Solid Residue Research Articles

Green coal and lubricant via hydrogen-free hydrothermal liquefaction of biomass

Biocrude derived from biomass via hydrothermal liquefaction (HTL) is a sustainable substitute for petroleum to obtain energy and biochemicals. Upgrading biocrude inevitably faces the trade-off between consuming large amounts of hydrogen via hydrotreating and high yield of solid residue without additional hydrogen. In this work, we report a non-hydrogenated refinery paradigm for nearly complete valorization (~90%), via co-generating green coal and bio-lubricant. The obtained green coal has higher heating values comparable to commercial coals, with a lower fuel ratio and reduced ash content. Viscosity of upgraded vacuum distillate is comparable to that of a lubricant oil. A life cycle assessment confirms 28% reduction in greenhouse gas emission and 35% reduction in energy input of this paradigm compared with conventional hydrotreating biorefinery. This approach presents an environmentally friendly, safe and convenient paradigm for biocrude refining from huge biowaste towards carbon-neutral society.

Potential of Ionizing Radiation Application for Reducing Environmental Risks Related to Solids Residues

The enormous amount of solids residues and related cost for a suitable disposal have increased in megacities as São Paulo and Buenos Aires. Inovative technologies may be used in order to face managing progams with inovative techniques for for recycling or recover of materials. Gamma radiation was applied in laboratory scale for two different types of residues: fungi control in vehicular air filters, and for rat bedding waste (RBW) disinfection. Both materials may be used after irradiation and the radiation doses required will be discussed. Part of experiments carried out in Argentina evidenced the suitable use of vermicomposting for growing Calendula officinalis. Radiation doses from 10 kGy up to 30 kGy were tested for controlling microorganisms during the projects and were very effective. For filters disinfection experiments, DNA sequencing analysis for the fungi that survived after irradiation not only confirmed the presence of Penicillium, Fusarium and Aspergillus (toxigenic), fungi but also improved the data: the contamination included Aspergillus niger, Aspergillus flavus, Penicillium glabrum specie complex and Fusarium incarnatum-equiseti specie complex.

Rapid electrothermal upcycling hexachlorobutadiene (HCBD) polluted distillation residue into turbostratic graphene for enhanced electromagnetic wave absorption.

The trichloroethylene production industry generates high-boiling-point solid residues during rectification, which contain high concentrations of chlorinated contaminants, particularly hexachlorobutadiene (HCBD). Traditionally, these distillation residues are managed through co-incineration or landfilling, leading to environmental and economic challenges. In this study, we present a rapid and environmentally friendly electrothermal approach for both detoxifying and upcycling distillation residue into graphene-based electromagnetic wave (EMW) absorbing materials. By employing a DC power pulse discharge with a 10 s duration, we achieved over 99 % HCBD degradation efficiency. Characterization results indicate that the thermal shock transforms the distillation residue into high-value turbostratic pulse graphene (tPG). This tPG, featuring a unique structure, demonstrates substantial potential as an EMW absorber, with an effective absorption bandwidth of 3.9 GHz and a reflection loss of -42.0 dB at a minimal matching thickness of 1.6 mm. The method offers a sustainable, cost-effective solution for hazardous waste management, combining rapid processing with high-value material production.

Effect of Hydrolysate Derived from Subcritical Seawater Treatment of Buckwheat Waste on the Growth of Lettuce (Lactuca sativa L.)

This study explores the effects of a subcritical seawater treatment (SST) on buckwheat waste (BW), and the use of the hydrolysate as a liquid fertilizer to improve the growth of lettuce (Lactuca sativa L.). Three temperature treatments (110 °C, 170 °C, 230 °C) were used for the SST, and the ionic composition in the seawater achieved the depolymerization and degradation of BW. The X-ray diffraction of the residual solids showed that the structure of BW was destroyed. Compared with seawater, the hydrolysate contained higher amounts of elements beneficial to plant growth, such as N, P, K, and organic compounds such as phenolics and sugars, as a result of the degradation of BW caused by the SST. The hydrolysate was tested as a liquid fertilizer (treatments H110°C, H170°C, H230°C) to irrigate lettuce. The content of proteins, phenolics, and chlorophyll, as well as the weight of the lettuce in the H110°C and H170°C treatments, were significantly higher than those in the seawater and the H230°C irrigation treatments (p < 0.05). The hydrolysate from the SST of BW, being rich in various organic and inorganic nutrients, can act as a liquid fertilizer that promotes the growth of lettuce, whereas hydrolysate from higher SST temperatures might inhibit the growth of lettuce, because of the excessive total nitrogen and organic acid.

