Structural characteristics of lignin in pruning residues of olive tree (Olea europaea L.)

AbstractOlive tree pruning (OTP) is an abundant and inexpensive agricultural lignocellulosic residue that is an interesting feedstock for producing bioethanol and other bio-products in the context of lignocellulosic biorefineries. However, the presence of lignin in OTP hinders the transformation processes as it limits the access to cell wall polysaccharides. On the other hand, the aromatic/phenolic structure of the lignin polymer makes it an interesting raw material for producing chemicals, fuels and other commodities that are nowadays produced from fossil fuels. Thus, the knowledge of the OTP lignin structure is crucial to develop tailor-made pretreatments for their removal as well as for additional valorization of the lignin polymer. In this work, the OTP lignin was isolated as milled wood lignin (MWL), a lignin preparation that is considered representative of the native lignin, and characterized by two-dimensional nuclear magnetic resonance (2D-NMR) and thioacidolysis. The results demonstrated that the lignin is mainly composed of guaiacyl (G) and syringyl (S) lignin units in similar abundances (S/G ratio of ~1), with minor amounts ofp-hydroxyphenyl (H) units. The most abundant lignin inter-unit linkages are β-O-4′ alkyl-aryl ethers (75% of all linkages), followed by the condensed phenylcoumarans (12%) and resinols (8%), and with lower amounts of dibenzodioxocins (2%) and spirodienones (3%). The analysis of the thioacidolysis dimers gave additional information regarding the distribution of the lignin units involved in condensed interunit linkages, including 5-5′, 4-O-5′, β-5′, β-1′ and β-β′. The high lignin content (25%), together with the relatively low S/G ratio and the abundance of condensed (carbon-carbon linked) structures, points to a low reactivity of OTP lignin during delignification pretreatments.

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New Insights on Structures Forming the Lignin-Like Fractions of Ancestral Plants

Frontiers in Plant Science ◽

10.3389/fpls.2021.740923 ◽

2021 ◽

Vol 12 ◽

Author(s):

Jorge Rencoret ◽

Ana Gutiérrez ◽

Gisela Marques ◽

José C. del Río ◽

Yuki Tobimatsu ◽

...

Keyword(s):

Structural Information ◽

2D Nmr ◽

Plant Evolution ◽

Pteridium Aquilinum ◽

Gas Chromatography Mass Spectrometry ◽

Aryl Ether ◽

Pyrolysis Gas ◽

Alkyl Aryl ◽

Two Samples ◽

G Ratio

In the present work, lignin-like fractions were isolated from several ancestral plants –including moss (Hypnum cupressiforme and Polytrichum commune), lycophyte (Selaginella kraussiana), horsetail (Equisetum palustre), fern (Nephrolepis cordifolia and Pteridium aquilinum), cycad (Cycas revoluta), and gnetophyte (Ephedra fragilis) species– and structurally characterized by pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS) and two-dimensional nuclear magnetic resonance (2D-NMR) spectroscopy. Py-GC/MS yielded marker compounds characteristic of lignin units, except in the H. cupressiforme, P. commune and E. palustre “lignins,” where they were practically absent. Additional structural information on the other five samples was obtained from 2D-NMR experiments displaying intense correlations signals of guaiacyl (G) units in the fern and cycad lignins, along with smaller amounts of p-hydroxyphenyl (H) units. Interestingly, the lignins from the lycophyte S. kraussiana and the gnetophyte E. fragilis were not only composed of G- and H-lignin units but they also incorporated significant amounts of the syringyl (S) units characteristic of angiosperms, which appeared much later in plant evolution, most probably due to convergent evolution. The latter finding is also supported by the abundance of syringol derivatives after the Py-GC/MS analyses of these two samples. Regarding lignin structure, β−O−4′ alkyl-aryl ethers were the most abundant substructures, followed by condensed β−5′ phenylcoumarans and β−β′ resinols (and dibenzodioxocins in the fern and cycad lignins). The highest percentages of alkyl-aryl ether structures correlated with the higher S/G ratio in the S. Kraussiana and E. fragilis lignin-like fractions. More interestingly, apart from the typical monolignol-derived lignin units (H, G and S), other structures, assigned to flavonoid compounds never reported before in natural lignins (such as amentoflavone, apigenin, hypnogenol B, kaempferol, and naringenin), could also be identified in the HSQC spectra of all the lignin-like fractions analyzed. With this purpose, in vitro synthesized coniferyl-naringenin and coniferyl-apigenin dehydrogenation polymers were used as standards. These flavonoids were abundant in H. cupressiforme appearing as the only constituents of the moss lignin-like fraction (including 84% of dimeric hypnogenol B) and their abundance decreased in those of S. Kraussiana (with amentoflavone and naringenin representing 14% of the total aromatic units), and the two ancient gymnosperms (0.4–1.2%) and ferns (0–0.7%).

