蛭石层状膜的制备及有机溶剂纳滤性能

受全球能源形势与环境问题影响,新型膜分离技术尤其是二维层状膜在分离领域展现出广阔的应用前景。然而,目前使用的二维纳米材料化学环境相对复杂,且膜制备成本高昂,限制了其工业化推广。天然蛭石廉价易得,剥离简单,表面只含有硅羟基且其含量易于调控,可精确调控所制备层状膜层间亲疏水性,实现有机溶剂的高效渗透和极性与非极性溶剂的高效分离。研究发现：蛭石层状膜展现出优异的极性溶剂分子传递能力,而非极性溶剂则相对较低,其中乙腈分子渗透性高达1650L/（m²·h·bar)（1bar=0.1MPa）,甲苯分子渗透性仅为37.8L/（m²·h·bar),乙腈与甲苯的分离因子高达43.6,展现出优异的分子分离性能。本文所制备蛭石层状膜具有1.36nm的规则平直层间传递通道,对分子动力学直径大于层间距的结晶紫（1.5nm）、亮蓝（1.6nm）、酸性黄14（1.9nm）等染料分子的截留率均大于90%,截留性能优良。同时,蛭石层状膜具有良好的压力循环稳定性及抗污染能力, 展现出巨大的分离应用潜力。     

Intercalation of cetyl trimethylammonium ion into sericite in the solvent of dimethyl sulfoxide

In order to improve the microenvironment between layers of sericite in the manufacture of polymer/sericite nanocomposites, a pre-modified sericite was intercalated by cetyl trimethylammonium ion (CTA⁺) in a dimetzhyl sulfoxide (DMSO) solvent. The relevant experimental conditions, such as intercalating time, temperature, solid content and pH value, were optimized, and the intercalated sericite was characterized by X-ray diffraction, Fourier transform infrared, and X-ray photoelectron spectroscopy analyses. At an intercalation rate of 94%, the amount of CTA⁺ intercalated in the interlayer space of sericite was 36.3% and an expansion of d₀₀₁ value from 1.00 nm to 5.07 nm was observed. The intercalated CTA⁺ in the interlayer space of sericite adopted a paraffin-type bilayer configuration with a tilting angle of 53.6°. Due to its unique structure, DMSO would be better than water as the solvent for intercalation of organic cations. The intercalated sericite was more suitable to combine with polymer to form polymer/sericite nanocomposites.     

Activity, selectivity and durability of VO–ZSM-5 catalysts for the selective catalytic reduction of NO by ammonia

ZSM-5 zeolite was loaded with vanadyl ions (VO²⁺) by treatment of Na–ZSM-5 with aqueous VOSO₄ solution at pH 1.5–2. The catalytic material was tested for the selective catalytic reduction of NO with ammonia at temperatures between 473 and 823 K and normal pressure using a feed of 1000 ppm NO, 1000 (or 1100) ppm NH₃ and 2% O₂ in He. The catalyst proved to be highly active, providing, e.g. initial NO conversions of >90% at 620 l g⁻¹ h⁻¹ (≈400 000 h⁻¹) and 723 K, and selective, providing nitrogen yields equal to NO conversion at equimolar feed in a wide temperature range and only minor N₂O formation at NH₃ excess. Admixture of SO₂ (200 ppm) resulted in an upward shift of the useful temperature range, but did not affect the catalytic behaviour at temperatures ≥623 K. No SO₂ conversion was noted at T ≤ 723 K and 450 l g⁻¹ h⁻¹. The poisoning effect of water (up to 4.5 vol%) was weak at temperatures between 623 and 773 K. VO-ZSM-5 catalysts are gradually deactivated already under dry conditions, probably by oxidation of the vanadyl ions into pentavalent V species. This deactivation is considerably accelerated in the presence of water.     

