应用红外光谱研究脱灰对伊敏褐煤结构的影响

对伊敏褐煤的原煤和脱灰煤进行了红外光谱分析,并通过分段分峰拟合分析了脱灰前后伊敏煤结构的变化。结果表明,脱灰处理对煤中有机结构会产生一定影响。对脂氢和羟基氢键有机结构影响较小,脱灰后,脂氢结构中CH₂不对称伸缩振动没有变化,CH伸缩振动明显减少,而CH₂对称伸缩振动和CH₃不对称伸缩振动略有增加;羟基氢键结构中羟基N羟基、自缔合羟基氢键以及羟基π氢键的强度有所降低,而环氢键和羟基醚氢键的吸收强度有所增加;对芳香结构和含氧官能团的影响较大,芳香结构由原煤中的苯环三取代占主导地位转变为脱灰煤中的苯环三和四取代;含氧官能团中烷基醚和脂肪羧酸脱灰后吸收峰的强度明显减弱,这是由于水解反应导致的,而酚羟基和羧酸脱灰后吸收强度明显增强。     

氟磺酸氯分子振动光谱的从头算研究

采用从头算HF方法以6-31G^*基组研究了对ClOSO₂F分子的几何结构、振动谐性力场和红外光谱.理论力场由Pulay的标度量子力学方法进行标度,算得的振动频率与实验值比较,平均偏差为6.0cm^-1.根据振动频率的势能分布和从头算红外光谱强度值对此分子的振动基频进行了理论归属.     

p-π共轭分子的氨基面外弯曲振动模的拉曼光谱

拉曼光谱是一种用途广泛的无损分子检测技术,其能够提供化学物质的分子结构指纹信息.一种面外弯曲振动模被称作wagging振动,它的信号尤为特殊,其频率和强度都非常依赖于检测环境.以乙烯胺和苯胺为例,采用密度泛函理论计算研究了p-π共轭分子分别与水簇和银簇作用的平衡结构、成键作用和拉曼光谱.结果表明,弱相互作用,如分子与金属表面的弱吸附作用以及分子与水之间的氢键作用,均使氨基面外弯曲振动模(ωNH2)的拉曼信号发生显著的变化.考虑溶剂化效应后,氢键作用减弱,计算拉曼光谱趋于一致.通过进一步对电子结构的分析,解释了面外弯曲振动信号显著增强的原因,揭示了面外弯曲振动模与分子p-π共轭作用之间的关系.     

星际炔氰分子电子结构和分子振动的理论研究

用MINDO/3法计算了星际炔氰分子(HC_2nCN,n=0,1,…,5)的电子结构和振动频率;得出了炔氰分子的HOMO、LUMO、电子总能量E_T与n之间的线性关系。炔氰分子n愈大,HOMO愈高,LUMO愈低,体系愈不稳定。由计算的振动频率和对振动模式的分析可知,在炔氰分子中(HCN除外),应有频率约为3820cm^-1的H-C伸缩振动和800cm^-1的H-C-C弯曲振动这样的特征振动。     

石墨烯诱导水凝胶成核的高强韧人造蛛丝

天然蜘蛛丝是由β-sheet交联的蛛丝蛋白溶剂流入S-型导管后经牵引拉伸形成,它显示了高强度与高韧性的完美结合。其优异的力学性质主要源于它的多级结构：交联、线性排列的纳米组装体以及核壳结构。受此启发,我们合成了一种交联的水凝胶,通过牵引拉丝的方法,制备了交联的、含有取向排列的纳米组装体结构以及核壳结构的凝胶纤维,并通过少量引入二维纳米材料—氧化石墨烯(0.01%),进一步调控纳米组装体的取向和尺寸,实现了蜘蛛丝般优异的力学性能(断裂强度560 MPa,断裂韧性200 MJ·m^–3,缓冲能94%)。这种纤维可以用于高速下落物体的能量耗散和降低冲击力。     

