Enhanced deconstruction and dissolution of lignocellulosic biomass in ionic liquid at high water content by lithium chloride

Fabricating an aqueous ionic liquid (IL) for deconstruction and dissolution of lignocellulose is attractive because addition of water could reduce the cost and viscosity of the solvent and improve the biomass processing, but the solvating power of the IL is usually depressed in the presence of water. In the present study, an aqueous IL consisting of 1-butyl-3-methylimidazolium chloride (BmimCl), water, and lithium chloride was fabricated for efficient deconstruction and dissolution of lignocellulose (bamboo). The dissolution of cell wall components (cellulose, lignin, and hemicelluloses) in the aqueous IL was investigated. The results indicated that the presence of water significantly reduced the solvating power of BmimCl; For example, 11.5 % water decreased the dissolution of bamboo in BmimCl from ~97 to ~53 %. Dissolution of cellulose and lignin was specifically depressed. However, addition of lithium chloride was able to improve the tolerance of BmimCl to water and enhance the deconstruction and dissolution of biomass in BmimCl with high water content. It was found that approximately 80 % bamboo could be dissolved in solvent consisting of 45 wt% BmimCl and 55 wt% LiCl·2H₂O (25 wt% overall water content in the solvent). In particular, lignin and hemicelluloses were selectively dissolved by 96 and 92 %, respectively. The undissolved residue was predominantly composed of cellulose (~86 %) with a small amount of lignin (<5 %). BmimCl-LiCl-H₂O is a promising and effective solvent system with low cost and viscosity for biomass processing.     

PVP-LiCl-DMF溶液体系的流变学特性及相互作用

利用流变学方法, 采用核磁共振和红外光谱技术开展了聚乙烯吡咯烷酮(PVP)和LiCl相互作用研究, PVP/LiCl/DMF浓溶液的表观粘度随着LiCl含量的增加而提高, 溶液的粘流活化能也相应增加. 13C NMR结果表明, 溶液中Li+与PVP的羰基之间存在相互作用, 这种相互作用改变了PVP分子的聚集状态. 红外光谱结果证实了PVP/LiCl复合物中Li+与PVP的羰基存在相互作用.     

Solution properties of poly(amic acid)–NMP containing LiCl and their effects on membrane morphologies

Physical properties of poly(amic acid) (PAA) casting solutions in N-methyl-2-pyrrolidone (NMP) containing lithium chloride (LiCl) were characterized by viscometry and dynamic light scattering (DLS) and were related to the morphological properties of asymmetric membranes prepared from these solutions. At a fixed polymer concentration, the increase in viscosity of the PAA solutions with increasing LiCl content is mainly determined by the viscosity of the salt–solvent medium, implying that the LiCl–NMP interactions are stronger than those between LiCl and PAA. Because of the strong salt–solvent interactions, complexes between LiCl and NMP are formed. The complexes reduce the solvent power of NMP for PAA inducing polymer aggregation (clustering) and/or transient cross-links in the solutions. Dynamic light scattering results for salt-containing solutions at low PAA concentrations support the existence of these aggregations. Solutions without salt showed a single relaxation, but solutions with LiCl exhibit multiple relaxation modes; two diffusional modes of cooperative and aggregates, and one angle independent transient network mode. The polymer aggregates and transient cross-links form a gel-like structure in the casting solution film and hinder macrovoid formation during phase inversion, resulting in asymmetric membranes with a primarily sponge-like structure.     

Characterization,solution properties,and morphologies of a hydrophobically associating cationic terpolymer

The acrylamide‐based terpolymers (PADB) with 4‐butylstyrene (BST) as the hydrophobic monomer and dimethyldiallyammonium chloride (DMDAAC) were synthesized by the micellar free radical technique. The polymer was determined by UV, FT‐IR and ¹HNMR, and the hydrophobic microblock structure of PADB was characterized successfully by the conventional DSC measurement. The use of DMDAAC improves the water solubility and intermolecular association of terpolymers. The feed amount of BST affects greatly the apparent viscosity of PADB solution. The polymer exhibits good viscosification property, salt resistance, temperature‐thickening, thixotropy, pseudoplastic behavior and shear‐thickening at low shear rate. The apparent viscosities of PADB solution remarkably increase by the addition of a small amount of surfactant. AFM measurements show that hydrophobic aggregates have been formed in 0.1 g dL^?1 PADB aqueous solution, indicative of strong associations of hydrophobic groups, which are reinforced with increasing PADB concentration. The microstructures of PADB are disrupted by the addition of small amounts of salt, resulting in the decrease in solution viscosity. However, with increasing NaCl concentration, the tree‐like associating structures are formed, leading to the increase in the solution viscosity of PADB. The AFM results reveal that the solution properties of PADB are due to the associating structures in the aqueous solution and brine solution. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 826–839, 2007     

