Lignin Removal Efficiency Research Articles

Combined pretreatment of malic acid and kraft pulping for the production of fermentable sugars and highly active lignin

The separation and utilization of cellulose, hemicellulose, and lignin in lignocellulosic biorefineries present significant challenges. This study proposes a pretreatment method for biomass refining by combining acid and kraft pulping. Firstly, the biomass was pretreated by malic acid, resulting in the isolation of xylo-oligosaccharides (XOS) with a yield of 86.26 % with optimized conditions of 180 °C, 1 wt% concentration, 40 min. Secondly, a mixture of 12.98 wt% NaOH and 1.043 wt% Na2S is employed to achieve lignin removal efficiency up to 63.42 %. Physical refinement techniques are then applied to enhance the enzyme digestion efficiency of cellulose, resulting in an increase from 55.03 % to 91.4 % for efficient cellulose conversion. The reacted samples exhibit a lignin composition rich in β-O-4 ether bonds, facilitating their high-value utilization. The results indicated that the combined pretreatment approach demonstrates high efficiency in separating cellulose, hemicellulose, and lignin while obtaining XOS, highly active lignin, and enzyme-digested substrates.

Optimizing delignification and saccharification process for sawdust processing using a central composite design

AbstractLignocellulosic mass consists of cellulose, hemicelluloses, and lignin. Although biomass promises to be efficiently used for biofuel production and many other value‐added products, lignin present in lignocellulosic biomass affects the hydrolysis of cellulose and hemicelluloses, making it necessary to develop techniques that provide better lignin removal efficiency and high cellulose hydrolysability. The current work aims to maximize lignin removal in sawdust and develop an understanding of the hydrolysis of pretreated biomass for sugar production. Different parameters such as solvent to solid ratio, temperature, and reaction time have been considered based on the design of experiment to understand the effect on the delignification and saccharification processes. After treating sawdust for 1.5 h, it was observed that a maximum of 85% lignin was removed at a temperature of 131°C and solid loading of 16 g. Subsequent hydrolysis of delignified sawdust at 131°C temperature, solvent to solid ratio 15, and 0.5 h resulted in a maximum reducing sugar production of 26.82 mg/mL. The study elucidated the optimum conditions for the effective processing of sawdust in terms of delignification and saccharification, leading to maximum benefits in lignin removal and sugar production.

In situ pretreatment of wood samples with deep eutectic solvents for enhanced lignin removal and enzymatic Saccharification efficiency optimization

Deep eutectic solvents (DESs) are commonly utilized as an effective pretreatment method for biomass materials, particularly for enhancing the value of lignocellulosic biomass. However, to the best of our knowledge, the utilization of DESs for in situ pretreatment of wood samples has been seldom reported. In this study, the ability of five DESs systems to in-situ pretreatment of balsa wood samples was investigated. Among of them, the Choline Chloride-Ethylene Glycol-P-Toluenesulfonic Acid (ChCl-EG-PTSA) system showing an excellent lignin removal rate (the lignin removal of 87.34 % and cellulose retention of 86.32 %), which is significantly better than the delignification effect of the traditional acid chlorite method (lignin removal of 72,13 % and cellulose retention of 64.57 %). In addition, in the subsequent enzymatic saccharification experiments, after the wood samples were pretreated in situ by the ChCl-EG-PTSA system, the enzymatic saccharification yield of cellulose reached 75.46 %, and the enzymatic saccharification yield of xylose reached 92 %. At the same time, this study also used SEM, FTIR, XPS, TGA and other testing technologies to conduct detailed analysis and characterization of the pretreated samples. This comprehensive analysis unequivocally demonstrated the viability of the ChCl-EG-PTSA system as an environmentally sustainable and efficient approach for pretreating forest biomass. Significantly, this in-situ wood pretreatment strategy significantly lays a robust research groundwork for the development of multifunctional wood fiber composites in subsequent stages.

