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The commercial production of cellulose nanocrystals (CNCs) requires high concentration of sulfuric or other acids such as hydrochloric, phosphoric, and nitric acids. However, these acids and the involved process are corrosive, toxic, energy-intensive, and not environmentally safe. In this work, a batch mixer reactive process that entails high shear was implemented using 1-butyl-3-methylimidazolium chloride (BmimCl) media and molten oxalic acid dihydrate (OA) to produce CNCs from cellulose. Through this, a maximum CNC yield (59 wt%) was obtained with a mixture composition of 1:0.7:0.075 (Cellulose:BmimCl:OA, w/w/w) and a processing time of 2.5 min. Further investigation revealed that the particle size, degree of crystallinity, and thermal stability of the produced CNCs were found to be competitive with those of a commercial CNC product. This study asserts the potential industrial application of an efficient ionic liquid and molten organic acid treatment for CNC production via reactive processing in a batch mixer.

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Composite silica xerogels were prepared via acid catalysed sol-gel route using tetraethoxysilan (TEOS) as silica precursor, and 1-butyl-3-methylimidazolium tetrafluoroborate [BMIM][BF4] or 1-butyl-3-methylimidazolium chloride [BMIM][Cl] ionic liquids, used simultaneously as co-solvents, catalysts and pore templates, at various IL-to-silica ratios. Morphology of the xerogels prepared using the different IL templating agents were investigated using scanning electron microscopy (SEM), nitrogen sorption and small angle neutron scattering (SANS). The thermal behavior of the composites was analyzed by thermal gravimetry, whereas the compositions were checked by infrared spectroscopy and EDX. The differences in the morphology and thermal behavior of the composites due to the different IL additives were revealed.

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This work demonstrates that acetylated maize starches (AMS) with varied degree of substitution (DS, 0.26-2.63) was synthesized in ionic liquids (ILs) (imidazolium chloride, imidazolium carboxylate and choline carboxylate) at 85 °C without catalyst. The DS of AMS and reaction efficiency increased with decreasing alkyl chain length of cations or anions, while decreased as the choline cation replaced the imidazolium cation and the chloride anion replaced the acetate anion. The AMS synthesized in imidazolium-based ILs exhibited much higher hydrophobicity and thermal stability than the native starch. Rheological properties of ILs and ATR-FTIR analysis of acetic anhydride/ILs mixtures indicated that a shorter alkyl side chain or the combination of an imidazolium cation and an acetate anion gave ILs lower viscosities and weaker interactions between acetic anhydride molecules, which favored the acetylation of starch. These findings provide insights into the design of green processes to modify starch and the application of acetylated starch.

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Lignin extraction from biomass is heavily dependent on chemical processes that are harmful to the environment and the quality of the recovered lignin. Ionic liquid solvents are some of the latest solutions in green processing; however, their implementation for lignin recovery is limited by their high cost, typically high loadings requirements, and long processing times. To overcome these issues, in this study, high loadings of mixed hardwood flour (MHF) were processed with 1-butyl-3-methylimidazolium chloride (BmimCl) in a batch mixer. The rheological behaviour of the biomass and ionic liquid mixture was studied. The mixture had a high complex viscosity (approx. 107 Pa s) at low shear rates and displayed pronounced shear thinning behavior at 50 wt% MHF loading. A 22 factorial design was also implemented to study the effects of MHF solid loading amount and residence time on lignin extraction yield. A maximum yield of 36.6% was obtained at the maximum solid loading amount and residence time (50 wt% and 45 min, respectively). The extracted lignin samples were also characterized in comparison with commercial Kraft lignin and lignosulfonate. The novelty of this study is the successful lignin extraction at high solid loadings and shorter residence times compared to previous biomass pre-treatments with ionic liquids that employs low solid loading and long processing times.

