Abstract

Hexenuronic acid (HexA) formed in alkaline pulping is known to react with bleaching agents, leading to increased production costs, and affecting product quality and environmental performance. This article focuses on environmental implications of HexA removal from Eucalyptus globulus kraft pulp using peroxymonosulphuric acid (Ps), before bleaching. The experimental work was conducted at laboratory scale and bleaching effluents were obtained using an ECF sequence (D0-E0-D1). Results show that Ps effectively removed HexA, to significant reductions in the kappa number. Moreover, ClO2 consumption was reduced by 42% - 77% as a result of such treatment, with a proportional reduction in AOX generation and phenolic compounds release. Finally, effluent TOC concentrations seem to be a function of the Ps load during pretreatment.