A novel additive promoting lignocellulose alkali pretreatment for its “two birds with one stone” role

Alkali pretreatment is one of the most commonly used pretreatment methods in lignocellulose bioprocessing. However, there are still some “pseudo-lignin” that hinder enzymatic hydrolysis and seriously affect the industrialization process of biorefining. Excellent pretreatment additives can effectively cover these shortages. However, most additives have disadvantages like high operating temperature, low effective utilization efficiency, or poor performance. To address this issue, we proposed a novel additive, dicyandiamide (DICY), by means of quantum chemical prediction, and verified its ability on assisting alkali to remove lignin by experiments. The results indicate that the lignin removal by KOH-DICY pretreatment is about 15% higher than KOH pretreatment, thereby increasing the enzymatic efficiency to 97%, while the reaction temperature was lower 20 ℃ than common alkali pretreatment. These are due to the “two birds with one stone” role of DICY on lignocellulose alkali-DICY pretreatment. DICY not only dissolves small amounts of lignin, but also assists alkali to remove lignin by reducing the diffusion resistance of KOH in lignin and blocking the generation of “pseudo-lignin”. Thus, DICY effectively improved the lignin removal and enzymatic hydrolysis efficiency of alkali pretreated lignocellulose, and performed better than urea. Moreover, the waste liquid pretreated by DICY combined with KOH has the potential on preparation of agricultural fertilizers. In summary, DICY is a new, environmentally friendly, and energy conservation additive for lign ocellulose alkali pretreatment

Comprehensive understanding of co-producing fermentable sugar, furfural, and xylo-oligosaccharides through the pretreatment with CTAB-based deep eutectic solvent containing Brønsted and Lewis acid

The deep eutectic solvents (DESs) with additional functionalities synthesized using the cationic surfactant cetyltrimethylammonium bromide (CTAB) have gained attention due to their remarkable enzymatic enhancement capability. By combining CTAB, lactic acid, and FeCl3, a DES containing both Brønsted and Lewis acids was synthesized and the pretreatment parameters were optimized using response surface methodology. The results demonstrated the selective and efficient delignification (83.2 %) and xylan removal (76.3 %) from canola straw by CTAB:LA:Fe3+, resulting in an increased saccharification efficiency of 81.8 %. Besides, abundant furfural (3.36 g/L) and xylo-oligosaccharides (3.41 g/L) were co-produced during pretreatment, providing comprehensive insights into the efficient co-production of fermentable sugars, furfural, and xylo-oligosaccharides. A thorough analysis of mass balance and energy flow was conducted to evaluate the entire process. Then, molecular dynamics (MD) simulations and quantum chemical calculations were performed on lignocellulosic biomass models and elucidate the interactions between the biomass and CTAB:LA:Fe3+ at the molecular level through the independent gradient model (IGM), thus explaining the high removal efficiency of hemicellulose and lignin. Furthermore, the physicochemical properties of the DESs were investigated, and molecular-level insights into the mechanism of CTAB:LA:Fe3+ pretreatment of lignocellulosic biomass were proposed in conjunction with biomass characterization such as FT-IR and CLSM, as well as MD simulations.

Improving saccharification efficiency of corn stover through ferric chloride-deep eutectic solvent pretreatment

An effective deep eutectic solvent (DES) and Iron(III) chloride (FeCl3) combination pretreatment system was developed to improve the removal efficiency of lignin and hemicellulose from corn stover (CS) and enhance its saccharification. N-(2-hydroxyethyl)ethylenediamine (NE) was selected as the hydrogen-bond-donor for preparing ChCl-based DES (ChCl:NE), and a mixture of ChCl:NE (60 wt%) and FeCl3 (0.5 wt%) was utilized for combination pretreatment of CS at 110 ℃ for 50 min. FeCl3/ChCl:NE effectively removed lignin (87.0 %) and xylan (55.9 %) and the enzymatic hydrolysis activity of FeCl3/ChCl:NE-treated CS was 5.5 times that of CS. The reducing sugar yield of pretreated CS was 98.6 %. FeCl3/ChCl:NE significantly disrupted the crystal structure of cellulose in CS and improved the removal of lignin and hemicellulose, enhancing the conversion of cellulose and hemicellulose into monomeric sugars. Overall, this combination of FeCl3 and DES pretreatment methods has high application potential for the biological refining of lignocellulose.