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Ionic liquids (ILs) are synthetic solvents used as replacements for volatile organic solvents. Human exposure occurs through dermal or oral routes. In rodents, several ILs were reported to induce dermal toxicity, irritation, and sensitization. Due to the potential for occupational exposure, and industrial use as nonvolatile solvents, 1-ethyl-3-methylimidazolium chloride (EMIM, 6.25% to 50% v/v), 1-butyl-3-methylimidazolium chloride (BMIM, 3.12% to 12.5% v/v), 1-butyl-1-methylpyrrolidinium chloride (BMPY, 0.825% to 6.25% v/v), and N-butylpyridinium chloride (NBuPY, 0.825% to 12.5% v/v) were nominated to the National Toxicology Program and evaluated for skin sensitization. The test compound was applied to the ears of female BALB/c mice daily for 3 days in a primary irritancy (IRR)/local lymph node assay (LLNA). Sensitization was assessed in vitro in the direct peptide reactivity assay (DPRA), KeratinoSens™ assay, and human cell line activation test (h-CLAT). In the LLNA, the butylated ILs, BMIM, and BMPY were more potent than NBuPY (butylated) or EMIM (ethylated), which was neither an irritant nor a sensitizer. NBuPY induced skin irritation in vivo at ≥3.12% (p ≤ 0.01), and sensitization in vitro in the KeratinoSens™ assay and h-CLAT, but was negative for sensitization in vivo and in the DPRA. Although SI3 was not achieved, dermal treatment with 12.5% BMIM or 6.25% BMPY increased (p ≤ 0.01) lymph node cell proliferation in the LLNA. In vitro, BMIM was positive for sensitization in the h-CLAT, and BMPY was positive in the h-CLAT and KeratinoSens™ assay; both were negative in the DPRA. Integrated data analyses, weighted toward in vivo data, suggested that BMIM and BMPY may induce weak to mild sensitization.

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The limited reactivity of starch towards maleic anhydride (MA) affords maleate with a low degree of MA substitutions (CC and COOH groups). In this study, we investigated the relationship between the starch structure, controlled by its amylose (AM)/amylopectin (AP) ratio, and the DS of starch maleates using C4[mim]Cl as the recyclable media, and catalyst. The results indicated that starches with varying AM/AP ratio produced maleates with comparable CC groups (DSNMR = 0.06-0.07). Following dissolution, the high amylose (DStitration = 1.17, yield = 69.2 %) and regular starches (DStitration = 1.17; yield = 59.3 %) produced high DStitration maleates (COOH groups) at MA/AGU ratio of 12:1 (80 °C, 10 min). Comparatively, DStitration value of waxy starch maleates (DStitration = 0.88, yield = 59.3 %) was lower than AM-based starches, possibly due to the crosslinking tendency of AP branches consisting of carboxylic end-groups. Interestingly, DStitration value for EHCS (1.17) ranged between its bulk (DSNMR: 0.06) and surface distribution of MA (DSSXPS 1.7); therefore, we considered it reliable for future reference.

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Thermostability and stability in ionic liquids are essential properties of cellulases that are applied in industrial processes of bioconversion. Engineering of protein surface of endoglucanase II from Penicillium verruculosum was used to improve the enzyme thermostability and stability in 1-butyl-3-methylimidazolium chloride ([Bmim]Cl). The engineering was based on analysis of the protein surface topography and enhanced by multiple sequence alignment and ΔΔG calculations. In the case of the thermostability, half-life time was improved in 1.3-1.6 times at 70 °C and 1.2-1.4 times at 80 °C. In the case of the stability in [Bmim]Cl, the residual activity after 72 h of incubation in the presence of [Bmim]Cl (50 g/L, 50 °C, pH 4.5) was 1.7-1.9 times greater for the tailored enzyme. The yield of reducing sugars after enzymatic hydrolysis of aspen wood pretreated with [Bmim]Cl was 10-20% higher with the tailored endoglucanase.

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It is still challenging to melt-process cellulose. In this paper, we proposed a method for the formation of thermally processable flexible cellulose films via gelation from its solution in ionic liquid (1-butyl-3-methylimidazolium chloride; BMIMCl). Cotton, as a source of cellulose, was dissolved (5 wt%) in BMIMCl and subsequently placed in different amounts of water. The obtained ion gels were dried at 60 °C for 24 h; during drying process, water was removed while BMIMCl was retained. It was found that the amount of retained BMIMCl had a critical role in determining the mechanical properties of the films. It was suspected that the processing conditions altered the degree of crystallinity of cellulose in the films as evidenced by X-ray diffraction measurement. The ionic liquid, i.e., BMIMCl induced the plasticity into the films, so that thermal processability to different shapes became possible.

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This study assessed the influence of hydrodynamic conditions on the degradation process of 1-butyl-3-methylimidazolium chloride (BMImCl) solution on a boron-doped diamond anode in a filter-type electrochemical reactor configuration. The results show that this parameter did not significantly affect this process when operating in the laminar regime. However, in the transition regime (Re ≥ 2000), higher flow rates resulted in a faster removal of BMImCl and total organic carbon, making the process more efficient. Following BMImCl degradation, nitrates were generated at the cathode, then reduced at the cathode to ammonium; combination with free chloride produced at the anode led to the transformation of chloride into combined chlorine forms instead of more toxic oxianions such as chlorate and perchlorate. Thus, the flow rate can be a key parameter for defining operating conditions in which the target BMImCl is more effectively degraded with reduced generation of undesirable secondary products.

