Na2CO3-assisted oxygen-alkali recyclable cellulose separation/pulping technology of straw and silicon controllable migration

A green recyclable Na 2 CO 3 -assisted oxygen-alkali (SCOA) low-temperature cellulose separation/pulping technology is explored in this work for overcoming the technical defects, such as high temperature, severe cellulose degradation, and interference from silicon elements in the conventional cellulose separation/pulping process of wheat straw. Compared with conventional oxygen-alkali (OA) technology, the unscreened and screened cellulose-based pulp yields increased by 8.2% and 5.6%, respectively, at 115°C and an alkali charge of 22% (as Na 2 O) with a Na 2 CO 3 proportion of 40%, and the cellulose crystallinity of pulp, the tensile index and ring crush of hand-sheet paper increased by 10.1%, 26%, and 23%, respectively. As an important interfering factor, silicon migration was mainly influenced by temperature and pH value, and only 18.2% of the initial dissolved silicon remained in the SCOA pulping black liquor, decrease of 53.4% compared with the OA technology. SCOA technology can obtained high-quality cellulose-based pulp with stable yield.