Search results for "Oxidation."
showing 10 items of 1877 documents
Methane oxidation in a boreal climate in an experimental landfill cover composed from mechanically–biologically treated waste
2007
The present study evaluated microbial methane (CH4) oxidation in a boreally located outdoor landfill lysimeter (volume 112 m3, height 3.9 m) filled with mechanically-biologically treated waste (MBT residual) and containing a cover layer made from the same MBT residual. The calculations based on gas emission and pore gas measurements showed that, between April and October 2005, a significant proportion (96%) of the methane produced (23 l CH4 m(-2) d(-1)) in the lysimeter was oxidized. Methane was oxidized mainly at the depths of 35-75 cm, as indicated by the upward decrease both in the methane concentration and in the methane-to-carbon dioxide ratio in the pore gas. Lower methane oxidation (…
Treatment of leachate from MSWI bottom ash landfilling with anaerobic sulphate-reducing process
2007
Abstract Removal of sulphate and toxic elements from the leachate of a field landfill lysimeter ( 112 m 3 ) , containing municipal solid waste incineration (MSWI) bottom ash, was studied. The leachate was treated in two parallel laboratory upflow anaerobic sludge blanket (UASB) reactors without and with ethanol as additional carbon source. With ethanol more than 65% of sulphate was removed, while without ethanol removal was negligible. The treatment removed Ba, Ca, Cu, Mn, Mo, Ni, Pb, Tl, Sb, Se, Sr, and Zn of the studied 35 trace and other elements. The sequential extraction of the reactor sludge at the end of runs confirmed that with a few exceptions (Ba, Ca, and Cu) the main mechanism by…
Azo-Dyes Photocatalytic Degradation in Aqueous Suspension of TiO2 Under Solar Irradiation
2002
Abstract The photodegradation of two common and very stable azo-dyes, i.e. methyl-orange (C14H14N3SO3Na) and orange II (C16H11N2SO4Na), is reported. The photocatalytic oxidation was carried out in aqueous suspensions of polycrystalline TiO2 irradiated by sunlight. Compound parabolic collectors, installed at the “Plataforma Solar de Almeria” (PSA, Spain) were used as the photoreactors and two identical reacting systems allowed to perform photoreactivity runs for the two dyes at the same time and under the same irradiation conditions. The disappearance of colour and substrates together with the abatement of total organic carbon content was monitored. The main sulfonate-containing intermediate…
Reliable method for assessing the COD mass balance of a submerged anaerobic membrane bioreactor (SAMBR) treating sulphate-rich municipal wastewater
2012
The anaerobic treatment of sulphate-rich wastewater causes sulphate reducing bacteria (SRB) and methanogenic archaea (MA) to compete for the available substrate. The outcome is lower methane yield coefficient and, therefore, a reduction in the energy recovery potential of the anaerobic treatment. Moreover, in order to assess the overall chemical oxygen demand (COD) balance, it is necessary to determine how much dissolved CH4 is lost in the effluent. The aim of this study is to develop a detailed and reliable method for assessing the COD mass balance and, thereby, to establish a more precise methane yield coefficient for anaerobic systems treating sulphate-rich wastewaters. A submerged anaer…
Microsomal and cytosolic epoxide hydrolases, the peroxisomal fatty acid beta-oxidation system and catalase. Activities, distribution and induction in…
1988
A number of structurally unrelated hypolipidaemic agents and certain phthalate-ester plasticizers induce hepatomegaly and proliferation of peroxisomes in rodent liver, but there is relatively limited data regarding the specific effects of these drugs on liver non-parenchymal cells. In the present study, liver parenchymal, Kupffer and endothelial cells from untreated and fenofibrate-fed rats were isolated and the activities of two enzymes associated with peroxisomes (catalase and the peroxisomal fatty acid beta-oxidation system) as well as cytosolic and microsomal epoxide hydrolase were measured. Microsomal epoxide hydrolase, cytosolic epoxide hydrolase and catalase activities were 7-12-fold…
Oxysterol mixture in hypercholesterolemia-relevant proportion causes oxidative stress-dependent eryptosis.
