Biofuels and chemicals can be produced from lignocellulosic feedstocks using biotechnological processes. The effective utilization of carbohydrates from biomass for the production of biofuels necessitates the development of pretreatment technologies to enhance their enzymatic digestibility. Among all the various pretreatment methods currently studied and developed, the organosolv processes, in which organic solvents or aqueous organic solvent mixtures are used as the pretreatment medium, appear to be specially promising in the context of the biorefinery because (1) they produce cellulosic pulp with a good enzymatic digestibility for monomeric glucose production and (2) they allow a clean fractionation of the major biomass components (cellulose, lignin, and hemicelluloses) into three process streams. In this chapter we give an updated overview of organosolv methods using conventional solvents and ionic liquids which have recently gained considerable interest as solvents for lignocellulosic biomass and pretreatment.
This study reports on the effects of unmodified autohydrolyzed ethanol organosolv lignin (AH EOL) and modified autohydrolyzed ethanol organosolv lignin on the structural characteristics and antioxidant properties upon incorporation of p-hydroxyacetophenone (AHP EOL). The lignin samples isolated from black liquor of oil palm fronds (OPF) were evaluated and compared using various complementary analyses; FTIR, 1H and 13C NMR spectroscopy, 2D-NMR spectroscopy (HMBC and HSQC), CHN, GPC, HPLC and thermal analyses (TGA and DSC). Chemically modified organosolv lignin (AHP EOL) provided lignin with lower molecular weight (Mw), which has smaller fragments that leads to higher solubility rate in water in comparison to unmodified organosolv lignin, AH EOL (DAHP EOL: 19.8% > DAH EOL: 14.0%). It was evident that the antioxidant properties of modified organosolv lignin has better reducing power in comparison to the unmodified organosolv lignin. Therefore, the functionalization of lignin polymers enhanced their antioxidant properties and structural features towards a various alternative approach in lignin-based applications.
A sensitive and rapid reversed-phase ultra performance liquid chromatographic (UPLC) method for the simultaneous determination of tocopherols (α-, β-, γ-, δ-), tocotrienols (α-, β-, γ-, δ-), α-tocopherol acetate and α-tocopherol nicotinate is described. The separation was achieved using a Kinetex pentafluorophenyl (PFP) column (150 × 2.1mm, 2.6 µm) with both photodiode array (PDA) and fluorescence (FL) detectors that were connected in series. Column was thermostated at 42°C. Under a gradient system consisting of methanol and water at a constant flow rate of 0.38 mL min(-1), all the ten analytes were well separated in less than 9.5 min. The method was validated in terms of linearity, limits of detection and quantitation, precision and recoveries. Calibration curves of the ten compounds were well correlated (r(2)>0.999) within the range of 100 to 25,000 μg L(-1) for α-tocopherol acetate and α-tocopherol nicotinate, 10 to 25,000 μg L(-1) for α-tocotrienol and 5 to 25,000 μg L(-1) for the other components. The method is simple and sensitive with detection limits (S/N, 3) of 1.0 to 3.0 μg L(-1) (FL detection) and 30 to 74 μg L(-1) (PDA detection). Relative standard deviations for intra- and inter-day retention times (<1%) and peak areas (≤ 4%) were obtained. The method was successfully applied to the determination of vitamin E in vegetable oils (extra virgin olive, virgin olive, pomace olive, blended virgin and refined olive, sunflower, soybean, palm olein, carotino, crude palm, walnut, rice bran and grape seed), margarines and supplements.
Lignin was extracted from coconut husk via alkaline pulping, either Kraft or soda. The isolated lignin samples were classified as hydroxy-benzaldehyde, vanillin, and syringaldehyde type according to Fourier-transform Infrared Spectroscopy, 1H and 13C Nuclear Magnetic Resonance (NMR) spectra. Soda lignin (SL) showed higher thermal stability and glass transition temperature (Tg) than Kraft lignin (KL) as proven by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), respectively. The soda-lignin-phenol-glyoxal (SLPG) resins with the optimum percentage of lignin substitution at 30% showed improved solid content and gel time in comparison to 30% of Kraft-lignin-phenol-glyoxal (KLPG) and phenol-glyoxal (PG) resin. The good mechanical properties in SLPG is due to the higher amount of molecular weight as well as higher phenolic and G-type unit in lignin that improve the properties of 30% SLPG adhesive. Moreover, the addition of layered double hydroxides (LDH) as reinforced filler up to 15%-30% SLPG adhesive blend shows a great performance (especially mechanical properties) as compared to 30% SLPG adhesive alone.