Produção de biogás com resíduos sólidos gerados na produção de bioetanol utilizando biomassa da bananicultura

ABSTRACT Santa Catarina is a significant banana producer, responsible for 722 tons annually. For every 1,000 kg of bananas harvested, approximately 3,000 kg of pseudostem, 650 kg of peels, and 350 kg of rejected fruit are generated. Studies have evaluated the use of banana residues for bioethanol production. Solid residues like banana pseudostem bagasse, banana peels, and vinasse (fermented broth residue) are produced during this process. This study aimed to quantify and characterize these residues for biogas and methane production. Banana peels and vinasse were more suitable for containing lower total solids content and favorable C:N (carbon:nitrogen) ratios (10-30:1), yielding higher biochemical potential of methane (260 mLCH4 gvs -1) compared to banana pseudostem bagasse (201 mLCH4 gvs -1). However, vinasse had a high hydrogen sulfide content (0.0783%), necessitating desulphurization for safe biogas use. The results indicate that banana pseudostem bagasse, banana peels, and vinasse have substantial potential for biogas and methane production due to their high degradation rates. The biogas composition meets the criteria for use, with adequate methane and carbon dioxide concentrations, highlighting the viability of these residues for energy generation and contributing to sustainability in banana cultivation.

Roasting-Water Leaching-Slag Cleaning Process for Recovery of Valuable Metals from Li-ion Battery Scrap

Abstract Waste lithium-ion batteries (LIBs) are important secondary sources of valuable materials, including Critical Raw Materials (CRMs) like lithium, cobalt, manganese, and graphite, as defined by the European Union (EU). LIBs also contain nickel and copper, classified as Strategic Raw Materials by the EU since 2023. Significant efforts have been made to develop efficient recycling processes for waste LIBs, with pyrometallurgical processes playing a key role. These technologies are relatively mature, with high adaptability for different raw materials and involve smelting waste batteries above the melting points of battery components, followed by separating metals through reduction reactions. This method efficiently recovers cobalt, copper, and nickel as a metal alloy or matte, while lithium and manganese are lost in the slag phase. The goal of this work was to enhance the recovery of valuable battery metals by combining hydro- and pyrometallurgical processes. Mechanically prepared battery black mass underwent selective sulfation roasting to convert LiCoO2 and Mn-oxides into Li, Co, and Mn sulfates. After roasting, the battery scrap was leached in distilled water at 60 °C, recovering 95% of lithium, 61% of manganese, and 35% of cobalt. The solid leaching residue was then mixed with industrial Ni-slag and biochar. Two experimental series were carried out, one with the addition of industrial Ni-concentrate and one without. The smelting experiments were conducted at 1350 °C in flowing argon atmosphere as a function of time (5–60 min) to investigate the reduction behavior of battery metals. The results show that Co and Ni from the slag and leach residue can be efficiently recovered in the slag cleaning stage. Graphical Abstract

Geochemistry and Mineralogy of Precipitates from Passive Treatment of Acid Mine Drainage: Implications for Future Management Strategies

Traditional mining activities in Zaruma-Portovelo (SE Ecuador) have led to high concentrations of pollutants in the Puyango River due to acid mine drainage (AMD) from abandoned waste. Dispersed alkaline substrate (DAS) passive treatment systems have shown efficacy in neutralizing acidity and retaining metals and sulfates in acidic waters, achieving near a 100% retention for Fe, Al, and Cu, over 70% for trace elements, and 25% for SO42−. However, significant solid residues are generated, requiring proper geochemical and mineralogical understanding for management. This study investigates the fractionation of elements in AMD precipitates. Results indicate that Fe3+ and Al3+ predominantly precipitate as low-crystallinity oxyhydroxysulfate minerals such as schwertmannite [Fe3+16(OHSO4)12–13O16·10–12H2O] and jarosite [KFe3+3(SO4)2(OH)6], which retain elements like As, Cr, Cu, Pb, and Zn through adsorption and co-precipitation processes. Sulfate removal occurs via salts like coquimbite [AlFe3(SO4)6(H2O)12·6H2O] and gypsum [CaSO4·2H2O]. Divalent metals are primarily removed through carbonate and bicarbonate phases, with minerals such as azurite [Cu(OH)2·2CuCO3], malachite [Cu2(CO3)(OH)2], rhodochrosite [MnCO3], and calcite [CaCO3]. Despite the effectiveness of DAS, leachates from the precipitates exceed regulatory thresholds for aquatic life protection, classifying them as hazardous and posing environmental risks. However, these residues offer opportunities for the recovery of valuable metals.

