Novel concepts of dissolving pulp production

Mechanical pretreatment improving hemicelluloses removal from cellulosic fibers during cold caustic extraction

“…The wood-based regenerated cellulose products which can be manufactured from dissolving pulps include viscose rayon, cellulose nitrate, and cellulose acetate, among others (Gübitz et al, 1997;Schild and Sixta, 2011). Also, the dissolving pulps can be superior raw materials for the production of nanofibrillation cellulose (NFC), nanocrystalline celluloses (NCC) and microcrystalline cellulose (MCC) (Wang et al, 2015;Sixta et al, 2013).…”

“…A low hemicelluloses content is one of the important quality parameters for the dissolving pulps (Schild and Sixta, 2011;Miao et al, 2014). There have been many studies reporting the negative impact of hemicelluloses on the manufacturing processes of various products and the properties of resulting products, from dissolving pulps (Sixta et al, 2013;Wang et al, 2014). Moreover, the removed hemicelluloses can be recovered and further converted into other products, such as bio-ethanol, furfural, and xylitol (Shi et al, 2011;Shen et al, 2013;Panthapulakkal et al, 2015;Liu et al, 2013a).…”

Purification of cellulosic pulp by hot water extraction

“…This increase, largely due to the demand for textile fibers but also for other cellulose specialty products like cellulose acetate, is still expected to prevail over the next 20-30 years (Haemmerle 2011;Sixta et al 2013). Dissolving pulps contain a high cellulose content ([90 % of the dry mass) of uniform degree of polymerization (DP) and low amounts of organic and inorganic impurities.…”

“…An alternative to the acid sulfite-HCE process for the production of viscose-grade pulps may be the SO 2 -Ethanol-Water (SEW) pulping. In addition to a good quality rayon pulp, the SEW process allows high flexibility in terms of raw materials, short cooking times, and a significant recovery of sugars from the pulping liquor (Iakovlev and Heiningen 2012;Sixta et al 2013). The production of viscose-grade pulps has also been investigated by applying a CCE stage to paper-grade pulps, which allows the removal of substantial amounts of shortchain hemicellulosic sugars while preserving the yield of cellulose (Gehmayr et al 2011;Schild and Sixta 2011).…”

“…In general, the purity of dissolving pulps produced by a combined HWE and SAQ pulping is rather low, although this largely depends on the selected raw material (Ribas Batalha et al 2011;Sixta et al 2013). Increasing the cellulose purity can be realized by increasing the HWE intensity.…”