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OBJECTIVE： To establish a method to determine the contents of rhynchophylline and isorhynchophylline in Uncaria rhynchophylla. METHODS： The separation degree of ionic liquid 1-butyl-3-methylimidazolium chloride （C4mimCl） as mobile phase additive was compared with that of mobile phase without additives and with traditional additive triethylamine （which damaged the chromatographic column）. The optimum concentration of C4mimCl was screened and the contents of rhynchophylline and isorhynchophylline in U. rhynchophylla from 4 habitats in Jiangxi province were determined by the newly established method. The determination was performed on Dikmatech Diamonsil Plus C18 column， the mobil phase was acetonitrile-buffer （0.1％ phosphoric acid+3.0 mmol/L C4mimCl）， gradient elution. UV detection wavelength was set at 245 nm and the flow rate was 1    mL/min. Sample size was 10 μL. RESULTS： When mobile phase had no additives or 3.0 mmol/L triethylamine and 3.0 mmol/L C4mimCl were added as additives， the separation of rhynchophylline from the front peak was 1.02， 1.23 and 1.72， and the separation from the back peak was 1.06， 6.00 and 4.25， respectively. The symmetry factors were 0.81， 0.86 and 1.13， respectively. The separation of isorhynchophylline from the front peak was 0.96， 3.89 and 4.05， and the separation from the back peak was 1.02， 2.34 and 2.36， respectively. The symmetry factors were 0.88， 0.81 and 0.96， respectively. The linear range of rhynchophylline and isorhynchophylline were 4.93-157.76 （r＝0.999 9） and 4.98-159.50 μg/mL （r＝1.000）， respectively. The quantitative limits were 0.486 4， 0.793 6 μg/mL， respectively. RSDs of precision， repeatability， stability and durability tests were all less than 5％ （n＝6）. The recovery rates were 102.9％-107.8％ （RSD＝1.7％，n＝6） and 95.4％-106.3％ （RSD＝3.9％，n＝6）， respectively. The content of rhynchophylline and isorhynchophylline in U. rhynchophylla from 4 habitats were 0.758-1.343         and 1.511-1.823 mg/g， respectively. CONCLUSIONS： Addition of C4mimCl into mobile phase can enhance its separation. Established HPLC method is rapid， accurate and reproducible， which can be used for content determination of rhynchophylline and isorhynchophylline in U. rhynchophylla.

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The purpose of this paper was to investigate the effect of ultrasound-ionic liquid (IL) pretreatment on the enzymatic and acid hydrolysis of the sugarcane bagasse and wheat straw. The lignocellulosic biomass was dissociated in ILs ([Bmim]Cl and [Bmim]AOC) aided by ultrasound waves. Sonication was performed at different frequencies (20, 28, 35, 40, and 50kHz), a power of 100W, a time of 30min and a temperature of 80°C. The changes in the structure and crystallinity of the cellulose were studied by Fourier transform infrared (FT-IR), X-ray diffraction (XRD) and thermal gravimetric analysis (TGA). The amounts of the total reducing sugars, glucose, cellobiose, xylose and arabinose in the hydrolysates were determined. The results of FT-IR, XRD and TGA revealed that the structure of cellulose of both biomass samples remained intact after the pretreatment, but the crystallinity decreased. The enzymatic and acid hydrolysis of the biomass samples pretreated with the ultrasound-IL result in higher yields of the reducing sugars compared with the IL-pretreated sample. Enzymatic hydrolysis of bagasse and wheat straw pretreated with [Bmim]Cl-ultrasound resulted in maximal yields of glucose at 20kHz (40.32% and 53.17%) and acid hydrolysis resulted in maximal yields of glucose at 40kHz (33.32% and 48.07%). Enzymatic hydrolysis of bagasse and wheat straw pretreated with [Bmim]OAc-ultrasound show maximal yields of glucose at 28kHz and acid hydrolysis at 50kHz. Combination of ultrasound with [Bmim]OAc is more effective than [Bmim]Cl in terms of the yields of reducing sugar.