High-pressure adsorption of methane on montmorillonite,kaolinite and illite

Methane (CH₄) adsorption of Ca^2 +-montmorillonite (Mt), kaolinite (Kaol) and illite (Il) at 60 °C and pressures up to 18.0 MPa was investigated, during which the adsorption capacity was evaluated by the Langmuir adsorption model. The influences of adsorbed water and the interlayer distance of the clay minerals on CH₄ adsorption were explored by using heated Mt products with different interlayer distances as the adsorbent. Mt, Kaol and Il showed high CH₄ adsorption capacities, and their maximum Langmuir adsorption capacities were Mt, 6.01 cm³/g; Kaol, 3.88 cm³/g; and Il, 2.22 cm³/g, respectively. CH₄ was adsorbed only on the external surface of Kaol and Il; however, adsorption also occurred in the interlayer space of Mt, which had a larger interlayer distance than the size of a CH₄ molecule (0.38 nm). CH₄ adsorption in the interlayer space of Mt was supported by the lower CH₄ adsorption capacity of heated Mt products (with the interlayer distance < 0.38 nm) than that of Mt at high pressures despite the higher external surface areas of the heated Mt samples. The entrance of CH₄ into the interlayer space of Mt occurred at low pressures, and more CH₄ molecules entered the interlayer space at high pressures. Moreover, the adsorbed water occupied the adsorption sites of the clay minerals and decreased the CH₄ adsorption capacity. These results indicate that clay minerals play a significant role in CH₄ adsorption of shale and indicate that the structure and surface properties of clay minerals are the important parameters for estimating the gas storage capacity of shale.     

层状Mg/Al氢氧化物/聚乙烯醇复合膜的制备及染料截留性能的研究

二维膜因其可控的结构和通道特有的物理化学性质,在气体分离、海水淡化、污水处理等诸多分离领域展现出巨大的应用潜力。通过层状Mg/Al氢氧化物（LDH）单片与聚乙烯醇（PVA）高分子链之间的氢键相互作用,层层堆叠构建了PVA/LDH复合膜。利用SEM、XRD考察了PVA与LDH的配比对于复合膜层状结构与层间距高度的影响规律。考察了PVA/LDH复合膜的纯水通量及染料模型分子的截留率。结果表明,不同PVA混合量的复合膜断面都具有层状结构。由于氢键作用导致复合膜较之于纯LDH膜的层间距有所缩小,随着PVA含量增加复合膜层间距先减小后增加;在PVA含量为15%时达到最小值,PVA含量超过15%后复合膜层间距有所增加。不同比例复合膜,以PVA质量分数为25%的复合膜的纯水通量最大;同时,该复合膜对分子量在300~800的染料分子具有优异的截留性能,截留率均超过97%。该工作为PVA/LDH复合膜在印染废水处理提供了新思路。     

Interaction of a model skin surface lipid with a modified triglyceride

A study of the interaction between a model skin surface lipid (SSL) and an oil base skin softener (G2) was made by comparing the phase behavior of these substances in combination with the water/triethanolamine: oleic acid (1:1 wt ratio) system. A principle feature of the water/G2/triethanolamine:oleic acid (TEA:OL) system was the formation of a lamellar liquid crystal region that incorporated an average of 40% G2 over the 10–45% water range. The phase behavior of the water/SSL/TEA:OL system demonstrated only over a 4–9% water range. At greater than 5% SSL, there is the complete absence of single phase regions above 10’% water. From comparison of the phase regions and the small angle X-ray diffraction results, it is found that for G2/SSL mixtures the phase behavior of the lamellar liquid crystal is dominated by the SSL and the interlayer spacing of the lamellar liquid crystal is dominated by G2.     