Kinetics and equilibria associated with the absorption and desorption of water and lithium chloride in an ethylene—vinyl alcohol copolymer

Sorption and desorption equilibria and kinetics for LiCl and H₂O in an ethylene—vinyl alcohol copolymer film containing 70 mole percent vinyl alcohol were investigated at 25°C. The swelling behavior of water in the polymer was characterized by vapor and liquid sorption experiments over a range of water activities. p]The effects of LiCl content on the water sorption kinetics and equilibria in the films are presented and discussed. The kinetics and mechanism of LiCl sorption have also been studied. The amount of salt sorbed into the polymeric films increases linearly with the salt concentration in the external aqueous solutions. Both the rate and the amount of sorbed water increase significantly as the LiCl content increases. p]The desorption of LiCl, previously sorbed into the polymer, was characterized for different salt loadings. The rate of fractional salt release is independent of LiCl concentration in the film. Initially, the salt release is controlled by the nearly constant-rate absorption of water. The salt release, at long times, lags behind the swelling-controlled water uptake, indicating that the salt release is not completely controlled by the water sorption and that diffusion in the swollen polymer matrix contributes significantly to the long term elution of LiCl. Independent thermal analysis experiments suggest the formation of a metal salt—poly(ethylene—vinyl alcohol) complex.     

The solid–liquid separation characteristics of pure LiCl–KCl eutectic salt using different types of crucibles

Uranium deposits were recovered at the solid cathode of an electrorefining system, and deposited uranium dendrite normally contains about 30–40 wt% LiCl–KCl eutectic salts. Therefore, a separation of the eutectic salts from deposited uranium is essential for reusing these salts and uranium. A process such as distillation was employed for cathode processing due to the advantages of a minimal generation of secondary waste, a compact unit process, and simple and low-cost equipment. However, the realization of a wide evaporation area or high distillation temperature is limited by various factors such as the material or structure of a distiller. Also, the electrical energy flow from outside has a lot of consumption to maintain the high temperature. Hence, in this study, solid–liquid separation experiments are proposed to increase the throughput of the salt removal process by the separation of the liquid salt prior to the distillation of the LiCl–KCl eutectic salt. The solid–liquid separation of salt was carried out in a vertical type distiller. The behavior of the solid–liquid separation of pure eutectic salt was investigated as a function of temperature, pressure, sieve size, and crucible shape. From the experimental results using pure eutectic salts, the amount of salt separation was achieved at more than 94 wt%. The rate of solid–liquid separation of salt using 600 °C is higher than that of 500 °C under the same condition. The influence of a vacuum for solid–liquid separation can be disregarded, and the separation rate of a 100 mesh was higher than that of a 150 mesh. In addition, the rate of separation for salts using a porous crucible is higher than that in a non-porous crucible.     

Cellulose-based fibers from liquid crystalline solutions. IV. Effects of lithium chloride on acetate/butyrate esters

Cellulose acetate butyrate (CAB) fibers were prepared by spinning from liquid crystalline (LC) solutions containing lithium chloride (LiCl). Ionic interactions were observed between carbonyl oxygen and lithium cation by ¹³C nuclear magnetic resonance (NMR) spectroscopy. Isotropization of the anisotropic phase by LiCl was found to cause a dramatic rise in the viscosity of LC solutions. The mechanosorptive creep behavior described earlier decreased in the presence of residual LiCl salt, possibly due to the formation of electrostatic interactions between Li⁺ and CAB backbone. © 1994 John Wiley & Sons, Inc.     

