Corn stover is an agricultural waste obtained after the corn grain harvest, formed by the stalks,
leaves and cobs of the plant. Its production worldwide accounts with more than 1 billion tons per
year, and it is usually considered as feed for livestock. However, due to its interesting composition
of cellulose and hemicellulose fractions, corn stover can be considered as a valuable biomass for
the production of biofuels or value-added chemicals. Among the different possibilities, the
production of lactic acid was chosen due to its broad application in the food and chemical
industries, as a food preservative or flavoring, or as a precursor of polylactic acid, respectively. In
this regard, a one-pot subcritical water treatment was proposed for the production of lactic acid
from corn stover. Under subcritical conditions, water ionic product increases to a great extent,
acquiring Brønsted acid properties, which combined with the Lewis acidity provided by the
lanthanide Yb3+, makes a synergistic effect and favors the lactic acid production route from the
pentoses and hexoses present in the biomass. The effect of temperature was tested from 180 to
260 °C. It was determined that a minimum temperature of 220 °C was required to successfully
hydrolyze the cellulose and hemicellulose fractions into convertible monosaccharides. This
temperature was selected as the optimum one, which yielded a 22 % lactic acid yield after just one
hour, and showed a low HMF production, showing the high selectivity of the process at this
temperature. One-pot subcritical water treatment of corn stover proved to be a sustainable solution
for the valorization of the agricultural waste.