Delignification of Different Lignocellulosic Biomass Using Hydrogen Peroxide and Acetic Acid (HPAC)

Lignocellulosic biomass will soon become the key source of feedstock for bioenergy to combat the impact of global warming and the depletion of fossil fuel resources. Lignin separation costs have been a key obstacle to bioenergy generation from lignocellulosic biomass. Pulp and paper, biofuel, and biomaterials sectors depend on wood delignification. This study examines delignification trends and advances, including standard and new methods. The study begins by explaining how delignification improves wood processability and value. It describes lignin's chemical structure and properties, highlighting its role in wood's mechanical and chemical qualities. Lignin from diverse lignocellulosic biomass sources is delignified using hydrogen peroxide and acetic acid in this study. A 1:1 hydrogen peroxide-acetic acid volume ratio was used after particle reduction. Experimental results show 96%, 89%, and 80% lignin removal efficiency for Ako, Mahogany, and mixed sawdust, respectively. A 30-minute reaction at 80°C yielded these results. The hydrogen peroxide-acetic acid mixture dignifies well and may be used in lignocellulosic biomass processing. This study also provides insights into optimizing delignification procedures and suggests approaches to improve the industrial use of lignocellulosic biomass. This study reveals that HPAC dignifies wood well. Understanding HPAC's role in the delignification of wood products could lead to developing an HPAC-based pretreatment technique that lowers the cost of biofuel generation from lignocellulosic biomass.

Pretreatments Applied to Wheat Straw to Obtain Bioethanol

This work is a comprehensive study focusing on various methods for processing wheat straw to enhance its suitability for bioethanol production. It delves into mechanical, physical, chemical, and biological pretreatments, each aimed at improving the enzymatic hydrolysis and fermentation processes necessary for bioethanol production. Mechanical and physical pretreatments involve reducing the size of wheat straw to improve enzymatic hydrolysis. Physical methods include heating and irradiation, which alter the structural properties of wheat straw. Chemical pretreatments involve using acids, alkalis, and organic solvents to remove lignin and hemicellulose, making cellulose more accessible for hydrolysis. Biological pretreatments utilize microorganisms and fungi to degrade lignin and other complex compounds, enhancing the breakdown of cellulose. The study presents data on the effectiveness of these treatments in terms of lignin removal, sugar yield, and overall bioethanol production efficiency. The research is aligned with the global move towards renewable energy sources and emphasizes the importance of utilizing agricultural waste, like wheat straw, for sustainable energy production.

Comparative analysis of photo-fermentation hydrogen production from pretreated corn stover by deep eutectic solvents

To compare the pretreatment effect of deep eutectic solvents (DESs) on corn stover, three types of DESs (acid, neutral, and alkaline) were used to pretreat corn stover, and their effects on lignin removal were investigated. Then the performance of photo-fermentation hydrogen production (PFHP) using DESs pretreated corn stover was compared and analyzed. The results showed that acid DESs had the best lignin removal efficiency, and the lignin removal percentages of choline chloride/formic acid (ChCl/Fac) and choline chloride/oxalate (ChCl/Oac) were 64.7% and 65.6%, respectively. The alkaline DESs had the second highest removal of lignin, while the neutral DESs had a poor effect on lignin removal. The comparison of hydrogen production indicated that the corn stover pretreated with ChCl/Oac had the best hydrogen production effect. In conclusion, the DESs pretreatment can obviously remove the lignin in corn stover, and then improve the hydrogen production capacity and efficiency of photo-fermentation, which provides a potential pretreatment method for the efficient utilization of straw biomass.