乐果和氧化乐果水解过程的衰减全反射-傅立叶变换红外光谱(ATR-FTIR)研究

运用ATR-FTIR深入探讨了乐果和氧化乐果分子结构的特征振动及其酸、碱条件下水解历程对其特征结构振动的变化规律. 由实验结果, ATR-FTIR能够显著地区分乐果和氧化乐果两分子的结构振动. 氧化乐果在3302 cm^－1 ν_as (NH), 3089 cm^－1ν_as (CH₂), 1739 cm^－1 ν (C-O), 1554 cm^－1 ν (O＝C-N) II等峰位明显区别于乐果分子对应结构的振动峰位及其峰位强度. 碱性水解条件下, 乐果的ATR-FTIR特征表现在2108 cm^－1平宽峰增强, 氧化乐果则表现为ν (P＝O)红移和ν_as (P-O-C)蓝移|酸性水解条件下, 乐果ATR-FTIR中高波段的NH, CH₃振动较强, 氧化乐果则因其分子链被破坏, 表现出无特征振动. 以上ATR-FTIR获得的结果从另一角度, 互补性地揭示了乐果和氧化乐果两分子内部的结构振动差别和酸、碱水解历程对其振动结构的影响变化. 为便捷、高效地区分物质分子结构的差异, 尤其是分子结构极为相似的细微结构的差异提供了较为完整的信息, 同时也为研究物质结构及其形态变化提供了十分有益的参考.     

受限于单壁碳纳米管中水分子结构、能量以及振动频率的密度泛函研究

利用密度泛函理论中的杂化泛函M06-2X研究了受限于不同管径单壁碳纳米管（SWCNT）内水分子团簇 （H₂O）_n=3～6的结构、能量以及振动频率. 结果显示由于SWCNT的限域效应,水分子团簇的几何构型与在真空相比发生了巨大变化,如受限（H₂O）₆能形成单链锯齿型水分子构型. 随着管直径的增大,纳米管与水之间的相互作用逐渐减弱,但水分子之间的氢键相互作用能变化不大. 对比受限和真空下水分子O-H振动频率发现,绝大部分O-H的振动频率由于碳纳米管与水的相互作用而发生了红移. AIM理论分析显示O-H振动频率的红移应归因于其电子密度的减小. 这也表明碳纳米管绝非简单的几何限制效应,而是与水分子之间存在弱电子相互作用,主要包括H…π氢键作用和O…π轨道作用,从而导致水分子的小部分电荷转移到了SWCNT上.     

层状K/Mg-Fe-Al催化剂的制备及其CO加氢性能研究

采用共沉淀法制备了系列不同Mg/Fe/Al配比MgFeAl-HTLcs前驱体,经焙烧、浸渍K改性、二次焙烧后用于CO加氢反应。采用N2吸附-脱附、SEM、TG、XRD、H2-TPR、XPS等手段对催化剂进行了表征。结果表明,共沉淀法制备的不同配比MgFeAl-HTLcs类水滑石前躯体均具有典型层状结构;焙烧后生成MgO、Fe2O3以及少量MgFeAlO4物相,三组元间相互作用增强,反应后以MgCO3和Fe3O4物相为主,同时出现较弱的Fe5C2相;K改性后发生结构重构,热稳定性增强,且随Al含量增加,比表面积显著单调下降;与K/Mg-Fe相比,K/Mg-Fe-Al样品中Fe2O3到Fe3O4的还原受到抑制;二次焙烧后,反应前表面相对富Fe,反应后表面富K。在CO加氢反应中,K/Mg-Fe-Al系列催化剂均表现出较高的反应活性以及烯烃选择性,随Fe/Al配比相对增加,C5+含量呈降低趋势,O/P值增加;与K/1.5Mg-0.67Fe相比,K/1.5Mg-0.67Fe-0.33Al催化剂C5+含量由22.17%降至10.90%,C=2-4含量由40.98%提高至47.28%。     

碱土金属叠氮化合物(CaN6)n (n＝1～5)团簇结构与性质的密度泛函理论研究

利用密度泛函理论在B3LYP/6-311G*水平上对碱土金属叠氮化合物(CaN₆)_n (n＝1～5)团簇各种可能构型进行了几何优化, 预测了各团簇的最稳定结构. 并对最稳定结构的成键特性、电荷分布、振动特性及稳定性进行理论研究. 结果表明, 叠氮化合物中叠氮基以直线型存在, CaN₆团簇的最稳定结构为线型结构, (CaN₆)_n (n＝2～5)团簇首先由两个叠氮基与两个Ca原子构成一个近似菱形, 再由菱形相互垂直形成链状最稳定结构; 叠氮基中间的N原子显示正电性, 两端的N原子显示负电性, 且与Ca直接作用的N原子负电性更强, 金属Ca原子和N原子之间形成很强的离子键; (CaN₆)_n (n＝1～5)团簇最稳定结构的IR光谱分为4个部分, 其最强振动峰均位于2195～2280 cm^－1, 振动模式为叠氮基中N-N键的反对称伸缩振动; 稳定性分析显示, (CaN₆)₃和(CaN₆)₅团簇相对于其他团簇较为稳定.     

