Effects of pretreatment on enzymatic hydrolysis of cellulose for waste paper.

In order to accelerate the recovery and reuse of biomass resources,such as waste paper,different pretreatment methods were adopted to pretreat shredded shoe boxes as a model of waste paper to enhance the enzymatic hydrolysis of cellulose.These pretreatment were steam explosion,NaClO2 pretreatment,a pretreatment combination of NaClO2 and NaOH,NaOH pretreatment and aqueous ammonia steeping.We investigated the modification of the concentration of lignin and hemicellulose,surface structure and degree of crystallinity of the materials after pretreatments and discussed the effects of these modifications on the enzymatic hydrolysis of cellulose.Our experimental results indicate that steam explosion is the most efficient method in the removal of lignin and hemicellulose,while the alkali pretreatment exhibits a weak capacity in the removal of hemicellulose.The surface of the pretreated material became coarser,especially for NaOH pretreated samples.The pretreatments also resulted in an increase or decrease in the degree of crystallinity of the material.The results of enzymatic hydrolysis revealed no significant correlation between the rate of enzymatic hydrolysis and concentrations of lignin and hemicellulose,nor with the degree of coarseness of the material surface.But we found a significant correlation between the degree of crystallinity and the rate of enzymatic hydrolysis:the lower the degree of crystallinity,the faster the rate of hydrolysis.The degree of crystallinity was lowest in the NaOH pretreated material,with the highest rate of cellulose hydrolysis,i.e.,45.4%.