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In this study, five ionic liquids (ILs) have been explored for biomass pretreatment for the production of fermentable sugar. We also investigated the driving factors responsible for improved enzymatic digestibility of various ILs treated biomass along with postulating the plausible mechanism thereof. Post pretreatment, mainly two factors impacted the enzymatic digestibility (i) structural deformation (cellulose I to II) along with xylan/lignin removal and (ii) properties of ILs; wherein, K-T parameters, viscosity and surface tension had a direct influence on pretreatment. A systematic investigation of these parameters and their impact on enzymatic digestibility is drawn. [C2mim][OAc] with ß-value 1.32 resulted 97.7% of glucose yield using 10 FPU/g of biomass. A closer insight into the cellulose structural transformation has prompted a plausible mechanism explaining the better digestibility. The impact of these parameters on the digestibility can pave the way to customize the process to make biomass vulnerable to enzymatic attack.

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In this study, potato starch was esterified with oleic acid, using 1-butyl-3-methylimidazolium chloride as a reaction medium and an immobilised lipase from Thermomyces lanuginosus as a catalyst. The degree of substitution (DS) of the products was determined by the volumetric method; and the best esterified product (with the highest DS) was determined by an elemental analysis. The effect of the reaction parameters on the DS, such as the time and the temperature, were also studied. The product with the highest DS (0.22) was found in the reaction carried out at 60 °C for 4h. Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) analyses confirmed the esterification of the potato starch. Furthermore, the results of X-ray diffraction (XRD) and a scanning electron microscopy (SEM) revealed that the crystallinity and the morphology of the native potato starch was slightly changed during its partial gelatinisation in the ionic liquid, and was completely destroyed as a result of the formation of the esters. The thermal stability of the starch oleate decreased, when compared to the unmodified starch, as was indicated by a thermal gravimetric analysis (TGA).

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A novel sulfonated cellulose microsphere adsorbent (CGS) was prepared by pre-irradiation induced emulsion grafting of glycidyl methacrylate (GMA) onto the cellulose microsphere, followed by sulfonation. The resulting CGS exhibited superior adsorption ability toward 1-alkyl-3-methylimidazolium chloride ([CnMIM]Cl) ionic liquids (ILs). The adsorption equilibrium could be attained rapidly within 40 min for representative 1-butyl-3-methylimidazolium chloride ([C4MIM]Cl) using CGS with different amounts of SO3H group. The adsorption behavior of CGS toward [C4MIM]Cl was well described by the pseudo-second-order model and the Langmuir model. The maximum adsorption capacity toward [C4MIM]Cl was 1.08 mmol/g in the wide range of pH (4.8-10.1). In addition, the adsorption capacity of CGS toward [CnMIM]Cl increased with the alkyl length of cations of [CnMIM]Cl due to the hydrophobic interaction and cation exchange adsorption. Spent CGS could be easily regenerated by 0.1 mol/L HCl or NaCl. The results indicated that this new adsorbent is useful in removing ILs from wastewater.

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Abundant lignocellulosic biomass could become a source of sugars and lignin, potential feedstocks for the now emergent bio-renewable economy. The production and conversion of sugars from biomass have been well-studied, but far less is known about the production of lignin that is amenable to valorization. Here we report the isolation of lignin generated from the hydrolysis of biomass dissolved in the ionic liquid 1-butyl-3-methylimidazolium chloride. We show that lignin can be isolated from the hydrolysate slurry by simple filtration or centrifugation, and that the ionic liquid can be recovered quantitatively by a straightforward wash with water. The isolated lignin is not only free from ionic liquid, but also lacks cellulosic residues and is substantially depolymerized, making it a promising feedstock for valorization by conversion into fuels and chemicals.

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In this study, a pretreatment by combining acidified aqueous ionic liquid 1-butyl-3-methylimidazolium chloride (IL [Bmim]Cl) solution with dilute NaOH extraction was employed to pretreat high crystallinity index (CrI) of corn stover before its enzymatic saccharification. After NaOH extraction, [Bmim]Cl-HCl-water (78.8:1.2:20, w/w/w) media was used for further pretreatment at 130 °C for 30 min. After being enzymatically hydrolyzed for 48 h, corn stover pretreated could be biotransformed into reducing sugars in the yield of 95.1%. Furthermore, SEM, XRD and FTIR analyses of untreated and pretreated corn stovers were examined. It was found that the intact structure was disrupted by combination pretreatment and resulted in a porous and amorphous regenerated cellulosic material that greatly improved enzymatic hydrolysis. Finally, the recovered hydrolyzates obtained from the enzymatic hydrolysis of pretreated corn stovers could be fermented into ethanol efficiently. In conclusion, the combination pretreatment shows high potential application in future.

