Production of hemicellulosic sugars and glucose from residual corrugated cardboard

Corrugated cardboard samples were subjected to two-step saccharification. A first prehydrolysis stage was carried out to solubilise the hemicellulosic fraction as hemicellulosic sugars, and the solid phase from prehydrolysis was used as a substrate for the enzymic hydrolysis of cellulose. The prehydrolysis step was carried out for 0–180 min in media containing 1–3 wt.% of H₂SO₄ and the fraction of solid recovered after treatments and the compositions of solid and liquid phases from treatments were measured. The susceptibility of prehydrolysed solids towards the enzymic hydrolysis was assessed in further experiments. Under selected prehydrolysis conditions (3% H₂SO₄, 180 min), 78.2% of initial hemicelluloses was saccharified, leading to liquors containing up to 10 g hemicellulosic sugars/l and 9.2 g glucose/l. The corresponding solid phase, enriched in cellulose, showed good susceptibility towards enzymatic hydrolysis, leading to solutions containing up to 17.9 g glucose/l (conversion yield=63.6%) and a glucose/total sugar ratio of 0.93 g/g. Mathematical models assessing the effects of the operational conditions on both the prehydrolysis stage and the susceptibility of substrates towards enzymic hydrolysis have been developed.