Artificial neural network modeling to predict the efficiency of phosphoric acid-hydrogen peroxide pretreatment of wheat straw

Phosphoric acid-hydrogen peroxide (PHP) pretreatment is an effective method to obtain a cellulose-enriched fraction from biomass. In this study, artificial neural network (ANN) was used to predict PHP pretreatment efficiency of cellulose content (C-C), cellulose recovery (C-Ry), hemicellulose removal (H-Rl), and lignin removal (L-Rl) under various conditions of pretreatment time (t), temperature (T), H3PO4 concentration (Cp), and H2O2 concentration (Ch). The final optimized topology structure of the ANN models had 1 hidden layers with 9 neurons for C-C and 10 neurons for C-Ry, 10 neurons for H-Rl, and 12 neurons for L-Rl. The actual testing data fit the predicted data with R2 values ranging from 0.8070 to 0.9989. The relative importance (RI) revealed that Cp and Ch were significant factors influencing the efficiency of PHP pretreatment with total RI values ranging from 12% to 62.6%. However, their weights for the three components of biomass were different. The value of T dominated hemicellulose removal effectiveness with an RI value of 78.6%, while t did not seem to be a main factor dominating PHP pretreatment efficiency. The results of this study provide insights into the convenient development and optimization of biomass pretreatment from ANN modeling perspectives.

Application of Fe(II)/peroxymonosulfate for efficient alkali lignin wastewater treatment: Insight into the synergistic interactions between redox reactions and coagulation

In this work, Fe(II)/Peroxymonosulfate (PMS) treatment with dual functionality of pre-oxidation and coagulation was applied to enhance the removal of alkali lignin in water. The removal efficiency of alkali lignin (2 g/L) could reach ∼ 99% at an optimal dosage of [Fe(II)] = 2.4 mM and [PMS] = 7.8 mM, which was efficiently superior than that using ferric and polymeric coagulant individually. Pre-oxidation, involving hydroxyl radical (•OH) and sulfate radical (SO4•−), has been demonstrated to play a crucial role in both oxidative degradation (∼30%) and reducing the molecular weight and hydrophilicity of lignin. Meanwhile, the formation of polynuclear Fe-hydroxide complexes was also fostered, which in turn greatly contribute to the removal of lignin through an enhanced coagulation mechanism. The reductive units present in alkali lignin was demonstrated to initiate a dynamic transition between Fe(III) and Fe(II) by donating electrons. This redox activity is anticipated to continuously promote the formation of electro-neutral and loose flocs, thereby resulting in an enhanced coagulation performance. Furthermore, ultrafiltration (UF) was also demonstrated as a viable liquid/solid separation method following Fe(II)/PMS treatment, effectively promoting membrane flux recovery rate to ∼90%. This highlights the remarkable potential of this method when combined with other treatment processes. This study aims to offer a complementary strategy for remediating alkali lignin wastewater while advancing the fundamental understanding of redox-reaction enhanced in-situ coagulation in water treatment applications.

Effects of various acid catalysts in dimethyl isosorbide/water co-solvent system for lignocellulosic biomass pretreatment

Novel organosolv pretreatments of biomass using biobased green solvents have attracted increasing attention to realize sustainable biorefinery. We have demonstrated that the feasibility of dimethyl isosorbide/water co-solvent in fractionating lignocellulosic biomass (Eucalyptus) for multiple products under a mild condition (120 °C, 60 min). To take a further step towards revealing the effects of catalysts, we explored various Brønsted (e.g., H2SO4, HCl, and p-TsOH), Lewis acid catalysts (e.g., AlCl3 and FeCl3) and their combinations in this co-solvent system. An interesting finding was that the delignification efficiency of AlCl3 was lower than that of H2SO4 (69.9% vs 91.2%), while the cellulose conversion efficiency of the pretreated pulp was similar (∼80%). It is hypothesized that the presence of Al3+ could inhibit the binding of lignin to cellulase, which was supported by the quantum chemistry calculations. Results revealed the presence of cation− π interactions between Al3+ and lignin with interaction energy (ΔE) was 1022.04 kJ/mol and 1003.04 kJ/mol for S and G type of lignin, respectively. In addition, the pretreatment with H2SO4 -AlCl3 co-catalyst could achieve a high lignin removal efficiency of 93.0% and almost complete enzymatic hydrolysis of obtained cellulose pulp (∼100%). This research demonstrated that the co-catalyst strategy effectively improved the overall performance of the solvent-based biorefinery.