Strategic Resource Extraction and Recycling from Waste: A Pathway to Sustainable Resource Conservation

This study examines calcium extraction from Bottom Ash (BA) and the use of Solid Residue (SR) as a substitute for White Lump Clay (WLC) in brick production. Experimental analyses identified calcium and silicon as the main elements in BA, with 50% of calcium carbonate recovered through leaching. SR was a viable alternative to WLC in ceramic bricks, as SEM-EDS and FTIR analyses revealed changes in composition and microstructure. This approach promotes circular economy principles by recovering resources and reducing waste. Calcium extraction from BA can produce 29,000 tons of CaCO3 annually for industrial use, while substituting SR for WLC in brick production could replace 30% of clay, saving 1500 tons of clay and producing millions of bricks annually. Less than 50% of incinerated Municipal Solid Waste (MSW) would require landfilling. The process supports sustainable construction by conserving natural resources, reducing landfill waste, and lowering CO2 emissions. It offers annual cost savings of 2,639,250 USD and preserves 74,812.5 tons of resources through waste and clay reduction. By demonstrating a scalable model for waste valorization, this research aligns with global goals for sustainable development, resource efficiency, and ecological balance.

Comparative Analysis of Freeze-Dried Pleurotus ostreatus Mushroom Powders on Probiotic and Harmful Bacteria and Its Bioactive Compounds

Pleurotus ostreatus (oyster mushroom) holds excellent promise worldwide, bringing several opportunities and augmenting the tool sets used in the biotechnology field, the food industry, and medicine. Our study explores the antimicrobial and probiotic growth stimulation benefits of freeze-dried P. ostreatus powders (OMP-TF, oyster mushroom powder from the total fresh sample; OMP-CSR, oyster mushroom powder from the cooked solid residue; OMP-CL, oyster mushroom powder from the cooked liquid), focusing on their bioactive compounds and associated activities. Our research examined polysaccharide fractions—specifically total glucans and α- and β-glucans—alongside secondary metabolites, including polyphenols and flavonoids, from freeze-dried mushroom powders. Additionally, carbon nanodots (CNDs) were also characterized. The growth inhibition was tested against Escherichia coli and Staphylococcus epidermidis, while the capacity for stimulating probiotic growth was evaluated using Lactobacillus plantarum and Lactobacillus casei. Evidence indicates that OMP-CL and OMP-CSR exhibit significant antimicrobial properties against S. epidermidis Gram-positive bacteria. OMP-CL notably promoted the growth of L. casei. OMP-CL, containing the most significant number of CNDs, has shown to be a valuable source for gut microbiota modulation, with its antimicrobial and probiotic-stimulating efficacy. However, further in vitro and in vivo studies should be performed to explore CNDs and their behavior in different biological systems.

Processing of chalcopyrite concentrate by sulfating roasting

Chalcopyrite (CuFeS2) is one of the primary minerals processed on an industrial scale for copper production and often dominates copper concentrates sent for pyrometallurgical processing. This study demonstrates the efficient and selective extraction of copper from chalcopyrite concentrate through sulfating roasting, sulfuric acid leaching, and solvent extraction. At a roasting temperature of 700 °C for 1.5 h, chalcopyrite fully decomposes into hematite (Fe2O3) and chalcanthite (CuSO4). Leaching the calcine with a 0.02 M sulfuric acid solution transfers most of the copper to the aqueous phase, while iron concentrates in the solid residue. Additionally, precious metals concentrate in the residue after leaching of the calcine, with the following content in g/t: Pd – 41.61, Pt – 5.65, Ag – 96.22, Au – 4.81. The removal of iron from the leach solution using solvent extraction with di-2-ethylhexyl phosphoric acid was highly effective: with a 25 % extractant solution and an organicto-aqueous ratio of 1:1 over two stages, the iron concentration in the aqueous phase dropped from 3.05 to 0.01 g/dm3, and with an organic-toaqueous ratio of 1:2 over four stages, it decreased to 0.006 g/dm3. After iron purification and solution evaporation, copper sulfate was obtained with the following composition (%): CuSO4·5H2O – 99.84 (equivalent to 25.42 % copper), Ni – 0.014, Al – 0.007, Fe – 0.0003, As – 0.0002.