LiCl熔盐急冷形成非晶固体的分子动力学计算机模拟研究

卤化物玻璃目前已成为引人注目的光纤新材料,用分子动力学方法研究液态急冷形成非晶态的过程,对于卤化物玻璃的形成过程研究也应是有用的。鉴于碱金属卤化物是最简单的熔盐,其动态结构亦很清楚。用分子动力学方法研究其急冷以形成玻     

PS-b-PAA两亲性嵌段聚电解质在水溶液中的聚集行为及其流变特性

以两嵌段共聚物聚苯乙烯-b-聚丙烯酸(PS-b-PAA)为研究对象,采用动态光散射(DLS)及透射电镜(TEM)表征了胶束及聚集体的结构,采用应力控制型旋转流变仪AR-G2研究了体系的流变特性.着重考察了聚电解质浓度、pH值以及外加盐(KBr)浓度对其在水中聚集行为的影响及对体系流变特性的影响.发现随着外加盐和聚电解质浓度的增高,体系中的胶束发生聚集,形成更大的聚集体.而pH值对胶束的聚集形态无明显的影响.胶束乳液均呈现明显的剪切变稀特征.然而,随着聚电解质浓度增加,低剪切速率下体系的表观粘度增高;高剪切速率时体系粘度趋于同一值(0.01Pa·s).与纯胶束乳液相比,外加盐的存在导致体系粘度增加;当外加盐浓度增加至4.31g/L,在低剪切速率下,体系出现牛顿平台区.溶液pH值对体系粘度无显著影响.     

聚二烯丙基甲基苄基氯化铵的合成及粘度行为

以甲胺、烯丙基氯、NaOH、氯化苄和偶氮二异丙基咪唑啉盐酸盐为原料,合成了聚二烯丙基甲基苄基氯化铵(PDAMABC),采用FT IR、1H NMR和元素分析对其结构进行表征,并考察了其在氯化钠、氯化钾、溴化钾、氯化钙、氯化镁、硫酸镁和硫酸钠溶液中的粘度行为。 将所得水相和低沸点馏分回用,二烯丙基甲基胺的收率从72.79%提高至83.41%;以水与乙醇为混合溶剂（V（H2O）∶V（C2H5OH）为1∶3~2∶3）,合成的二烯丙基甲基苄基氯化铵收率较高且水溶性好。 PDAMABC的比浓粘度随外加盐浓度增加而降低。 在0.1 mol/L NaCl溶液中,当其质量浓度低于0.031 25 g/L时,表现为聚电解质行为;质量浓度大于0.125 g/L时,表现为中性聚合物的粘度行为。 外加盐对比浓粘度的影响顺序为：Na2SO4＜NaCl＜KCl＜MgSO4＜MgCl2＜CaCl2＜KBr。 阴离子的屏蔽作用是导致比浓粘度降低的主要原因。     

Effect of borax additives on the rheological properties of sodium hyaluronate aqueous solutions

The rheological properties of sodium hyaluronate aqueous solutions are studied, and the effect of borax additives on them is investigated. It is shown that, at low concentrations, sodium hyaluronate behaves as a typical linear polyelectrolyte in the limit of a high concentration of the salt in both a 0.1 M NaCl aqueous solution and a salt-free solvent. The addition of 1 mole of borax per base-mole of the polymer to the solution of sodium hyaluronate significantly decreases the specific viscosity of the solution if no salt is added and has practically no effect on the viscosity of the solution in 0.1 M NaCl. The viscosity of a semidilute solution of sodium hyaluronate without the added salt decreases as the shear rate is increased in the range 1.5–656 s^?1. With an increase in temperature, viscosity decreases and its dependence on shear rate becomes less pronounced. The same effect is exerted by small amounts of borax. The properties of salt-free solutions are explained by the presence of admixtures of low-molecular-mass ions in them that screen the Coulomb repulsion of charges linked to sodium hyaluronate chains, and the effect of borax may be rationalized by the screening effect of ions resulting from the hydrolysis of borax.     

Experimental investigation toward obtaining a new correlation for viscosity of WO3 and Al2O3 nanoparticles-loaded nanofluid within aqueous and non-aqueous basefluids

