Fractionation and characterization of lignin-carbohydrate complexes (LCCs) from eucalyptus fibers

Holzforschung ◽  
2011 ◽  
Vol 65 (1) ◽  
pp. 43-50 ◽  
Author(s):  
Jiebing Li ◽  
Raquel Martin-Sampedro ◽  
Cristiane Pedrazzi ◽  
Göran Gellerstedt
Keyword(s):  
Milling Time ◽  
Molecular Size ◽  
Solvent System ◽  
Tetrabutylammonium Hydroxide ◽  
Flax Fibers ◽  
Tetrabutylammonium Fluoride ◽  
Solvent Systems ◽  
Time Required ◽  
Molecular Size Distribution

Abstract The effect of milling time on the structure of lignin was investigated by analyzing the quantity and molecular size distribution of thioacidolysis products obtained from wood and pulp of eucalypt (Eucalyptus globulus). After milling, the ability of three solvent systems was determined to completely dissolve the wood or pulp meal. It was found that a mixture of DMSO and 50% aqueous tetrabutylammonium hydroxide was superior to either dimethylacetamide-LiCl or DMSO-tetrabutylammonium fluoride as solvent. By applying the minimum milling time required for complete dissolution, structurally unaltered wood or pulp could be further separated into lignin-carbohydrate fractions. These were analyzed by thioacidolysis. From eucalypt pulp, two different lignin-carbohydrate fractions were obtained, one glucan- and one xylan-enriched fraction, with the latter having more syringyl units in its lignin moieties. The developed solvent system seems to be universal because spruce and flax fibers and pulps could also be dissolved in it after milling.

Structure of Polybutadienes

1967 ◽  
Vol 40 (5) ◽  
pp. 1529-1543 ◽  
Author(s):  
W. S. Bahary ◽  
D. I. Sapper
Keyword(s):  
Light Scattering ◽  
Molecular Size ◽  
Structural Features ◽  
Melting Point Depression ◽  
Linear Polymers ◽  
Long Chain Branching ◽  
Molecular Weights ◽  
Catalyst Systems ◽  
Molecular Size Distribution

Abstract Polybutadienes made with six different catalyst systems were examined: (1) butyllithium, (2) “nickel-based”, (3) alfin, (4) “titanium-based”, (5) “cobalt-based”, and (6) free radical emulsion. The microstructure and macrostructure of the polybutadienes have been determined and are compared to the results published in the literature. These polybutadienes may be considered to be random terpolymers of cis, trans, and vinyl addition of butadiene. The glass transition temperature is specified by the vinyl content. The crystalline melting points of the high trans and also the high cis polybutadienes obey to a high measure Flory's equation for melting point depression of a random terpolymer. The molecular weights of the polybutadienes have been determined by light scattering and osmometry and the degree of long chain branching has been determined by the branching index, 〈g′〉. The macro-structural features of the linear polymers are confirmed by fractionation. However, the polydispersities calculated from fractionation data do not agree with those determined from light scattering and osmometry for the branched samples. The discrepancy is attributed to the method of characterization of the fractions. A distinction is made between molecular weight distribution and molecular size distribution.

Characterization of Landfill Leachates by Molecular Size Distribution, Biodegradability, and Inert Chemical Oxygen Demand

2009 ◽  
Vol 81 (5) ◽  
pp. 499-505 ◽  
Author(s):  
Míriam C. S. Amaral ◽  
Cynthia F. A. Ferreira ◽  
Liséte Celina Lange ◽  
Sérgio F. Aquino
Keyword(s):  
Chemical Oxygen Demand ◽  
Size Distribution ◽  
Oxygen Demand ◽  
Molecular Size ◽  
Landfill Leachates ◽  
Molecular Size Distribution

scholarly journals Comparative Extraction Performance of Solvent Systems in the Extraction and Characterization of Pectin from Prosopis Africana Seed Gum

