Effect Of Ionic Liquid Pretreatment Research Articles

The Dual Effect of Ionic Liquid Pretreatment on the Eucalyptus Kraft Pulp during Oxygen Delignification Process.

Oxygen delignification presents high efficiency but causes damage to cellulose, therefore leading to an undesired loss in pulp strength. The effect of ionic liquid pretreatment of [BMIM][HSO4] and [TEA][HSO4] on oxygen delignification of the eucalyptus kraft pulp was investigated at 10% IL loading and 10% pulp consistency, after which composition analysis, pulp and fiber characterizations, and the mechanism of lignin degradation were carried out. A possible dual effect of enhancing delignification and protecting fibers from oxidation damage occurred simultaneously. The proposed [TEA][HSO4] pretreatment facilitated lignin removal in oxygen delignification and provided fibers with improved DP, fiber length and width, and curl index, resulting in the enhanced physical strength of pulp. Particularly, its folding endurance improved by 110%. An unusual brightness reduction was identified, followed by detailed characterization on the pulps and extracted lignin with FTIR, UV, XPS, and HSQC. It was proposed that [TEA][HSO4] catalyzed the cleavage of β-O-4 bonds in lignin during the oxygen delignification, with the formation of Hibbert’s ketones and quinonoid compounds. The decomposed lignin dissolved and migrated to the fiber surface, where they facilitated the access of the oxidation agent and protected the fiber framework from oxidation damage. Therefore, it was concluded that ionic liquid pretreatment has a dual effect on oxygen delignification.

Effect of ionic liquid pretreatment on the physicochemical properties of hemicellulose from bamboo

Ionic liquid (IL) pretreatment of lignocellulosic biomass has been the focus of attention due to its numerous advantages compared with conventional methods. The change in the physicochemical properties of the three main components of this biomass during IL pretreatment is the key factor for their further utilization and conversion. In this study, hemicellulose extracted from bamboo was dissolved in three ILs with different imidazolium cations and the same anion of acetate, including 1-ethyl-3-methylimidazolium acetate (EmimAc), 1-butyl-3-methylimidazolium acetate (BmimAc), and 1-allyl-3-methylimidazolium acetate (AmimAc). The solubility of hemicellulose in the ILs was measured as a function of temperature from 120 °C to 150 °C. Hemicelluloses regenerated from the saturated IL solutions were characterized by using Fourier transform infrared spectroscopy, gel permeation chromatography, gas chromatography–mass spectrometry, 13C–1H heteronuclear single-quantum correlation nuclear magnetic resonance, and thermogravimetry. The solubility of hemicellulose in the three ILs was greatly affected by temperature, and the solubility increased with increasing temperature. The highest solubilities per 100 g of IL were 15.56, 15.09, and 6.73 g in BmimAc, EmimAc, and AmimAc, respectively. Hemicelluloses regenerated from saturated IL solutions showed similar physicochemical features with that of the original hemicellulose before being pretreated with ILs. These features included molecular weight, relative neutral sugar composition, structural feature, and thermal stability. Hence, hemicellulose was litter degraded during IL solving. In addition, the recovered EmimAc was analyzed after dissolving hemicellulose to a saturated state at 150 °C by using 13C and 1H NMR. The recovered IL contained minimal amounts of ethanol and other impurities.

Insight into the dissolution of lignite with ionic liquid [Bmim]cl

Ionic liquid as a green solvent have shown good performance in coal and biomass pretreatment, but the effects of ionic liquids pretreatment on the coal structures is still not properly understood. In this work, the changes of radical concentration in lignite during the pretreatment with ionic liquid 1-butyl-3-methyl-imidazolium chloride [Bmim]Cl were investigated by the electron spin-resonance spectroscopy (ESR) in detail and the effect of ionic liquid pretreatment on the change of coal structure was investigated by the diffuse reflectance infrared fourier transform spectroscopy (DRIFT) and thermogravimetric analysis (TGA). It was found that the pretreatment temperature and the ratio of [Bmim]Cl to lignite had a great impact on the radical concentration of lignite. The radical concentration of lignite decreased when the pretreatment temperature lower than 100 °C, which was attributed to the coupling of free radicals dissolved from coals. When the pretreatment temperature was higher than 100 °C, the radical concentration of lignite increased, which was attributed to the cleavage of weak bonds in lignite. It was also found that pretreatment with ionic liquid can fracture the oxygen-containing functional groups in the coal can be dissociated after pretreatment with ionic liquids, which leads to an increase in the content of carboxyl and ether bonds and a decrease in the content of hydrogen bonds.

