Previous studies indicated high xylose yield could be achieved after pretreatment using organic acids, but
it is necessary to systematically investigate the effects of different parameters during organic acid
pretreatments. Corn stover was pretreated with sulfuric, oxalic, citric, tartaric and acetic acid at 50 and
90 mM from 130 to 190 C. The xylan balance for each different acid was distinct, but all balances were
very close to 100% by determining xylan recovery, xylooligomer yield, xylose yield and furfural yield. The
effects of combined severity on the recovery or yields of these components were also studied. The acid
pKa value affected the proportion of xylan degradation products. The maximum value of xylose and
xylooligomer yield for specific acid pretreatment was also determined by pKa value. The maximum xylose
yield was obtained after pretreatment with sulfuric and oxalic acid, but more xylooligomers were
obtained after pretreatment with weaker acids.