Thermogravimetric desorption and de novo tests I: method development and validation

Area of Science:

• Environmental Chemistry
• Analytical Chemistry
• Combustion Science

Background:

• Filter dust from thermal processes like incineration can contain dioxin precursors.
• Understanding de novo dioxin formation is crucial for environmental protection.

Purpose of the Study:

• To simulate de novo dioxin formation in filter dust under controlled thermal conditions.
• To develop and validate a new method for analyzing dioxin surrogates and precursors in TGA effluent.

Main Methods:

• Combining thermogravimetric analysis (TGA) with evolved gas analysis (EGA).
• Utilizing a novel sampling tube method for collecting and analyzing TGA effluent via thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS).
• Optimizing and validating the method for chlorinated benzenes (10-1000 ppb range).

Main Results:

• The developed method achieved average recoveries exceeding 85% for di- to hexa-chlorinated benzenes.
• Potential sources of error and losses during sampling and analysis were identified and considered.
• Results were comparable to those from similar studies by other research groups.

Conclusions:

• The method effectively simulates de novo dioxin synthesis in fly ash.
• It provides a reliable and flexible tool for estimating de novo activity in filter dust.
• This facilitates a better understanding of dioxin formation mechanisms in thermal processes.