Browsing by Author "Elsayed, Sherif"

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Air gap spinning of a cellulose solution in [DBNH][OAc] ionic liquid with a novel vertically arranged spinning bath to simulate a closed loop operation in the Ioncell® process
(2021-02-05) Guizani, Chamseddine; Larkiala, Sauli; Moriam, Kaniz; Sawada, Daisuke; Elsayed, Sherif; Rantasalo, Sami; Hummel, Michael; Sixta, Herbert
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
A novel, small-volume vertically arranged spin bath was successfully developed for an air gap lyocell-type spinning process. A maximum regeneration bath length with a minimum free volume characterizes the concept of the new spin bath. Using the ionic liquid (IL) 1,5-diazabicyclo[4.3.0]non-5-enium acetate [DBNH][OAc], the spin bath showed very good spinning performances of IL-cellulose dopes at high draw ratios and spinning duration for single filament spinning experiments. Using this new device, it was possible to get a step further in the optimization of the Ioncell® process and simulate a process closed loop operation by performing single filament spinning in IL/H2O mixtures. Good dope spinnability and preserved fibers mechanical properties were achieved in a coagulation bath containing up to 30 wt% IL. It is only at 45 wt% of IL in the bath that the spinnability and fibers mechanical properties started to deteriorate. The fibers fibrillar structure was less pronounced in IL-containing spinning bath in comparison to a pure water bath. However, their crystallinity after washing was preserved regardless of the spinning bath composition. The results presented in this work have a high relevance to the upscaling of emerging IL-based cellulose dissolution and spinning processes.
Recycling and Spinning of Superbase-Based Ionic Liquid Solutions in the Lyocell Process: Potential and Limitations
(2021) Elsayed, Sherif
School of Chemical Technology | Doctoral dissertation (article-based)
This thesis demonstrates the recyclability of superbase-based ionic liquids in the scope of developing a sustainable Lyocell process for the man-made cellulose fiber industry. Ioncell is a Lyocell-based technology that utilizes ionic liquids in the direct dissolution of cellulose and the production of textile-grade fibers via a dry-jet wet spinning process. In order to commercialize this technology, there are several important criteria to be met: The selection of a solvent with a strong cellulose dissolution power, a stable spinning process, good mechanical properties of the regenerated fibers, and above of all, the quantitative recovery of the solvent from the coagulation bath without impairing its solvation power. The work presented herein aspires to cover all the mentioned challenges. We chose a thermal recovery path to recycle the ionic liquids while identifying potential solvent alterations taking place. Such alterations include the consumption of the ionic liquid in nucleophilic hydrolysis reactions, the selective vaporization of the base during recovery, and the residual water in the recovered solvent. The combination of these alterations can interfere with the dissolution process. Initially, we investigated the potential of guanidine- and amidine-based ionic liquids, in comparison to N-methylmorpholine N-oxide, as solvents capable of producing textile-grade fibers. We also presented the recyclability of the guanidine-based ionic liquid, 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-enium acetate, and the amidine-based ionic liquid, 1,5-diaza-bicyclo[4.3.0]non-5-enium acetate, in the Ioncell process, while we quantitively analyzed the changes in solvent composition (= alterations) occurring during the thermal recovery stages. The results revealed that the 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-enium acetate is hydrothermally more stable, implying that the alterations in the solvent did not affect its dissolution capabilities. Contrarily, a relatively large fraction of the 1,5-diaza-bicyclo[4.3.0]non-5-enium acetate was consumed in undesired hydrolysis reactions and in the vaporization of the neutral base, which inhibited the dissolution power of the recovered solvent. Additionally, we simulated the solvent alterations in both ionic liquids to explore the thresholds for cellulose dissolution and the impact of the alterations on the rheological properties of the solution and the spinnability of the fibers. The outcome confirmed the tolerance of 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-enium acetate to substantially more alterations in its composition, while the fibers produced from it exhibited superior properties. These findings favor 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-enium acetate as a promising solvent in the Lyocell process and can be regarded as an important milestone in the scaling up of the Ioncell process.