The most critical issues faced by the world nowadays is to provide the sustainability of consumption for energy and natural resources. Lignin is said to be one of the alternative new discoveries best-suited lignocellulosic biomass due to its low cost, sufficient availability and environmentally safe. The valuable properties exhibited by lignin can give broader applications usage such as in composite materials, wood industries, polymer composite industries, pharmaceutical and corrosion inhibitor industries. Many biomass wastes resources, isolation processes and treatments are undergoing development in order to enhance the producing new lignin-based materials on an industrial scale. Therefore, this review discussed on the current knowledge on the structure and chemistry of isolation of lignin from different sources using various common methods, its characterization, properties and its applications.
Lignin extracted from oil palm fronds (OPF) underwent chemical modification by incorporating m-cresol into the lignin matrix. This study reports on the physicochemical properties and antioxidant activity of unmodified autohydrolyzed ethanol organosolv lignin (AH EOL) and the modified autohydrolyzed ethanol organosolv lignin (AHC EOL). The lignin samples were analyzed by FTIR, 1H and 13C NMR spectroscopy, 2D NMR: HSQC spectroscopy, CHN analysis, molecular weight distribution analysis; GPC and thermal analysis; DSC and TGA. The lignin modification has reduced the hydrophobicity of its complex structure by providing better quality lignin with smaller fragments and higher solubility rate in water (DAHCEOL: 42%>DAHEOL: 25%). It was revealed that the modification of lignin has improved their structural and antioxidant properties, thus venture their possible applications.
Oil palm frond (OPF) is one of largest contributions to the biomass waste from oil palm plantation. In this work, OPF has been successfully utilized to prepare cellulose nanocrystal (OPF-CNC) by acid hydrolysis. OPF was initially treated with autohydrolysis treatment. The obtained OPF-CNC was characterized via complementary analyses. The produced OPF-CNC showed a high crystallinity index value (60%) and high BET surface area (26.10 m2 g-1) as compared to α-cellulose (crystallinity index: 54% and BET surface area:7.14 m2g-1). The surface analyses via scanning electron microscope (SEM) and transmission electron microscopy (TEM) demonstrated that the OPF-CNC has a smooth surface with a needle-like shape, where the average length and diameter are 95.09 nm and 6.81 nm, respectively. The corrosion analyses via electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PD) illustrate that the coated mild steel with the inclusion of 0.5 wt% OPF-CNC has managed to sharply reduce the corrosion (99%). The coated mild steel with the inclusion of 0.5 wt% OPF-CNC showed the highest hydrophobicity (100.5 ± 0.7°) and has lowest amount of O via water contact angle and energy dispersive X-ray spectroscopy (EDX) analyses respectively, indicating lowest corrosion rate.
Lignocellulosic materials can significantly contribute to the development of eco-friendly wood adhesives. In this work, glyoxal-phenolic resins for plywood were prepared using organosolv lignin, which was isolated from black liquor recovered from organosolv pulping of oil palm fronds (OPF) and considered to be an alternative to phenol. Glyoxal, which is a dialdehyde obtained from several natural resources, was used as substitute for formaldehyde. The structure of organosolv lignin and the resins were characterized by FTIR and NMR, and for thermal stability by TGA and DSC. The resins were further studied for their viscosity, pH, solids content and gel times. The resins performance as wood adhesive was further established from mechanical test in terms of tensile strength and modulus of elasticity (MOE) to obtain the optimum ratios of organosolv lignin, which replaces phenol in organosolv lignin phenol glyoxal (OLPG) resins. The adhesive composition having 50% (w/w) of phenol substituted by organosolv lignin, termed as 50% OLPG showed highest adhesive strength compared to phenol formaldehyde (PF) commercial adhesive.
The effects of steam explosion (SE) pretreatment on the structural properties of lignin isolated from coconut husk (CH) biomass via soda pulping were investigated in this work. The isolated SE lignin was classified as dilute acid impregnation SE lignin (ASEL), water impregnation SE lignin (WSEL), and 2-naphthol impregnation SE lignin (NSEL). The various types of functional groups isolated from SE lignin were characterized and compared using a variety of complementary analyses: FTIR spectroscopy, NMR spectroscopy, GPC chromatography, HPAEC-PAD chromatography and thermal analyses. It was revealed that ASEL has the highest solid recovery with 55.89 % yield as well as the highest sugars content compared to WSEL (45.66 % yield) and NSEL (49.37 % yield). Besides, all isolated SE lignin contain a significant quantity of non-condensed G-type and S-type units but less amount of H-type units as supported by previous research. The SE lignin produced lignin with higher molecular weight (Mw ASEL: 72725 g mol-1 > Mw WSEL: 13112 g mol-1 > Mw NSEL: 6891 g mol-1) seems to influence the success of the synthesis reaction of phenolic resins. Because of the large variances in the physicochemical properties of SE lignin polymers, their structural properties were increased toward numerous alternative techniques in lignin-based applications.