In this study, the effect of temperature and mass fraction of Al₂O₃ and WO₃ nanoparticles dispersed in deionized water and liquid paraffin was investigated on dynamic viscosity of nanofluid. The results of the TEM tests showed that the size of Al₂O₃ and WO₃ nanoparticles was ranged from 10 to 60 nm, and the results showed that nanoparticles were semi-spherical. Also the results of DLS and zeta potential tests, respectively, exhibited the uniform size and high stability of the nanoparticles in the basefluid environment. The findings showed that adding a certain amount of nanoparticles to water and liquid paraffin increases dynamic viscosity, and in the case of various shear rates, the viscosity is constant for the water-based nanofluids, which indicates the Newtonian behavior of the nanofluid. In addition, for those prepared by liquid paraffin as a basefluid, the viscosity does not remain constant at different shear rates and at low amount of shear rate the viscosity achieves higher value, indicating non-Newtonian behavior of liquid paraffin-based nanofluids. The results showed that by increasing the temperature in liquid paraffin-based nanofluid the uniformity and linearity of the viscosity curve at various shear rates could be observed, which represents an approach for Newtonian behavior of nanofluid at higher temperatures. These results also showed that with increasing the mass fraction of nanoparticles in water and liquid paraffin, the viscosity increases at different shear rates. Finally, the correlation presented in this study shows that for nanofluid viscosity as a function of nanoparticles load and temperature, the deviation of correlated data from experimental values is less than 10%.

     

Unusual S-shaped binodal curves of the systems water+lithium chloride+1-butanol or 2-butanol or 2-methyl-1-propanol

Solid–liquid–liquid equilibrium data of the ternary systems water+LiCl+2-butanol, water+LiCl+2-methyl-1-propanol (i-butanol) and water+LiCl+1-butanol have been experimentally determined at 25°C. The equilibrium diagrams determined show differences between the systems. In the system with 1-butanol, the solid phase of the liquid–liquid–solid region is monohydrated salt. However, in the systems with 2-butanol and 2-methyl-1-propanol it is anhydrous salt. With respect to the liquid+liquid zone, the three diagrams are very similar with an unusual S-shaped solubility curve in the organic branch that can be explained depending on whether the organic solvent takes part in the solvation of ions. The more salt, the more numbers of ions solvated by water and organic solvent and the solubility of water and salt in the organic phase increase notably producing the unusual S-shaped solubility curve.     

Distillation of LiCl from the LiCl–Li2O molten salt of the electrolytic reduction process

Electrolytic reduction of the uranium oxide in LiCl–Li₂O molten salt for the treatment of spent nuclear fuel requires the separation of the residual salt from the reduced metal product, which contains about 20 wt% salt. In order to separate the residual salt and reuse it in the electrolytic reduction, a vacuum distillation process was developed. Lab-scale distillation equipment was designed and installed in an argon atmosphere glove box. The equipment consisted of an evaporator in which the reduced metal product was contained and exposed to a high temperature and reduced pressure; a receiver; and a vertically oriented condenser that operated at a temperature below the melting point of lithium chloride. We performed experiments with LiCl–Li₂O salt to evaluate the evaporation rate of LiCl salt and varied the operating temperature to discern its effect on the behavior of salt evaporation. Complete removal of the LiCl salt from the evaporator was accomplished by reducing the internal pressure to <100 mTorr and heating to 900 °C. We achieved evaporation efficiency as high as 100 %.     

Entropy of cellulose dissolution in water and in the ionic liquid 1-butyl-3-methylimidazolim chloride

The entropic driving forces of cellulose dissolution in water and in the ionic liquid 1-butyl-3-methylimidazolium chloride (BmimCl) are investigated via molecular dynamics simulations and the two-phase thermodynamic model. An atomistic model of cellulose was simulated at a dissociated state and a microfibril state to represent dissolution. The calculated values of entropy and internal energy changes between the two states inform the interplay of energetic and entropic driving forces in cellulose dissolution. In both water and BmimCl, we found that the entropy associated with the solvent degrees of freedom (DOF) decreases upon cellulose dissolution. However, solvent entropy reduction in BmimCl is much smaller than that in water and counteracts the entropy gain from the solute DOF to a much lesser extent. Solvent entropy reduction in water also plays a major role in making the free energy change of cellulose dissolution unfavorable at room temperature. In BmimCl, the interaction energies between solvent molecules and glucan chains and the total entropy change both contribute favorably to the dissolution free energy of cellulose. Calculations at different temperatures in the two solvents indicate that changes in total internal energy are a good indicator of the sign of the free energy change of cellulose dissolution.     

