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Pretreatmentof biomass is expected to improve the pulp propertiesand facilitate the main components in the raw materials to be betterused. In this work, the refining energy consumption and propertiesof the poplar chemithermomechanical pulp (CTMP) from different autohydrolysispretreatment intensities of wood chips were investigated, and thepulp bleaching ability was also studied. The results showed that theCTMP with autohydrolysis pretreatment at a severity factor of 3.47could have a 26% energy reduction in pressurized refining, a 60% energysaving in PFI refining, and 44% and 46% increases in tensile and tearindices, respectively. Autohydrolysis pretreatment prior to pulpingcould result in CTMP with a higher water retention value, higher finescontent, better strength properties, lower shives content, and lowerbulk and ISO brightness after PFI refining. The brightness of CTMPcan be improved by alkaline peroxide bleaching. [ABSTRACT FROM AUTHOR]

Pre-extraction of hemicelluloses prior to pulping andconversionof the extracted hemicelluloses to other byproducts will provide additionalrevenue to the traditional pulp and paper industry. The effect ofhemicelluloses pre-extraction with dilute sulfuric acid on the propertiesand bleachability of aspen (Populus tremuloides)chemithermomechanical pulp (CTMP) was investigated. The acid pre-extractionsignificantly reduced refining energy consumption to a given freeness.However, at the same freeness, the acid pre-extraction resulted inthe reduction of bulk, tensile index, and zero-span breaking length,fewer long fibers and more fines, but an increase of the Scott bondstrength.Alkaline peroxide bleaching can compensate the strength loss, butthe bleachability of pulps with acid pre-extraction was lower thanthat of the control. [ABSTRACT FROM AUTHOR]

Photocatalytic degrading pollutants driven by visible-light irradiation has attracted tremendous attention. One strategy of preparing carbonized cellulose nanofibrils/Ti 3 C 2 T x MXene/g-C 3 N 4 (CMCN) as a photocatalyst was developed. The as-prepared CMCN was comprehensively characterized in terms of the chemical composition, chemical and crystal structure, morphology, and photoelectrochemical properties. The CMCN was explored as a photocatalyst and exhibited good photocatalytic performance in degrading MB (96.5%), RhB (95.4%), and TC (86.5%) under visible-light conditions. In addition, the CMCN as a photocatalyst exhibited good reusability and stability. It is found that the incorporation of cellulose nanofibrils provided a high carbon content, a high porosity, and a large specific surface area, enhanced the electron transfer, improved the photocatalytic performance, and ensured a semiconductor with a high stability. It is believed that this study would provide an effective approach to preparing a photocatalyst and broaden the potential application of cellulose nanofibrils in photocatalysis.

A portion of hemicelluloses and acetic acid can be pre-extracted with dilute sulfuric acid prior to the aspen chemithermomechanical pulp process. The streams collected from the second press-impregnation stage after acid pre-extraction contain a significant amount of acid pre-extracted hemicelluloses. Most of the total sugars obtained from the pressate were xylan, in which xylan was further hydrolyzed to sugar monomers under the acid pre-extraction condition. To fully understand the characteristics of hemicelluloses yielded prior to pulping, the pre-extracted hemicelluloses were separated and characterized by FT-IR, (1)H NMR, and thermogravimetric analysis in this study. Most of the FT-IR bonds from the hemicelluloses agreed well with the other two spectra of birch xylan and CA0050 xylan, except a new absorption at 1734 cm(-1) contributed to acetyl groups. The hemicelluloses obtained from acid pre-extraction began to decompose significantly at about 225 °C, slightly lower in comparison with organosolv and alkaline hemicelluloses reported in the literature.