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Area, M. C., Felissia, F. E., Carvalho, M. G. V. S., Ferreira, P. J., Barboza, O. M., and Bengoechea, D. I. (2011). "Characterization of Eucalyptus grandis kraft pulps treated with phosphonates in different stages of TCF bleaching," BioRes. 6(2), 2077-2090.


The addition of a phosphonated chelant (DTPMPA) at different points of a TCF bleaching sequence and its effect on pulp properties were studied in this work. An industrial Eucalyptus grandis kraft pulp was submitted to a counter-ion exchange (Ca2+ or Na+ form) and was then bleached using DTPMPA in the washing or in the bleaching stages of two distinct sequences: OOpP and OQOpP (20 pulps). The counter-ion exchange affected fibre length, as well as the handsheets bulk and air permeability (higher for Na+-based pulps) and handsheet tensile strength, brightness, skeletal density, and total porosity based on Hg porosimetry (higher for Ca2+-based pulps). The hydrogen peroxide consumption in Op and P stages achieved the lowest values when the chelant was distributed rather than applied in a separate Q stage. The addition of chelant in the P stage provides pulps with higher ISO brightness (>85%). The chelant effects were always more noticeable in Ca2+-based pulps.
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