2020 ◽  
Vol 3 (3a) ◽  
pp. 93-98
Author(s):  
PA Adie ◽  
CO Ikese ◽  
EA Otache
Keyword(s):  
Functional Food ◽  
Solvent System ◽  
Ash Content ◽  
Equivalent Weight ◽  
Food Ingredient ◽  
Prosopis Africana ◽  
Solvent Systems ◽  
Extraction Performance ◽  
Seed Gum

Pectin was separately extracted in warm water bath from sun-dried and crushed Prosopis africana seed gum, using 0.05 M solutions of HCl, H2SO4, CH3COOH, C6H8O7 and a 3:2 blend of (H2SO4: C6H8O7). The physicochemical properties of pectin extracted from the Prosopis africana seed gum shows the following: colour varied from beige-brown to wheat brown, equivalent weight (1,818.18 mg/mol to 25,000 mg/mol), methoxyl content (0.124 % to 1.705 %), moisture content (12 % to 38 %) and ash content (2 %) for all the solvent system used. Also, the comparative solvent performance shows that the H2SO4:C6H8O7 solvent blend was the most effective for pectin extraction followed by the solvent HCl and H2SO4, while C6H8O7 was the least effective. The comparative pectin yield of Prosopis africana seed gum using selected acid solvent ranged from 6.94 % to 15.28 %. Among the solvents under study, the H2SO4:C6H8O7 solvent blend gave the highest pectin yield (15.28 %) with beige-brown, low methoxyl pectin of high purity and could be used as a functional food ingredient domestically and industrially

Preparation and Characterization of Porous PLGA Scaffold for Tissue Engineering

2014 ◽  
Vol 898 ◽  
pp. 322-325
Author(s):  
Xue Jun Wang ◽  
Tao Lou ◽  
Zhen Yang ◽  
Kun Peng He
Keyword(s):  
Tissue Engineering ◽  
Mixed Solvent ◽  
Solvent System ◽  
High Porosity ◽  
Thermally Induced Phase Separation ◽  
Plga Scaffold ◽  
Thermally Induced ◽  
Fibrous Matrix ◽  
Solvent Systems

Scaffold plays an important role in tissue engineering. In this study, porous PLGA scaffold was successfully prepared by mixed solvent systems using the thermally induced phase separation method. The PLGA scaffold shows fibrous matrix and interconnective pores, and the scaffold has high porosity and compressive modulus with dioxane/THF solvent system, which could be a very promising scaffold for tissue engineering.

OPTIMIZATION OF THIN LAYER CHROMATOGRAPHY METHODS FOR SEPARATION AND IDENTIFICATION OF ANTIDEPRESSANTS IN THEIR MIXTURE

2014 ◽  
Vol 21 (1) ◽  
pp. 11-15
Author(s):  
Daiva Kazlauskienė ◽  
Guoda Kiliuvienė ◽  
Palma Nenortienė ◽  
Giedrė Kasparavičienė ◽  
Ieva Matukaitytė
Keyword(s):  
Thin Layer ◽  
Thin Layer Chromatography ◽  
Solvent System ◽  
Ammonia Solution ◽  
Relative Standard ◽  
Rf Values ◽  
Solvent Systems ◽  
Paroxetine Hydrochloride ◽  
Fluvoxamine Maleate ◽  
Layer Chromatography

