Modern Approaches to the Design of Environmentally Benign Stabilizers of Peroxy Compounds in Pulp Bleaching, 2007 Engineering, Pulping & Environmental Conference

Please Note: This document will be available in PDF format in the "My Electronic Documents" link on the home page once your order has been completed. Please make sure you have the latest version of Acrobat Reader. Click on the Acrobat Reader icon to check for the latest version, it’s FREE. To print a hardcopy of a PDF file correctly you must have a postscript printer. If you are not sure if your printer is a postscript printer please refer to your owner’s manual.



Large quantities of complexing agents are used for the deactivation of iron and manganese ions prior to or in the actual bleaching of mechanical or chemical pulp with oxygen chemicals, i.e. hydrogen peroxide, or peroxy acids. Iron and manganese ions catalyze the decomposition of peroxy compounds leading to unfavourable radical reactions with inferior brightness and strength properties of the pulp as a result. The most commonly used chelating agents in the P&P industry are ethylenediamine tetraacetic acid (EDTA) and diethylenetriamine pentaacetic acid (DTPA).

Due to the low biodegradability and large consumption volumes, the environmental fate of EDTA and DTPA has become under debate. The ability of these strong complexing agents to mobilize heavy metal ions (Hg, Cd, Pb) from the sediments is considered to be an environmental fate. Moreover, the ability of chelating agents to release ferrous ions from iron phosphate sediments is believed to mobilize phosphates in the natural waters.

The development of environmentally benign complexing agents having higher biodegradability, lower nitrogen content and a sufficient behaviour in the pulp bleaching applications have been the drivers of our research for over a decade. This presentation gives an overview of our approach towards the problem.