Simultaneous pretreatment with ultraviolet light and alkaline H2O2 to promote enzymatic hydrolysis of corn stover

Pretreatment processes are essential for the preparation of biofuels from lignocellulosic feedstocks. Based on alkaline H2O2 pretreatment, photocatalytic alkaline H2O2 pretreatment (U-AHP) was investigated to examine the effects of reaction time, alkali concentration, and H2O2 concentration on the enzymatic digestion of corn stover. The optimum process conditions were determined by orthogonal tests: 1% NaOH, 2% H2O2, and reaction time of 8 h. Under these conditions, the lignin removal efficiency of UH-AHP was 90.2% and the saccharification yield was 94.7%. Furthermore, FT-IR, XRD, and SEM analyses showed that U-AHP pretreatment caused structural damage to the maize straw and increased the crystallinity of the cellulose, and it was speculated that the U-AHP pretreatment reaction was a complex mechanism, which might be a multiple synergistic reaction. This study shows that U-AHP pretreatment is a simple, green and effective method to promote lignin removal.

Renewable deep eutectic solvents pretreatment improved the efficiency of anaerobic digestion by lignin extraction from willow

Lignin extraction from lignocellulosic biomass can enhance its bioconversion efficiency, whilst the recovered lignin can provide added economic value. This study comprehensively investigated the impacts of short-chain carboxylic acid-based deep eutectic solvents (DESs) pretreatments on lignin extraction from willow and assessed subsequent biomethane production through anaerobic digestion. Process parameters (including the DESs type, molar ratios of DESs components, temperature and reaction time) in the DESs pretreatments of willow for lignin extraction were optimized using the central composite surface response methodology. Results showed that lactic acid-based DES pretreatment outperformed acetic acid and propionic acid-based DES pretreatments in terms of lignin removal efficiency and methane production. Under the optimal conditions (choline chloride:lactic acid with a molar ratio of 1:10 at 160 °C for 15 min) lactic acid-based DES pretreatment retained over 94% of the glucan content in the raw willow whilst achieved the highest lignin removal of 80%. The recovered lignin showed a purity of above 81%. Compared with the biomethane production of 89.9 mL/g total solid from raw willow, the biomethane production significantly increased by 36.3% after the lactic acid-based DES pretreatment. The optimal condition reduced the digestion time from 22 to 10 days. The overall energy conversion efficiency of 62.7% demonstrated that lactic acid-based DES pretreatment of lignocellulose could be a promising method to co-produce renewable gaseous fuels and lignin in a sustainable approach.

Highly effective fractionation chemistry to overcome the recalcitrance of softwood lignocellulose

The efficient fractionation and thus production of individual biomass components are pivotal processes in the biorefinery concept. However, the recalcitrant nature of lignocellulose biomass, especially in the case of softwood, is one of the main obstacles to the wider application of biomass-based chemicals and materials. In this study, the use of aqueous acidic systems in the presence of thiourea was studied for the fractionation of softwood in mild conditions. Despite relatively low temperature (100 °C) and treatment times (30–90 min), notable high lignin removal efficiency (approximately 90 %) was obtained. Chemical characterization and the isolation of minor fraction of cationic, water-soluble lignin indicated that the fractionation proceed via nucleophilic addition of thiourea to lignin, resulting in dissolution of lignin in acidic water in relatively mild conditions. Besides high fractionation efficiency, both fiber and lignin fractions were obtained with bright color, significantly elevating their usability in material applications.