Evaluation of Cellulase, Pectinase, and Hemicellulase Effectiveness in Extraction of Phenolic Compounds from Grape Pomace.

Grape pomace, the solid residue from winemaking, is a rich source of polyphenolic compounds with significant antioxidant properties. However, the efficient extraction of these valuable compounds remains a challenge. This study focuses on optimizing the conditions for the enzyme-assisted extraction of polyphenolic compounds from red grape pomace using cellulase, hemicellulase, and pectinase. The key variables investigated in this study were enzyme concentration, extraction time, and solid/liquid ratio. The results highlight the importance of selecting enzymes based on target compounds, as different enzymes were found to be more effective for specific phenolic fractions. Hemicellulase was most effective for phenolic acids, cellulase for catechins, and pectinase for anthocyanins. Enzyme-assisted extraction significantly increased the yield of phenolic compounds and resulted in higher total phenolic content and antioxidant activity compared to control samples treated with solid/liquid extraction without enzyme addition. These findings confirm that enzyme-assisted extraction is a promising approach for enhancing the recovery of polyphenolic compounds from grape pomace.

Optimization of Cl and heavy metal removal during heat treatment of municipal solid waste incineration fly ash and municipal sludge after co-washing.

Heat treatment, known for its detoxification and volume reduction characteristics, is a promising technology for the management of municipal solid waste incineration fly ash (MFA) and municipal sludge (MS). This paper uses the solid residue from MFA and MS after co-washing as the raw material to study the melting properties, phase transformations, changes in Cl content, heavy metal removal efficiency, and leaching toxicity. The results indicated that co-processing of MFA and MS can effectively reduce the melting temperature. The migration of Cl elements was influenced by the CaO/(SiO2 + Al2O3) ratio and the formation of Cl-containing phases. During the heat treatment process, Cr and Ni remained relatively stable, while Zn, Pb, Cu, and Cd were affected by Cl migration. Chlorine can promote the volatilization and escape of these heavy metals, but as Cl became fixed within Ca10(SiO4)3(SO4)3Cl2 and Ca5(PO4)3Cl, the removal efficiency decreased. To achieve the highest removal rates for these elements, the addition of MFA should be limited to no more than 20%, and the CaO/(SiO2 + Al2O3) ratio should be below 2.9. After heat treatment, the leaching concentrations of Zn, Pb, Cu, Cr, Cd, and Ni met applicable standards. The findings of this study could provide a method for the treatment of MFA and MS after co-washing and can serve as guidance for heat treatment processes.

Review on Gallium in Coal and Coal Waste Materials: Exploring Strategies for Hydrometallurgical Metal Recovery.

Gallium, a critical and strategic material for advanced technologies, is anomalously enriched in certain coal deposits and coal by-products. Recovering gallium from solid residues generated during coal production and utilization can yield economic benefits and positive environmental gains through more efficient waste processing. This systematic literature review focuses on gallium concentrations in coal and its combustion or gasification by-products, modes of occurrence, gallium-hosting phases, and hydrometallurgical recovery methods, including pretreatment procedures that facilitate metal release from inert aluminosilicate minerals. Coal gangue, and especially fly ashes from coal combustion and gasification, are particularly promising due to their higher gallium content and recovery rates, which can exceed 90% under optimal conditions. However, the low concentrations of gallium and the high levels of impurities in the leachates require innovative and selective separation techniques, primarily involving ion exchange and adsorption. The scientific literature review revealed that coal, bottom ash, and coarse slag have not yet been evaluated for gallium recovery, even though the wastes can contain higher gallium levels than the original material.

