Mixed Peracids: Manufacture and Use as Non-Chlorine Delignification and Bleaching Agents, 1993 Pulping Conference Proceedings

Both customers and regulators are providing bleached pulp manufacturers incentives to search for non-chlorine delignifying and brightening technologies. Oxygen, hydrogen peroxide, and ozone are broadly viewed as leading candidates around which those non-chlorine technologies will develop. However, these chemicals are not without drawbacks. They either have limited oxidizing capability, or require large amounts of capital to implement, or both.

A strongly oxidizing, non-chlorine chemical, that requires little capital, would offer mills interesting features to use along with oxygen, peroxide, and ozone to modify their operations to meet low-AOX, ECF, TCF, or closed mill needs. Non-chlorine peracids such as peracetic, performic, and Caro’s acids are known to be strong oxidizers that effectively delignify and brighten pulp. Their reactivity makes them unsuitable for long-term storage or shipping in concentrated form, two factors that make on-site manufacture preferred. To date, their use in bleaching has been limited partly by lack of an easily operated, efficient, on-site manufacturing process.

This paper describes a low-investment, efficient method for on-site manufacture of a solution of two peracids, and illustrates how those peracids can be used for modifying bleach sequences to meet mills’ needs for non-chlorine bleaching.