A selective fractionation method of lignocellulosic materials using electro-assisted organosolv pretreatment

Organosolv pretreatment: an in-depth purview of mechanics of the system

The concept of biorefinery has been advancing globally and organosolv pretreatment strategy has seen an upsurge in research due to its efficiency in removing the recalcitrant lignin and dissolution of cellulose. The high-performance organosolv system uses green solvents and its reusability contributes concurrently to the biorefinery sector and sustainability. The major advantage of the current system involves the continuous removal of lignin to enhance cellulose accessibility, thereby easing the later biorefinery steps, which were immensely restricted due to the recalcitrant lignin. The current system process can be further explored and enhanced via the amalgamation of new technologies, which is still a work in progress. Thus, the current review summarizes organosolv pretreatment and the range of solvents used, along with a detailed mechanistic approach that results in efficient pretreatment of LCB. The latest developments for designing high-performance pretreatment systems, their pitfalls, and advanced assessments such as Life Cycle Assessment along with Techno-Economic Assessment have also been deliberated to allow an insight into its diverse potential applicability towards a sustainable future.

Photobiological effects of converting biomass into hydrogen - Challenges and prospects

In comparison to other methods of producing hydrogen, the production of biohydrogen is significantly less harmful to the surrounding ecosystem when it was produced from the biological origin such as microalgae. It could take the place of conventional fossil fuels while avoiding the emission of greenhouse gases. The substrates such as food, agricultural waste, and industrial waste can be readily utilized after the necessary pretreatment, led to an increase in the yield of hydrogen. Improving the production of biofuels at each stage can have a significant impact on the final results, making this method a potentially useful instrument. As a consequence of this, numerous approaches to pretreat the algal biomass, numerous types of enzymes and catalyst that play a crucial role for hydrogen production, the variables that influence the production of hydrogen, and the potential applications of genetic engineering have all been comprehensively covered in this study.

Promising seawater hydrothermal combining electro-assisted pretreatment for corn stover valorization within a biorefinery concept

In this study, for the first time, seawater hydrothermal (SH) pretreatment combining subsequent electrogenerated alkaline hydrogen peroxide (EAHP) pretreatment was proposed to achieve an effective fractionation of corn stover into high value-added products. During SH pretreatment, complex ions in natural seawater (Mg²⁺, Ca²⁺ and Cl^-) were used to promote depolymerization of xylan into xylo-oligosaccharides with 49.37% yield (190 °C,40 min), 18.52% higher than that of deionized water. Subsequent EAHP treatment not only provided a green and economical way to produce hydrogen peroxide but also synchronously realized satisfied delignification (94.91%). The integrated pretreatment resulted in 91.16% of glucose yield, which was about 5.6 times more than that of unpretreated corn stover. In addition, the recovered lignin fraction which has a potential application in functional materials were investigated by FTIR, 2D-HSQC NMR and GPC. In short, this work provided a novel and environmentally-friendly strategy for biorefinery-based fractionation of corn stover.

Boosting levoglucosan and furfural production from corn stalks pyrolysis via electro-assisted seawater pretreatment

The seawater electrochemical pretreatment (ECP) was employed to upgrade the bio-oil of corn stalk in the paper. The seawater and its simulants were used as electrolytes without additional reagents. Moreover, the effect of seawater ECP under different conditions on the products distribution of pyrolysis bio-oil of pretreated corn stalks was investigated. The results showed that pretreatment effectively deconstructed the lignin and made cellulose exposed. Especially, under the optimum conditions (3.5 wt% NaCl, 15 V and 4 h), most of lignin was destroyed, and cellulose and hemicellulose were remained in residual solids. Furthermore, the levoglucosan and furfural were enriched in the pyrolysis bio-oil of corn stalk after seawater ECP, reaching 23.22 % and 14.14 %, respectively. Overall, this work presented a novel and green pretreatment process to optimize the components and structure of corn stalks as well as upgrade the bio-oil of corn stalk pyrolysis.