Comparative Study of Effective Pretreatments on the Structural Disruption and Hydrodepolymerization of Rice Straw

Rice straw (RS) is the most potentially renewable agricultural waste resource widely distributed in nature. Considering the complex recalcitrant structure and components of RS, three pretreatment methods, including high-temperature hydrothermal, medium-temperature microwave, and low-temperature cryocrushing pretreatment were performed. The components and structure of RS residues were examined and analyzed after the pretreatments. Pretreatment with hydrothermal yielded the lowest rice straw recovery (59.0%); after being pretreated at 180 °C for 10 min, the hemicellulose recovery was only 14.1%, and the removal efficiency of lignin was the largest (41.3%), which was 32.2% and 18.8% higher than that achieved from cryocrushing and microwave pretreatment, respectively. Pretreatment with cryocrushing yielded the highest recovery rates of rice straw (92.9%), hemicellulose and cellulose (88.8% and 90.4%, respectively). Results of scanning electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, and the analysis of specific surface area and apertures demonstrated that all three pretreatments could effectively disrupt the structure of RS and reduce its cellulose crystallinity. The three pretreatments were found to enhance the hydrodepolymerization of RS residues. Furthermore, cryocrushing pretreatment yielded the highest cellulose conversion rate (56.8%), and the yields of glucose, xylose, and arabinose were 29.6%, 56.2%, and 17.8%, respectively. Apart from the use of acids and enzymes, hydrodepolymerization of RS was among the few methods that can effectively degrade cellulose, presenting an ideal solution for the degradation of biomass.

Sustainable recovery and recycling of natural deep eutectic solvent for biomass fractionation via industrial membrane-based technique

Natural deep eutectic solvents (NADES) have been proven efficient and biocompatible as solvents and conversion medium in many fields. Multicomponent composition makes it hard to direct recovery NADES after utilization process. Industrial application of NADES requires sustainable and economic recovery technology. In this study, hybrid membrane-based technique of ultrafiltration (UF) with bipolar membrane electrodialysis (BMED) was employed for sustainable recovery and recycling of NADES choline chloride-urea in pine wood fractionation. UF and BMED worked based on retaining of macromolecules and distinguished separation of each NADES solute. The highest NADES recovery ratio was 97.7 % and the lowest specific energy consumption for NADES recovery was 8.4 kWh/kg. Regenerated NADES was recycled in biomass fractionation for 3 batches. Removal efficiency of hemicellulose (∼25.4 %) and lignin (∼18.1 %) could be retained with regenerated NADES. Besides, NADES recovery cost by UF-BMED was close to 3.0 % of its purchasing price according to calculation results. Insight gained from the research proposed a sustainable and low-cost technique for NADES recycling in biomass utilization.

Pretreatment of Grape Pomaces and Stalks Using Deep Eutectic Solvents for Succinic Acid Production Integrated in a Biorefinery Concept

Deep eutectic solvents (DES) have been employed for the pretreatment of grape pomace and stalks within a biorefinery concept. Four DES, produced with choline chloride (ChCl) as hydrogen bond acceptor and four carboxylic acids as hydrogen bond donors, namely formic acid (FA), acetic acid (AA), lactic acid (LA) and oxalic acid (OA), were evaluated considering lignin removal efficiency, polysaccharide hydrolysis efficiency into C5 and C6 sugars, recyclability and reusability. The mixture of ChCl:LA at 1:10 molar ratio, 120°C and 1 h pretreatment, led to 40% lignin removal over four pretreatment cycles. Enzymatic hydrolysis of the remaining solids after the first pretreatment cycle resulted in 92.7% glucan and 36.6% hemicellulose hydrolysis yield. The hydrolysate was used as fermentation feedstock in batch Actinobacillus succinogenes bioreactor cultures leading to 36 g/L succinic acid with a yield of 0.62 gSA per g total sugars and 0.65 g/(L⋅h) productivity. Using 2 kg of grape pomace and stalks in each pretreatment cycle, the succinic acid that could be produced in five consecutive cycles is 200.8 g, 208 g, 204.9 g, 184.5 g and 94.3 g.Graphical