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Scope of biodiesel from oils of woody plants: a review

Clean Energy ◽

10.1093/ce/zkaa006 ◽

2020 ◽

Vol 4 (2) ◽

pp. 89-106

Author(s):

Baskar Thangaraj ◽

Pravin Raj Solomon

Keyword(s):

Woody Plants ◽

Fossil Fuels ◽

Edible Oils ◽

Raw Materials ◽

Structural Characteristics ◽

Chemical Properties ◽

Raw Material ◽

Biodiesel Production ◽

Primary Methods ◽

Environmental Consequences

Abstract Non-edible oils obtained from chosen non-conventional woody plants are considered as potential raw materials for biodiesel production. These plants mostly grow in wastelands. Structural characteristics of these oils as raw material are very much in tune with the properties of biodiesel such as long-chain hydrocarbon, having an adequate level of unsaturation with branched chain. Four primary methods are being followed to make biodiesel from vegetable oil. They are direct use through blending, microemulsion, thermal cracking (pyrolysis) and transesterification. Non-edible oil would eliminate the issue of food vs fuel. The biodiesel manufactured from oils of woody plants may partially reduce the demand for liquid-fuel energy and addresses the environmental consequences of using fossil fuels. Oil from a total of 17 species of woody plants (Angiosperms) belonging to 14 families are considered in this paper. The habit, habitat and geographical distribution of each species are also presented. The physico-chemical properties of their oil, with special reference to the fatty-acid profile that ultimately decides the characteristics of the biodiesel prepared from them, are reviewed.

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Structural Characteristics of the Guaiacyl-Rich Lignins From Rice (Oryza sativa L.) Husks and Straw

Frontiers in Plant Science ◽

10.3389/fpls.2021.640475 ◽

2021 ◽

Vol 12 ◽

Author(s):

Mario J. Rosado ◽

Jorge Rencoret ◽

Gisela Marques ◽

Ana Gutiérrez ◽

José C. del Río

Keyword(s):

Oryza Sativa ◽

Rice Straw ◽

Oryza Sativa L ◽

Structural Characteristics ◽

Analytical Techniques ◽

Gas Chromatography Mass Spectrometry ◽

Aryl Ether ◽

Rice Husks ◽

Alkyl Aryl ◽

G Ratio

Rice (Oryza sativa L.) is a major cereal crop used for human nutrition worldwide. Harvesting and processing of rice generates huge amounts of lignocellulosic by-products such as rice husks and straw, which present important lignin contents that can be used to produce chemicals and materials. In this work, the structural characteristics of the lignins from rice husks and straw have been studied in detail. For this, whole cell walls of rice husks and straw and their isolated lignin preparations were thoroughly analyzed by an array of analytical techniques, including pyrolysis coupled to gas chromatography-mass spectrometry (Py-GC/MS), nuclear magnetic resonance (NMR), and derivatization followed by reductive cleavage (DFRC). The analyses revealed that both lignins, particularly the lignin from rice husks, were highly enriched in guaiacyl (G) units, and depleted in p-hydroxyphenyl (H) and syringyl (S) units, with H:G:S compositions of 7:81:12 (for rice husks) and 5:71:24 (for rice straw). These compositions were reflected in the relative abundances of the different interunit linkages. Hence, the lignin from rice husks were depleted in β–O–4′ alkyl-aryl ether units (representing 65% of all inter-unit linkages), but presented important amounts of β–5′ (phenylcoumarans, 23%) and other condensed units. On the other hand, the lignin from rice straw presented higher levels of β–O–4′ alkyl-aryl ethers (78%) but lower levels of phenylcoumarans (β–5′, 12%) and other condensed linkages, consistent with a lignin with a slightly higher S/G ratio. In addition, both lignins were partially acylated at the γ-OH of the side-chain (ca. 10–12% acylation degree) with p-coumarates, which overwhelmingly occurred over S-units. Finally, important amounts of the flavone tricin were also found incorporated into these lignins, being particularly abundant in the lignin of rice straw.

