Different catalytic effects by copper and chromium on the formation and degradation of chlorinated aromatic compounds in fly ash.

• Fly ash from municipal solid waste incineration may catalytically enhance the formation and degradation of chlorinated aromatic compounds. The activities of three Deacon catalysts in this process were investigated in a statistically designed experiment. Chlorides of copper, chromium, and nickel were added to fly ash samples and the resulting samples heated at 300 degrees C for 2 h in an air atmosphere. The addition of copper increases the formation of all chlorinated aromatic compounds except the low chlorinated congeners of polychlorinated dibenzo-p-dioxins and dibenzofurans. The addition of chromium decreased the formation of most chlorinated aromatic compounds except the highest chlorinated species, where it was without effect. The addition of nickel did not show any significant effect. The outcome of the experiment can be interpreted as two competing processes: the chlorination of aromatic rings and the oxidation of carbon-carbon and carbon-oxygen bonds. The delicate balance between chlorination and oxidation could probably be further exploited to minimize both the emissions and the net production of chlorinated aromatic compounds from combustion.

Subject headings

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Miljövetenskap (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Environmental Sciences (hsv//eng)

Keyword

Persistent organic pollutant

Organic compounds

Competitive reaction

Reaction mechanism

Nickel

Chromium

Copper

Catalyst

Comparative study

Fly ash

Thermal degradation

Pollutant formation

Dioxin derivatives

Organic chlorine compounds

Air pollution

Urban waste

Solid waste

Incineration plant

Environmental chemistry

Miljökemi

Environmental Chemistry

Miljökemi

Publication and Content Type

ref (subject category)

art (subject category)