Polycylic aromatic hydrocarbons (PAHs) are listed as carcinogenic and mutagenic priority pollutants, belonging to the environmental endocrine disrupters. Most PAHs in the environment stem from the atmospheric deposition and diesel emission. Consequently, the elimination of PAHs in the off-gases is one of the priority and emerging challenges. Catalytic oxidation has been widely used in the destruction of organic compounds due to its high efficiency (or conversion of reactants), its economic benefits and good applicability.
This study investigates the application of the catalytic oxidation using Pt/γ-Al2O3 catalysts to decompose PAHs and taking naphthalene (the simplest and least toxic PAH) as a target compound. It studies the relationships between conversion, operating parameters and relevant factors such as treatment temperatures, catalyst sizes and space velocities. Also, a related reaction kinetic expression is proposed to provide a simplified expression of the relevant kinetic parameters.
The results indicate that the Pt/γ-Al2O3 catalyst used accelerates the reaction rate of the decomposition of naphthalene and decreases the reaction temperature. A high conversion (over 95%) can be achieved at a moderate reaction temperature of 480 K and space velocity below 35,000 h−1. Non-catalytic (thermal) oxidation achieves the same conversion at a temperature beyond 1000 K. The results also indicate that Rideal–Eley mechanism and Arrhenius equation can be reasonably applied to describe the data by using the pseudo-first-order reaction kinetic equation with activation energy of 149.97 kJ/mol and frequency factor equal to 3.26 × 1017 s−1. 相似文献
The results of investigation of the modification of the Armenian minerals with fluorine-containing oligomers show that a modified product appears when the mineral fillers are treated with fluoroalkanes. The product preserves the structure of the fillers with a “grafted” fluoroalkane layer in which chlorine atoms locate mainly over their periphery. The composite materials based on heterochained polymers and the modified fillers possess a stronger wear resistance and a low friction coefficient. 相似文献
This article is devoted to work done in 2002–2006 as part of the unified project Reabilitatsiya to rehabilitate radiation
hazardous objects and sections of the radioactively contaminated territory of the Russian Science Center Kurchatov Institute.
The main objects of the rehabilitation work were old storage sites built for radioactive wastes on the territory of the Institute
when military and civilian nuclear technologies were under development. The structural features of the storage sites, including
the volumes and characteristics of the wastes stored, are presented. The salient aspects of the disposal sites, taken into
account during the rehabilitation work, are discussed. The organization of the rehabilitation operations and the sequence
in which they are performed, the special features of the technical design solutions used, the technological methods, and ways
for conducting the work are described.
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Translated from Atomnaya énergiya, Vol. 102, No. 5, pp. 300–306, May, 2007. 相似文献
Through the use of selective nickel (Ni) electroplating, patterned laser liftoff technique, and surface roughing of the top n-GaN epilayer, a novel process for the fabrication of vertical-structured metal-substrate GaN-based light-emitting diodes (VM-LEDs) to avoid difficulties in Ni substrate dicing and improve device yield was proposed and demonstrated. In conjunction with a sidewall passivation with SiO2 and keeping the size of epilayer smaller than that of Ni island, a considerable improvement in yield and device performance were shown. As compared to conventional lateral-structured GaN-based LEDs, VM-LEDs show an increase in light output power about 174% at 350 mA with a significant decrease in forward voltage from 3.5 to 3.17 V 相似文献
Research on the properties and characteristics of glass that determine the serviceability of the most massive glass objects and glassware is reviewed. The theoretical assumptions, general questions concerning the strength, chemical resistance (corrosion), and spectral characteristics of glass are noted. The properties and characteristics indicated are examined for sheet glass, glass fiber, and glassware. 相似文献
It is generally accepted that diamond is resistant to a wide spectrum of electromagnetic radiation from the ultraviolet through to the soft X-ray range, which makes it very attractive for the fabrication of diamond-based photodetectors. However the effect of photon radiation on the diamond structure has not yet been examined. In the work presented here, photoelectron spectroscopy has been used to study the graphitization of nanodiamond crystallites exposed to extreme ultraviolet radiation. Under such irradiation, the surface hydrogen groups and graphite species are found to prevent graphitization. The mechanism of radiation-induced nanodiamond graphitization is discussed. 相似文献
We present a numerical study of the packing of uniform spheres under three-dimensional vibration using the discrete element method (DEM), focusing on the effects of vibration condition (amplitude and frequency) and inter-particle frictions (sliding and rolling frictions). The results are analysed in terms of packing density, coordination number (CN), radial distribution function (RDF) and pore structure. It is shown that increasing either the vibration amplitude or frequency causes packing density to increase initially to a maximum and then decrease. Both vibration frequency and amplitude should be considered to characterize the effect of vibration process on packing structure. The sliding and rolling frictions between particles can decrease packing density since they dissipate energy, although the effect of rolling friction is less significant. In line with the change of packing density, microstructural properties such as CN, RDF and pore distribution also change: a looser packing often corresponds to smaller CN, less peaked RDF and larger but more widely distributed pores. 相似文献