Ozonation of pine kraft lignin in alkaline solution. Part 1: Ozonation, characterization of kraft lignin and its ozonated preparations

Holzforschung ◽  
2004 ◽  
Vol 58 (6) ◽  
pp. 622-630 ◽  
Author(s):  
Rui Wang ◽  
Chen-Loung Chen ◽  
Josef S. Gratzl
Keyword(s):  
Molecular Mass ◽  
Sodium Hydroxide Solution ◽  
Group Analysis ◽  
Kraft Lignin ◽  
Oxygen Radical ◽  
Active Oxygen ◽  
Radical Species ◽  
Average Molecular Mass ◽  
Air Stream ◽  
Ph Range

Abstract Pine kraft lignin was purified to obtain a kraft lignin preparation (KL) with weight average molecular mass (Mw) of 5500. The KL was then ozonated with an ozone-air stream containing 2–2.5% of ozone in 0.1 M sodium hydroxide solution to prepare ozonated kraft lignin preparations with ozone consumption of 10, 25, 30 and 40% per KL; Oz-10-KL, Oz-25-KL, Oz-30-KL and Oz-40-KL, respectively. The pH of reaction mixture was decreased with increasing ozone consumption, while the carboxylic acid content and the Mw of resulting ozonated lignins increase with increasing ozone consumption. The KL and its ozonated preparations were then characterized by elemental composition, functional group analysis, molecular mass distribution and nitrobenzene-K4MnO4 oxidation. The results showed that the KL extensively undergoes oxidative cleavage of both side chains and aromatic moieties without decrease in the Mw as well as dehydrogenationive coupling of phenolic degraded fragments by active oxygen radical species, such as hydroperoxyl and hydroxyl radicals. The formation of these active oxygen radical species are produced by way of a series of reactions initiated by the reaction of ozone with hydroxide anions at pH range of 12.4–10.5, producing superoxide (-O2•) and hydroperoxyl (HOO•) radicals.

scholarly journals How many carboxyl groups does an average molecule of humic-like substances contain?

2008 ◽  
Vol 8 (3) ◽  
pp. 10005-10020 ◽  
Author(s):  
I. Salma ◽  
G. G. Láng
Keyword(s):  
Molecular Mass ◽  
Group Analysis ◽  
Weak Acid ◽  
Biologically Active ◽  
Carboxyl Groups ◽  
Carboxyl Group ◽  
Average Molecular Mass ◽  
Solubility In Water ◽  
Functional Group Analysis ◽  
The Mean

Abstract. The carboxyl groups of atmospheric humic-like substances (HULIS) are of special interest because they influence the solubility in water, affect the water activity and surface tension of droplets in the air, and allow formation of chelates with biologically active elements. Experimentally determined abundances of the carboxyl group within HULIS by functional group analysis are consistent with our knowledge on the average molecular mass of HULIS if the number of dissociable carboxyl groups is assumed to be rather small. The best agreement between the average molecular mass derived from the existing abundance data and the average molecular mass published earlier occurs for assuming approximately one dissociable carboxyl group only. This implies that HULIS can not be regarded as polycarboxilic acid. The average molecular mass of HULIS derived from our electrochemical measurements with the assumption of one dissociable carboxyl group per molecule ranges from 248 to 305 Da. It was concluded that HULIS are a moderately strong/weak acid with a dissociation constant of about pK=3.4, which fits well into the interval represented by fulvic and humic acids. The mean number of dissociable carboxyl groups in HULIS molecules was refined to be between 1.1 and 1.4.

scholarly journals Photo-mediated selective deconstructive geminal dihalogenation of trisubstituted alkenes

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Han Wang ◽  
Ren Wei Toh ◽  
Xiangcheng Shi ◽  
Tonglin Wang ◽  
Xu Cong ◽  
...  
Keyword(s):  
Olefin Metathesis ◽  
Oxygen Radical ◽  
Active Oxygen ◽  
Double Bonds ◽  
Molecular Scaffolds ◽  
Homolytic Cleavage ◽  
Radical Species ◽  
Benzyl Alcohols ◽  
Wide Range ◽  
Trisubstituted Alkenes

Abstract Selective deconstructive functionalization of alkenes, other than the well-established olefin metathesis and ozonolysis, to produce densely functionalized molecular scaffolds is highly attractive but challenging. Here we report an efficient photo-mediated deconstructive germinal dihalogenation of carbon-carbon double bonds. A wide range of geminal diiodoalkanes and bromo(iodo)alkanes (>40 examples) are directly prepared from various trisubstituted alkenes, including both cyclic and acyclic olefins. This C=C cleavage is highly chemoselective and produces geminal dihalide ketones in good yields. Mechanistic investigations suggest a formation of alkyl hypoiodites from benzyl alcohols and N-iodoimides, which undergo light-induced homolytic cleavage to generate active oxygen radical species.

scholarly journals How many carboxyl groups does an average molecule of humic-like substances contain?