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Alternative pretreatments of rice and tobacco wastes for the production of fermentable sugars

Revista Facultad de Ingeniería Universidad de Antioquia ◽

10.17533/10.17533/udea.redin.n91a03 ◽

2019 ◽

Author(s):

C. Curbelo Hernández ◽

E. Véliz Lorenzo ◽

J. M. Ameneiros Martínez

Keyword(s):

Fossil Fuels ◽

Lignin Content ◽

Raw Material ◽

Rice Hull ◽

Procedure Time ◽

Lignin Concentration ◽

Rice Hulls ◽

Second Stage ◽

Lignocellulosic Wastes ◽

Agroindustrial Wastes

Thescarce oil supplies and the emissions of gases of greenhouse effect have caused the interest in production and utilization of lignocellulosic bioethanol. This can substitute partially or totally the fossil fuels. The stages of pretreatment and enzymatic hydrolysis are the most expensive. Different pretreatments have been studied for ethanol production from these materials. Their results depend on the method characteristics and on biomass used. The agroindustrial wastes present a composition with possibilities of being evaluated like raw material for bioethanol production. In the present research, the pretreatment stages with Ultrasound and Ozone are studied, in order to decrease the lignin content and to increase the performance of the fermentative sugars in the lignocellulosic wastes (rice hull and dark tobacco vein). In the first pretreatment procedure, time and waste type were studied and in the second stage, the ozone concentration, waste type and moisture content were the studied variables. A combined procedure was applied to the best preliminary results. It is demonstrated that a decrease in the lignin concentration and the structural transformation of the materials under consideration come true. The best results were gotten for the rice hulls.

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Evaluating Lignin-Rich Residues from Biochemical Ethanol Production of Wheat Straw and Olive Tree Pruning by FTIR and 2D-NMR

International Journal of Polymer Science ◽

10.1155/2015/314891 ◽

2015 ◽

Vol 2015 ◽

pp. 1-11 ◽

Cited By ~ 33

Author(s):

José I. Santos ◽

Raquel Martín-Sampedro ◽

Úrsula Fillat ◽

José M. Oliva ◽

María J. Negro ◽

...

Keyword(s):

Ethanol Production ◽

Wheat Straw ◽

Internal Energy ◽

Energy Use ◽

Value Added ◽

Olive Tree ◽

2D Nmr ◽

Cellulosic Biomass ◽

G Ratio ◽

Tree Pruning

Lignin-rich residues from the cellulose-based industry are traditionally incinerated for internal energy use. The future biorefineries that convert cellulosic biomass into biofuels will generate more lignin than necessary for internal energy use, and therefore value-added products from lignin could be produced. In this context, a good understanding of lignin is necessary prior to its valorization. The present study focused on the characterization of lignin-rich residues from biochemical ethanol production, including steam explosion, saccharification, and fermentation, of wheat straw and olive tree pruning. In addition to the composition and purity, the lignin structures (S/G ratio, interunit linkages) were investigated by spectroscopy techniques such as FTIR and 2D-NMR. Together with the high lignin content, both residues contained significant amounts of carbohydrates, mainly glucose and protein. Wheat straw lignin showed a very low S/G ratio associated withp-hydroxycinnamates (p-coumarate and ferulate), whereas a strong predominance of S over G units was observed for olive tree pruning lignin. The main interunit linkages present in both lignins wereβ-O-4′ethers followed by resinols and phenylcoumarans. These structural characteristics determine the use of these lignins in respect to their valorization.

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Levulinic Acid Production from Macroalgae: Production and Promising Potential in Industry

Sustainability ◽

10.3390/su132413919 ◽

2021 ◽

Vol 13 (24) ◽

pp. 13919

Author(s):

Maria Dyah Nur Meinita ◽

Amron Amron ◽

Agus Trianto ◽

Dicky Harwanto ◽

Wahyu Caesarendra ◽

...

