Acid hydrolysis optimization
Following the selection of acid hydrolysis with H2SO4 as the
best method for disruption/sugar extraction, the temperature, biomass
loading, acid concentration and reaction time, were screened
and optimized. The number of extraction cycles for the recovery of
sugars was also studied.
The effect of temperature (bath at 58 C and 82 C, and autoclaving
at 120 C) over 30 min was evaluated. The optimum sulfuric
acid concentration was determined performing different essays
in a sulfuric acid range of 0.05 N–10 N, in an autoclave at 120 C,
using dry and concentrated biomass (0.5 g).
The effect of biomass loading was tested using 5 mL of H2SO4
2 N and biomass amounts from 0.1 to 2.5 g.
To evaluate the efficiency of the sugar extraction cycles and to
find the optimum number of extractions, the residues from acid
pre-treatment with varying biomass loading were collected and
centrifuged (HERAEUS Multifuge 38 R+, Thermo Scientific) at
12,000 rpm at room temperature during 10 min. The supernatant
was removed and the residue was extracted with 5 mL distilled
water at 50 C in a vortex agitator, during 2 min. The suspension
was centrifuged again and the supernatant was taken for further
analysis. This procedure was performed five times for each sample.