Are metal ions important in FAS bleaching?

Yes.

Metal ions such as:

Fe

Cu

Mn

can influence reducing bleaching systems.

Depending on the furnish and process water quality, a mill may evaluate the use of a chelating agent such as:

EDTA

DTPA

Other commercially appropriate chelants

The purpose is to control metal-ion interference and improve bleaching efficiency.

Therefore, when a FAS trial produces inconsistent results, the investigation should not focus only on FAS dosage.

The complete chemical environment should be examined.