Usually the sulfonating agent is sulfur trioxide.

See also Incineration Scrubber Flue gas emissions Flue gas stacks References External links Schematic process flow of FGD plant 5000 MW FGD Plant (includes a detailed process flow diagram) Alstom presentation to UN ECE on air pollution control (includes process flow diagram for dry, wet and seawater FGD) Flue Gas Treatment article including the removal of hydrogen chloride, sulfur trioxide, and other heavy metal particles such as mercury.