Oxidative decomposition of dioxins

Oxidative decomposition of dioxin coming from incinerator outlet gases by La203-supported AuNPs integrated with Pd/... 

Consequently, the control of dioxin emissions from incinerators is one of the most urgent needs in environmental protection today [466, 516]. There are several treatment techniques presently in use, including the raising of the waste gas temperature to cause catalytic oxidative decomposition [516]. However, when the initial investment and mechanical complexity is taken into account, this method is not practicable for small-scale incinerators. A novel solution for this task would be to decompose dioxin and its derivatives at the dust filter using catal3dic oxidation, preferably below 473 K. This particular temperature is relevant since the waste gases are usually reduced to this temperature at the dust filter after efficient heat recovery. 

Hagenmaier [158] studied the catalytic effect of metals, oxides and carbonates on the decomposition of chloroaromatics such as polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofuranes. Copper catalyses dechlorination/hydrogenation of these compounds at temperatures of about 553 K. After heating for 15 minutes the amount of most polychlorinated compoimds was below 0.1 ng. 

HAZARD RISK Moderate fire and explosion hazard violent reactions with water and strong oxidizers decomposition emits toxic fumes of hydrogen chloride, dioxins and chlorinated phenols NFPA Code H 3 F 0 R 0. 

In this work, we calculate enthalpy, entropy and heat capacity values for thirty groups found in unsaturated and oxygenated hydrocarbons and in addition the C/CD2/C/H the groups are listed in Table 4.1. We have focussed on groups needed to estimate the molecules formed during the oxidation and pyrolysis decomposition of polyaromatics, dioxins and furans. 

At temperatures above 500 °C more than 90 % of the organic bonded bromine was converted into bromide. By adding oxygen complete breakdown to carbon dioxide, bromide and water is possible. Under supercritical water oxidation conditions more than 99 % of the organic bonded bromine was found in the aqueous phase. A formation of bromine, hydrogen bromide and dioxines as in thermal decomposition was not observed. 

NURELLE (95-95-4) Reacts in alkaline medium at high temperatures, producing dioxin. Heat of decomposition may cause explosion. Reacts with strong oxidizers. Incompatible with acid chlorides and acid anhydrides, strong oxidizers. 

HAZARD RISK Fire hazard combustible under specific conditions decomposition spurred by contact with heat and/or strong oxidants emits toxic fiimes of chlorine and hydrochloric acid explodes upon heated decomposition reacts under basic conditions and high temperatures to produce toxic chlorinated dioxins NFPA Code not available. 

Very often compounds being extracted by superheated water react in the medium by hydrolysis or otherwise. It is know from other studies involving pure contaminants that they will react, for example chlorinated hydrocarbons are often dechlo-rinated and converted into hydrocarbons. In other cases benign materials are obtained from pollutants. In the extraction of the explosives TNT, RDX and HMX from contaminated soil, decomposition occurs non-dramatically and completely to benign substances [48]. These compounds contain an oxidative reagent within the molecule. Soil obtained from a bomb disposal site contaminated with 120 000 ppm (12%) of TNT, after treatment in a static ceU at 275°C for 1 h, contained only 2 ppm and the water remaining 4 ppm. Dioxins in contaminated soil treated for 4 h at were found to be reduced by 99.4%, 94.5% and 60% at temperatures of 350°C, 300°C and 150°C, respectively [49]. 

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