熔纺聚氨酯系中空纤维膜的结构与性能

将聚氨酯/聚偏氟乙烯/聚乙二醇(PU/PVDF/PEG)熔融共混纺丝制得中空纤维膜,对纤维膜的微孔结构与性能进行研究,分析影响其水通量衰减的因素。结果表明:所得纤维膜具有界面及非界面微孔结构;随着水通量工作环境的变化,膜孔结构发生相应变化,表现出压力及温度响应性能;而经热处理后,所得膜部分微孔闭合,水通量下降;随测试时间延长,膜结构趋于致密化,水通量衰减。     

FT-IR AND MICROCALORIMETRY STUDIES ON WATER/TX-100/HEXANOL/OCTANE REVERSE MICROEMULSION SYSTEM

ABSTRACT

Water/TX-100/Hexanol/Octane reverse microemulsions were investigated by Microcalorimetry and FT-IR. Experiments show that the formation of this reverse microemulsion is an exothermic process, and it's a two-step reaction. The first step is action of TX-100 monomers with water to form hydrogen bond while the second is interaction between polyethylene oxide groups in reverse micelles and water. The characterizations of FT-IR and Microcalorimetry indicate that aqueous core of the microemulsion droplets are composed of bound and free water while a small amount of trapped water, OH stretching vibration peak of bound water, free water, and trapped water are at 3400 ±20 cm^?1, 3220 ± 20 cm^?1, and 3550 ± 20 cm^?1 respectively. Polyethylene oxide ether of TX-100 is prior to phenyl ether in acting with water because its polarity is stronger than phenyl ester.     

Determination of water states and the structural parameters of W/O microemulsions

The states of water in sodium bis(2-ethylhexyl) sulfosuccinate (AOT)/isooctane/water reverse(W/O) microemulsions system have been investigated by using Fourier transform infrared spectroscopy(FT-IR) technique. The broad peak obtained for hydroxy(O-H) of water has been resolved by least square curve-fitting. It has been observed that the water solubilized in microemul-sion droplets has four states, i.e. bound water with sulfo-group, free water, bound water with sodium counterion in the water pool of microemulsion droplets and a small amount of trapped water in the palisade layer of microemulsion droplets. The following have also been determined: the aggregation number (n), the radius of the water pool in the microemulsions(rw), the thickness of the bound water with sulfo-group(d1), the thickness of the bound water with sodium counterion(d2), the total thickness of the bound water (d) and the effective area of head groups of AOT(AAOT).     

水/Triton X-100/正丁醇/环己烷反相微乳液体系中水结构的FT-IR研究

用FT-IR法研究了水/辛烷基苯酚聚氧乙烯醚（Triton X-100）/正丁醇/环己烷组成的反相微乳液体系水池中存在的束缚、结合和自由3种不同的水的状态.分别考察了水与表面活性剂物质的量之比（Rw）、水油比φ（水与环己烷的质量比）、助剂正丁醇的含量对3种状态水含量的影响.发现在φ=2.8、m正丁醇/mTriton X...     

聚乙二醇在Triton X-114/正辛烷/正丁醇/水反相微乳液中的增 溶研究

研究了加入聚合物对TritonX-114/正辛烷/正丁醇/水组分体系相态的影响。利用次甲基蓝(MB)作为吸附探针,而以恶唑烷氮氧自由基(5-doxylstearicacid,5-DNS)作为自旋探针,研究了加入聚合物对TX-114/正辛烷/正丁醇/水反相微乳液的微结构影响。结果表明:聚合添加使W/O微乳液区缩小,而液晶区则更靠近水一端(增溶更多水)。该反相微乳液中存在三种状态水:结合水、束缚水、体相水。加入聚合物可以替代先前存在于TX-114聚氧乙烯链上的一些水分子,使其微极性减小,而且使表面活性剂分子在界面上的排列更为松散,本研究结果对探讨聚合物对W/O微乳液微结构的影响及此类体系在其它方面应用有重要意义。     

Effect of Polyvinylpyrrolidone on the States of Water in Water-in-Oil Microemulsions with Betaine Surfactant

A water-in-oil (w/o) microemulsion was prepared with the zwitterionic surfactant dodecyl betaine (C₁₂BE), n-pentanol (C₅OH), n-heptane (C₇H₁₆) and water. Effects of polyvinylpyrrolidone (PVP) with different molecular weight on the state of water in w/o microemulsions at a given water/C₁₂BE molar ratio were investigated by FT-IR and differential scanning calorimetry (DSC). The experimental results showed that addition of PVP resulted in an increase of the content of the bound water in water pool of a w/o microemulsion, but a decrease of the amount of the bulky water. The higher the molecular weight of PVP, the more bound water; and the less bulk water. The change of the trapped water was not obvious due to the interference of C₅OH.     

