First,
the optimal time (from 15 to 180 min) for hydrolysis was deter-mined with initial substrate concentrations of 50, 11 and 12 g/L
for dry pulps, wet birch pulp and wet conifer pulp, respectively.
Sulfate ions were removed from the solution by adding calcium
oxide (41.35 g CaO/100 mL 55% H2SO 4) and MQ-water (4:5 v/v)
to the reaction mix, which also stopped acid hydrolysis due to neu-tralization. The reaction mix was cooled down to room tempera-ture and the solids were removed by filtration (0.45 lm,
Whatmann GC/C-filters), after which the concentrations of total
sugars were analyzed.