Development of phosphorus-based inhibitors for PCDD/Fs suppression

Area of Science:

• Environmental Chemistry
• Combustion Science
• Materials Science

Background:

• Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) are toxic byproducts of incomplete combustion.
• Effective inhibitors are needed to mitigate PCDD/F formation during incineration.

Purpose of the Study:

• To investigate the inhibition mechanisms of sulfur-, nitrogen-, and phosphorus-based compounds on PCDD/F de novo synthesis.
• To explore the role of carbon, chlorine, and copper speciation in fly ash during inhibition.

Main Methods:

• Laboratory-scale experiments analyzing fly ash composition.
• Speciation analysis of carbon, chlorine, and copper.
• Kinetic modeling and simulated chemical reaction equilibrium.

Main Results:

• Thiourea (TUA) and ammonium dihydrogen phosphate (ADP) achieved >97% inhibition of PCDD/Fs.
• Inhibitors increased carbon oxidation and converted Cu²⁺ to Cu⁺.
• Sulfur and phosphorus deactivated catalytic copper species, while NH₃ reduced chlorination potential.

Conclusions:

• TUA and ADP are highly effective inhibitors of PCDD/F formation.
• Inhibition involves altered surface chemistry, metal deactivation, and reduced chlorination.
• Findings support the use of these inhibitors in full-scale incinerators.