scholarly journals Chemical Characterization of Kraft Lignin Prepared from Mixed Hardwoods

Molecules ◽  
2021 ◽  
Vol 26 (16) ◽  
pp. 4861
Author(s):  
Ji-Sun Mun ◽  
Justin-Alfred Pe Pe III ◽  
Sung-Phil Mun
Keyword(s):  
Carbon Content ◽  
Structural Changes ◽  
Chemical Characterization ◽  
Structural Features ◽  
Kraft Lignin ◽  
Kraft Pulping ◽  
Nucleophilic Attack ◽  
Low Oxygen ◽  
Structural Modifications

Chemical characterization of kraft lignin (KL) from mixed hardwoods (Acacia spp. from Vietnam and mixed hardwoods (mainly Quercus spp.) from Korea) was conducted for its future applications. To compare the structural changes that occurred in KL, two milled wood lignins (MWLs) were prepared from the same hardwood samples used in the production of KL. Elemental analysis showed that the MWL from acacia (MWL-aca) and mixed hardwood (MWL-mhw) had almost similar carbon content, methoxyl content, and C9 formula. KL had high carbon content but low oxygen and methoxyl contents compared to MWLs. The C9 formula of KL was determined to be C9H7.29O2.26N0.07S0.12(OCH3)1.24. The Mw of KL and MWLs was about 3000 Da and 12,000–13,000 Da, respectively. The structural features of KL and MWLs were investigated by Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance spectrometry (1H, 13C NMR). The analyses indicated that KL underwent severe structural modifications, such as γ-carbon cleavage, demethylation, and polycondensation reactions during kraft pulping, which resulted in increased aromatic content and decreased aliphatic content. The main linkages in lignin, β-O-4 moieties, were hardly detected in the analysis as these linkages were extensively cleaved by nucleophilic attack of SH- and OH- during pulping.

Characterization of non-cellulosic glucans in Eucalyptus globulus Labill. wood and kraft pulp

Holzforschung ◽  
2007 ◽  
Vol 61 (5) ◽  
pp. 478-482 ◽  
Author(s):  
Sara A. Lisboa ◽  
Dmitry V. Evtuguin ◽  
Carlos Pascoal Neto
Keyword(s):  
Eucalyptus Globulus ◽  
Fiber Surface ◽  
2D Nmr ◽  
Structural Features ◽  
Kraft Pulping ◽  
Hot Water ◽  
Pulp Yield ◽  
Naoh Solution ◽  
Nmr Techniques

Abstract The amount of non-cellulosic glucans in Eucalyptus globulus wood (approx. 4.5%) was assessed by extraction of sawdust with a 0.5 M NaOH solution at 90–120°C and the structural features were elucidated in a glucan-enriched polysaccharide fraction isolated by hot water extraction (120°C, 2 h). Isolated soluble glucans were characterized by wet chemistry methods and a set of 1D and 2D NMR techniques. The major proportion of glucans consisted of amylose (20%) and amylopectin (80%), although a small proportion of β-(1→3)-glucan (<0.2% on wood weight) was also detected. Although glucans are easily removed in the initial phase of kraft pulping, notable amounts were found in unbleached pulp and it was supposed that in the final stage of kraft pulping a fraction of α-glucan is precipitated onto the fiber surface and contributes to the pulp yield.

Chemical characterization of lignin from kraft pulping black liquor of Acacia mangium

2017 ◽  
Author(s):  
Euis Hermiati ◽  
Lucky Risanto ◽  
M. Adly Rahandi Lubis ◽  
Raden Permana Budi Laksana ◽  
Aniva Rizkia Dewi
Keyword(s):  
Black Liquor ◽  
Chemical Characterization ◽  
Acacia Mangium ◽  
Kraft Pulping

Raman Spectroscopic Characterization of Photonanocatalyst Aided Alkaline Pretreated Corn Stover Biomass

