Instabilities in the System NMMO/Water/Cellulose (Lyocell Process) Caused by Polonowski Type Reactions

Holzforschung ◽  
2002 ◽  
Vol 56 (2) ◽  
pp. 199-208 ◽  
Author(s):  
Thomas Rosenau ◽  
Antje Potthast ◽  
Andreas Hofinger ◽  
Herbert Sixta ◽  
Paul Kosma
Keyword(s):  
Molecular Weight ◽  
Acetic Acid ◽  
Exchange Resin ◽  
Degradation Products ◽  
Ion Exchange Resin ◽  
Low Molecular Weight ◽  
Acid Component ◽  
Degradation Reactions ◽  
Polyglucuronic Acid

Summary Polonowski type degradation reactions are a major reason for the frequently observed instability of solutions of cellulose in N-methylmorpholine-N-oxide monohydrate (NMMO, 1). The degradation is induced by degradation products of cellulose and NMMO generated in situ in the Lyocell system. The presence of both an amine component, such as morpholine or N-methylmorpholine, and an acid component is required for the decomposition process to proceed. The latter might be a low-molecular-weight compound, such as formic acid, acetic acid or gluconic acid, or also a high-molecular-weight acid, such as polyglucuronic acid or ion exchange resin.

scholarly journals Kinetics of soybean oil epoxidation with peracetic acid formed in situ in the presence of an ion exchange resin: Pseudo-homogeneous model

2017 ◽  
Vol 23 (1) ◽  
pp. 97-111 ◽  
Author(s):  
Milovan Jankovic ◽  
Snezana Sinadinovic-Fiser ◽  
Olga Govedarica ◽  
Jelena Pavlicevic ◽  
Jaroslava Budinski-Simendic
Keyword(s):  
Acetic Acid ◽  
Ion Exchange ◽  
Soybean Oil ◽  
Peracetic Acid ◽  
Exchange Resin ◽  
Homogeneous Model ◽  
Ion Exchange Resin ◽  
Rate Coefficients ◽  
Epoxy Ring

A kinetic model was proposed for the epoxidation of vegetable oils with peracetic acid formed in situ from acetic acid and hydrogen peroxide in the presence of an acidic ion exchange resin as a catalyst. The model is pseudo-homogeneous with respect to the catalyst. Besides the main reactions of peracetic acid and epoxy ring formation, the model takes into account the side reaction of epoxy ring opening with acetic acid. The partitioning of acetic acid and peracetic acid between the aqueous and organic phases and the change in the phases? volumes during the process were considered. The temperature dependency of the apparent reaction rate coefficients is described by a reparameterized Arrhenius equation. The constants in the proposed model were estimated by fitting the experimental data obtained for the epoxidations of soybean oil conducted under defined reaction conditions. The highest epoxy yield of 87.73% was obtained at 338 K when the mole ratio of oil unsaturation:acetic acid:hydrogen peroxide was 1:0.5:1.35 and when the amount of the catalyst Amberlite IR-120H was 4.04 wt.% of oil. Compared to the other reported pseudo-homogeneous models, the model proposed in this study better correlates the change of double bond and epoxy group contents during the epoxidation process.

scholarly journals Preparation of Porous Polymers by ”in Situ Precipitation” Using Low Molecular Weight Gelators

2002 ◽  
Vol 34 (6) ◽  
pp. 474-477 ◽  
Author(s):  
Masahiro Suzuki ◽  
Yasuhiko Sakakibara ◽  
Satoshi Kobayashi ◽  
Mutsumi Kimura ◽  
Hirofusa Shirai ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Porous Polymers ◽  
Low Molecular Weight ◽  
Low Molecular Weight Gelators

Ruthenium Recovery from Acetic Acid Waste Solution by Using PEI-Coated Biomass-Chitosan Composite Fiber

2015 ◽  
Vol 1130 ◽  
pp. 577-580 ◽  
Author(s):  
Jeong Ae Kim ◽  
Myung Hee Song ◽  
Yeoung Sang Yun
Keyword(s):  
Molecular Weight ◽  
Acetic Acid ◽  
Freeze Drying ◽  
Ion Exchange Resin ◽  
Composite Fiber ◽  
Drying Methods ◽  
Drying Method ◽  
Waste Solution ◽  
Chitosan Composite ◽  
Acid Waste