2014
Background/Aims: Oxysterol activity on the erythrocyte (RBC) programmed cell death (eryptosis) had not been studied yet. Effects of an oxysterol mixture in hyper-cholesterolemic-relevant proportion, and of individual compounds, were investigated on RBCs from healthy humans. Methods: Membrane phosphatidylserine (PS) externalization, calcium entry, ROS production, amino-phospholipid translocase (APLT) activity were evaluated by cytofluorimetric assays, cell volume from forward scatter. Prostaglandin PGE2 was measured by ELISA; GSH-adducts and lipoperoxides by spectrophotometry. Involvement of protein kinase C and caspase was investigated by inhibitors staurosporin, calphostin C, and Z-DEVD-FM…
Exposure to malondialdehyde induces an early redox unbalance preceding membrane toxicity in human erythrocytes.
2002
This work investigated the oxidative injury to human red blood cells (RBCs) by the exposure to exogenous malondialdehyde (MDA), in a physiological environment. When a 10% RBC suspension was incubated in autologous plasma, in the presence of 50 microM MDA, 30% of MDA entered into the cells. A time-course study showed that MDA caused early (30-120 min) and delayed (3-18 h) effects. MDA caused a fast depletion of reduced glutathione, and loss of the glucose-6-phosphate dehydrogenase activity, followed by a decrease of HbO2. Accumulation of methemoglobin, and formation of small amounts of hemichrome were later evident. Also, an HbO2-derived fluorescent product was measured in the membrane. The …
Effect of the cerium loading on the HMS structure. Preparation, characterization and catalytic properties
2013
Abstract Ce–HMS mesoporous materials were prepared by incipient wetness method starting from HMS synthesized in acid condition. The effect of cerium quantity, in the range of Ce/Si atomic ratio 0.02–0.3, on its structure and properties was investigated. Results showed that the HMS hexagonal structure was maintained after the cerium adding. Furthermore, the surface area and the pore volume were reduced. The presence of the cerianite nanoparticles located within the HMS channels up to 0.05, thus covering the HMS surface at higher Ce/Si atomic ratio, was observed. The catalytic performances of the materials were tested in ethanol partial oxidation reaction.
Reactions at Interfaces: Oxygenation of n-Butyl Ligands Anchored on Silica Surfaces with Methyl(trifluoromethyl)dioxirane
2011
The oxygenation of n-butyl and n-butoxy chains bonded to silica with methyl(trifluoromethyl)dioxirane (1) revealed the ability of the silica matrix to release electron density toward the reacting C(2)-H σ-bond through the Si-C(1) and Si-O(1) σ-bonds connecting the alkyl chain to the surface (silicon β-effect). The silica surface impedes neither the alkyl chain adopting the conformation required for the silicon β-effect nor dioxirane 1 approaching the reactive C(2) methylene group. Reaction regioselectivity is insensitive to changes in the solvation of the reacting system, the location of organic ligands on the silica surface, and the H-bonding character of the silica surface. Reaction rates…
Relationship between bulk phase, near surface and outermost atomic layer of VPO catalysts and their catalytic performance in the oxidative dehydrogen…
2017
Abstract A set of vanadium phosphorous oxide (VPO) catalysts, mainly consisting of (VO) 2 P 2 O 7 , VO(PO 3 ) 2 or VOPO 4 ·2H 2 O bulk crystalline phases, has been investigated for the oxidative dehydrogenation (ODH) of ethane to ethylene, a key potential reaction for a sustainable industrial and socioeconomic development. The catalytic performance on these VPO catalysts has been explained on the basis of the main crystalline phases and the corresponding surface features found by XPS and LEISS at 400 °C, i.e. within the temperature range used for ODH reaction. The catalysts based on (VO) 2 P 2 O 7 phase presented the highest catalytic activity and productivity to ethylene. Nevertheless, the…