SUSTAINABLE LITHIUM RECOVERY FROM LITHIUM-ION BATTERIES: A COMPARATIVE STUDY OF PYRO AND HYDROMETALLURGICAL TECHNIQUES

Different sort of Batteries are used in many diversified applications such as cars, radios, laptops, mobile phones, and watches. They are classified as primary and secondary batteries. The former one is known as alkaline batteries made up of zinc and manganese as primary source and mainly used for household purposes, which convert directly chemical energy into electrical energy. The later one is usually made up of nickel (Ni), cadmium, nickel metal hydride or lithium-ion and it is mainly used in mobile phones, electronic items, cameras etc. The main concern of using batteries is the threat to the environment at the end of their usages. Among all type of batteries, Lithium-ion batteries (LIBs) are gaining world-wide interest owing to their use in almost all modern life devices. In addition, it is of paramount importance to develop new technologies to minimize any environment impact caused while disposing of such heavy metal bearing residues, since, on the one hand, the metals they contain can affect the environment and, on the other hand, such metals are valuable at an industrial level. In this work, the recoveries of lithium and manganese from the cathodes of exhausted lithium-ion batteries will be investigated using a pyrometallurgical chlorination process, followed by a hydrometallurgical process for the proper solubilisation of the lithium, manganese and cobalt chlorides formed. The tests were carried out in isothermal conditions, in alumina reactor so that it will be possible to operate in corrosive atmospheres. The effect of temperature and reaction time on lithium, manganese and cobalt extractions were also considered. The reagents, products and solid residues of chlorination were characterized by atomic absorption spectrometry (AAS) and X-ray diffraction (XRD). The experimental results were be analysed to assess the efficiency of lithium, manganese and cobalt extractions as LiCl, MnCl2 and CoCl2, respectively. Once these metals were solubilized, lithium was precipitated in the form of carbonate, which is the raw material for the subsequent production of the batteries.

Effects of wood meal particle size and polyethylene glycol 400 content on glycol lignin production

Glycol lignin (GL) produced via acidic solvolysis of cedar wood meal with polyethylene glycol (PEG) is a highly functional material. In this study, the effects of wood meal particle size and amount of PEG added on the properties of PEG400-modified GLs (GL400s) were examined. For this purpose, cedar wood meal with four different particle sizes ranging between 0.18 and 2.00 mm and PEG400 at liquid ratios of 5 and 3 with respect to the wood meal were used. Acidic solvolysis at 140 °C successfully decreased the amount of solid residue with increasing GL400 yield and reaction time at both liquid ratios of 5 and 3. Overall, wood meal size remarkably affected the physical properties of GL400s at low PEG400 content (liquid ratio 3). In addition, the glass transition temperature Tg and thermal flow temperature Tf increased with decreasing wood meal size. Consequently, GL400s with varying thermal properties (Tg = 63 to 97 °C, Tf = 109 to 149 °C) were successfully prepared by adjusting the PEG400 liquid ratios and wood meal size. The data will support the development of a stable manufacturing process for the mass production of GL.

Torrefaction Temperature Effects on Grindability of Wheat Straw Using TG-FTIR Analysis

Abstract Torrefaction used for pretreatment of biomass can enhance grindability along with significant reduction of energy consumption required for pulverization to aid in large-scale utilization of biomass energy. In this study, torrefaction experiments of wheat straw were conducted at different temperatures using an experimental furnace facility. The influence of torrefaction temperature on the grindability of resulting wheat straw was explored using a Hardgrove grindability index tester and thermogravimetric-Fourier transform infrared spectroscopy (TG-FTIR). Increase in torrefaction temperature significantly enhanced the carbon content of wheat straw and decreased oxygen content to result in decreased O/C ratio from 0.66 to 0.39. The calorific value increased by 24% from 15.42 MJ/kg to 19.17 MJ/kg. Increase in torrefaction temperature from 220 °C to 269 °C increased the grindability index from 29 to 115. The grindability of wheat straw can be controlled to values similar to that of coal by tuning the torrefaction temperature. The main gas components released during torrefaction were H2O, CH4, CO2, and CO. Thermogravimetric data showed 29% solid residue from the raw wheat straw. Increase in torrefaction temperature increased the solid residue to 41%. Pyrolysis of wheat straw at different torrefaction temperatures can be grouped into three stages of dehydration, rapid pyrolysis, and carbonization. This study reveals effective large-scale utilization of torrefied wheat straw biomass having high heating value of the solid fuel after torrefaction pretreatment.

Reductive Depolymerization of Lignin to Aromatic Compounds over Promoted Nickel Catalysts in Sub‐ and Supercritical Methanol

AbstractThe use of γ‐Al2O3‐supported Ni catalysts promoted with either Cu or Fe was investigated for the reductive catalytic fractionation (RCF) of hybrid poplar in methanol at 200 and 250 °C. The effectiveness of lignin depolymerization was quantified in terms of the lignin oil production, the quantity and distribution of identifiable monomers present in the lignin oil, and the yield of residual solids. All of the Ni‐based catalysts tested provided improved yields of lignin oil and monomers, along with reduced char formation, relative to blank (sans catalyst) runs. The highest monomer yield of 51 % was obtained at 250 °C over a 20 wt.% Ni‐5 wt.% Cu/Al2O3 catalyst, the improved performance obtained through Cu promotion being attributed to the ability of Cu to facilitate NiO reduction, resulting in an increased amount of Ni0 on the catalyst surface and, consequently, improved hydrogenation activity. The main monomers formed were propanol‐, propyl‐ and propenyl‐substituted guaiacol and syringol, the S/G ratio of the products corresponding closely to that in the native lignin.

