离子液体中的相互作用对硝基苯扩散系数的影响

应用紫外吸收光谱法和循环伏安法研究了离子液体中的相互作用及对离子液体中硝基苯的扩散系数的影响。结果表明,硝基苯的紫外光谱受离子液体EMimBF₄(1-甲基-3-乙基咪唑四氟硼酸盐)与其相互作用的影响,硝基的吸收峰红移,210 nm以下的末端吸收消失,而苯环的吸收基本不变;离子液体与硝基苯之间的作用主要发生在硝基上。在离子液体中电还原,硝基苯的扩散系数受硝基苯与离子液体、水与离子液体的相互作用的影响。同一离子液体中,随硝基苯浓度增加,扩散系数减小。相同硝基苯浓度时,不同离子液体的咪唑阳离子侧链越长扩散系数越小,但扩散系数减小得越缓慢;同一离子液体中,随着水浓度增加,硝基苯扩散系数增大;不同离子液体中,咪唑侧链越长,随着水的浓度增加,硝基苯扩散系数增加越快。     

离子液体RMimBF4中硝基苯电还原传荷特性

采用循环伏安法研究了离子液体RMimBF₄中硝基苯在微铂电极上电还原动力学特性参数——传递系数α的变化规律。研究结果表明,离子液体中,硝基苯电还原过程的第2个电子转移反应是速度控制步骤。该反应的传递系数α随硝基苯浓度增加而减小;相同浓度时,温度升高,α迅速增大。在离子液体EMimBF₄-水-硝基苯体系中,相同硝基苯浓度下,随水含量增加,α先减小,后增大。不同离子液体中,α的变化规律为：EMimBF₄＞〖JP〗BMimBF₄＞HMimBF₄。     

二元离子液体OMImBF_4/HMImPF_6中硝基苯的电化学还原

将离子液体OMImBF_4与HMImPF_6二元复合,研究了离子液体复合前后电导率、红外谱峰等的变化,在不同体积比的OMImBF_4/HMImPF_6体系中采用循环伏安法(CV)、计时电流法(CA)和电化学原位红外光谱法(In-situ FTIRS)等方法探究了硝基苯在铂电极上的电化学还原行为。研究结果表明,OMImBF_4/HMImPF_6的电导率随HMImPF_6体积比的增大而减小,红外谱峰较单一离子液体变化明显;硝基苯在体积比为3:1的二元离子液体OMImBF_4/HMImPF_6体系中的还原峰电位及还原峰电流均优于单一离子液体,且主要产物偶氮苯的选择性及硝基苯的转化率都要优于单一离子液体。硝基苯在此二元离子液体体系中的还原过程受扩散控制,扩散系数D为2.024×10~(-7) cm~2·s~(-1)。     

二元离子液体OMImBF4/HMImPF6中硝基苯的电化学还原

将离子液体OMImBF₄与HMImPF₆二元复合,研究了离子液体复合前后电导率、红外谱峰等的变化,在不同体积比的OMImBF₄/HMImPF₆体系中采用循环伏安法(CV)、计时电流法(CA)和电化学原位红外光谱法(In-situ FTIRS)等方法探究了硝基苯在铂电极上的电化学还原行为。研究结果表明,OMImBF₄/HMImPF₆的电导率随HMImPF₆体积比的增大而减小,红外谱峰较单一离子液体变化明显;硝基苯在体积比为3:1的二元离子液体OMImBF₄/HMImPF₆体系中的还原峰电位及还原峰电流均优于单一离子液体,且主要产物偶氮苯的选择性及硝基苯的转化率都要优于单一离子液体。硝基苯在此二元离子液体体系中的还原过程受扩散控制,扩散系数D为 2.024×10^-7 cm²·s^-1。     

离子强度和溶质浓度对蛋白质在Q Sepharose FF中吸附动力学的影响

采用孔扩散模型, 模拟不同盐浓度和不同蛋白质初始浓度条件下,吸附牛血清白蛋白(BSA)的动态吸附曲线并获得孔扩散系数;考察了离子强度和溶质浓度对蛋白质在阴离子交换剂Q Sepharose FF中吸附动力学的影响.结果表明,蛋白质的孔扩散系数随初始浓度的增大而下降;在氯化钠浓度小于0.10 mol•L^-1的范围内,蛋白质的孔扩散系数随着盐浓度的增加而增大,但当盐浓度增大到0.15 mol•L^-1时又有所降低,表明存在着一个最佳的离子强度,使蛋白质的孔扩散系数最大.     