Dynamics of water confined within reverse micelles

We report structural and dynamical properties of water confined within reverse micelles (RMs) ranging in size from R = 10 A to R = 23 A as determined from molecular dynamics simulations. The low-frequency infrared spectra have been calculated using linear response theory and depend linearly on the fraction of bulklike water within the RMs. Furthermore, these spectra show nearly isosbestic behavior in the region near 660 cm(-1). Both of these characteristics are present in previously measured experimental spectra. The single dipole spectra for interfacial trapped, bound, and bulklike water within the RMs have also been calculated and show region-dependent frequency shifts. Specifically, the bound and trapped water spectra have a peak at lower frequencies than that for the inner core water. We therefore assign the low-frequency band in the IR spectra to bound and trapped interfacial water. Finally, region-dependent hydrogen bonding profiles and spatial distribution functions are also presented.     

Study of water solubilized in AOT/n-decane/water microemulsions

The state of water in AOT-n-decane-water microemulsions has been studied by using Fourier Transform Infrared spectroscopy (FT-IR). The existence of three kinds of water, which correspond to water populations with different degrees of organization, has been observed. Densities of these microemulsions have been measured. From these studies (FT-IR and densities), the apparent molar volumes of the different types of water molecules have been estimated. These apparent molar volumes, as well as their variations with respect to the composition of the microemulsion, depend on the type of water. The volume of the water bound to the ionic heads of the surfactant is lower than that for bulk water and shows a slight dependence on the molar ratio W. In contrast, no dependence on W is found for the volume of water trapped between the tails of the surfactant.     

Role of solubilized water in the reverse ionic liquid microemulsion of 1-butyl-3-methylimidazolium tetrafluoroborate/TX-100/benzene

The ionic liquid (IL) 1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF4) can form nonaqueous microemulsions with benzene by the aid of nonionic surfactant TX-100. The effect of water on ionic liquid-in-oil (IL/O) microemulsions was studied, and it was shown that the addition of small amount of water to the IL microemulsion contributed to the stability of microemulsion and thus increased the amount of solubilized bmimBF4 in the microemulsion. The conductivity measurements also showed that the attractive interactions between IL microdroplets were weakened, that is, the IL/O microemulsion becomes more stable in the present of some water. Fourier transform IR was carried out to analyze the states of the added water, and the result showed that these water molecules mainly behaved as bound water and trapped water, indicating that the water molecules are located in the palisade layers of the IL/O microemulsion. Furthermore, 1H NMR and 19F NMR spectra suggested that the added water molecules built the hydrogen binding network of imidazolium cations and H2O, BF4- anion and H2O, and at the same time the electronegative oxygen atoms of the oxyethylene units of TX-100 and water in the palisade layers, which made the palisade layers more firm and thus increased the stability of the microemulsion. The study can help in further understanding the formation mechanism of microemulsions. In addition, the characteristic solubilization behavior of the added water can provide an aqueous interface film for hydrolysis reactions and therefore may be used as an ideal medium to prepare porous or hollow nanomaterials.     

萃取过程的量热研究 II: 微乳状液形成的滴水量热曲线

采用滴定量热法研究P204钠(钾、铵)-仲辛醇-煤油等体系在滴加水过程中的热量变化, 得到两种不同类型的量热曲线, 在此基础上解释了微乳状液的形成过程和水以两种状态─缔合水和自由水存在, 还以简化的模型定性地讨论了滴水过程中微乳状液颗粒大小的变化。     

卵磷脂/正丙醇/肉豆蔻酸异丙酯/水微乳体系的相结构研究

以卵磷脂为表面活性剂,正丙醇为助表面活性剂,肉豆蔻酸异丙酯(IPM)为油相,配制成W/O型微乳。并通过浊点法、电导法、动态光散射法(DLS)以及差示扫描量热法(DSC)研究了微乳相结构随含水量的变化。对于选定配比微乳,浊点法在含水量超过10.71%时变浑浊;电导率在含水量达到3.85%之前增长缓慢,之后快速增大,含水量超过10.71%时电导率下降;DLS显示微乳粒径随含水量先减小后增大,其转折点在5.66%,而含水量超过10.71%后粒径突增3个数量级;DSC曲线在含水量超过3.85%后出现水的结晶峰,且随含水量的增大峰位往高温方向平移,同时峰面积增大。当含水量达到11.5%时出现两水峰叠加。研究表明含水量在3.85%~5.66%范围内属于W/O向双连续相转变的过程,而含水量10.71%则是体系发生相分离的临界点。