Evaluating the utilization of municipal solid waste incineration ash in enhancing ceramsite aerated concrete blocks

In an effort to forge a new pathway for the resourceful utilization of municipal solid waste (MSW) incineration ash, thereby transforming waste into treasure and detriment into benefit, this study investigates the impact of incineration ash on the fundamental properties of expanded clay aggregate aerated concrete blocks. Granular ash and powdered ash were separated from MSW incineration ash. These were then used as replacements for pottery sand and fly ash, respectively, in the production of ceramsite aerated concrete blocks. Replacement ratios were set at 0 %, 10 %, 20 %, 30 %, 40 %, and 50 % of the dry mass proportion. An experimental study was conducted on the product performance indicators of grade CA50.B07 ceramsite aerated concrete blocks at 28 days, including dry density, compressive strength, and thermal conductivity. Furthermore, X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) were employed to analyze the micro-material composition and pore structure. The results show that when the replacement rate of granular ash to sand is 20 %, and the replacement rate of powdered ash to fly ash is 10 %, the produced aerated concrete blocks exhibit optimal technical performance while meeting product quality standards. This successfully demonstrates the resource utilization potential of municipal solid waste incineration residues.

Exploring pyrolysis-based alternatives for the valorization of used diapers through a comprehensive understanding of all generated products

This study provides an in-depth evaluation of a pyrolysis process designed for the valorization of baby diaper waste from the rejected fraction of municipal solid waste treatment facilities. The diapers were separated, identified, and classified into distinct fractions/layers, each subjected to Thermogravimetric Analysis to determine the optimal temperature range for operation. This study identified that hydrogen and methane production is maximized at 575 °C. At this temperature, yields reach up to 7.4 mmol of hydrogen and 6.3 mmol of methane, with a total of 23 mmol of non-condensable gases per gram of diaper waste. The temperature of 525 °C optimized the production of lighter liquid fractions. This temperature yielded compounds with boiling points similar to heavy naphtha and comprised over 63 % of the liquid products. The solid residue resulting from pyrolysis was a partially amorphous carbonaceous material, with a maximum surface area of 9.7 m2/g achieved at 575 °C, which is considered low. The analysis is completed with a study of the degradation of the used diapers by TGA/MS-FTIR and the determination of the effective activation energy as a function of conversion. This study highlights the significant potential of pyrolysis technology for treating diaper waste, which generates several potentially usable or valuable products, including hydrogen, methane, light liquid compounds, and carbonaceous material.

Deep eutectic solvent pretreatment of oil palm biomass: Promoted lignin pyrolysis and enzymatic digestibility of solid residues.

Herein, choline chloride/oxalic acid (ChCl/OA) and choline chloride/oxalic acid/ethylene glycol (ChCl/OA/EG) pretreatments of oil palm empty fruit bunches (EFB) and mesocarp fibers (MSF) were conducted to achieve protection of the lignin structure, while improving the enzymatic efficiency of the solid residues. Under the operating conditions of 90 °C and 6 h, ChCl/OA/EG demonstrated a higher lignin extraction selectivity and obtained solid residues with higher hemicellulose content compared to ChCl/OA. The digestibility of glucan and xylan in solid residues obtained using ChCl/OA/EG achieved 98.56 % and 95.63 %, respectively, for EFB and 75.95 % and 88.60 %, for MSF. Uncondensed lignin enriched with 71.79-81.61 % of β-O-4 bonds was obtained from EFB and MSF using ChCl/OA/EG. 2D HSQC NMR and the density functional theory calculation confirmed that substituting the lignin Cα position by ethylene glycol changed the local potentials of the β-O-4 bonds, impeding the attack of protons (H+). The higher β-O-4 linkage content in ChCl/OA/EG-Ls led to the formation of several oxygenated alkyl methoxy phenols and alkyl methoxy phenols were promoted during the pyrolysis. Moreover, molecular dynamics simulations showed that the main factor affecting lignin extraction and dissolution in this study was the diffusion coefficient of lignin in DESs.