Effect of ionic liquid pretreatment on paper physical property and pulp refining performance

Abstract Ionic liquids (IL) of 1-butyl-3-methylimidazolium chloride (BmimCl) homogeneously mixed with bleached kraft pulp (BKP) were used to investigate the change of paper properties and refining performance under the general conditions. Fiber morphology and paper strength were determined by fiber analyzer and paper physical property tester. The surface morphology and chemical properties of fiber was also performed by scanning electron microscope (SEM), X-ray Diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The results indicated the optimized conditions of BmimCl pretreatment were BmimCl dosage of 1.5 mL/g, the time and temperature of 30 min and 80 °C, respectively. The physical properties of paper and internal bond strength of fiber was improved by BmimCl pretreatment. BmimCl pretreatment facilitated swelling and fibrillation of fiber, increased the crystalline index of fiber and decreased the lignin and extractives on the surface of fiber, which leading to improve fiber strength and tensile strength. For the same refining energy input, saving the maximum refining energy consumption was 14.0 % after BmimCl pretreatment, which is beneficial to improve the application of ionic liquid in pulp and papermaking.

Effects of ionic liquid pretreatment on pyrolysis characteristics of a high-sulfur bituminous coal

Four different ionic liquids (ILs) were used to identify their extraction properties on high-sulfur bituminous coal. And the effect of ILs pretreatment on pyrolysis characteristic was investigated in a fixed-bed reactor. The imidazolium-based ILs used namely: 1-butyl-3-methyl-imidazolium chloride ([Bmim]Cl), 1-butyl-3-methyl-imidazolium bromide ([Bmim]Br), 1-butyl-3-methylimidazolium hydrogen sulfate ([Bmim]HSO4), 1-butyl-3-methyl-imidazolium tetrafluoroborate ([Bmim]BF4). All the selected ILs exhibited extraordinary extraction ability for oxygen-containing compounds, mainly furans and ethers. Among them, [Bmim]Cl got the highest extraction yields of 20.82% and performed selective extraction ability for sulfur-containing compounds with a relative content of 5.10% in light oils. Compared with pyridine pretreated coal (R-PY), the yields of CO and CO2 in pyrolysis gas showed increase trend when coal pretreated by ILs (R-ILs). The relative contents of tricyclic and larger PAHs, sulfur-containing compounds, and oxygen-containing compounds in tar from pyrolysis of [Bmim]Cl and [Bmim] Br treated coal increased significantly than R-PY tar, while phenols got decreased. High carbon number components from R-ILs tar reduced dramatically compared with R-PY tar, which was conducive to the upgrading of tar, after pretreated with ILs, the sulfur content was reduced. The crosslinks between coal macromolecules structure were destroyed after pretreated by ILs, and the pyrolysis products distribution had evident change. The oil phase yield got a substantial increase while [Bmim]Cl obtained highest oil yield of 24.89%.

Comparative effect of ionic liquids pretreatment on thermogravimetric kinetics of crude oil palm biomass for possible sustainable exploitation

