The effect of organic solvents on the selectivity and brightness of hi
gh consistency ozone bleaching of radiata pine I(raft-oxygen pulp was
investigated. Among several organic compounds, formic acid is the most
attractive one, as this solvent improves ozone delignification and, e
fficiency and also prevents cellulose degradation. The selectivity at
different ozone concentrations (1.1-1.7%) shows that formic acid incre
ases the amount of ozone transferred and its accessibility to lignin.
A peroxide stage (P) was carried out after ozonation (Z). The ZP seque
nce was used to reach high brightness (83.1%) pulp.