By conducting the toxicological analysis it is meaningful to determine the analytical system that could identify simultaneously several medicinal preparations quickly and precisely. The purpose of this work was to create and validate the method of thin-layer chromatography that would be suitable to separate the components of antidepressant mixture (amitriptyline hydrochloride, paroxetine hydrochloride, sertraline hydrochloride, fluvoxamine maleate and buspirone hydrochloride) and to identify them. The system was validated with regard to the sensitivity, repetition of data, resistance and particularity. The solvent systems with potential of high separation of components in their mixture were created: acetonitrile, methanol, ammonia solution 25 percent (85:10:5); acetonitrile, methanol, ammonia solution 25 percent (75:20:5); dichlormethane, 1,4-dioxane, ammonia solution 25 percent (50:45:5); dichlormethane, 1,4-dioxane, ammonia solution 25 percent (42:55:3); trichlormethane, 1,4-dioxane, ammonia solution 25 percent (25:70:5); trichlormethane, 1,4-dioxane, ammonia solution 25 percent (60:36:4). One of the most suitable solvent systems for separation of the analyzed mixture (sertraline, amitriptyline, paroxetine, buspirone, fluvoxamine) was determined – acetonitrile, methanol, ammonia solution 25 percent (85:10:5). When this solvent system was used, the average Rf values of the analyzed compounds differed the most. Validation was conducted – the relative standard deviation (RSD, percent) of the average Rf value of the analyzed compounds varied from 0,6 to 1,8 percent and did not exceed the permissible error of 5 percent. The sensitivity of methodology was determined by assessing the intensity of the mixture’s spots on the chromatographic plate. The detection limit of buspirone was 0,0012 µg; sertraline – 0,0008 µg; amitriptyline – 0,0004 µg; fluvoxamine – 0,0004 µg; paroxetine – 0,0008 µg. The resistance of results to the changed conditions – it was determined that when the amounts of the solvents acetonitrile and methanol were increased or decreased to two milliliters, the average Rf values of the analyzed compounds did not change statistically significantly

Determination of the Size Distribution of Dissolved Organics in Effluents

1973 ◽  
Vol 8 (1) ◽  
pp. 1-15 ◽  
Author(s):  
L.A. Addie ◽  
K.L. Murphy ◽  
J.L. Robertson
Keyword(s):  
Size Distribution ◽  
Biological Treatment ◽  
Oxygen Demand ◽  
Molecular Size ◽  
Monitoring Systems ◽  
Clean Surface ◽  
Sephadex Column ◽  
Dissolved Organics ◽  
Molecular Size Distribution

Abstract The importance of removing the small amounts of residual organics is increasing as the sources of clean surface water decrease. Knowledge of the nature of these soluble residual organics will be needed in order to assess the type of treatment required for their removal. Residual organics in three different biological treatment plants were analyzed and compared. An attempt was made to characterize these organics by a molecular size distribution on a Sephadex column monitored by differential ultraviolet and refractive index detectors. The organic carbon and chemical oxygen demand of the fractions collected from the column was also determined. An investigation of some of the problems inherent in the monitoring systems was conducted.

Molecular Size Distribution of Lignin in Wood

Nature ◽  
1967 ◽  
Vol 214 (5086) ◽  
pp. 410-411 ◽  
Author(s):  
W. BROWN ◽  
S. I. FALKEHAG ◽  
E. B. COWLING
Keyword(s):  
Size Distribution ◽  
Molecular Size ◽  
Molecular Size Distribution

Ultrasound-Assisted Oxidative Desulfurization of Diesel Fuel in H2O2/Heteropoly Acid/Solvent System

2014 ◽  
Vol 1033-1034 ◽  
pp. 85-89 ◽  
Author(s):  
Guo Xian Yu ◽  
Qian Zhong ◽  
Mei Jin ◽  
Ping Lu
Keyword(s):  
Sulfur Content ◽  
Ultrasonic Irradiation ◽  
Diesel Fuel ◽  
Oxidation Reaction ◽  
Heteropoly Acid ◽  
Oxidative Desulfurization ◽  
Solvent System ◽  
Oxidative Reaction ◽  
Solvent Systems ◽  
Ultrasound Assisted

Ultrasound-assisted oxidative desulfurization (UAODS) of diesel fuel in H2O2/Heteropoly acid/Solvent systems, was investigated. Effects of solvent, catalyst, ultrasound and reaction temperature on the oxidation desulfurization of diesel fuel were investigated. When MPA/oil was 2%wt, methanol/diesel fuel was 20%wt, ultrasound power was 400 W and ultrasound time was 10 min, the sulfur content of diesel fuel was decreased from 211 ppm to 19 ppm. The use of ultrasonic irradiation in H2O2/Heteropoly acid/Solvent system significantly improved the efficiency of the oxidation reaction, and solvent was helpful to make the oxidative reaction happen in the same one phase.

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