Self-assembly template during morphological transition of a linear ABC triblock copolymer from lamellar to Gyroid structure

Morphological transition of the ABC-type triblock copolymer from lameller to tricontinuous Gyroid structure has been observed. The sample used is a symmetric poly(isoprene-block-styrene-block-2-vinylpyridine), whose volume fractions of three components are 0.26, 0.48 and 0.26, and the total molecular weight is 1.0×10⁵. The solvent cast films were prepared and dried well, followed by annealing at 423 K, the temperature well above the glass transition temperatures of three polymer components. The structural transition was investigated by varying the annealing time from 1 h up to 7 days with two methods, transmission electron microscopy and small-angle X-ray scattering. It was confirmed that the as-cast film shows lamellar structure, however, the structure started to transform into Gyroid structure after annealing 14 h and it took more than 2 days to accomplish the transition. Furthermore, it was also confirmed that Gyroid structure is oriented with its (110) normal to the film surface, the length of its repeating unit along with (110), 55 nm, is similar to its original lamellar domain spacing, 58 nm.     

蛭石矿物材料层间水的赋存状态研究

利用红外光谱研究了蛭石矿物材料层间水的赋存状态。结果表明：蛭石晶层的层间距主要受层间水分子层数的影响,而后者又主要由层间阳离子的离子势大小决定。在层间都为2层水的情况下,蛭石层间距与层间阳离子的离子半径成正相关,这是由于蛭石层间为强静电场的缘故。利用Fourier自消卷积分峰技术,得到蛭石层间水的反对称伸缩振动、对称伸缩振动和弯曲振动的泛音等红外吸收谱,其中对称伸缩频率与层间水脱失温度成负相关,弯曲振动频率及其泛音与层间水脱失温度成正相关。     

Scanning force microscopy of oriented iso- and syndiotactic polypropylene films

Summary Different scanning force microscopy (SFM) modes were applied for the examination of drawn films of isotactic and syndiotactic polypropylene, iPP and sPP. Uniaxially stretched films with a draw ratio =6 were studied at ambient conditions, and under water. In iPP films striated patterns of 40–50 nm in width, which are oriented along the stretching direction, exhibit shish-kebab morphology. The dominating nanoscale features are nanofibrils of 10–15 nm in width, and lamellar platelets, which are 40–50 nm in width and 30–35 nm in length. In many places lamellar platelets are closely packed, and they form periodical sequences with a repeat distance of 30–35 nm, which is consistent with thelong period. Similar and differing morphological features were found comparing the images of iPP and sPP films. Extended fibrillar patterns of sPP exhibit similar width in the 40–50 nm range, while the lamellar structure is more compact, and the platelets are less uniform in length than those in iPP. The length of lamellar platelets ranges from 30 to 60 nm, and they form local periodical patterns.Prof. Dr. Joachim Meissner zu seinem 65. Geburtstag herzlichst gewidmet     

Classification of the asphalts and their source rock from the Dead Sea Basin (Israel): the asphaltene/kerogen vanadyl porphyrins

The asphaltenes of the asphalts from the Dead Sea Basin were examined for the occurrence of vanadyl porphyrins. These examinations demonstrate that the asphalts fall into two broad class types: one which exhibits a relatively high vanadyl porphyrins content (>300 ppm), and the other characterized with no vanadyl porphyrins (<10 ppm). It is concluded that these asphalts belong to two distinct types and have separate origins. The kerogens isolated from the petroleum-source rock of the Dead Sea Basin were also analyzed. Two genetic types of kerogen appeared to exist: a marine one highly enriched with these pigments and a terrestrial one with no vanadyl porphyrins. For comparison, the asphaltenes of typical asphaltic crude oils from Western Venezuela and kerogen from their La Luna source rock were also examined. Previous detailed geochemical studies[1] indicated that the La Luna kerogen is derived from marine organic matter source. These materials have higher concentrations of vanadyl porphyrins than the Dead Sea asphaltenes and kerogens are enriched with these compounds. Our results strengthen the potential of vanadyl porphyrins of both petroleum asphaltenes and source-rock kerogen for use in genetic and correlation studies.     

