Use of a Nitrogen‐Centered Peroxide Activator to Increase the Chromophore Removal Potential of Peroxide‐Lignin Model Compound Study

Abstract

The kinetics of reaction of a lignin model compound, acetovanillone (4′‐hydroxy‐3′‐methoxyacetophenone), in tetraacetylethylenediamine (TAED)/H₂O₂ and peroxide‐alone systems were investigated. The oxidation of acetovanillone followed first‐order kinetics in both systems. In the TAED‐peroxide system, the first‐order rate constant, k, was 0.34 min⁻¹ with a half‐life, t _1/2, of 2 min, compared to k of 0.0035 min⁻¹ and t _1/2 of 220 min in the peroxide‐alone system. Thus, TAED/H₂O₂ oxidized acetovanillone about one hundred times faster than peroxide alone. The results of the study explain why, when using TAED/H₂O₂ to bleach TMP softwood pulp, the initial pH should be about 11 for increased production of peroxyacetic acid, and the final pH should be about 7 to minimize decomposition and increase bleaching efficiency and reactivity.

Keywords:

• Acetovanillone
• tetraacetylethylenediamine
• TAED
• hydrogen peroxide
• lignin model
• activators
• peroxyacetic acid

The authors acknowledge the financial assistance of the Mechanical and Chemical Pulps Network and Canada Research Chair in Value‐added Paper.