Superbase-based protic ionic liquids for cellulose filament spinning
(2021-01) Elsayed, Sherif; Hummel, Michael; Sawada, Daisuke; Guizani, Chamseddine; Rissanen, Marja; Sixta, Herbert
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Abstract: Lyocell fibers have received increased attention during the recent years. This is due to their high potential to satisfy the rising market demand for cellulose-based textiles in a sustainable way. Typically, this technology adopts a dry-jet wet spinning process, which offers regenerated cellulose fibers of excellent mechanical properties. Compared to the widely exploited viscose process, the lyocell technology fosters an eco-friendly process employing green direct solvents that can be fully recovered with low environmental impact. N-methylmorpholine N-oxide (NMMO) is a widely known direct solvent that has proven its success in commercializing the lyocell process. Its regenerated cellulose fibers exhibit higher tenacities and chain orientation compared to viscose fibers. Recently, protic superbase-based ionic liquids (ILs) have also been found to be suitable solvents for lyocell-type fiber spinning. Similar to NMMO, fibers of high mechanical properties can be spun from the cellulose-IL solutions at lower spinning temperatures. In this article, we study the different aspects of producing regenerated cellulose fibers using NMMO and relevant superbase-based ILs. The selected ILs are 1,5-diazabicyclo[4.3.0]non-5-ene-1-ium acetate ([DBNH]OAc), 7-methyl-1,5,7-triazabicyclo[4.4.0] dec-5-enium acetate ([mTBDH]OAc) and 1,8-diazabicyclo[5.4.0]undec-7-enium acetate ([DBUH]OAc). All ILs were used to dissolve a 13 wt% (PHK) cellulose pulp. The study covers the fiber spinning process, including the rheological characterization of the various cellulose solutions. Moreover, we discuss the properties of the produced fibers such as mechanical performance, macromolecular properties and morphology. Graphic abstract: [Figure not available: see fulltext.].
γ-valerolactone fractionation of pine wood
(2016-08-23) Elsayed, Sherif
Kemian tekniikan korkeakoulu | Master's thesis
Fractionation of milled pine wood using γ-valerolactone (GVL)/ water solution as a novel organosolv treatment is proposed. Milled pine wood of 0.125 mm was cooked with GVL/water solution of different ratios. The reaction took place at 180 °C for 120 min in a monowave reactor. It was found that the highest delignification in pulp was achieved over the range of 50% to 60% wt. GVL/water. Under these conditions, the lignin content in the pulp was 12.7% and 14.4% O.D. wood basis, and the pulp yield was 60% and 65% respectively. Additionally, delignification increased when a different batch of samples at 50% and 60% wt. GVL were tested at 200 °C for 120 min. The residual lignin was the lowest at 60% wt. GVL with only 5.9% remaining. There was no significant change in delignification observed when the reaction time was increased to 150 min for the 50% and 60% wt. GVL samples at 180 °C. On the other hand, minor losses in cellulose content were detected at the first reaction conditions. The losses in the cellulose content slightly increased when temperature was raised to 200 °C. On the contrary, hemicelluloses content in pulp, xylan and glucomannan, were readily hydrolyzed. The hydrolysis of hemicelluloses was greatly affected by the increase in temperature, the final hemicelluloses content in pulp at 200 °C was 2.6% O.D. wood at 60% wt. GVL. For the aim of studying the trend behavior of delignification and polysaccharides hydrolysis, the fractionation reactions were carried out at 180 °C, 195°C and 210°C. As expected, delignification was maximum at 210 °C with only 45 min reaction time, while the least delignification was achieved at 180 °C and 180 min. The same trend is adopted by the hydrolysis of the polysaccharides, where intensive hydrolysis of hemicelluloses was noticed at 210 °C compared to 180 °C. On the contrary, cellulose losses were minor and residual cellulose values were not significantly affected by the increase in temperature. Finally, the rate constants (K) for delignification and polysaccharides hydrolysis were determined at the reaction temperatures of 180 °C, 195°C and 210°C. The K values showed faster delignification reactions at 210°C with 0.0378 1/min to 0.0225 at 195 °C, while the slowest delignification rate constant was 0.0038 1/min at 180 °C. The activation energy (E) for the delignification reactions was found to be 140.1 KJ/mol. As for polysaccharides, ’semi-crystalline’ cellulose hydrolysis was much slower compared to ’amorphous’ hemicelluloses hydrolysis at any given temperature, and xylan hydrolysis was faster than that of glucomannan.
γ-valerolactone/water Fractionation of Softwood
(2017-03-28) Elsayed, Sherif; Le, Huy; Borrega Sabate, Marc; Sixta, Herbert
A4 Artikkeli konferenssijulkaisussa