离子液体对溶菌酶晶体形态和活性的影响

以鸡蛋清溶菌酶为模型蛋白,采用冷却结晶法结晶以及浊度法测定酶活性,研究了分别添加4种亲水性离子液体(1-丁基-3-甲基咪唑四氟硼酸盐([C₄mim]BF₄)、1-丁基-3-甲基咪唑氯盐([C₄mim]Cl)、1-丁基-3-甲基咪唑溴盐([C₄mim]Br)和1,3-二甲基咪唑碘化物([dmim]I))条件下溶菌酶晶体形态和晶体活性的变化。利用光学显微镜对溶菌酶结晶过程的晶体形态进行分析,结果表明添加离子液体会影响溶菌酶的晶体形态和尺寸。离子液体[C₄mim]BF₄介导的溶菌酶形成棒状晶体。与未添加离子液体相比,[C₄mim]Cl和[C₄mim]Br均未改变溶菌酶晶体形态,均呈块状晶体,但[C₄mim]Cl和[C₄mim]Br促进溶菌酶晶体生长,晶体尺度均增加。而添加[dmim]I,溶菌酶呈现针状晶体。采用浊度法测定溶菌酶晶体活性,结果表明不同的离子液体对溶菌酶晶体的活性...     

离子液体体系用于盐湖卤水提取锂

3种咪唑类离子液体:1-丁基-3-甲基咪唑六氟磷酸盐([C₄mim][PF₆])、1-己基-3-甲基咪唑六氟磷酸盐([C₆mim][PF₆])、1-辛基-3-甲基咪唑六氟磷酸盐([C₈mim][PF₆])被作为绿色溶剂用于盐湖卤水分离镁锂, 建立了以离子液体(ILs)、磷酸三丁酯(TBP)分别为萃取介质和萃取剂的盐湖卤水锂萃取体系, 并与使用传统有机溶剂磺化煤油和氯仿的萃取效果进行了对比。研究发现, 该离子液体体系较使用传统挥发性有机溶剂的萃取体系有更高的萃取率。锂的萃取率随离子液体中烷基碳原子数的减小而增加。详细考察了溶液pH、离子液体浓度、相比对萃取效率的影响, 获得了离子液体体系萃取的最优条件。在最佳萃取条件下, 3种离子液体体系对锂的单级萃取效率均高于80%, 分离系数最高达到100以上。机理研究表明:离子液体体系是以阳离子交换实现对锂的萃取, Li⁺与TBP形成[Li·2TBP]⁺络合物进入有机相。     

木瓜蛋白酶在[Cnmim]BF4-NaH2PO4双水相体系中的分配行为

为了研究木瓜蛋白酶在[C_nmim]BF₄-NaH₂PO₄双水相体系中的分配行为, 在298.15 K条件下利用浊点法测定了[C_nmim]BF₄-NaH₂PO₄双水相体系的双节线和液液相平衡数据, 建立了木瓜蛋白酶在该体系中的三维分配模型。利用Merchuk方程、Othmer-Tobias方程和Bancroft方程分别关联了双节线数据、液液相平衡数据, 拟合度分别在0.975、0.994以上, 结果满意。木瓜蛋白酶分配系数的对数与该体系上相的离子液体浓度和下相的盐浓度相关度都较高, 故通过Matlab建立了三者之间的分配模型, 实验值和预测值之间的相对偏差均在5%以内, 表明该模型能有效地预测木瓜蛋白酶在[C_nmim]BF₄-NaH₂PO₄双水相体系中的分配行为。     

咪唑类离子液体对木质纤维预水解液的脱毒

针对燃料乙醇生物炼制过程中抑制物对酵母乙醇发酵的抑制作用,以水洗稀酸蒸汽爆破预处理玉米秸秆得到的预水解液为研究对象,采用新型绿色脱毒技术--离子液体进行萃取脱毒,研究比较了两种咪唑类离子液体[烷基咪唑六氟磷酸盐离子液体[C_nmim][PF₆](n 4,6,8)和烷基咪唑四氟硼酸盐离子液体[C_nmim][BF₄](n 6,8)]对预水解液的萃取性能。结果表明,随着咪唑类离子液体阳离子烷基链长度的增加,离子液体对抑制物的萃取性能下降,具有更强电负性的阴离子为BF₄^-的离子液体比阴离子为PF₆^-的离子液体萃取效率更高。通过比较糖与抑制物的萃取率,最终选择[C₈mim][BF₄]作为预水解液的萃取剂,结果显示其对主要抑制物甲酸、乙酸、5-羟甲基糠醛的萃取率分别为53.22%、47.53%和85.13%,总酚的萃取率为65.05%,而糖的损失率在6%以内。     