Crude oil palm biomass (OPB) residue is an important source of lignocellulose and could be transformed into biofuels through thermochemical conversion for heat and power in CHP plants or act as sustainable reinforcement in the biocomposite industry. Effective pretreatment is an essential task for the utilization of waste biomass for bioenergy and biomaterials. The comparative effect of two ionic liquids (ILs), 1-butyl-3-methylimidazolium chloride ([bmim][Cl]) and 1-ethyl-3-methylimidazolium diethylphosphate ([emim[dep]), on OPB pyrolysis kinetic and thermodynamic parameters was studied using thermogravimetric analysis (TGA) coupled with Coats-Redfern integral method. The OPB residue was pretreated with ILs [bmim][Cl] and [emim][dep] under mild processing conditions of 90 °C for 3 h and was also subjected to three other conventional pretreatment methods called dilute acid, alkaline, and hot compressed water to better understand and compare the performance of ILs for pretreatment of lignocellulosic OPB. Results reveal that ILs pretreatment was superior in terms of delignification of OPB and produced the cellulose-rich fiber with 48.2% and 41.2% cellulose compared to cellulose fraction of 26.4% for the untreated sample. The values of apparent activation energies were found to be 81.8, 90.9, 92.0, 84.9, 83.8, and 93.5 kJ/mol for untreated, [bmim][Cl], [emim][dep], dilute acid, base, and hot compressed water pretreatments respectively. Further calculation of thermodynamic parameters led to the change in Gibb's free energy (ΔG°) values of 188.9, 208.0, 210.9, 219.1, 217.4 and 217.1, kJ/mol for untreated, [bmim][Cl], [emim][dep], dilute acid, base, and hot compressed water pretreatments respectively. The higher change in entropy (ΔS°) values of ILs-pretreated fibers compared to the untreated one showed that dissolution and regeneration from ILs solution had unlocked the complex 3D structure of lignocellulose, resulting in increased disorder. The results plainly revealed that ILs-based pretreatment could be a promising and environmentally benign technology for efficient utilization of agricultural residues in the fields of biofuels and biocomposite materials.

Effect of ionic liquids pretreatment on thermal degradation kinetics of agro-industrial waste reinforced thermoplastic starch composites

Converting agricultural lignocellulosic waste into marketable composite product is a promising approach to protect the environment and earn financial gain. Ionic liquids (ILs) have emerged as the innovative and effective solvents for pretreatment of lignocellulosic materials to produce potential reinforcements for biocomposite manufacturing. Kinetic predictions are particularly essential for practical utilization of kinetic analysis for process design and to assess the performance of composite product during service life. This work aims to explore the impact of ILs assisted pretreatment of oil palm biomass on the thermal degradation kinetics of their fabricated biocomposites with thermoplastic starch as polymer matrix. The approach combines the pretreatment of oil palm frond (OPF) fiber with ILs 1-butyl-3-methylimidazolium chloride ([Bmim][Cl]) and 1-ethyl-3-methylimidazolium diethylphosphate ([Emim][dep]) prior to fabricate thermo-molded composite panels. Flynn–Wall–Ozawa method based on the model-free isoconversional approach was chosen to predict the activation energy of the biocomposites. Further, the influence of ILs pretreatment on physico-chemical properties of the OPF fiber was assessed by lignocellulosic characterization and crystallinity measurement. The results indicated that composites prepared with ILs pretreated OPF fiber exhibited 10–125% higher activation energy as compared to untreated composite over a conversion range of α=0.1–0.6. Characterization of the untreated and pretreated fibers by examining the lignocellulosic fraction and analyzing the degree of crystallinity evidenced that ILs pretreatment increased the cellulose contents by 1.5–1.8 folds and caused significant reduction in the crystallinity of the OPF fiber. The present findings plainly indicate the promising potential of ILs based pretreatment as a new and clean processing approach for manufacturing of engineered composite panels from agricultural waste.

The effect of ionic liquids pretreatment on the distribution and structure of alkali-soluble hemicelluloses from Eucalyptus

Abstract In this study, Eucalyptus was treated by an integrated process based on ionic liquids ([Bmim]Cl and [Bmim]OAc) combined with successive alkali solutions (0.5, 2.0, and 4.0% NaOH). The dynamic distribution changes of hemicelluloses on the morphologically distinct regions in the treated Eucalyptus cell walls revealed that the dissolution of hemicelluloses mainly occurred in the secondary layers during this process. In addition, the structural features of alkali-soluble hemicelluloses dissolved from ionic liquids pretreated Eucalyptus were thoroughly investigated. The [Bmim]OAc pretreatment promoted the separation of hemicelluloses with relatively high molecular weights in the following alkali extractions, accompanying with slightly structural changes. The alkali-soluble hemicelluloses obtained from Eucalyptus are characterized to be a linear backbone of (1 → 4)-linked-β-D-xylopyranosyl residues decorated with branch at O-2 of 4-O-methyl-α-glucuronic acid unit. Additionally, the thermal stability of hemicelluloses was also increased by the ionic liquids pretreatment.

