Effect of pretreatments on the enzymatic chemical pulping of wheat straw

Effects of the pretreatment methods, e.g. chemical-, vapor-, hot water- and mechanical-pretreatment, on the enzymatic-chemical pulping (ECP) of wheat straw were studied. The results showed that efficiency of enzymatic treatment was improved and pulpability of wheat straw was enhanced by pretreatment before or after enzymatic treatment in the ECP process. The improvement extent of pulpability was related to the pretreatment method. Relatively, mechanical pretreatment prior to enzymatic treatment was good and effective. The ECP of wheat straw with mechanical pretreatment resulted in a higher efficiency of the enzymatic treatment, a lower pulp kappa number (lower by 2.96) and consumption of the effective alkali during cooking (lower by 6.76%), as compared with the conventional ECP. Pulps' ISO brightness increased by various pretreatments (with 0.6-4.1% ISO, compared to conventional enzymatic pulp), yet the strength properties of pulps from pretreated wheat straw decreased slightly.