[Cnmim]Br/FeCl3型离子液体萃取脱除二苯并噻吩

合成了6种咪唑型离子液体[C_3-8mim]Br/FeCl₃,采用红外光谱和拉曼光谱对其进行表征,并考察了离子液体对二苯并噻吩的萃取脱除效果。结果发现,[C₃mim]Br/FeCl₃的萃取脱硫效果最佳,升高温度和增大剂油比均有利于脱硫率的提高,剂油比1:1(体积比)时,萃取时间达到12 min就可使脱硫率高达92%。且萃取反应完成后,离子液体不做处理继续重复使用,重复使用5次,脱硫率可以达到60%。     

2,6-二甲氧基苯酚在1-丁基-3-甲基咪唑四氟硼酸盐水溶液中溶解行为的红外光谱分析

利用衰减全反射红外光谱(ATR-IR)和二维相关红外技术研究2, 6-二甲氧基苯酚(2, 6-DMP)在1-丁基-3-甲基咪唑四氟硼酸盐([C₄mim]BF₄)水溶液(离子液体摩尔分数x_IL=1.0～0.02)中的溶解行为。随着水量增大, 2, 6-DMP溶解度先增大而后急剧减小, 对应的x_IL阈值为0.1。2, 6-DMP与[C₄mim]BF₄之间存在强相互作用, 2, 6-DMP上的甲氧基是重要作用位点之一;当少量的水加入[C₄mim]BF₄(x_IL=0.1～1.0), 致密的离子簇结构被解离, 2, 6-DMP容易与[C₄mim]BF₄作用, 溶解度增大;随着大量水加入(0.02IL<0.1), 离子簇完全解离为大分子水簇包围的离子对, 憎水的2, 6-DMP与[C₄mim]BF₄作用困难, 溶解度减小。这种由于水量改变引起的[C₄mim]BF₄水溶液微观结构变化影响2, 6-DMP溶解行为。     

Electrical conductivities for four ternary electrolyte aqueous solutions with one or two ionic liquid components at ambient temperatures and pressure

Thiswork provides amethod to explore the transport property of the electrolyte aqueous solutionswith one or two ionic liquids, especially focus on their electrical conductivity. The conductivities were measured for the ternary systems NaCl–[C₆mim][Cl] (1-hexyl-3-methylimidazolium chloride)–H₂O, [C₆mim][BF₄]–[C₆mim][Cl]–H₂O, NaNO₃–[C₆mim][BF₄](1-hexyl-3-methylimidazolium tetrafluoroborate)–H₂O, and [C₄mim][BF₄] (1-butyl-3- methylimidazolium tetrafluoroborate)–[C₆mim][BF₄]–H₂O, and their binary subsystems NaNO₃–H₂O, NaCl–H₂O, [C₆mim][BF₄]–H₂O, [C₆mim][Cl]–H₂O, and [C₄mim][BF₄]–H₂O, respectively. The conductivities of the ternary systems were also determined using generalized Young's rule and semi-ideal solution theory in terms of the data of their binary solutions. The comparison showed that the two simple equations provide good predictions for conductivity of mixed electrolyte solutions and the mixed ionic liquid solutions based on the conductivity of their binary subsystems.     

离子液体用于燃油萃取脱硫的选择与过程优化

针对基于COSMO-SAC模型分子设计方法的准确性问题,采用离子液体脱硫机理分析和实验的方法对其进行了验证,即对[HMIM] [BF₄]、[HMIM] [PF₆]、[BMIM] [BF₄]、[BMIM] [PF₆]、[EMIM] [BF₄]、[EMIM] [PF₆] 6种离子液体作萃取剂时的脱硫效果进行了脱硫机理的分析和实验的验证,得到的脱硫性能排序与离子液体分子设计结果基本一致,且均认为[HMIM] [PF₆]脱硫率较高。以[HMIM] [PF₆]为萃取剂,通过液相色谱法测定萃取后的液相组成,考察萃取时间、萃取温度、剂油比3个因素对脱硫率、分配系数和选择性系数的影响。通过正交实验设计确定了萃取时间40 min、萃取温度20℃、剂油比2：1为较优操作条件,单次脱硫率为72.74%,四级萃取可将模型油的含硫量由1200 μg·g^-1降至6.98 μg·g^-1,符合国Ⅴ标准。     

