Cellulose nanopaper (CNP) is of great interest to researchers mainly due to its renewability, excellent mechanical properties and optical properties. However, CNP is usually sensitive to water, resulting in the loss of strength and durability. To overcome this issue, in this work, an efficient and sustainable route, which involved ammonium sulfite cooking and formic acid hydrolysis, was reported to isolate lignin-containing cellulose nanofibrils (CNFs) from tobacco stalk. The resultant CNFs were directly used to fabricate strong, flexible, and water resistant CNP without any complex chemical modification. The residual lignin was found to act as a reinforcing agent between CNFs in CNP. The tensile strength and toughness of the lignin-containing CNP (255 MPa and 19.7 MJ m−3) were much higher compared with those of the one without lignin (179 MPa and 12.8 MJ m−3). The water-resistance of the CNP was also improved extraordinarily, and its maximum wet tensile strength reached up to 83 MPa which is the highest value in comparison with the reported CNP. Compared to the lignin-free CNP, the lignin-containing CNP also showed the better thermal stability and excellent UV-blocking properties. The present work designed a new route to prepare lignin-containing CNFs and CNP, which are potential candidates to replace petroleum-based materials in many advanced applications.
Background Tobacco stalk (TS), a major agricultural waste abundant in pectin, has resulted in concerns about the need for its reuse. The nicotine in TS is considered a chemical that is to\xic and hazardous to the environment. Results In this study, Bacillus tequilensis CAS-MEI-2-33 was isolated from cigar wrappers to produce alkaline pectinase using TS. Subsequently, the medium and fermentation conditions for the production of pectinase by B . tequilensis CAS-MEI-2-33 were optimized. The optimal fermentation period, pH of the initial fermentation medium, concentration of TS, and inoculum amount for B . tequilensis CAS-MEI-2-33 were 40 h, 40 g/L, 7.0, and 3%, respectively. Under optimal conditions, the pectinase activity was 1370 U/mL. Then, the enzymatic properties, such as the optimum pH, reaction temperature, temperature stability, and effects of metal ions, were studied. The optimal pH was determined to be 10.0, indicating that the enzyme was an alkaline pectinase. The optimal temperature was 40 °C, and pectinase activity was stable at 40 °C. The Ag + metal ions were shown to remarkably promote enzyme activity. The pectinase was partly purified by ammonium sulfate precipitation, ion exchange chromatography, and Sephacryl S-100 chromatography. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and LC-MS/MS analyses were utilized to analyze the pectinase. Conclusions This study provided a new alkaline pectinase candidate and a new strategy for the use of TS.
危险品化学品经营许可证（带存储）