Lactic acid production by alkaline hydrothermal treatment of corn cobs

An experimental study was carried out for the corn cobs thermal conversion to obtain the maximum content in lactic acid. For this purpose, under the same conditions (275 °C and 30 min) different concentrations of Ca(OH)2 as alkaline catalyst were used (from 0.32 M to 1 M). The maximum content of lactic acid (6.72 ± 0.31 g/L) was obtained with 0.7 M of Ca(OH)2. With this catalyst concentration, different reaction conditions were used (250, 275 and 300 °C and 15, 30 and 45 min). The optimal conditions to produce the highest yield of lactic acid from corn cobs in alkaline conditions were determined at 300 °C and 30 min, achieving 44.76 ± 2.59% respect to the total cellulose and hemicellulose contained in the initial corn cobs (7.38 ± 0.43 g/L of lactic acid).

► Corn cobs hydrothermal conversion was studied to obtain a high yield of lactic acid.
► Effect of catalyst concentration, temperature and time of reaction on yield was evaluated.
► 45% of total cellulose and hemicellulose was converted into lactic acid.