吡啶类离子液体体系对模拟盐湖老卤中锂的萃取研究

采用磷酸三丁酯(TBP)为萃取剂、N-丁基吡啶六氟磷酸盐([BPy][PF₆])为协萃剂、二氯乙烷(C₂H₄Cl₂)为稀释剂，构建了[BPy][PF₆]-TBP-C₂H₄Cl₂萃取体系，并用于盐湖卤水中分离锂离子。通过单因素实验考察了水相酸度、离子液体浓度、TBP浓度等因素对锂萃取率的影响。结果表明该萃取体系的最优条件为：离子液体浓度为0.3 mol/L;TBP的体积分数为60%；相比(有机相与水相的体积比)为2.5/1。在最优条件下得到Li⁺的单级萃取率为91.65%、Mg²⁺的单级萃取率为5.86%，该萃取体系对Li⁺有较好的选择性。热力学研究表明，该离子液体体系对锂离子的萃取反应是自发的放热反应。该研究为离子液体体系提取分离溶液中锂离子提供了一定的基础和参考依据。     

愈创木酚在[C4mim]Cl-H2O中的溶解行为

采用紫外光谱和荧光光谱研究了木质素模型化合物愈创木酚(guaiacol)在[C₄mim]Cl-H₂O体系中的溶解行为。分析了[C₄mim]Cl-H₂O二元体系和[C₄mim]Cl-H₂O-guaiacol三元体系的谱图, 发现在不同[C₄mim]Cl浓度下, 紫外光谱中芳香环的K带与B带的变化不同, 对愈创木酚的溶解影响也不相同;愈创木酚的加入会使[C₄mim]Cl-H₂O出现荧光猝灭现象, 其原因在于愈创木酚与[C₄mim]Cl-H₂O形成氢键, 此弱分子间作用力影响了溶液的光谱行为。     

1-丁基-3-甲基咪唑氯盐离子液体水溶液对纤维素的作用

在温度90℃, 压力1 MPa条件下, 研究[C₄mim]Cl-水溶液对纤维素的溶解和结构变化的影响。在离子液体含量为60%～95%时, 无定形纤维素可以部分溶解, 并且加去离子水后有纤维素再生。经过[C₄mim]Cl-水溶液处理一段时间后, 微晶纤维素的晶型并没有发生改变, 但纤维素的结晶指数和晶粒尺寸的大小都有明显的变化, 纤维素的分子内和分子间氢键相对强度也有明显变化。离子液体含量不同对微晶纤维素的作用程度不同。     

Optimization on the Conversion of Bamboo Shoot Shell to Levulinic Acid with Environmentally Benign Acidic Ionic Liquid and Response Surface Analysis

Levulinic acid (LA) has been identified as a promising green, biomass derived platform chemical. Response surface analysis (RSA) with a four-factor-five-level central composite design (CCD) was applied to optimize the hydrolysis conditions for the conversion of bamboo (Phyllostachys Praecox f. preveynalis) shoot shell (BSS) to LA catalyzed with ionic liquid [C₄mim]HSO₄. The effects of four main reaction parameters including temperature, time,C_[C4mim]HSO4(initial [C₄mim]HSO₄ concentration) and X_BSS (initial BSS intake) on the hydrolysis reaction for yield of LA were analyzed. A quadratic equation model for yield of LA was established and fitted to the data with an R² of 0.9868, and effects of main factors and their corresponding relationships were obtained with RSA. Model validation and results of CCD showed good correspondence between actual and predicted values. The analysis of variance (ANOVA) of the results indicated that the yield of LA in the range studied was significantly (P<0.05) affected by the four factors. The optimized reaction conditions were as follows: temperature of 145 ℃, time of 103.8 min,C_[C4mim]HSO4 of 0.9 mol·L^-1 and X_BSS of 2.04% (by mass), respectively. A high yield [(71±0.41)% (by mol), triplicate experiment] was obtained at the optimum conditions of temperature of 145 ℃, time of 104 min,C_[C4mim]HSO4 of 0.9 mol·L^-1 and X_BSS of 2% (by mass), which obtained from the real experiments, concurred with the model prediction [73.8% (by mol) based on available C₆ sugars in BSS or 17.9% (by mass) based on the mass of BSS], indicating that the model was adequate for the hydrolysis process.     