Keyword(s):

Levulinic Acid ◽

Fossil Fuels ◽

Lignin Content ◽

Industrial Sector ◽

Department Of Energy ◽

Raw Material ◽

Industrial Scale ◽

Limited Information ◽

Alternative Source ◽

Advantages And Disadvantages

The development of macroalgal biorefinery products as an alternative source of renewable fuels is an opportunity to solve the dependence on fossil fuels. Macroalgae is a potential biomass that can be developed as a raw material for producing platform chemicals such as levulinic acid (LA). In the industrial sector, LA is among the top 12 biomass-derived feedstocks designated by the U.S. Department of Energy as a high-value chemical. Several studies have been conducted on the production of LA from terrestrial-based biomass, however, there is still limited information on its production from macroalgae. The advantages of macroalgae over terrestrial and other biomasses include high carbohydrate and biomass production, less cultivation cost, and low lignin content. Therefore, this study aims to investigate the potential and challenge of producing LA from macroalgae in the industrial sector and determine its advantages and disadvantages compared with terrestrial biomass in LA production. In this study, various literature sources were examined using the preferred reporting items for systematic reviews and meta-analyses (PRISMA) method to identify, screen, and analyze the data of the published paper. Despite its advantages, there are some challenges in making the production of levulinic acid from macroalgae feasible for development at the industrial scale. Some challenges such as sustainability of macroalgae, the efficiency of pretreatment, and hydrolysis technology are often encountered during the production of levulinic acid from macroalgae on an industrial scale.

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Production of Biofuel (Bio-Ethanol) From Fruitwaste: Banana Peels

International Journal of Engineering and Advanced Technology - Regular Issue ◽

10.35940/ijeat.a3024.109119 ◽

2019 ◽

Vol 9 (1) ◽

pp. 5897-5901

Keyword(s):

Fossil Fuels ◽

Fermentation Process ◽

Lignin Content ◽

Raw Material ◽

Cellulose Content ◽

Biomass Hydrolysis ◽

Hydrolysis Process ◽

Alkaline Conditions ◽

Ph Conditions ◽

Pre Treatment

Bio-ethanol, a type of biofuel, is known as renewable energy source as it is derived from biomass as its raw material. Biomass can be found in abundance and sustainable i.e. sources are available continuously, unlike the currently used conventional fossil fuels where these sources are limited and depleting. In this study, biomass from fruit waste, banana peels, were utilized to produce bio-ethanol via hydrolysis and fermentation process. Banana peels, a lignocellulosic biomass, possesses compositions which favour these processes, where the banana peels are rich in cellulose content and low in lignin content. Mechanical pre-treatment of the banana peels was conducted to further ease the hydrolysis process by reducing the particle size of the biomass. Hydrolysis was carried out for 24 hours at 50ºC at different pH using sulfuric acid H2SO4 acid and sodium hydroxide NaOH as the base, to study the effect of pH on the hydrolysis process and hence the final bio-ethanol production, in terms of concentration. Fermentation of the hydrolysis products were carried out using glucose-yeast broth for 4 days at temperature of 35ºC. Water content in the bio-ethanol product from fermentation process was separated using rotary evaporator, prior to ethanol analysis using Gas Chromatography (GC-MS). Concentration of ethanol was found to be the highest at acidic pH conditions; pH 4 to 6. Lowest ethanol concentration was recorded at higher pH values, indicating alkaline conditions do not favour the hydrolysis process.

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Renewable Biomass Utilization: A Way Forward to Establish Sustainable Chemical and Processing Industries

Clean Technologies ◽

10.3390/cleantechnol3010014 ◽

2021 ◽

Vol 3 (1) ◽

pp. 243-259

Author(s):

Yadhu N. Guragain ◽

Praveen V. Vadlani

Keyword(s):

Fossil Fuels ◽

Process Intensification ◽

Raw Material ◽

Biomass Composition ◽

Biomass Feedstocks ◽

Renewable Biomass ◽

Sustainability Criteria ◽

Biomass Component ◽

Biomass Resources ◽

Multiple Challenges

Lignocellulosic biomass feedstocks are promising alternatives to fossil fuels for meeting raw material needs of processing industries and helping transit from a linear to a circular economy and thereby meet the global sustainability criteria. The sugar platform route in the biochemical conversion process is one of the promising and extensively studied methods, which consists of four major conversion steps: pretreatment, hydrolysis, fermentation, and product purification. Each of these conversion steps has multiple challenges. Among them, the challenges associated with the pretreatment are the most significant for the overall process because this is the most expensive step in the sugar platform route and it significantly affects the efficiency of all subsequent steps on the sustainable valorization of each biomass component. However, the development of a universal pretreatment method to cater to all types of feedstock is nearly impossible due to the substantial variations in compositions and structures of biopolymers among these feedstocks. In this review, we have discussed some promising pretreatment methods, their processing and chemicals requirements, and the effect of biomass composition on deconstruction efficiencies. In addition, the global biomass resources availability and process intensification ideas for the lignocellulosic-based chemical industry have been discussed from a circularity and sustainability standpoint.

