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To achieve a breakthrough in the application of cold caustic extraction, it is necessary to limit the amount of alkali and to dissolve the hemicelluloses sufficiently. A NaOH/ZnO aqueous solution system was used to separate hemicelluloses from bleached bamboo pulp efficiently and selectively. The NaOH/ZnO process proved to be more successful in the removal of hemicelluloses. Under the conditions of 0.5% ZnO concentration, the NaOH/ZnO aqueous solution system decreased the hemicelluloses content to 4.99%, which was lower than 7.46% of the control sample treated with NaOH alone at the same 7% NaOH concentration. Correspondingly, the NaOH/ZnO system led to an increase in alpha-cellulose content with significantly improved hemicelluloses removal efficiency and selectivity. As a result of the NaOH/ZnO process, a higher degree of polymerization was observed, and the cellulose I structure was always maintained, which provided good benefits for the subsequent utilization of cellulose. [ABSTRACT FROM AUTHOR]

Because of the wide adaptability to samples in various states, UV–vis diffuse reflectance spectroscopy has attracted increasing attention. In the present work, it was firstly used to analyze lignocellulosic biomass material and develop the possible use for rapid detection. Through the analysis of the spectra, it was observed that the extremely pure microcrystalline cellulose, filter paper and purchased xylan have almost no absorption, whereas the chemical pulps, dissolving pulps and extracted hemicellulose with residual trace impurities show a weak absorption in the range from 200 nm to 400 nm. The prominent sensitivity to the trace impurities, such as residual lignin, makes the UV–vis diffuse reflectance spectroscopy a potential tool for the rapid detection of the purity of cellulose and hemicellulose. As for lignin, the spectrum is characterized by a broader strong absorption at 250–280 nm and 280–350 nm, of which the latter is similar to UV absorption spectra. In addition, UV–vis diffuse reflectance spectroscopy can be potentially used in monitoring lignin-like substance formation in the biomass engineering. [ABSTRACT FROM AUTHOR]

In this work, a simple two-stage pretreatment (TSP) was utilized to improve hemicellulose separation and alleviate lignin condensation and therefore facilitate hemicellulose extraction and subsequent kraft pulping. In contrast to single-stage pretreatment, TSP showed a significant improvement for hemicellulose extraction and hemicellulose degradation and provided an almost identical cellulose loss. The hemicellulose separation efficiency was significantly improved using TSP with 60 min first followed by 30 min. More importantly, proper pretreatment is beneficial to the subsequent delignification; extensive pretreatment can retard delignification. [ABSTRACT FROM AUTHOR]

Herein, an ionic liquid/water (IL/w) system was developed to separate hemicelluloses from the chemical pulp with enhanced efficiency by employing xylanase. In the traditional IL/w process, when the water content was in the range 20-15%, the extraction of hemicelluloses was 71–80%. However, the highly efficient hemicelluloses removal was always accompanied with an increased cellulose loss. In this regard, xylanase (X) pretreatment was introduced to facilitate the IL/w process for improving the separation selectivity/efficiency of the hemicelluloses. In the case of the IL/w-20 (water content is 20%) procedure, X 30 (30 mg/g xylanase) pretreatment could increase hemicelluloses removal from 71 to 78%, while the separation selectivity increased from 11.0 to 43.8. Additionally, X pretreatment also reduced IL usage/charge to achieve the same degree of hemicelluloses removal. [ABSTRACT FROM AUTHOR]

To further explore the factors that resist hemicelluloses degradation and release, the chemical composition and molecular weight (MW) in both the interior and exterior portions of the hydrothermally pretreated bamboo substrates were characterized. The chemical composition analysis showed that pretreatment made the lignin tend to accumulate on the exterior surface of the bamboo chips; and therefore gave rise to a large difference of lignin content between exterior and interior. Along with the degradation of hemicelluloses, the difference of hemicelluloses content in both the exterior and interior part became small. On the contrary, the hemicelluloses from the both exterior and interior portions had an invariable MW in the early stage of pretreatment; whereas, the difference of hemicelluloses MW between the exterior and interior part increased with the pretreatment continue, indicating low MW of hemicelluloses in the interior portion. Long time pretreatment promoted increasingly lignin covering on the surface of the chips; the lignin coatings might act as a hydrophobic layer blocking the access of the degraded hemicelluloses. [ABSTRACT FROM AUTHOR]

• The TRO application allows a reduction of NaOH with comparable hemicellulose extraction. • The TRO/CCE procedure can make the cellulose fiber more flexible and more accessible. • The reactivity of dissolving pulp is related to accessibility of cellulose materials. The development of effective separation of hemicelluloses from fully bleached cellulosic pulp fibers is conducive to the development and utilization of high value-added cellulose products. In this study, Turkey Red Oil (sulfonated castor oil) (TRO), a renewable source, was proposed to facilitate hemicelluloses separation from chemical pulp in cold caustic extraction (CCE). As expected, TRO application can significantly promote hemicelluloses separation in the CCE process. By contrast to the traditional CCE process, TRO/CCE could decrease the hemicelluloses content from 9.1 to 6.1%, while the hemicelluloses removal selectivity increased from 72.5 to 82.3% and efficiency, increased from 52.4 to 68.1%. Moreover, without sacrificing hemicelluloses removal, the TRO utilization can reduce the alkaline consumption and therefore preserve the cellulose I crystal from conversion to cellulose II. Additionally, the TRO/CCE procedure made the cellulose fiber more flexible and more accessible to react with CS 2 and therefore a high Fock reactivity. [ABSTRACT FROM AUTHOR]