己内酰胺-四丁基氟化铵离子液体表面张力研究

离子液体因其溶解能力良好,物理、化学性质稳定,沸点高,难挥发,不会造成二次污染等诸多优点,成为了21世纪最有前景的绿色溶剂之一。将己内酰胺-四丁基氟化铵离子液体配置成不同浓度的水溶液,测定其表面张力。结果表明,该离子液体的表面张力随温度的升高而降低,随离子液体浓度的增加而减小;在一定浓度的时候,离子液体的表面张力小于水的表面张力。     

SO2／离子液体体系热力学性质的分子动力学模拟

为研究SO2对咪唑类普通离子液体输运特性、体积的影响,本文通过分子动力学方法模拟了293．15K时,常压下[bmim][PFs]和[bmim][BF4]与soz的？昆合物。结果表明,咪唑类普通离子液体的扩散系数随气体溶质摩尔分数的增加而增大,粘度则相应减小。吸收SO2对离子液体体积的影响极小。混合物摩尔体积随SO2摩尔分数增加呈直线下降。     

硝基苯在离子液体BPyBF4/H2O中的电化学行为

在离子液体1-丁基吡啶四氟硼酸盐(BPyBF₄)的水溶液中,采用循环伏安法(CV)、计时电流法(CA)、恒电位电解及原位红外光谱法(in-situ FTIRS)等研究了硝基苯在铂电极上的电化学还原行为。研究结果表明:硝基苯在离子液体BPyBF₄/H₂O体系中的还原过程是受扩散控制的,其还原产物主要是偶氮苯,经估算得到硝基苯在该体系中的扩散系数为3.1×10^-7 cm²·s^-1,提高温度和加入一定浓度的水均有利于硝基苯在该体系中的电化学还原。     

烯丙基哌啶类离子液体的合成与物化性能研究

以哌啶、溴代正丁烷和烯丙基溴为原料,采用两步法合成出了烯丙基哌啶类离子液体,并用红外光谱（IR）对产物进行了分析表征。同时考察了其在不同溶剂中的溶解性能及导电性能。结果表明,离子液体在水、乙醇、乙酸、丙酮中可以较好的溶解,而在乙醚、正己烷中基本不溶;离子液体的电导率随浓度的增大和温度的升高而增大。     

室温离子液体1-丁基-3-甲基咪唑磷酸二丁酯的电导率研究

利用磷酸三丁酯与N-甲基咪唑在恒温150℃下一步合成了离子液体1-丁基-3-甲基咪唑磷酸二丁酯,考察了其在丙酮,水,DMF,乙酸溶剂中的电导率及摩尔电导率。实验发现该离子液体在不同溶剂中的电导率(κ)相差很大,其顺序为κa(水)>κb(DMF)>κc(丙酮)>κd(乙酸)。在相同温度下,电导率及摩尔电导率随浓度的增大而增大;在相同浓度下,电导率及摩尔电导率随温度的升高而增大。     

Diffusion in aqueous polymer solutions

The diffusion of Direct Blue 76 dye in aqueous dilute polymer solutions was studied using the capillary method. The polymer systems studied included dilute solution of carboxymethyl cellulose, poly(ethylene oxide), and polyacrylamide. It was found that the diffusion coefficient of Direct Blue 76 in carboxymethyl cellulose is higher than that in pure water, while in polyacrylamide and poly(ethylene oxide) solutions the value is lower than that in pure water. The diffusion coefficient of Direct Blue was found to decrease with increasing polymer concentration in case of poly(ethylene oxide) and polyacrylamide, while in case of carboxymethyl cellulose the diffusion coefficient increases with polymer concentration. The effect of temperature on the diffusion coefficient of Direct Blue 76 in the three polymers was found to obey the Arrhenius equation. The activation energy for diffusion of Direct Blue 76 in water, poly(ethylene oxide), polyacrylamide, and carboxymethyl cellulose was found to be 4.38, 7.7, 5.44, and 5 kcal, respectively, for polymer concentration of 0.25 g/l.     

