High-purity cellulose production from birch wood by γ-valerolactone/water fractionation and IONCELL-P process.

This study presents an environmentally friendly process to produce high-purity cellulose (dissolving pulp) from birch wood by combining γ-valerolactone (GVL)/water fractionation and ionic liquid treatment of pulp, IONCELL-P (IP). A paper grade pulp was produced from optimal GVL cook with a similar composition to birch kraft pulp and was bleached with ECF sequence before the hemicelluloses were removed using the IONCELL-P process. The purity of the GVL-IP pulp significantly exceeded that of commercial prehydrolysis kraft (PHK) and prehydrolysis soda-anthraquinone (PH-Soda-AQ) pulps. IONCELL-P extraction removed more than 90% of the hemicelluloses, resulting in a dissolving pulp with a purity of 96% and a high molecular mass fraction, 2.3 times higher than that of a conventional PHK pulp. GVL-IP pulps are suitable not only for regenerated cellulose fibers or films, but also for high-purity, high-viscosity cellulose acetate and ethers, which cannot be produced in an environmentally friendly way by conventional processes.

Concurrent production of sodium lignosulfonate and ethanol from bagasse spent liquor.

This study was done with the aim of lignosulfonate and ethanol production from different spent liquors of bagasse pulping process. For this purpose, alkali lignin from bagasse alkali liquor was separated and was sulfomethylated to produce soda lignosulfonate (SLig). Furthermore, raw bagasse was directly treated with sodium sulfite in acidic and neutral conditions to produce BLig and NLig bagasse lignosulfonate, respectively. In addition, the pentoses and hexoses impurities in lignosulfonates were fermented to ethanol using Candida guilliermondii. Results showed that the molecular weight of NLig lignosulfonate was considerably high comparing to the SLig and BLig lignosulfonates. A high level of thermal resistance was found in case of SLig regarding to the other samples at 500 °C. Fermentation of the spent liquors with Candida guilliermondii led to a maximum ethanol yield of 7.0, 1.0 and 5.1 g L-1 in NLig, SLig and BLig, respectively.

Effects of hemicellulose pre-extraction and cellulose nanofiber on the properties of rice straw pulp.

The aim of this study was to evaluate the influence of mild alkaline pre-extraction on the hemicelluloses removal of rice straw. In addition, the performance of cellulose nanofibers (CNFs) addition on some physico-mechanical properties obtained from extracted and un-extracted (control) samples were investigated. An optimum compromise was found as operating conditions (10% soda, 50°C, and 90min) that provided moderate hemicelluloses removal (48.1%). The residual extracted rice straw particles were subjected to soda-anthraquinone pulping at 160°C for 30-60min with 6 to 18% active alkali charge. Compared with the control samples, the screened yield and Kappa number for extracted pulps decreased slightly. Extracted samples showed better air resistance compared with the un-extracted (control) pulps. However, pre-extraction was found to negatively impact on some mechanical properties such as decrease in burst and tensile indices while addition of CNFs and refining of fibers could improve the strength properties considerably. In general, the addition of CNFs in any concentrations considerably enhanced tensile and burst indices of the sheets in extracted and un-extracted conditions, compared with the unfilled ones. The improvement in mechanical properties was considered one of the key benefits brought by CNFs reinforcement. On the other hand, the stretch properties of the beaten pulps are higher than those of control samples. SEM observations showed that CNFs were deposited on the voids between the rice straw fibers.