scholarly journals Extraction Behaviors of Lignin and Hemicellulose-Derived Sugars During Organosolv Fractionation of Agricultural Residues Using a Bench-Scale Ball Milling Reactor

Energies ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 352
Author(s):  
Tae Hoon Kim ◽  
Hyun Kwak ◽  
Tae Hyun Kim ◽  
Kyeong Keun Oh
Keyword(s):  
Ball Milling ◽  
Agricultural Residues ◽  
Barley Straw ◽  
Conversion Yield ◽  
Fractionation Process ◽  
Molecular Weight Distributions ◽  
Lignin Extraction ◽  
Similar Chemical ◽  
Weight Distributions ◽  
Hydrolysis Of

Ethanol organosolv fractionation combined with ball milling was conducted on three major agricultural residues: Rice husk (RH), rice straw (RS), and barley straw (BS). The highest lignin extraction yields of RH, RS, and BS were 55.2%, 53.1%, and 59.4% and the purity of lignin recovered was 99.5% for RH and RS, and 96.8% for BS, with similar chemical characteristics, i.e., low molecular weight distributions (1453–1817 g/mol) and poly dispersity index (1.15–1.28). However, considering the simultaneous production of hemicellulose-derived sugars, distinctive fractionation behaviors were shown for the three agricultural residues. The highest hemicellulose-derived sugar yield was 73.8% when RH was fractionated at 170 °C for 30 min. Meanwhile, very low sugar yields of 31.9% and 35.7% were obtained from RS and BS, respectively. The highest glucan-to-glucose conversion yield from enzymatic hydrolysis of fractionated RH reached 85.2%. Meanwhile, the enzymatic digestibility of the fractionated RS and BS was 60.0% and 70.5%, respectively. Consequently, the fractionation efficiency for RH can be improved with fine refinement. For the case of RS, other fractionation process should be applied to achieve effective fractionation performance.

Kinetics and fundamental mechanisms of starch removal by activated sludge: hydrolysis of starch to maltose and maltotriose is the rate-determining step

1999 ◽  
Vol 40 (1) ◽  
pp. 61-68 ◽  
Author(s):  
Y. Ubukata
Keyword(s):  
Molecular Weight ◽  
Activated Sludge ◽  
Removal Rates ◽  
Molecular Weights ◽  
Rate Determining Step ◽  
Molecular Weight Distributions ◽  
Uptake Rates ◽  
Weight Distributions ◽  
Sludge Hydrolysis ◽  
Hydrolysis Of

The mechanisms of hydrolysis and uptake of starch, a polymer in sewage, by activated sludge (AS) were investigated, taking into consideration the mechanisms of the maltose transport system, responsible for the uptake of hydrolysis products of starch, in Gram-negative bacteria. AS was acclimated to dextrin, and the molecular weight distributions of the substrates during dextrin removal are analyzed using a GPC method. The removal rates of substrates such as dextrin, various maltodextrins (maltotriose, etc.), maltose and glucose by AS, and the oxygen uptake rates (OURs) of AS during the removal of these substrates were compared. Low-molecular-weight saccharides such as glucose, maltose and maltotriose were undetectable in the substrates during dextrin removal. The removal rates of maltose and maltotriose were higher than those of dextrin and glucose, and the OURs of AS during the removal of maltose and maltotriose were higher than those for other substrates. Therefore, hydrolysis of starch to maltose (dimer) and maltotriose (trimer), and not to glucose (monomer), appears to be the rate-determining step during the removal of starch, although maltodextrins with molecular weights up to 1152 (maltoheptaose) appear to penetrate the bacterial outer membrane.

scholarly journals Lignin Extraction from Waste Pine Sawdust Using a Biomass Derived Binary Solvent System

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1090
Author(s):  
Solange Magalhães ◽  
Alexandra Filipe ◽  
Elodie Melro ◽  
Catarina Fernandes ◽  
Carla Vitorino ◽  
...  
Keyword(s):  
Morphological Changes ◽  
Extraction Time ◽  
Added Value ◽  
Binary Solvent ◽  
Waste Biomass ◽  
Biomass Waste ◽  
Fractionation Process ◽  
Pine Sawdust ◽  
Renewable Chemicals ◽  
Lignin Extraction