Diffusivity of protein in aqueous solutions

The diffusion coefficient of lysozyme, a globular protein, was measured at various conditions as functions of lysozyme concentration, salt concentration, and solution ‘age’ in concentrated, saturated, and supersaturated solutions, employing Gouy interferometry. Distilled water, 0.05 M potassium phosphate buffer, and 0.1 M sodium acetate buffer solutions with 0, 2, 4, and 5 wt% NaCl were used as solvents. The pH of lysozyme solutions in distilled water was 4.75 due to the self-buffering capacity of lysozyme. The pH’s of the lysozyme solutions in the potassium phosphate and sodium acetate buffers were adjusted to 6.8 and 4.0, respectively. The experimental temperature was 25°C. In a salt-free system, the concentration dependent diffusion of lysozyme showed typical electrolyte diffusion behavior, while a salt-polyelectrolyte system exhibited the behavior of a non-electrolyte. Diffusion results in the supersaturated region showed a little effect of concentration or solution ‘age’ al a fixed NaCl concentration. A rapid decline in diffusion coefficient with increasing NaCl concentration in the supersaturated region, however, was observed.     

新型煤基吸附剂吸附硝基苯的机理研究

以神府煤为原料经过超细粉碎、化学处理、复合成型和后处理制得两种煤基超细复合吸附剂MMCA和AHCA，研究了二者对水溶液中硝基苯的吸附性能和吸附机理．结果表明，MMCA和AHCA对硝基苯的吸附过程符合二级吸附动力学模型，MMCA吸附硝基苯的过程由膜扩散控制，而AHCA吸附硝基苯过程由颗粒内扩散控制，求出了吸附速率常数和颗粒内有效扩散系数．MMCA和AHCA对硝基苯的吸附符合Langmuir吸附等温式，其单层饱和吸附量分别为109．89mg／g和229．57mg／g．     

Flavour retention in drying preconcentrated food liquids

The loss of volatile flavours from food liquids during evaporative drying and freeze-drying is independent of the relative volatility of the flavours and fully controlled by the rate at which the flavours can migrate to the evaporating surface. This rate of transfer is in solids and liquids without internal circulation directly proportional to the molecular diffusion coefficient of the flavour component. The diffusion coefficients of the flavour components are strongly dependent on water concentration and decrease much more steeply with decrease in water concentration than the diffusion coefficient of water. Below a critical water concentration the system becomes selectively permeable to water and completely impermeable to flavour molecules. The critical moisture content is dependent on the nature of the dissolved solids, and increases with increasing size of the flavour molecule and decreasing temperature. Drying conditions leading to a steep water concentration gradient and a rapid decrease in the water concentration at the liquid-or solid-gas interface down to the domain of selective permeability result in high flavour retention. The effect of these process conditions on retention have been studied experimentally for spray drying and freeze drying.     

硝基苯在Cu-SPE复合电极上的电还原反应特性研究

以国产NF - 1型离子膜为SPE膜材料 ,采用浸渍还原法制备了Cu SPE复合电极 ,研究了硝基苯在此电极上的电还原反应及其主要影响因素 ,并建立了相应的扩散模型。结果表明 :Cu SPE复合电极对硝基苯的电还原反应具有较高的电催化活性 ,硝基苯及其产物在SPE膜内的扩散是反应的控制步骤 ,反应主要发生在Cu SPE界面的内表面 ,其扩散系数D0 =8.1× 10 -7cm2 /s ;经HPLC分析表明电还原产物主要为苯胺。     

Concentration‐Dependent Diffusion Coefficients for Fructose in Highly Permeable Chitosan Polymers

The concentration‐dependent diffusion coefficient of fructose in precipitated chitosan membranes was determined using diffusion cells. Experiments showed that boundary layers on both sides of the membrane could not be neglected when the diffusion coefficient in chitosan is close to the free diffusion coefficient. Hence, the influence of the boundary layers was covered by measuring membranes with different thickness. The diffusion coefficient in chitosan at infinite dilution was found to be around the free diffusion coefficient. With increasing concentration, the diffusion coefficient in chitosan decreases faster than the free diffusion coefficient. Thus, the product of diffusion coefficient and concentration difference shows a maximum implying an optimum concentration for mass transfer.