Vapor pressure measurement and correlation of acetonitrile+1-butyl-3-methylimidazolium chloride,+1-butyl-3-methylimidazolium tetrafluoroborate,and+1-hexyl-3-methylimidazolium chloride

Vapor pressures were measured for acetonitrile+1-butyl-3-methylimidazolium chloride ([C4mim][Cl]),+1-butyl-3-methylimidazolium tetrafluoroborate ([C4mim][BF4]) and+1-hexyl-3-methylimidazolium chloride ...     

Highly selective synthesis for 4,4′-bisphenol F from phenol and formaldehyde catalyzed with [C_4mim][HSO_4] ionic liquid

The effects of N-methylimidazole cation [Cnmim] with different alkyl chain lengths, the types of cations and anions of ionic liquids and the reaction parameters on the catalytic activity and the selectivity for 4,4′-bisphenol F were investigated. The hydrogen bonding between the hydroxyl of phenol and the C2-position hydrogen of imidazole moiety in hydrophilic imidazole-based ionic liquid has important influence on the selectivity for 4,4′-bisphenol F, and under the conditions of the molar ratio of phenol/[C4mim][HSO4] 1:1, reaction temperature65 °C and the theoretical molar ratio of phenol/formaldehyde 2:1, the selectivity for 4,4′-bisphenol F reached69.1%. Compared with the high phenol/formaldehyde ratio reported in literatures, the low molar ratio of phenol/formaldehyde and the low reaction temperature can greatly reduce energy consumption, and has important significance for industrial application.     

Rheological behavior of mixed system of ionic liquid [C8mim]Br and sodium oleate in water

We report on the rheological behavior of wormlike micelles constructed by ionic liquid surfactant [C₈mim]Br (1-octyl-3-methylimidazolium bromide) and anionic surfactant sodium oleate (NaOA) in aqueous solution. The effects of surfactant composition, total surfactant concentration, added salts, and temperature were investigated. The prevailing surfactant effect at lower concentration and the leading cosolvent effect at higher concentration of [C₈mim]Br may be the main reasons for appearance of well-established maximum in key rheological parameters with variation of surfactant composition and total surfactant concentration. The Cole-Cole plots demonstrate that the systems (total surfactant concentration falls within 0.17–0.35 mol·L^-1 and molar ratio 0.33≤R≤0.50) fit the Maxwell’s mechanical model as linear viscoelastic fluid. The addition of NaBr or sodium salicylate decreases significantly the viscosity and the relaxation time of the wormlike micelle solution but cannot change the value of plateau modulus G₀. The present system has low rheological tolerance to temperature. The increase of temperature decreases the average contour length and viscosity of wormlike micelles and thus strengthens the relaxation progress of diffusion and weakens the relaxation progress of reptation. Increasing the temperature also decreases the value of plateau modulus G₀ and shifts the minimum value of the loss modulus G^″_min to higher frequencies.     

溴化1-辛基-3-甲基咪唑聚集状态对蛋白质结晶的影响研究

研究了离子液体溴化1-辛基-3-甲基咪唑（［C₈mim］Br）添加剂的聚集状态对蛋白质结晶过程的影响。实验发现［C₈mim］Br可以改善溶菌酶晶体形貌,影响晶体数量和晶体尺寸。通过测定不同浓度［C₈mim］Br下溶菌酶的溶解度、结晶动力学、聚集状态和ζ-电势,揭示了离子液体［C₈mim］Br对溶菌酶结晶的影响机理。结果表明,［C₈mim］Br与溶菌酶的作用方式随［C₈mim］Br的聚集状态而改变。当［C₈mim］Br浓度较低（<0.1 mol/L）时,［C₈mim］⁺与溶菌酶分子之间存在疏水作用,可以促进蛋白质分子聚集,促进结晶过程。当［C₈mim］Br浓度较高（>0.1 mol/L）时,［C₈mim］⁺自发聚集成胶束,并与蛋白质分子相互作用形成溶菌酶-胶束复合物;动态光散射（DLS）结果显示结晶过程以溶菌酶-胶束复合物为基本单元聚集,因此结晶过程减缓,晶体质量提高。