Novel Catalytic Dielectric Barrier Discharge Reactor for Gas-Phase Abatement of Isopropanol

Catalytic gas-phase abatement of air containing 250ppm of isopropanol (IPA) was carried out with a novel dielectric barrier discharge (DBD) reactor with the inner catalytic electrode made of sintered metal fibers (SMF). The optimization of the reactor performance was carried out by varying the voltage from 12.5 to 22.5kV and the frequency in the range 200-275Hz. The performance was significantly improved by modifying SMF with Mn and Co oxide. Under the experimental conditions used, the MnO x /SMF showed a higher activity towards total oxidation of IPA as compared to CoO x /SMF and SMF electrodes. The complete destruction of 250ppm of IPA was attained with a specific input energy of ∼235J/L using the MnO x /SMF catalytic electrode, whereas, the total oxidation was achieved at 760J/L. The better performance of the MnO x /SMF compared to other catalytic electrodes suggests the formation of short-lived active species on its surface by the in-situ decomposition of ozon

Graphite and carbon black materials as catalysts for wet peroxide oxidation

This study explores the application of non-porous carbon materials, two graphites (G-F, G-S) and two carbon blacks (CB-V and CB-C) as catalysts for wet peroxide oxidation (CWPO). The activity, efficiency and stability of these carbon materials have been evaluated using phenol as target compound. The catalyst screening experiments were carried out batch-wise at CPhenol,0=1g/L, CH2O2,0=5g/L, Ccat=2.5g/L, T=80°C and pH0=3.5. The results allow concluding that CB-C was the most stable catalyst, although it showed a lower oxidation and mineralization activity than G-S and CB-V. Increasing the temperature up to 90°C allowed complete phenol conversion and around 70% TOC reduction with 100% efficiency of hydrogen peroxide consumption upon 20h reaction time at 5g/L CB-C load. As a consequence of the initial oxidation of the carbon surface, the electrochemical properties of CB-C were favorably changed upon CWPO and its catalytic performance was improved from the first to the second use and then maintained upon successive applications in a five-cycle testThe authors wish to thank the Spanish MICINN for the financial support through the projects CTQ2008-03988/PPQ and CTQ2010-14807. The Comunidad Autónoma de Madrid is also gratefully acknowledged for the financial support through the project S2009/AMB-158

Catalytic abatement of volatile organic compounds assisted by non-thermal plasma - Part II. Optimized catalytic electrode and operating conditions

Catalytic purification of air containing 250 ppm of toluene assisted by non-thermal plasma was carried out with a novel dielectric barrier discharge (DBD) reactor with an inner electrode made of sintered metal fibers (SMF). The optimization of the reactor performance was carried out by modifying the SMF with Mn and Co oxides, varying the voltage from 12.5 to 22.5 W and the frequency in the range of 200-450 Hz. Under the experimental conditions used, the MnOx/SMF showed better activity than CoOx/SMF and SMF during the total oxidation of toluene. The complete oxidation of 250 ppm of toluene was possible with the MnOx/SMF catalytic electrode at the specific input energy (SIE) of similar to 1650 J/l. A higher SIE of similar to 2100 J/l was required with CoOx/SMF for the total oxidation of toluene to CO2. The better performance of the MnOx/SMF compared to other catalytic electrodes seems to be related to the formation of short-lived species by the in situ decomposition of ozone. XPS analysis of the solid deposit formed on the electrode surface shows the formation of carbonaceous species containing oxygen and nitrogen groups. (c) 2006 Published by Elsevier B.V

The use of cyclic voltammetry to assess the activity of carbon materials for hydrogen peroxide decomposition

It is known that carbon materials catalyze hydrogen peroxide decomposition in aqueous media. However, the catalytic activity of a particular carbon is dependent on various coupled structural, textural and chemical characteristics of the material, such that, formerly, the prediction of activity has not been possible. Here, the application of cyclic voltammetry (CV) is introduced as a rapid and conclusive technique in this respect. Three classes of carbon materials have been investigated: activated carbons, carbon blacks, and graphites, including some selected acid-washed samples which were used to examine the roles of mineral matter and surface oxygen. Characterization by electrochemical capacity measurements with CV, together with catalytic activity tests for hydrogen peroxide decomposition, reveal that the exchange current is directly proportional to the catalytic activity for hydrogen peroxide decomposition. That is, a linear dependence was found between this variable and the apparent first order catalytic decomposition rate constant. CV measurements with modified carbons also allow the elucidation of the effects of physicochemical characteristics of carbon materials on the rate of hydrogen peroxide decompositionThe authors wish to thank the Spanish MICINN for the financial support for the projects CTQ2008-03988/PPQ, CTQ2010-14807 and S2009/AMB-1588. Our gratitude to the anonymous reviewer for his/her helpful comments and recommendations which have significantly contributed to improve the quality of the pape

Non-thermal Plasma - Nanometer TiO2 Photocatalysis for Formaldehyde Decomposition

In non-thermal plasma-nanometer TiO2 photocatalysis, the techniques of photocatalysis and plasma are combined, and do not need ultraviolet light. It can make use of some kinds of energy in the process of decomposing, while at the same time producing much free hydroxide and improving the efficiency of decomposing. It is regarded as one of the most promising technologies in air cleaning. A non-thermal plasma-nanometer TiO2 photocatalysis purifier was placed in a stimulant air conditioning room, followed by pumping in a mixture of formaldehyde and air. The purifier was then turned on to carry on the static state experiment of decomposing formaldehyde. The INTERSCAN4160 analysis instrument was adapted to analyze the variety of the formaldehyde density in the room. The fan was turned on in the room to keep the diffusion circulating in the room and alter the velocity of the air and the density for the experiment. The experiment shows that the efficiency of the decomposing formaldehyde in static state increased up to 90% after the Non-thermal Plasma-Nanometer TiO2 Photocatalysis process. In an air-conditioned room, the purifier can decrease the density of formaldehyde effectively. The concentration increasing effect of decomposing is more promising

Ciliary Hedgehog Signaling Restricts Injury-Induced Adipogenesis

Injured skeletal muscle regenerates, but with age or in muscular dystrophies, muscle is replaced by fat. Upon injury, muscle-resident fibro/adipogenic progenitors (FAPs) proliferated and gave rise to adipocytes. These FAPs dynamically produced primary cilia, structures that transduce intercellular cues such as Hedgehog (Hh) signals. Genetically removing cilia from FAPs inhibited intramuscular adipogenesis, both after injury and in a mouse model of Duchenne muscular dystrophy. Blocking FAP ciliation also enhanced myofiber regeneration after injury and reduced myofiber size decline in the muscular dystrophy model. Hh signaling through FAP cilia regulated the expression of TIMP3, a secreted metalloproteinase inhibitor, that inhibited MMP14 to block adipogenesis. A pharmacological mimetic of TIMP3 blocked the conversion of FAPs into adipocytes, pointing to a strategy to combat fatty degeneration of skeletal muscle. We conclude that ciliary Hh signaling by FAPs orchestrates the regenerative response to skeletal muscle injury