2008 ◽  
Vol 8 (20) ◽  
pp. 5997-6002 ◽  
Author(s):  
I. Salma ◽  
G. G. Láng
Keyword(s):  
Molecular Mass ◽  
Group Analysis ◽  
Weak Acid ◽  
Biologically Active ◽  
Carboxyl Groups ◽  
Carboxyl Group ◽  
Average Molecular Mass ◽  
Solubility In Water ◽  
Functional Group Analysis ◽  
The Mean

Abstract. The carboxyl groups of atmospheric humic-like substances (HULIS) are of special interest because they influence the solubility in water, affect the water activity and surface tension of droplets in the air, and allow formation of chelates with biologically active elements. Experimentally determined abundances of the carboxyl group within HULIS by functional group analysis are consistent with our knowledge on the average molecular mass of HULIS if the number of dissociable carboxyl groups is assumed to be rather small. The best agreement between the average molecular mass derived from the existing abundance data and the average molecular mass published earlier occurs for assuming approximately one dissociable carboxyl group only. This implies that HULIS can not be regarded as polycarboxilic acid in diluted solutions. The average molecular mass of HULIS derived from our electrochemical measurements with the assumption of one dissociable carboxyl group or equivalently, one dissociable sulphate ester per molecule ranges from 250 to 310 Da. It was concluded that HULIS are a moderately strong/weak acid with a dissociation constant of about pK=3.4, which fits well into the interval represented by fulvic and humic acids. The mean number of dissociable hydrogen (i.e. of carboxyl groups and sulphate esters jointly) in HULIS molecules was refined to be between 1.1 and 1.4 in acidic solutions.

Extraction of polyethylene glycols with dicarbolide solutions in nitrobenzene

1990 ◽  
Vol 55 (8) ◽  
pp. 1959-1967 ◽  
Author(s):  
Petr Vaňura ◽  
Pavel Selucký
Keyword(s):  
Polyethylene Glycol ◽  
Molecular Mass ◽  
Extraction Constant ◽  
Metal Extraction ◽  
Polyethylene Glycols ◽  
Relative Molecular Mass ◽  
Published Data ◽  
Average Molecular Mass ◽  
Peg 400 ◽  
Extraction Constants

The extraction of polyethylene glycol of average molecular mass 400 (PEG 400) with dicarbolide solution in nitrobenzene and of longer-chain polyethylene glycol, of average molecular mass 1 500 (PEG 1 500), with chlorinated dicarbolide solution in nitrobenzene was studied. During the extraction of PEG 400, the polyethylene glycol solvates the Horg+ ion in the organic phase giving rise to the HLorg+ species (L is polyethylene glycol). The obtained value of the extraction constant Kex(HLorg+) = 933 is consistent with published data of metal extraction. Extraction of PEG 1 500 was treated applying the simplified assumption that the thermodynamic behaviour of PEG 1 500 is the same as that of n molecules of polyethylene glycol with relative molecular mass 1 500/n, each solvating one cation. For this model, the value of n = 3.2 ± 1.1 and the values of the extraction constants of the HL1/n,org+ and HL2/n,org+ species were obtained by using the adapted program LETAGROP. This value of n is consistent with published extraction data in the presence of polyethylene glycol with a relative molecular mass from 200 to 1 000.

scholarly journals Nanomechanical Molecular Mass Sensing Using Suspended Microchannel Resonators

Sensors ◽  
2021 ◽  
Vol 21 (10) ◽  
pp. 3337
Author(s):  
Alberto Martín-Pérez ◽  
Daniel Ramos ◽  
Javier Tamayo ◽  
Montserrat Calleja
Keyword(s):  
Molecular Mass ◽  
Mass Density ◽  
Applied Pressure ◽  
Atomic Mass ◽  
Liquid Sample ◽  
Mass Sensing ◽  
Average Molecular Mass ◽  
Fluid Properties ◽  
Molecular Masses ◽  
Microchannel Resonators

In this work we study the different phenomena taking place when a hydrostatic pressure is applied in the inner fluid of a suspended microchannel resonator. Additionally to pressure-induced stiffness terms, we have theoretically predicted and experimentally demonstrated that the pressure also induces mass effects which depend on both the applied pressure and the fluid properties. We have used these phenomena to characterize the frequency response of the device as a function of the fluid compressibility and molecular masses of different fluids ranging from liquids to gases. The proposed device in this work can measure the mass density of an unknown liquid sample with a resolution of 0.7 µg/mL and perform gas mixtures characterization by measuring its average molecular mass with a resolution of 0.01 atomic mass units.

scholarly journals Levan-Producing Leuconostoc citreum Strain BD1707 and Its Growth in Tomato Juice Supplemented with Sucrose

2015 ◽  
Vol 82 (5) ◽  
pp. 1383-1390 ◽  
Author(s):  
Jin Han ◽  
Xiaofen Xu ◽  
Caixia Gao ◽  
Zhenmin Liu ◽  
Zhengjun Wu
Keyword(s):  
Molecular Mass ◽  
Sugar Content ◽  
Carbon Sources ◽  
Viable Cell ◽  
Monosaccharide Composition ◽  
Tomato Juice ◽  
Average Molecular Mass ◽  
Content Type ◽  
Leuconostoc Citreum ◽  
Sucrose Medium