Polyethylenimine (PEI)-coated biomass-chitosan composite fiber (PBCF) was fabricated to recover Ru from acetic acid waste solution. The present work aimed to understand the effects of molecular weight of chitosan and drying method on stability and sorption performance of the PBCF. For this, the PBCF was prepared by extruding the mixed solutions of chitosan and Corynebacteriumglutamicum to form the composite fibers which were modified with ionic polymer, PEI. The degree of swelling of PBCFs prepared by hot-air, natural, and freeze drying methods were 1.25, 1.34, and 1.07 %, respectively, indicating that the freeze-drying method was the best. Batch biosorption studies showed that the maximum Ru uptake could be achieved with PBCF prepared with medium molecular weight chitosan, and could reach 34.1 mg/g, which was 7.9 times higher than that of the commercial ion exchange resin, LEWATIT® MonoPlus M 500 (4.3 mg/g). Therefore, PBCF can be considered as an alternative sorbent to synthetic resin for recovery of Ru form industrial acetic acid waste solution.

scholarly journals Ion-exchange-resin-catalyzed adamantylation of phenol derivatives with adamantanols: Developing a clean process for synthesis of 2-(1-adamantyl)-4-bromophenol, a key intermediate of adapalene

2012 ◽  
Vol 8 ◽  
pp. 227-233 ◽  
Author(s):  
Nan Wang ◽  
Ronghua Wang ◽  
Xia Shi ◽  
Gang Zou
Keyword(s):  
Acetic Acid ◽  
Ion Exchange ◽  
Sulfonic Acid ◽  
Exchange Resin ◽  
Ion Exchange Resin ◽  
Phenol Derivatives ◽  
Resin Catalyst ◽  
Acid Resin ◽  
Free Process ◽  
Sulfonic Acid Resin

A clean process has been developed for the synthesis of 2-adamantylphenol derivatives through adamantylation of substituted phenols with adamantanols catalyzed by commercially available and recyclable ion-exchange sulfonic acid resin in acetic acid. The sole byproduct of the adamantylation reaction, namely water, could be converted into the solvent acetic acid by addition of a slight excess of acetic anhydride during the work-up procedure, making the process waste-free except for regeneration of the ion-exchange resin, and facilitating the recycling of the resin catalyst. The ion-exchange sulfonic acid resin catalyst could be readily recycled by filtration and directly reused at least ten times without a significant loss of activity. The key intermediate of adapalene, 2-(1-adamantyl)-4-bromophenol, could be produced by means of this waste-free process.

γ-Ray Irradiation Practical Conditions for Low Molecular Weight Chitosan Material Production

2003 ◽  
Vol 792 ◽  
Author(s):  
Rangrong Yoksan ◽  
Mitsuru Akashi ◽  
Mikiji Miyata ◽  
Siriratana Biramontri ◽  
Suwabun Chirachanchai
Keyword(s):  
Molecular Weight ◽  
Acetic Acid ◽  
Solid State ◽  
Primary Structure ◽  
Low Molecular Weight ◽  
Aqueous Acetic Acid ◽  
Low Molecular Weight Chitosan ◽  
Backbone Structure ◽  
Γ Ray ◽  
Terminal Chain

ABSTRACTThe present work focuses on the γ-ray irradiation doses and conditions (dry solid state, solid state dispersing in 0.5–2 % aqueous H2O2 solution, solid state dispersing in 1% aqueous acetic acid, and 2% aqueous K2S2O8) to determine the level that the molecular weight of chitosan is lowered significantly without changing its primary structure. Molecular weight of chitosan (105-106 Dalton) is reduced approximately 50% under the γ-ray dose of 20 kGy in the dry solid state. The decrease in molecular weight is enhanced up to 80% when chitosan is suspended in 0.5–2 % aqueous H2O2 solution during γ-ray irradiation. In either condition, the backbone structure of the irradiated product is maintained with little change in the terminal chain. In the cases of (i) chitosan suspended in 2% aqueous K2S2O8 and (ii) chitosan in 1% aqueous acetic acid, chitosans lose their primary structures and physical properties.

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