2014 ◽  
Vol 875-877 ◽  
pp. 1576-1580 ◽  
Author(s):  
Chao Wang ◽  
Chang Geun Yoo ◽  
Chen Xu Yu ◽  
Tae Hyun Kim
Keyword(s):  
Corn Stover ◽  
Structural Changes ◽  
Chemical Characterization ◽  
Spectroscopic Characterization ◽  
Processing Parameters ◽  
Cellulosic Biomass ◽  
Raman Spectroscopic ◽  
Processing Cost ◽  
Sodium Hydrate

The most expensive and principal step in the process of converting cellulosic biomass into biorenewables and biofuel is the pretreatment during which lignin and cellulose crystalline structure is broken down. In this study, TiO2nanoparticles were utilized as photocatalyst in addition to alkaline (ammonia and sodium hydrate) treatment of corn stover biomass to improve delignification ability and reduce the energy and chemical loadings to make the process more environmentally friendly. Raman Spectroscopic imaging, as an accurate and rapid chemical characterization method, was utilized to investigate the molecular compositional and structural changes occurring during the pretreatment process in the corn stover biomass qualitatively. Lignin characteristic peaks at 1,600, 1,620 and 1,690 cm-1as well as cellulose characteristic peaks at 1,059 and 2,888 cm-1were identified through Raman Spectroscopic measurement as indicators of the effects of the pretreatment. Real-time quantitative analysis of these functional peaks revealed the molecular structural changes during delignification, potentially may lead to optimization of the processing parameters to reduce the processing cost in the future.

scholarly journals LC–HRMS and Chemical Derivatization Strategies for the Structure Elucidation of Caribbean Ciguatoxins: Identification of C-CTX-3 and -4

Marine Drugs ◽  
2020 ◽  
Vol 18 (4) ◽  
pp. 182 ◽  
Author(s):  
Fedor Kryuchkov ◽  
Alison Robertson ◽  
Christopher O. Miles ◽  
Elizabeth M. Mudge ◽  
Silvio Uhlig
Keyword(s):  
Chemical Characterization ◽  
Diagnostic Value ◽  
Chemical Derivatization ◽  
Oxidation Reactions ◽  
Structural Modifications ◽  
Low Concentrations ◽  
Simple Chemical ◽  
Product Ions ◽  
Mass Spectrometric Fragmentation

Ciguatera poisoning is linked to the ingestion of seafood that is contaminated with ciguatoxins (CTXs). The structural variability of these polyether toxins in nature remains poorly understood due to the low concentrations present even in highly toxic fish, which makes isolation and chemical characterization difficult. We studied the mass spectrometric fragmentation of Caribbean CTXs, i.e., the epimers C-CTX-1 and -2 (1 and 2), using a sensitive UHPLC–HRMS/MS approach in order to identify product ions of diagnostic value. We found that the fragmentation of the ladder-frame backbone follows a characteristic pattern and propose a generalized nomenclature for the ions formed. These data were applied to the structural characterization of a pair of so far poorly characterized isomers, C-CTX-3 and -4 (3 and 4), which we found to be reduced at C-56 relative to 1 and 2. Furthermore, we tested and applied reduction and oxidation reactions, monitored by LC–HRMS, in order to confirm the structures of 3 and 4. Reduction of 1 and 2 with NaBH4 afforded 3 and 4, thereby unambiguously confirming the identities of 3 and 4. In summary, this work provides a foundation for mass spectrometry-based characterization of new C-CTXs, including a suite of simple chemical reactions to assist the examination of structural modifications.

scholarly journals Deep-sea Hydrothermal Vent Bacteria as a Source of Glycosaminoglycan-Mimetic Exopolysaccharides

Molecules ◽  
2019 ◽  
Vol 24 (9) ◽  
pp. 1703 ◽  
Author(s):  
Agata Zykwinska ◽  
Laëtitia Marchand ◽  
Sandrine Bonnetot ◽  
Corinne Sinquin ◽  
Sylvia Colliec-Jouault ◽  
...  
Keyword(s):  
Deep Sea ◽  
Hydrothermal Vent ◽  
Biomedical Applications ◽  
Biological Activities ◽  
Chemical Characterization ◽  
Structural Features ◽  
Chemical Diversity ◽  
Regenerative Medicines ◽  
Compositional Patterns