A Review: Research Progress in Modification of Poly (Lactic Acid) by Lignin and Cellulose

With the depletion of petroleum energy, the possibility of prices of petroleum-based materials increasing, and increased environmental awareness, biodegradable materials as a kind of green alternative have attracted more and more research attention. In this context, poly (lactic acid) has shown a unique combination of properties such as nontoxicity, biodegradability, biocompatibility, and good workability. However, examples of its known drawbacks include poor tensile strength, low elongation at break, poor thermal properties, and low crystallization rate. Lignocellulosic materials such as lignin and cellulose have excellent biodegradability and mechanical properties. Compounding such biomass components with poly (lactic acid) is expected to prepare green composite materials with improved properties of poly (lactic acid). This paper is aimed at summarizing the research progress of modification of poly (lactic acid) with lignin and cellulose made in in recent years, with emphasis on effects of lignin and cellulose on mechanical properties, thermal stability and crystallinity on poly (lactic acid) composite materials. Development of poly (lactic acid) composite materials in this respect is forecasted.

A Review of Lignocellulosic-Derived Nanoparticles for Drug Delivery Applications: Lignin Nanoparticles, Xylan Nanoparticles, and Cellulose Nanocrystals

Due to their biocompatibility, biodegradability, and non-toxicity, lignocellulosic-derived nanoparticles are very potential materials for drug carriers in drug delivery applications. There are three main lignocellulosic-derived nanoparticles discussed in this review. First, lignin nanoparticles (LNPs) are an amphiphilic nanoparticle which has versatile interactions toward hydrophilic or hydrophobic drugs. The synthesis methods of LNPs play an important role in this amphiphilic characteristic. Second, xylan nanoparticles (XNPs) are a hemicellulose-derived nanoparticle, where additional pretreatment is needed to obtain a high purity xylan before the synthesis of XNPs. This process is quite long and challenging, but XNPs have a lot of potential as a drug carrier due to their stronger interactions with various drugs. Third, cellulose nanocrystals (CNCs) are a widely exploited nanoparticle, especially in drug delivery applications. CNCs have low cytotoxicity, therefore they are suitable for use as a drug carrier. The research possibilities for these three nanoparticles are still wide and there is potential in drug delivery applications, especially for enhancing their characteristics with further surface modifications adjusted to the drugs.

Electrochemical Lignin Conversion

Lignin is the largest source of renewable aromatic compounds, making the recovery of aromatic compounds from this material a significant scientific goal. Recently, many studies have reported on lignin depolymerization and upgrading strategies. Electrochemical approaches are considered to be low cost, reagent free, and environmentally friendly, and can be carried out under mild reaction conditions. In this Review, different electrochemical lignin conversion strategies, including electrooxidation, electroreduction, hybrid electro-oxidation and reduction, and combinations of electrochemical and other processes (e. g., biological, solar) for lignin depolymerization and upgrading are discussed in detail. In addition to lignin conversion, electrochemical lignin fractionation from biomass and black liquor is also briefly discussed. Finally, the outlook and challenges for electrochemical lignin conversion are presented.

Integrated process for the production of fermentable sugar and methane from rubber wood

Pretreatment is required for the enhancement of the bioconversion of lignocellulosic biomass. This study aimed to develop an integrated process producing efficient biochemical conversion of rubber wood waste (RW) into co-biofuels, fermentable sugar and methane. The glucan conversion was enhanced to 93.8% with temperature (210 °C) and delignification by organosolv pretreatment (OS). Thereafter, anaerobic digestion of the residue left after enzymatic hydrolysis was conducted which further improved the methane yield (205.5 LCH₄/kg VS) by 33% over hydrothermal pretreatment (154.3 LCH₄/kg VS). Delignification during OS plays a key role in improving the degradability of RW resulting in efficient energy recovery (11.23 MJ/kg pretreated RW) which was clearly higher than an integrated process based on hydrothermal (HT) or HT plus process water. Scaled up to a biorefinery, the integrated process based on OS would economically produce fermentable sugar while other value-added chemicals might be produced from the process water.