Effect of Ionic Liquid Pretreatment on the Porosity of Pine: Insights from Small-Angle Neutron Scattering, Nitrogen Adsorption Analysis, and X-ray Diffraction

Small-angle neutron scattering (SANS) was used to study the porosity of pine samples before and after ionic liquid (IL) pretreatment. Pine samples were pretreated using 1-ethyl-3-methylimidazolium acetate ([C2C1Im][OAc]) at 110 °C for 3 h at biomass concentrations of 5, 10, 15, 20, and 25 wt % and at 130 °C for 3 h at biomass concentrations of 5 and 25 wt %. For the first time, relative changes in porosity of pretreated pine samples derived from SANS were compared with those obtained from the nitrogen adsorption analysis. Biomass crystalline structures were measured by X-ray diffraction (XRD). Both porosity and XRD data suggest that [C2C1Im][OAc] interacted with pine samples more efficiently at higher biomass concentrations during pretreatment. This was attributed to the presence of resin acid in the pine samples.

Ionic liquid pretreatment at high solids loading: A clean approach for fabrication of renewable resource based particulate composites

Recently, the concept of high solids loading in ionic liquid (IL) based pretreatment of lignocellulosic biomass has gained numerous attention due to significant economic, environmental, and sustainability benefits. The objective of the present work was to investigate the impact of ILs pretreatment of lignocellulosic oil palm frond (OPF) biomass at high solids loading on the mechanical and thermal properties of the composite panels. The process combines the pretreatment of OPF particles with ILs [bmim][Cl] (1‐butyl‐3‐methylimidazolium chloride) and [emim][OAc] (1‐ethyl‐3‐methylimidazolium acetate) followed by IL recovery by rinsing with acetone‐water mixture prior to mixing of OPF particles with polymer binder to fabricate compression‐molded composite panels. Untreated and treated OPF particles were characterized by scanning electron microscopy, X‐ray diffraction, thermogravimetric analysis, and chemical composition analysis. Further, the effect of ILs pretreatment on kinetics of thermal degradation of biocomposites was evaluated by activation energy approach. Maximal flexural strength, modulus, and strain energy density (SED) of 25 MPa, 1,928 MPa, and 0.48 MJ/m3, respectively, were found for IL [emim][OAc] treated composite. Besides, thermal properties of IL treated composites were also improved. Present study could be a significant step toward practical IL pretreatment strategies for manufacturing of lignocellulosic based composite materials. POLYM. COMPOS., 39:1994–2003, 2018. © 2016 Society of Plastics Engineers

The Effect of Ionic Liquid Pretreatment on the Bioconversion of Tomato Processing Waste to Fermentable Sugars and Biogas

Tomato pomace is an abundant lignocellulosic waste stream from industrial tomato processing and therefore a potential feedstock for production of renewable biofuels. However, little research has been conducted to determine if pretreatment can enhance release of fermentable sugars from tomato pomace. Ionic liquids (ILs) are an emerging pretreatment technology for lignocellulosic biomass to increase enzymatic digestibility and biofuel yield while utilizing recyclable chemicals with low toxicity. In this study, pretreatment of tomato pomace with the ionic liquid 1-ethyl-3-methylimidazolium acetate ([C2mim][OAc]) was investigated. Changes in pomace enzymatic digestibility were affected by pretreatment time and temperature. Certain pretreatment conditions significantly improved reducing sugar yield and hydrolysis time compared to untreated pomace. Compositional analyses suggested that pretreatment primarily removed water-soluble compounds and enriched for lignocellulose in pomace, with only subtle changes to the composition of the lignocellulose. While tomato pomace was effectively pretreated with [C2mim][OAc] to improve enzymatic digestibility, as of yet, unknown factors in the pomace caused ionic liquid pretreatment to negatively affect anaerobic digestion of pretreated material. This result, which is unique compared to similar studies on IL pretreatment of grasses and woody biomass, highlights the need for additional research to determine how the unique chemical composition of tomato pomace and other lignocellulosic fruit residues may interact with ionic liquids to generate inhibitors for downstream fermentation to biofuels.

