A compound enzyme with synergistic interaction to treat cotton stalk chemi-mechanical pulp to improve the properties of wastepaper pulp

In this work, a compound enzyme treated cotton stalk chemi-mechanical pulp (CE-CSCMP) that could improve the properties of wastepaper pulp was investigated. Firstly, according to whether the enzymes (cellulase, xylanase, pectinase and lipase) could promote the mechanical properties of cotton stalk chemi-mechanical pulp (CSCMP) paper, xylanase, pectinase and lipase were selected to prepare compound enzyme. Afterwards, the underlying mechanism of enzymatic treatment of CSCMP was elucidated through the loss of cellulose, hemicellulose and lignin. Single enzymes, such as xylanase, pectinase or lipase, could only directly act on one substrate when treating CSCMP, while non-enzymatic substrates could impede the hydrolysis of the substrate. Therefore, the exposure area of cellulose was small, and the improvement of CSCMP paper strength was limited. It is found that there was a synergistic interaction between the three components in the compound enzyme, leading to a higher hydrolysis efficiency compared to that of single enzyme. Consequently, the area available for hydrogen bonding on the fiber surface was greatly increased, and CE-CSCMP obtained the best paper properties. Finally, CSCMP were furnished with wastepaper pulp, which resulted obvious improvement of the tensile strength, tear strength and ring compressive strength of wastepaper pulp. In conclusion, CE-CSCMP was a high-yield pulp of non-wood raw materials with better performance and could be used to improve wastepaper pulp.