Effect of Tetra Acetyl Ethylene Diamine (TAED) use in final phase of alkali peroxide bleaching on hardwoods Chemi-Mechanical Pulp (CMP) properties

The pulp color reversion, at the end of bleaching, and non-totally consumption of peroxide are two problems in high-yield pulp bleaching. In this study, the effect of TAED, at the end phase of bleaching, on process and pulp properties was investigated. Hardwoods chemi-mechanical pulp (CMP) (85% yield), was bleached by mono-stage alkali peroxide process. Treatments comprising three different charges of peroxide (1.5, 2 and 3%) and alkali (sodium hydroxide) (1.12, 1.5 and 2.25) with and without using TAED at the end phase of bleaching i.e. the last 10 minutes. The results indicated that, the pulp brightness and bleaching selectivity increased by chemical charge rising, but with decreasing slope procedure. The chemical charge rising led to an increase in residual peroxide and filtrate COD load. TAED using, through reduction of alkali darkening reaction, caused to improve the brightness and selectivity, and reduce the COD load. Residual peroxide amounts of treatments, which have TAED treatment, were significantly decreased.