ABSTRACTA levan-producing strain, BD1707, was isolated from Tibetan kefir and identified asLeuconostoc citreum. The effects of carbon sources on the growth ofL. citreumBD1707 and levan production in tomato juice were measured. The changes in pH, viable cell count, sugar content, and levan yield in the cultured tomato juice supplemented with 15% (wt/vol) sucrose were also assayed.L. citreumBD1707 could synthesize more than 28 g/liter of levan in the tomato juice-sucrose medium when cultured at 30°C for 96 h. Based on the monosaccharide composition, molecular mass distribution, Fourier transform infrared (FTIR) spectra, and nuclear magnetic resonance (NMR) spectra, the levan synthesized byL. citreumBD1707 was composed of a linear backbone consisting of consecutive β-(2→6) linkedd-fructofuranosyl units, with an estimated average molecular mass of 4.3 × 106Da.

Red Mud (RM) and Soil Amelioration

2019 ◽  
pp. 151-167 ◽  
Author(s):  
Amit Kumar
Keyword(s):  
Red Mud ◽  
Sodium Hydroxide Solution ◽  
Bauxite Residue ◽  
Acid Soils ◽  
Large Area ◽  
Vegetation Growth ◽  
Ground Water Pollution ◽  
Trace Metal Content ◽  
Rich Material ◽  
Ph Range

Rapid growth in industrialization, which is necessary and inevitable for society progress, has also created negative encroachment. Red mud produced during alumina production has strong alkanity in a pH range of 10-13% because of the sodium hydroxide solution used in the refining process. The base is strong enough to kill plant and animal life, and due to finer particle and trace metal content, it creates soil contamination, ground water pollution, and suspension in ocean; hence, we need precautions while we use this waste to add with soil. Red mud occupies a large area or its deposition in it. Red mud has properties similar to sandy clay. Red mud has property similar to clay and sand, even if it does not contain quartz or clay mineral. Bauxite residue/red mud can be mixed with variant type of saline soils, acid soils organic rich material, and silicate soil suitable pH conditions were achieved to promote vegetation growth.

Photo-Degradation Alkali Lignin by Bis-(2-Methyl Quinoline) Squarylium Cyanine TiO2 Photocatalyst in Sunlight

2013 ◽  
Vol 838-841 ◽  
pp. 2717-2720
Author(s):  
Y. L. Ma ◽  
Shi Xue Ren ◽  
Shi Yan Han
Keyword(s):  
Solar Energy ◽  
Energy Conversion ◽  
Molecular Mass ◽  
Energy Conversion Efficiency ◽  
Average Molecular Mass ◽  
Photo Degradation ◽  
Alkali Lignin ◽  
Squaraine Dye ◽  
Solar Energy Conversion Efficiency ◽  
Alcoholic Hydroxyl

Photo-degradation alkali lignin was prepared in sunlight by the system of TiO2 and squaraine dye (QSC). The influence of the ratio of QSC to TiO2 on the solar energy conversion efficiency was tested; the principle of degradation alkali lignin by TiO2 photocatalyst in sunlight was researched. The results showed that the number-average and mass-average molecular mass of degradation alkali lignin and the control lignin were 1,548 and 2,822, respectively, the phenolic hydroxyl of degradation alkali lignin is 5.63% with the control is 4.64%, and alcoholic hydroxyl of degradation alkali lignin is 3.21% with the control is 3.77%.

Microstructure and Basic Properties of Domestic Butyl Rubber 1751

2014 ◽  
Vol 912-914 ◽  
pp. 235-242
Author(s):  
Nai Xiu Ding ◽  
Pei Yan Zuo ◽  
Yi Jia ◽  
Li Li Wang ◽  
Hai Tao Wang
Keyword(s):  
Molecular Mass ◽  
Gel Permeation Chromatography ◽  
Mechanical Analysis ◽  
Volatile Matter ◽  
Matter Content ◽  
Butyl Rubber ◽  
Gravimetric Analysis ◽  
Average Molecular Mass ◽  
Basic Properties

The characterization of microstructure and basic properties of domestic butyl rubber 1751 ( IIR 1751) was performed with different testing , such as 1H-NMR spectrum, gel permeation chromatography, dynamic mechanical analysis, thermal gravimetric analysis and differential scanning calorimeter. And the comparison with Butyl 268 and Butyl 301 was made. The results showed that IIR1751 had a narrower molecular mass distribution, lower number-average molecular mass and lower weight-average molecular mass. The unsaturation degree of IIR1751 was close to Butyl 268 and Butyl 301. Its thermal stability was higher than the other and its ash content and volatile matter content was lower. Its glass transition temperature was same to Butyl 268’s, which was slightly higher than the Butyl 301. Dispersion of carbon black in IIR1751 vulcanizates was poor, but IIR1751 vulcanizates had good processing property, had a longer scorch safety period and fast curing rate. Its fatigue performance was good and its mechanical properties can achieve a better balance.

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