Evaluation of PCDD/Fs emissions during ceramic production: a laboratory study

Area of Science:

• Environmental Chemistry
• Industrial Emissions

Background:

• Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) are ubiquitous environmental pollutants.
• Kaolinitic clays used in ceramics contain PCDD/Fs, suggesting the ceramic industry as a potential emission source.
• Limited research exists on PCDD/F emissions from ceramic production.

Purpose of the Study:

• To investigate PCDD/F emissions during laboratory-scale ceramic production.
• To determine the impact of firing temperature and glaze coatings on PCDD/F release.

Main Methods:

• Experimental firing of ceramic pieces in an electric laboratory batch kiln.
• Analysis of PCDD/F congeners and their distribution in raw clay and emissions.
• Varying firing temperatures and applying glaze coatings to test pieces.

Main Results:

• Significant PCDD/F release occurred before high-temperature destruction (1200°C).
• 27.5% (mass basis) and 46.2% (toxic equivalent basis) of raw clay PCDD/Fs were emitted.
• Emissions reduced to 16.3% when initial kiln temperature was raised to 600°C.
• Glaze coating significantly decreased PCDD/F emissions.

Conclusions:

• Ceramic production is a notable source of environmental PCDD/F pollution.
• Early-stage emissions are driven by dechlorination reactions, forming diverse congeners.
• Process modifications like pre-heating and glazing can mitigate PCDD/F release.