Rheological properties of poly(ethylene glycol) solutions and gels

By the interaction of a water–glycol solution of poly(ethylene glycol) (PEG) with calcium chloride dihydrate, a gel was produced. It was determined that, below a certain shear rate, this gel is a Newtonian fluid; however, above a certain shear rate, which depends on the gel viscosity, the properties of this gel are anomalous: the gel flow instantaneously completely stops. The viscosity of the gels was found to exponentially increase with increasing concentration of the cross-linking metal at constant PEG concentration. The density of the gels linearly increases with increasing concentration of the cross-linking metal at constant PEG concentration.     

Interactions between metal chlorides and poly(vinyl pyrrolidone) in concentrated solutionsand solid‐state films

The rheological behavior of poly(vinyl pyrrolidone) (PVP)/N,N‐dimethylformamide (DMF) solutions containing metal chlorides (LiCl, CaCl₂, and CoCl₂) were investigated, and the results showed that the nature of the metal ions and their concentration had an obvious effect on the steady‐state rheological behavior of PVP–DMF solutions with different molecular weights. The apparent viscosity of the PVP–DMF solutions increased with an increasing metal‐ion concentration, and the viscosity increment was dependent on the metal‐ion variety_. For a CaCl₂‐containing PVP–DMF solution, for example, the critical shear rate at the onset of shear thinning became smaller with increasing CaCl₂ concentration. It was believed that multiple interactions among metal ions, carbonyl groups of PVP, and amide groups in DMF determined the solution properties of these complex fluids; therefore, ¹³C NMR spectroscopy was used to detect the interactions in systems of PVP–CaCl₂–DMF and PVP–LiCl–DMF solutions. NMR data showed that there were obvious interactions between the metal ions and the carbonyl groups of the PVP segments in the DMF solutions. Furthermore, IR spectra of the PVP/metal chloride composites demonstrated that the interaction between the metal ions and carbonyl groups in the PVP unit occurred and that the PVP chain underwent conformational variations with the metal‐ion concentration. DSC results indicated that the glass transition temperatures of the PVP/metal chloride composites increased with the addition of metal ions. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1589–1598, 2007     

Differential scanning calorimetry and large deformation behaviour of kappa-carrageenan gels containing alkali metal ions

Differential scanning calorimetry and extension tests were carried out on kappa-carrageenan gels in the presence of the alkali metal salts LiCl, NaCl, KCl and CsCl. The endothermic peak accompanying the melting of gels shifted to higher temperatures with increasing concentrations of alkali metal salt. The breaking force of gels increased with increasing concentrations of added KCl and CsCl, and decreased with increasing concentrations of added NaCl. The breaking force of the gel containing LiCl decreased with the first level of addition, then increased slightly with two further additions and finally decreased again at the highest level of addition.     

Salt addition effect on partition coefficient of some phenolic compounds constituents of olive mill wastewater in 1-octanol-water system at 298.15 K

The 1-octanol-water partition coefficient is an important property to measure the hydrophobicity of organic compounds, which has been demonstrated to be a parameter in studying the conformation of biomolecules in aqueous solutions. For biological systems, electrolytes play an important role in thermodynamic properties. The salt addition effect on the distribution of phenolic compounds between water and 1-octanol at 298.15 K has been studied. The phenolic compounds used were vanillic acid, protocatechuic acid, vanillin, tyrosol, cathecol, caffeic acid and syringic acid, and the considered salts were potassium chloride, sodium chloride and lithium chloride. The influence of both the concentration and size of the added salt on the partition coefficient (K _ow) have been considered. This study shows a salting in with the following decreasing order: LiCl > NaCl > KCl. The Gibbs energies of transfer of phenolic compounds (168–1) form chloride solutions to organic phase have been calculated using experimental 1-octanol-water partition coefficients.     

The effect of octyl glucoside on rheological behavior of diluted and concentrated lamellar phases

We have investigated the rheological properties of lamellar liquid crystal formed by nonionic surfactants at low and high surfactant concentrations with a small amount of octyl glucoside and their relationship with the topology of the bilayer. Rheology is a specific signature of each bilayer topology. The decrease in viscosity by increasing the shear rate according to a power law with exponent close to -0.8 was found for the concentrated system of LSB/1-butanol/water and 1% in weight of OG. On the contrary, the decrease in the viscosity by increasing the shear rate for the diluted system is less pronounced with lower exponent values. The rheological data agrees with the presence of vesicles. A special case is the system with benzyl alcohol. The apparent viscosity does not follow the same power law than for alkanols.