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DNA-Guided Assembly for Fibril Proteins

Mathematics ◽

10.3390/math9040404 ◽

2021 ◽

Vol 9 (4) ◽

pp. 404

Author(s):

Alexandru Amărioarei ◽

Frankie Spencer ◽

Gefry Barad ◽

Ana-Maria Gheorghe ◽

Corina Iţcuş ◽

...

Keyword(s):

Computational Model ◽

Structural Properties ◽

Self Assembly ◽

Structural Characteristics ◽

Computational Modelling ◽

Shape Reconstruction ◽

Raw Material ◽

Dna Assembly ◽

Mesh Structure ◽

Elementary Fibril

Current advances in computational modelling and simulation have led to the inclusion of computer scientists as partners in the process of engineering of new nanomaterials and nanodevices. This trend is now, more than ever, visible in the field of deoxyribonucleic acid (DNA)-based nanotechnology, as DNA’s intrinsic principle of self-assembly has been proven to be highly algorithmic and programmable. As a raw material, DNA is a rather unremarkable fabric. However, as a way to achieve patterns, dynamic behavior, or nano-shape reconstruction, DNA has been proven to be one of the most functional nanomaterials. It would thus be of great potential to pair up DNA’s highly functional assembly characteristics with the mechanic properties of other well-known bio-nanomaterials, such as graphene, cellulos, or fibroin. In the current study, we perform projections regarding the structural properties of a fibril mesh (or filter) for which assembly would be guided by the controlled aggregation of DNA scaffold subunits. The formation of such a 2D fibril mesh structure is ensured by the mechanistic assembly properties borrowed from the DNA assembly apparatus. For generating inexpensive pre-experimental assessments regarding the efficiency of various assembly strategies, we introduced in this study a computational model for the simulation of fibril mesh assembly dynamical systems. Our approach was based on providing solutions towards two main circumstances. First, we created a functional computational model that is restrictive enough to be able to numerically simulate the controlled aggregation of up to 1000s of elementary fibril elements yet rich enough to provide actionable insides on the structural characteristics for the generated assembly. Second, we used the provided numerical model in order to generate projections regarding effective ways of manipulating one of the the key structural properties of such generated filters, namely the average size of the openings (gaps) within these meshes, also known as the filter’s aperture. This work is a continuation of Amarioarei et al., 2018, where a preliminary version of this research was discussed.

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Structural characteristics of plant cell wall elucidated by solution-state 2D NMR spectroscopy with an optimized procedure

Green Processing and Synthesis ◽

10.1515/gps-2020-0049 ◽

2020 ◽

Vol 9 (1) ◽

pp. 650-663

Author(s):

Wanwan Wang ◽

Jibao Cai ◽

Zhenyu Xu ◽

Yi Zhang ◽

Fanchao Niu ◽

...

Keyword(s):

Cell Wall ◽

Quantum Coherence ◽

Nmr Spectra ◽

Plant Cell Wall ◽

Milling Time ◽

Structural Characteristics ◽

2D Nmr ◽

2D Nmr Spectroscopy ◽

Complete Representation

AbstractA method was developed for rapid qualitative determination of lignocellulose in the tobacco cell wall by utilizing 2D heteronuclear single quantum coherence NMR spectra (2D HSQC NMR). Traditional methods for analyzing the structure of lignocellulose involve many steps of separation and extraction, which is labor-intensive. In this work, the whole cell wall was milled and dissolved in deuterium solvent. The solvent dimethylsulfoxide (DMSO-d6) containing hexamethylphosphoramide (HMPA-d18) enhanced swelling of the sample and gave high-resolution spectra. The tobacco samples are ball milled at different ball milling times, and the state of the particles is observed through an electron microscope, and then the probability of the particles being less than 5 µm is counted. Through the comparison of the abundance and integration of the peak signals in the spectra under different transmittances, it was determined that when the milling time was 6 h, the quality of the NMR spectra was the best. The optimum conditions of characterizing tobacco structure were DMSO-d6/HMPA-d18 solution and 6 h milling time. Under these conditions, complete representation of the structure of lignocellulose and simplified process could be achieved.

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