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The utilization of ultrasonics to rapidly dissolve switchgrass in ionic liquid, 1-butyl-3-methylimidazolium chloride ([Bmim][Cl]) was evaluated in this work. The objective of the study focused on determining the effects of various ultrasonic conditions on the recovery of carbohydrate from biomass, lignin removal, and enzymatic hydrolysis. Dried ground switchgrass was added to ionic liquid, then sonicated at a frequency of 20kHz. The experiments were conducted using a catenoidal horn at varying amplitudes of 96µm, 128µm, and 160µm and sonication times of 2, 3, and 4min. Similarly, ground switchgrass was dissolved in ionic liquid assisted by conventional heat treatment at 130°C for 12 and 24h. The results showed good delignification results of 53% for the 24h heat pretreated samples and of 50.8% for ultrasonic assisted samples at 160µm amplitude and 4min. Even in the presence of lignin in the recovered biopolymer, both of heat treated and ultrasonicated samples obtained 100% glucan digestibility after only 3h of enzymatic hydrolysis. Heat pretreated samples exhibited 44-59% lower xylan digestibility compared to ultrasonic pretreated samples (160µm amplitude and 4min sonication time). Scanning electron microscope images displayed significant changes in biomass structure from intact and crystalline of the untreated biomass to disintegrated and amorphous of the treated biomass (heat treated and ultrasonicated). With increasing ultrasonic amplitude the carbohydrate recovery decreased. Also, more than 50% of the hemicellulose fraction was lost during biomass recovery. Overall, it was concluded that ultrasonication was a promising technology to enhance dissolution of lignocellulose in ionic liquid.

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Nanocelluloses were prepared from sugarcane bagasse celluloses by dynamic high pressure microfluidization (DHPM), aiming at achieving a homogeneous isolation through the controlling of shearing force and pressure within a microenvironment. In the DHPM process, the homogeneous cellulose solution passed through chambers at a higher pressure in fewer cycles, compared with the high pressure homogenization (HPH) process. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) demonstrated that entangled network structures of celluloses were well dispersed in the microenvironment, which provided proper shearing forces and pressure to fracture the hydrogen bonds. Gel permeation chromatography (GPC), CP/MAS (13)C NMR and Fourier transform infrared spectroscopy (FT-IR) measurements suggested that intra-molecular hydrogen bonds were maintained. These nanocelluloses of smaller particle size, good dispersion and lower thermal stability will have great potential to be applied in electronics devices, electrochemistry, medicine, and package and printing industry.

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We report a novel approach to concurrently improve the tolerance to ionic liquids (ILs) as well as reduce lignin inhibition of Trichoderma reesei cellulase via engineering enzyme charge. Succinylation of the cellulase enzymes led to a nearly twofold enhancement in cellulose conversion in 15% (v/v) 1-butyl-3-methylimidazolium chloride ([BMIM][Cl]). The improvement in activity upon succinylation correlated with the apparent preferential exclusion of the [Cl] anion in fluorescence quenching assays. Additionally, modeling analysis of progress curves of Avicel hydrolysis in buffer indicated that succinylation had a negligible impact on the apparent KM of cellulase. As evidence of reducing lignin inhibition of T. reesei cellulase, succinylation resulted in a greater than twofold increase in Avicel conversion after 170 h in buffer with 1 wt% lignin. The impact of succinylation on lignin inhibition of cellulase further led to the reduction in apparent KM of the enzyme cocktail for Avicel by 2.7-fold. These results provide evidence that naturally evolved cellulases with highly negative surface charge densities may similarly repel lignin, resulting in improved cellulase activity. Ultimately, these results underscore the potential of rational charge engineering as a means of enhancing cellulase function and thus conversion of whole biomass in ILs.

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We report a novel chitosan derivative, chitosan-ionic liquid (CS-IL) conjugation for anion adsorption. Specifically, CS-IL conjugation was synthesized through the reaction of amino groups of chitosan with carboxylic groups of 1-carboxybutyl-3-methylimidazolium chloride. Due to the amphiphilic structure, CS-IL conjugation could self-assemble into nanoparticles in distilled water. This novel chitosan derivative revealed good anion adsorption performance, and the adsorption capacity of Cr2O7(2-) and PF6(-) was 0.422 mmol/g and 0.840 mmol/g, respectively. The adsorption of Cr2O7(2-) and PF6(-) could be improved at low pH, which was ascribed to the adsorption of protonated NH2 on chitosan. Importantly, the chitosan derivative would aggregate in the water after the adsorption and could be easily separated. The properties enable CS-IL conjugation to be used as a novel anion adsorbent for wastewater treatment.

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