Bacteria have developed a unique strategy to survive in extreme environmental conditions through the synthesis of an extracellular polymeric matrix conferring upon the cells a protective microenvironment. The main structural component of this complex network constitutes high-molecular weight hydrophilic macromolecules, namely exopolysaccharides (EPS). EPS composition with the presence of particular chemical features may closely be related to the specific conditions in which bacteria evolve. Deep-sea hydrothermal vent bacteria have already been shown to produce EPS rich in hexosamines and uronic acids, frequently bearing some sulfate groups. Such a particular composition ensures interesting functional properties, including biological activities mimicking those known for glycosaminoglycans (GAG). The aim of the present study was to go further into the exploration of the deep-sea hydrothermal vent IFREMER (French Research Institute for Exploitation of the Sea) collection of bacteria to discover new strains able to excrete EPS endowed with GAG-like structural features. After the screening of our whole collection containing 692 strains, 38 bacteria have been selected for EPS production at the laboratory scale. EPS-producing strains were identified according to 16S rDNA phylogeny. Chemical characterization of the obtained EPS highlighted their high chemical diversity with the presence of atypical compositional patterns. These EPS constitute potential bioactives for a number of biomedical applications, including regenerative medicines and cancer treatment.

scholarly journals Revealing Structural Modifications of Lignin in Acidic γ-Valerolactone-H2O Pretreatment

Polymers ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 116
Author(s):  
Suxiang Li ◽  
Chengke Zhao ◽  
Fengxia Yue ◽  
Fachuang Lu
Keyword(s):  
Structural Changes ◽  
Solvent System ◽  
Side Chain ◽  
Solvent Mixtures ◽  
Aryl Ether ◽  
Structural Modifications ◽  
System A ◽  
Nmr Characterization ◽  
Lignin Model

γ-valerolactone (GVL)/H2O/acid solvent mixtures has been used in chemical pretreatment of lignocellulosic biomass, it was claimed that GVL lignins were structurally close to proto (native) lignins, or having low molecular weight with narrow polydispersity, however, the structural changes of GVL lignins have not been investigated. In this study, β-O-4 (β-aryl ether, GG), β-5 (phenylcoumaran), and β-β (resinol) lignin model compounds were treated by an acidic GVL-H2O solvent system, a promising pretreatment of lignocellulose for biomass utilization, to investigate the structural changes possibly related to the lignin involved. NMR characterization of the products isolated from the treated GG indicated that a phenyl dihydrobenzofuran, having typical C-H correlations at δC/δH 50.74/4.50 and 93.49/4.60 ppm in its HSQC spectrum, was produced from GG. In the pretreatment, the released formaldehyde from GG reacted fast with GG to form a novel 1,3-dioxane intermediate whose characteristic HSQC signals were: δC/δH 94.15–94.48/4.81–5.18 ppm and 80.82–83.34/4.50–4.94 ppm. The β-5 model, dihydrodehydrodiconiferyl alcohol, was converted into phenylcoumarone and stilbene having benzaldehyde that resulted from the allyl alcohol side chain. The β-β model, syringaresinol, was isomerized to form a mixture of syringaresinol, epi-, and dia-syringaresinol although being degraded slightly.

Skeletal elements of crinoid echinoderms: High-resolution structural and microanalytical results

1983 ◽  
Vol 41 ◽  
pp. 194-195
Author(s):  
D. F. Blake ◽  
L. F. Allard ◽  
D. R. Peacor
Keyword(s):  
High Resolution ◽  
Marine Invertebrates ◽  
Sea Urchins ◽  
Structural Features ◽  
Sea Stars ◽  
High Resolution Tem ◽  
Relationship Of ◽  
The Relationship ◽  
Insight Into

