulfur species to scavenge hydroxyl radical and protect mitochondria

2021 ◽  
Author(s):  
Qingda Wang ◽  
Zhigang Chen ◽  
Xi Zhang ◽  
Yuping Xin ◽  
Yongzhen Xia ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Hydrogen Peroxide ◽  
Hydroxyl Radical ◽  
Superoxide Anion ◽  
Fenton Reaction ◽  
Aerobic Respiration ◽  
Oxygen Species ◽  
Sulfur Species ◽  
Ex Ante ◽  
Generate Superoxide Anion

During aerobic respiration, mitochondria generate superoxide anion (O2&middot−), hydrogen peroxide (H2O2), and hydroxyl radical (HO·), and these reactive oxygen species (ROS) are detrimental to mitochondria. Mitochondrial damage is linked to a broad spectrum of pathologies such as Alzheimer's disease, hemochromatosis, and diabetes. Mitochondria contain several enzymes for rapidly removing superoxide anion and hydrogen peroxide, but how they antagonize HO· is elusive, representing a loophole in the anti-ROS system. Herein, we discovered that Rhodanese 2 (Rdl2) is critical for maintaining the functionality and integrity of mitochondria under sub-lethal ROS stress in Saccharomyces cerevisiae. Rdl2 converts stable sulfur species (thiosulfate and dialkyl polysulfide) to reactive sulfane sulfur including persulfide that protects mitochondrial DNA via scavenging HO·. Surprisingly, hydrogen sulfide (H2S) promotes HO· production through stimulating the Fenton reaction, leading to increased DNA damage. Our study may reveal an ex-ante mean for antagonizing HO·, patching the loophole of the anti-ROS system in mitochondria.

scholarly journals Free radical degradation in aqueous solution by blowing hydrogen and carbon dioxide nanobubbles

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Toyohisa Fujita ◽  
Hiromi Kurokawa ◽  
Zhenyao Han ◽  
Yali Zhou ◽  
Hirofumi Matsui ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Aqueous Solution ◽  
Ethylene Glycol ◽  
Hydroxyl Radical ◽  
Superoxide Anion ◽  
Uv Light ◽  
Pure Water ◽  
Porous Ceramic ◽  
Radical Scavenging ◽  
Ultrasonic Waves

AbstractThe main findings are the hydroxyl radical scavenging and the superoxide anion diminishing by mixing the carbon dioxide (CO2) nanobubbles after hydrogen nanobubble blowing in water and alcohol aqueous solution. The nanobubbles produce the hydroxyl radical by ultrasonic waves, changing the pH and catalyst and so on, while the nanobubble is very reactive to scavenge free radicals. In this research especially hydrogen (4% H2 in argon) and CO2 nanobubbles have been blown into hydrogen peroxide (H2O2) added pure water, ethanol, and ethylene glycol aqueous solution through a porous ceramic sparger from the gas cylinder. The aqueous solutions with H2O2 are irradiated by ultraviolet (UV) light and the produced hydroxyl radical amount is measured with spin trapping reagent and electron spin resonance (ESR). The CO2 nanobubble blowing extremely has reduced the hydroxyl radical in water, ethanol, and ethylene glycol aqueous solution. On the other hand, when H2 nanobubbles are brown after CO2 nanobubble blowing, the hydroxyl radical amount has increased. For the disinfection test, the increase of hydroxyl radicals is useful to reduce the bacteria by the observation in the agar medium. Next, when the superoxide anion solution is mixed with nanobubble containing water, ethanol, and ethylene glycol aqueous solution, H2 nanobubble has reduced the superoxide anion slightly. The water containing both CO2 and H2 nanobubble reduces the superoxide anion. The less than 20% ethanol and the 30% ethylene glycol aqueous solution containing CO2 nanobubbles generated after H2 nanobubble blowing can diminish the superoxide anion much more. While the H2 nanobubble blowing after CO2 nanobubble blowing scavenges the superoxide anion slightly. The experimental results have been considered using a chemical reaction formula.

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