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Kinetics of Eucalypt Lignosulfonate Oxidation to Aromatic Aldehydes by Oxygen i...
Santos, Sonia G.; Marques, Ana P.; Lima, Diana L. D.; Evtuguin, Dmitry V.; Esteves, Valdemar I.The oxidation kinetics of lignosulfonates (LS) from acidic magnesium-based sulfite pulping of Eucalyptus globulus wood with oxygen under alkaline conditions was studied. The analysis of oxidation products in the reaction system O(2)/NaOH revealed a predominance of aromatic aldehydes (vanillin and syringic aldehyde) though small amounts of vanillic and syringic acids and acetophenone/phenylacetaldehyde derivativ...
ECF bleaching with a final hydrogen peroxide stage: Impact of the chemical comp...
Loureiro, Pedro E. G.; Domingues, Eva F.; Evtuguin, Dmitry V.; Carvalho, M. Graça V. S.Two industrial elemental chlorine free (ECF) bleaching sequences, D0(EOP)D1(EP)D2 and OQ(PO)DP, are compared with respect to the bulk content of lignin, carboxyl, hexeneuronic acids (HexA), and reducing groups after each bleaching stage. HexA groups contribute significantly to the total content of carboxyl groups, and their degradation during chlorine dioxide bleaching is reflected by a decrease of the carboxyl...
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