Multimode ultrasound and ternary deep eutectic solvent sequential pretreatments enhanced the enzymatic saccharification of corncob biomass

Corncob (CB) is a valuable agricultural waste in high abundance. It is mainly composed of cellulose, hemicellulose and lignin that link in a complex interlocking matrix. The key to its utilization depends on separating cellulose from lignin and hemicellulose using an environment-friendly and effective pretreatment method to improve glucose yield. The study aimed to investigate the effect of sequential pretreatment of CB with ultrasound (US) in conjunction with ternary deep eutectic solvent (TDES). The US, type and molar ratio of TDES, temperature, and time were optimized. The results showed that under the optimum conditions, US (40 +60 kHz, 60 min) + TDES (ChCl-Gly-LA, 1:1:2, 120 ℃, 3 h), the removal of lignin and hemicellulose were 87.54 % and 67.00 %, respectively, and the recovery of cellulose was 82.18 %. After 72 h of enzymatic hydrolysis , the yield of glucose and xylose were 76.94 % and 41.26 %, respectively. Comparatively, pretreated CB yielded 61.58 % glucose and 26.90 % xylose higher than the untreated. Scanning electron microscopy revealed that the surface of the CB became cracked and rugged. X-ray diffraction showed that the CrI increased significantly from 36 % to 59 %. Fourier transform mid-infrared spectroscopy indicated significant changes in the characteristic functional groups of lignin and hemicellulose. Increases in Tonset, Tendset, Tp, Vmax and decreases in Char at 600 °C all corresponded to increases in thermal stability. These results further confirmed that TDES combined with ultrasonic pretreatment effectively removed lignin and hemicellulose. In conclusion, this approach could greenly and efficiently pretreat CB as a new method for biomass pretreatment. • Double hydrogen bond acceptor (donor) ternary pretreatment DES was studied. • The lignin removal efficiency of ternary DES was higher than binary DES. • TDES containing lactic acid reduced significantly the lignin content. • TDES combined with ultrasonic pretreatment increased lignin removal rate. • TDES combined with ultrasonic pretreatment enhanced sugar yields.

Influence of peracetic delignification on biomass lignocellulosic complex

The process of delignification of plant biomass with peracetic acid was studied and the effect of the duration of peracetic delignification on the degree of delignification and the degree of removal of the carbohydrate complex in the final cellulose products was established. The treatment of different representatives of plant biomass was performed with peracetic acid at a concentration of 8% and at different time of the process. The study was focused on the process of chemical treatment of six different representatives of non-wood plant raw materials in the form of straw, agricultural waste, as well as stems of fast-growing industrial and fodder crops. Cellulose products were obtained with a yield of about 50% and a whiteness of greater than 60%. It was shown that an increase in the duration of processing naturally leads to a decrease in the yield of the final product, which is associated with the intensive oxidation and removal of lignin, as well as partial destruction of the polysaccharide component of biomass. The investigated method of delignification proved to be effective for the removal of more than 90% of lignin in the entire studied time interval, but the selectivity of the removal of lignin and carbohydrates depended significantly on the type of plant material. By an increase in the efficiency of lignin removal with peracetic acid, the studied plants are located in the following row: sverbiga (bunias orientalis)>shchavnat>lavatera>rapeseed>wheat straw>amaranth. Conducted research work gives grounds to claim that peracetic delignification is an effective method of chemical treatment of plant biomass; it allows obtaining cellulose products that can be used in the production of paper products for various purposes, as well as for the chemical industry.