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Pulp bleaching is the chemical treatment of lignocellulosic pulp to increase optical brightness and reduce colour by selectively modifying, depolymerizing, and/or solubilizing residual lignin and other light-absorbing chromophoric structures remaining after pulping ^[1][2]. It is performed through one or more reaction stages using oxidative, and occasionally reductive, bleaching agents under controlled conditions of pH, temperature, consistency, and reaction time. Common oxidative reagents include oxygen, hydrogen peroxide, ozone, and chlorine dioxide; their reactions alter lignin’s conjugated aromatic and carbonyl-containing structures and may promote lignin removal during subsequent alkaline extraction ^[1][3]. Unlike pulping, which primarily liberates fibres through bulk delignification of lignocellulosic material, bleaching acts principally on the comparatively small fraction of residual lignin and chromophores associated with already separated pulp fibres ^[2]. A bleaching sequence is therefore defined by the ordered combination of chemical stages and intermediate washing operations designed to attain a specified brightness while limiting degradation of cellulose and hemicellulosic carbohydrates ^[1]. Chemical pulp bleaching encompasses elemental-chlorine-free and total-chlorine-free sequences, distinguished by the bleaching reagents included rather than by the pulping method that produced the initial pulp ^[3].