Lignocellulosic biomass fractionation is typically performed using methods that are somehow harsh to the environment, such as in the case of kraft pulping. In recent years, the development of new sustainable and environmentally friendly alternatives has grown significantly. Among the developed systems, bio-based solvents emerge as promising alternatives for biomass processing. Therefore, in the present work, the bio-based and renewable chemicals, levulinic acid (LA) and formic acid (FA), were combined to fractionate lignocellulosic waste (i.e., maritime pine sawdust) and isolate lignin. Different parameters, such as LA:FA ratio, temperature, and extraction time, were optimized to boost the yield and purity of extracted lignin. The LA:FA ratio was found to be crucial regarding the superior lignin extraction from the waste biomass. Moreover, the increase in temperature and extraction time enhances the amount of extracted residue but compromises the lignin purity and reduces its molecular weight. The electron microscopy images revealed that biomass samples suffer significant structural and morphological changes, which further suggests the suitability of the newly developed bio-fractionation process. The same was concluded by the FTIR analysis, in which no remaining lignin was detected in the cellulose-rich fraction. Overall, the novel combination of bio-sourced FA and LA has shown to be a very promising system for lignin extraction with high purity from biomass waste, thus contributing to extend the opportunities of lignin manipulation and valorization into novel added-value biomaterials.

The Use of Novel F-RAFT Agents in High Temperature and High Pressure Ethene Polymerization: Can Control be Achieved?

2007 ◽  
Vol 60 (10) ◽  
pp. 788 ◽  
Author(s):  
Markus Busch ◽  
Marion Roth ◽  
Martina H. Stenzel ◽  
Thomas P. Davis ◽  
Christopher Barner-Kowollik
Keyword(s):  
Molecular Weight ◽  
High Pressure ◽  
High Temperature ◽  
Degree Of Polymerization ◽  
Molecular Weight Distributions ◽  
High Pressure High Temperature ◽  
Reversible Addition ◽  
Weight Distributions ◽  
Raft Agent ◽  
Initial Results

Simulations are employed to establish the feasibility of achieving controlled/living ethene polymerizations. Such simulations indicate that reversible addition–fragmentation chain transfer (RAFT) agents carrying a fluorine Z group may be suitable to establish control in high-pressure high-temperature ethene polymerizations. Based on these simulations, specific fluorine (F-RAFT) agents have been designed and tested. The initial results are promising and indicate that it may indeed be possible to achieve molecular weight distributions with a polydispersity being significantly lower than that observed in the conventional free radical process. In our initial trials presented here (using the F-RAFT agent isopropylfluorodithioformate), a correlation between the degree of polymerization and conversion can indeed be observed. Both the lowered polydispersity and the linear correlation between molecular weight and conversion indicate that control may in principle be possible.

Environmentally Benign Adhesive Synthesized by Dispersion Copolymerization of Styrene and Butyl Acrylate

2006 ◽  
Vol 11-12 ◽  
pp. 757-760
Author(s):  
Jun Ying Zhang ◽  
Peng Dou
Keyword(s):  
Molecular Weight ◽  
Butyl Acrylate ◽  
Monomer Concentration ◽  
Environmentally Benign ◽  
Functional Monomer ◽  
Molecular Weights ◽  
Molecular Weight Distributions ◽  
Stabilizer Concentration ◽  
Ethanol Medium ◽  
Weight Distributions

Environmentally benign adhesive was synthesized by dispersion copolymerization of styrene(St) and butyl acrylate (BA) in an ethanol medium with benzoyl peroxide (BPO) as the initiator and poly(vinylpyrrolidone) as the stabilizer in the presence of acrylic acid(AA) as the functional monomer. The effect of the concentration of stabilizer, initiator and functional monomer on the conversions, molecular weights and molecular weight distributions was investigated. The results show that the conversions almost keep invariable with the increasing of stabilizer concentration, but the molecular weights increase and molecular weight distributions decrease. Conversions increase with the increasing of initiator concentration, but the molecular weights and molecular weight distributions decrease. However with the increasing of functional monomer concentration, conversions and molecular weight distributions increase but the molecular weights decrease.

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