Effect of Ionic Liquid Pretreatment on the Structure and Enzymatic Saccharification of Cassava Stillage Residues

Cassava stillage residue (CSR), the solid wastes generated from cassava-based bio-ethanol production, can be used to produce ethanol because of its high contents of cellulose. This study has focused on the pretreatment of CSR using the ionic liquid (IL) of 1-butyl-3-methyl imidazolium chloride ([Bmim]Cl). The changes in surface morphology, particle size and functional groups of pretreated CSR were examined by scanning electron microscopy (SEM), laser diffraction instrument and Fourier transform infrared (FTIR) spectroscopy. The results showed that [Bmim]Cl pretreatment could significantly damage the structure of cassava cellulose and increase the enzymatic saccharification rate.

Effect of Ionic Liquid Pretreatment on the Enzymatic Saccharification of Sugarcane Bagasse

onic liquid, 1-n-butyl-3-methylimidazolium chloride ([C4mi Cl) was used to pretreat sugarcane bagasse (SCB), followed by regeneration of SCB by addition of deionized water. The regenerated SCB exhibited enhancement in enzymatic saccharification with an average 3.1-fold enhancement in yield of reducing sugar produced compared to untreated SCB in the kinetic study. The maximum yield of glucose and reducing sugar produced were 2.6% and 4.3% respectively for untreated SCB, whereas the maximum yield of glucose and reducing sugar produced were more significant with value of 7.2% and 16.6% respectively for IL-pretreated SCB. This paper suggested that the IL-pretreatment of SCB could be a useful pretreatment method to increase the yield of sugars produced in enzymatic saccharification.

Effect of [Emim]Ac pretreatment on the structure and enzymatic hydrolysis of sugarcane bagasse cellulose

Effect of ionic liquid pretreatment on enzymatic hydrolysis of cellulose was investigated in terms of the changes in the chemical and physical structure of the preparation. In this case, original cellulose isolated from sugarcane bagasse was subjected to ionic liquid ([Emim]Ac) dissolution at a mild temperature (90°C) followed by regeneration in water and subsequently hydrolyzed by commercial cellulases. The original and regenerated cellulose were thoroughly characterized by XRD, FT-IR, CP/MAS 13C NMR, and SEM. It was found that the original cellulose experienced an increase in glucose content from 80.0–83.3% to 91.6–92.8%, a decrease in the degree of polymerization from 974–1039 to 511–521, a crystal transformation from cellulose I to cellulose II, as well as an increase of surface area during the pretreatment. The results suggested that pretreatment led to effective disruption of cellulose for subsequent enzyme hydrolysis as evidenced by a high glucose conversion yield of 95.2%.

Effect of ionic liquid pretreatment on the composition, structure and biogas production of water hyacinth (Eichhornia crassipes)

The effect of the pretreatment of water hyacinth with ionic liquid and co-solvent on the lignocellulosic composition, structural change and biogas production was evaluated in this study. The results from regenerated water hyacinth indicate that, the content of the lignocellulosic composition was changed, the crystallinity of the structure was decreased, and the surface became more porous. After the pretreatment with 1-N-butyl-3-methyimidazolium chloride ([Bmim]Cl)/dimethyl sulfoxide (DMSO) under 120°C for 120min, the cellulose content of regenerated water hyacinth was increased by 27.9%, 49.2% of the lignin was removed, and the biogas yield was increased by 97.6% as compared with unpretreated water hyacinth. The ionic liquids and co-solvents were successfully recovered by forming aqueous biphasic systems with K3PO4.

Effect of Ionic Liquid Pretreatment on the Structure of Hemicelluloses from Corncob

Pretreatment is the key to unlock the recalcitrance of lignocellulosic biomass for the productions of biofuels. Ionic liquid pretreatment has drawn increased attention because of its numerous advantages over conventional methods. In this study, corncob was submitted to pretreatments with 1-ethyl-3-methylimadazolium acetate (EMIMAc) and/or H(2)O/dimethyl sulfoxide (DMSO) followed by alkaline extraction to isolate hemicelluloses. The hemicellulosic fractions obtained were comprehensively characterized with a series of chemical and spectroscopic technologies, including gel permeation chromatography (GPC), thermogravimetric analysis (TGA), high-performance anion-exchange chromatography (HPAEC), Fourier transform infrared (FTIR) spectroscopy, and one- and two-dimensional nuclear magnetic resonance (NMR). The results showed that the fractions prepared with ionic liquid pretreatments exhibited relatively higher average molecular weights (196,230-349,480 g/mol) than the fraction prepared without pretreatment (M(w), 96,260 g/mol). Furthermore, the pretreated fractions demonstrated higher thermal stability compared to the fractions without pretreatment. Structural characterization indicated that all of the fractions had similar structures, which are composed of a (1 → 4)-linked β-D-xylopyranosyl backbone substituted with arabinofuranosyls attached to O-2 and O-3 and with 4-O-methyl-α-D-glucuronic acid also linked to O-2.

