TCF bleaching of soda-anthraquinone and diethanolamine pulp from oil palm empty fruit bunches

The AOpAZRP bleaching sequence (A is an acid treatment, Op an oxygen and peroxide stage, Z an ozone stage, R a reductive treatment and P a peroxide stage) have been applied to oil palm empty fruit bunches (EFB) soda-anthraquinone and diethanolamine pulp. On similar Kappa numbers for the two types of pulp (14.2 and 17.3), paper from unbleached soda-anthraquinone pulp exhibited increased tensile index (25.8 Nm/g), stretch (2.35%), burst index (1.69 kN/g), tear index (0.50 mN m2/g) and brightness (60.6%) relative to paper for unbleached diethanolamine pulp; but the latter type of pulp exhibited higher viscosity (659 mL/g) than the former. Upon bleaching with the AOpAZRP sequence, diethanolamine pulp exhibited higher viscosity (783 mL/g), and the properties of the paper sheets were close to or even better to those from soda-anthraquinone pulp, namely: 22.2 vs 20.4 Nm/g tensile index, 1.30 vs 1.42 kN/g burst index, 0.71 vs 0.70 mN m2/g tear index and 71.3% vs 77.5% brightness. Therefore, the properties of paper from diethanolamine pulp evolved more favourably during bleaching than did those of paper from soda-anthraquinone pulp.