Caroate Delignification IV. The Generation and Role of Hydroxyl Radicals, 1996 Pulping Conference Proceedings
A.R. Negri, G. Jimenez, R.T. Hill* and R.C. Francis
Empire State Paper Research Institute
State University of New York
Probably the most serious drawback of peroxymonosulfate or caroate (HSO5 - ) delignification is cellulose depolymerization in the pH range 1.0 - 2.0. The cellulose can be partially protected by the addition of Ag + , Br - or Cl - which scavenge the sulfate radical anion (SO;). However, the degree of protection is dependent on the transition metal profile of the pulp. It was postulated that some metals were generating both SO4 - and OH, which is not effectively scavenged. Of the relevant metals only Cu(II) generated a significant amount of *OH. When 10 ppm Cu(II) was added to acid-washed, kraft pulps cellulose depolymerization was significantly enhanced during caroate delignification. Depolymerization was less severe with Co(II) which generated SO; but not .OH.
Caroate Delignification IV. The Generation and Role of Hydroxyl Radicals, 1996 Pulping Conference Pr