Over the past few years, nanocellulose (NC), cellulose in the form of nanostructures, has been proved to be one of the most prominent green materials of modern times. NC materials have gained growing interests owing to their attractive and excellent characteristics such as abundance, high aspect ratio, better mechanical properties, renewability, and biocompatibility. The abundant hydroxyl functional groups allow a wide range of functionalizations via chemical reactions, leading to developing various materials with tunable features. In this review, recent advances in the preparation, modification, and emerging application of nanocellulose, especially cellulose nanocrystals (CNCs), are described and discussed based on the analysis of the latest investigations (particularly for the reports of the past 3 years). We start with a concise background of cellulose, its structural organization as well as the nomenclature of cellulose nanomaterials for beginners in this field. Then, different experimental procedures for the production of nanocelluloses, their properties, and functionalization approaches were elaborated. Furthermore, a number of recent and emerging uses of nanocellulose in nanocomposites, Pickering emulsifiers, wood adhesives, wastewater treatment, as well as in new evolving biomedical applications are presented. Finally, the challenges and opportunities of NC-based emerging materials are discussed.
Nanostructured materials are fascinating since they are promising for intensely enhancing materials' performance, and they can offer multifunctional features. Creating such high-performance nanocomposites via effective and mild approaches is an inevitable requirement for sustainable materials engineering. Nanocomposites, which combine two-star nanomaterials, namely, cellulose nanofibrils (CNFs) and graphene derivatives (GNMs), have recently revealed interesting physicochemical properties and excellent performance. Despite numerous studies on the production and application of such systems, there is still a lack of concise information on their practical uses. In this review, recent progress in the production, modification, properties, and emerging uses of CNFs/GNMs hybrid-based nanocomposites in various fields such as flexible energy harvesting and storage, sensors, adsorbents, packaging, and thermal management, among others, are comprehensively examined and described based on recent investigations. Nevertheless, numerous challenges and gaps need to be addressed to successfully introduce such nanomaterials in large-scale industrial applications. This review will certainly help readers understand the design approaches and potential applications of CNFs/GNMs hybrid-based nanocomposites for which new research directions in this emerging topic are discussed.
The present study sheds light on the physical and chemical characteristics of microcrystalline cellulose (MCC) isolated from oil palm fronds (OPF) pulps. It was found that the OPF MCC was identified as cellulose II polymorph, with higher crystallinity index than OPF α-cellulose (CrIOPFMCC: 71%>CrIOPFα-cellulose: 47%). This indicates that the acid hydrolysis allows the production of cellulose that is highly crystalline. BET surface area of OPF MCC was found to be higher than OPF α-cellulose (SBETOPFMCC: 5.64m(2)g(-1)>SBETOPFα-cellulose:Qa(0) 2.04m(2)g(-1)), which corroborates their potential as an adsorbent. In batch adsorption studies, it was observed that the experimental data fit well with Langmuir adsorption isotherm in comparison to Freundlich isotherm. The monolayer adsorption capacity (Qa(0)) of OPF MCC was found to be around 51.811mgg(-1) and the experimental data fitted well to pseudo-second-order kinetic model.
Each year, 50 to 70 million tonnes of lignin are produced worldwide as by-products from pulp industries and biorefineries through numerous processes. Nevertheless, about 98% of lignin is directly burnt to produce steam to generate energy for the pulp mills and only a handful of isolated lignin is used as a raw material for the chemical conversion and for the preparation of various substances as well as modification of lignin into nanomaterials. Thus, thanks to its complex structure, the conversion of lignin to nanolignin, attracting growing attention and generating considerable interest in the scientific community. The objective of this review is to provide a complete understanding and knowledge of the synthesis methods and functionalization of various lignin nanoparticles (LNP). The characterization of LNP such as structural, thermal, molecular weight properties together with macromolecule and quantification assessments are also reviewed. In particular, emerging applications in different areas such as UV barriers, antimicrobials, drug administration, agriculture, anticorrosives, the environment, wood protection, enzymatic immobilization and others were highlighted. In addition, future perspectives and challenges related to the development of LNP are discussed.