Echinodermata is a phylum of marine invertebrates which has been extant since Cambrian time (c.a. 500 m.y. before the present). Modern examples of echinoderms include sea urchins, sea stars, and sea lilies (crinoids). The endoskeletons of echinoderms are composed of plates or ossicles (Fig. 1) which are with few exceptions, porous, single crystals of high-magnesian calcite. Despite their single crystal nature, fracture surfaces do not exhibit the near-perfect {10.4} cleavage characteristic of inorganic calcite. This paradoxical mix of biogenic and inorganic features has prompted much recent work on echinoderm skeletal crystallography. Furthermore, fossil echinoderm hard parts comprise a volumetrically significant portion of some marine limestones sequences. The ultrastructural and microchemical characterization of modern skeletal material should lend insight into: 1). The nature of the biogenic processes involved, for example, the relationship of Mg heterogeneity to morphological and structural features in modern echinoderm material, and 2). The nature of the diagenetic changes undergone by their ancient, fossilized counterparts. In this study, high resolution TEM (HRTEM), high voltage TEM (HVTEM), and STEM microanalysis are used to characterize tha ultrastructural and microchemical composition of skeletal elements of the modern crinoid Neocrinus blakei.

Ultrastructural identification of three types of sensory setae on copepod antennae

1995 ◽  
Vol 53 ◽  
pp. 956-957
Author(s):  
T. M. Weatherby ◽  
P.H. Lenz
Keyword(s):  
Phase Locking ◽  
Membrane Surface ◽  
Reaction Times ◽  
High Sensitivity ◽  
Structural Features ◽  
Calanoid Copepods ◽  
Marine Food Webs ◽  
Dendritic Membrane ◽  
Ultrastructural Characterization

Crustaceans, as well as other arthropods, are covered with sensory setae and hairs, including mechanoand chemosensory sensillae with a ciliary origin. Calanoid copepods are small planktonic crustaceans forming a major link in marine food webs. In conjunction with behavioral and physiological studies of the antennae of calanoids, we undertook the ultrastructural characterization of sensory setae on the antennae of Pleuromamma xiphias.Distal mechanoreceptive setae exhibit exceptional behavioral and physiological performance characteristics: high sensitivity (<10 nm displacements), fast reaction times (<1 msec latency) and phase locking to high frequencies (1-2 kHz). Unusual structural features of the mechanoreceptors are likely to be related to their physiological sensitivity. These features include a large number (up to 3000) of microtubules in each sensory cell dendrite, arising from or anchored to electron dense rods associated with the ciliary basal body microtubule doublets. The microtubules are arranged in a regular array, with bridges between and within rows. These bundles of microtubules extend far into each mechanoreceptive seta and terminate in a staggered fashion along the dendritic membrane, contacting a large membrane surface area and providing a large potential site of mechanotransduction.

Quantitative nano-characterization of heterogeneous catalysts

1995 ◽  
Vol 53 ◽  
pp. 398-399
Author(s):  
P.A. Crozier ◽  
M. Pan
Keyword(s):  
Heterogeneous Catalysts ◽  
Low Dose ◽  
Imaging Techniques ◽  
Structural Features ◽  
Catalyst Characterization ◽  
New Developments ◽  
Double Phase ◽  
Phase Systems ◽  
Dose Imaging

Heterogeneous catalysts can be of varying complexity ranging from single or double phase systems to complicated mixtures of metals and oxides with additives to help promote chemical reactions, extend the life of the catalysts, prevent poisoning etc. Although catalysis occurs on the surface of most systems, detailed descriptions of the microstructure and chemistry of catalysts can be helpful for developing an understanding of the mechanism by which a catalyst facilitates a reaction. Recent years have seen continued development and improvement of various TEM, STEM and AEM techniques for yielding information on the structure and chemistry of catalysts on the nanometer scale. Here we review some quantitative approaches to catalyst characterization that have resulted from new developments in instrumentation.HREM has been used to examine structural features of catalysts often by employing profile imaging techniques to study atomic details on the surface. Digital recording techniques employing slow-scan CCD cameras have facilitated the use of low-dose imaging in zeolite structure analysis and electron crystallography. Fig. la shows a low-dose image from SSZ-33 zeolite revealing the presence of a stacking fault.

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