Elucidation of the effect of ionic liquid pretreatment on rice husk via structural analyses.

BackgroundIn the present study, three ionic liquids, namely 1-butyl-3-methylimidazolium chloride ([BMIM]Cl), 1-ethyl-3-methylimidazolium acetate ([EMIM]OAc), and 1-ethyl-3-methylimidazolium diethyl phosphate ([EMIM]DEP), were used to partially dissolve rice husk, after which the cellulose were regenerated by the addition of water. The aim of the investigation is to examine the implications of the ionic liquid pretreatments on rice husk composition and structure.ResultsFrom the attenuated total reflectance Fourier transform-infrared (ATR FT-IR) spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM) results, the regenerated cellulose were more amorphous, less crystalline, and possessed higher structural disruption compared with untreated rice husk. The major component of regenerated cellulose from [BMIM]Cl and [EMIM]DEP pretreatments was cellulose-rich material, while cellulose regenerated from [EMIM]OAc was a matrix of cellulose and lignin. Cellulose regenerated from ionic pretreatments could be saccharified via enzymatic hydrolysis, and resulted in relatively high reducing sugars yields, whereas enzymatic hydrolysis of untreated rice husk did not yield reducing sugars. Rice husk residues generated from the ionic liquid pretreatments had similar chemical composition and amorphousity to that of untreated rice husk, but with varying extent of surface disruption and swelling.ConclusionsThe structural architecture of the regenerated cellulose and rice husk residues showed that they could be used for subsequent fermentation or derivation of cellulosic compounds. Therefore, ionic liquid pretreatment is an alternative in the pretreatment of lignocellulosic biomass in addition to the conventional chemical pretreatments.

Effect of ionic liquid pretreatment on the chemical composition, structure and enzymatic hydrolysis of energy cane bagasse

Ionic liquids (ILs) are promising solvents for the pretreatment of lignocellulose as they are thermally stable, environmentally friendly, recyclable, and have low volatility. This study evaluated the effect of 1-ethyl-3-methylimidazolium acetate ([EMIM][OAc]) for the pretreatment of energy cane bagasse in terms of biomass composition, structural changes and enzymatic digestibility. Energy cane bagasse was pretreated with [EMIM][OAc] (5% (w/w)) at 120°C for 30min followed by hydrolysis with commercially available enzymes, Spezyme CP and Novozyme 188. IL-treated energy cane bagasse resulted in significant lignin removal (32.0%) with slight glucan and xylan losses (8.8% and 14.0%, respectively), and exhibited a much higher enzymatic digestibility (87.0% and 64.3%) than untreated (5.5% and 2.8%) or water-treated (4.0% and 2.1%) energy cane bagasse in terms of both cellulose and hemicellulose digestibilities, respectively. The enhanced digestibilities of IL-treated biomass can be attributed to delignification and reduction of cellulose crystallinity as confirmed by FTIR and XRD analyses.

Promotional Effect of Ionic Liquid on the Enzymatic Shrink-Resistant Finishing of Wool Fabrics

In the paper, wool samples were pretreated by [BmiCl ionic liquid, followed by protease. The effect of ionic liquid pretreatment on the enzymatic shrink-resistant finishing of wool fabrics was studied. The results showed that the epicuticle was damaged by pretreatment, and the wettability of wool fabric was improved. These changes of wool surface made a promotional effect on proteolytic reactions. They could remarkably improve the accessibility of protease and thus increasing the efficiency of protease treatment. The weight loss of the sample pretreated with ionic liquid was dramatically increased, and the encouraging shrink-resistance was also achieved after the combination of ionic liquid and protease treatments.