The role of transition metal species in delignification with distilled peracetic acid
1998
Zhang, D.B. | Francis, R.C. | Dutton, D.B. | Hill, R.T.
An acid-washed, oxygen-delignified, softwood kraft pulp was delignified with peracetic acid (Pa) at initial pH 2.5, 4.8 and 7.0. The inclusion of 5 ppm on pulp of Mn(2+), Fe(3+), Cu(2+), V(5+), or Co(2+) caused wasteful decomposition of Pa while Ni(2+) had no effect. None of the cations caused a significant decrease in kappa number while Co(2+) at all pHs and Fe(3+) at pH 2.5 resulted in lower viscosities. In pulp-free solutions, Co(2+) and V(5+) catalyzed Pa decomposition much more aggressively than the other cations. The kinetic data supported a previous free-radical mechanism for Co(2+) and a similar type mechanism appears to be partially responsible for Pa decomposition by vanadium (V).
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