Ozonation of lignin rich solid fractions from corn stalks

Various kinds of solid materials containing lignin were obtained by fractio nation (autohydrolysis and organosolvolysis) of corn (Zea mays) stalks. The se materials were further ozonated in order to observe the behaviour of the ir constituent polymers, particular attention being paid to lignin, and the evolution of the water soluble reaction products during oxidation. An opti mal moisture content for these materials of 60% was found, which led to the highest degree of solubilization during ozone treatment. Results indicate that lignin is the most severely affected polymer, followed by hemicellulos es and finally by cellulose. The ozonation of autohydrolyzed material invol ved its gradual delignification, the elimination of lignin being more easy at the beginning of the reaction than at the end. The following acids were identified by GC/MS and injection of standards in GC/FID: glycolic, oxalic, malonic, glyoxylic, glyceric, p-hydroxybenzoic and malic. In addition, p-h ydroxybenzaldehyde and vanillin were also identified. During the ozonation of lignin-containing lignocellulosic materials in moistened solid stale, oz one rapidly oxidized the initially generated oxyaromatics and transformed t hem into short chain aliphatic carboxylic acids.