Evaluation of the microporosity of pillared [Fe(CN)6]–MgAl–LDHs

Layered double hydroxides (LDHs) containing Mg²⁺ and Al³⁺ in the basic layers and NO⁻₃ as an interlayer anion were synthesized by the method of coprecipitation (pH 10). By changing the Mg²⁺/Al³⁺ ratio (1.5–4.5), the charge density on the (NO₃)–MgAl–LDH sheets was varied. After pillaring with Fe(CN)³⁻₆, which was based on an anion exchange process, the interlayer space became accessible. This was reflected in the large created surface areas and micropore volumes. The applied models for the calculation of the micropore size distributions (Maes–Zhu–Vansant and Horvath–Kawazoe) gave matching results, revealing narrow distributions for all the samples, with the majority of the pores smaller than 0.71 nm. A correlation was found between the Mg²⁺/Al³⁺ ratio and the resulting microporosity after pillaring. The optimal ratio was situated around 3.3, resulting in a pillared [Fe(CN)₆]–MgAl–LDH with a Langmuir surface area of 499 m²/g and a micropore volume between 0.158 ml/g (μPV_min) and 0.177 ml/g (μPV_max). As an alternative, direct coprecipitation of the pillared LDHs was evaluated. This one-step mechanism proved to be a method producing similar results. Taking all this into consideration, one can conclude that hexacyanoferrate(III) complexes form ideal anionic pillars for the creation of microporous layered double hydroxides.     

载药蒙脱石/海藻酸钠凝胶球的制备和释放性能

以离子交换方式将硫酸氢氯吡格雷插入蒙脱石层间,再用海藻酸钠包衣得到凝胶球。利用XRD、FTIR进行表征以及体外释放实验检测缓释效果。结果表明,硫酸氢氯吡格雷成功地插入蒙脱石层间,蒙脱石的层间距由1.25 nm增大到1.48 nm;体外释放实验显示在1 h内载药凝胶球的累积释放量为12.9%,表明载药蒙脱石/海藻酸钠凝胶球能明显的减少药物突释,因此可将它作为硫酸氢氯吡格雷的缓释载体。     

Preparation and crystal structure of RUB-18 modified for synthesis of zeolite RWR by topotactic conversion

The systematic study on the synthetic route of the siliceous zeolite RWR with a small 8-MR straight channel by topotactic conversion of crystalline layered silicate RUB-18 was carried out by using several topotactic precursors obtained from Na-RUB-18. Intermediate layered structures of topotactic precursors were designed by intercalation of amine molecules and acid treatment. Crystal structures of two kinds of TMAOH intercalated RUB-18s (TMA-RUB-18-poly1 and TMA-RUB-18-poly2) and their acidified TMA-RUB-18 were determined by ab initio structure analysis using X-ray powder diffraction data. The layered structure of TMA-RUB-18-poly1 and TMA-RUB-18-poly2 had tetragonal symmetry of space group P4₂/nmc, and the lattice parameters were estimated to be a = 7.4121 Å, c = 22.615 Å for TMA-RUB-18-poly1 and a = 7.3718 Å, c = 29.342 Å for TMA-RUB-18-poly2. Two silicate layers were involved in a unit-cell and TMA⁺ cations were intercalated in the interlayer. The layer stacking sequence was completely different from that of Na-RUB-18. Structure of acidified TMA-RUB-18 had also tetragonal symmetry of space group I4₁/amd and lattice parameters a = 7.4722 Å, c = 37.242 Å with four silica layers. Stacking sequence in acidified TMA-RUB-18 was similar to that of Na-RUB-18 although a large shrinking of interlayer distance (ca. 2.0 Å) was observed. In the acidified TMA-RUB-18, one-dimensional pseudo pore was constructed by semi-circular geometry derived from the framework structure and stabilized by formation of hydrogen bonding between the terminal silanol groups, which faced each other with atomic distance d(O–O) of ca. 2.5 Å. By the dehydration–condensation of silanol groups during careful calcination, zeolite RWR could be successfully prepared from the acidified TMA-RUB-18.     

Changes to structure of hydrated portland cement on drying and rewetting observed by helium flow techniques

Helium flow techniques are applied to the hydrated portland cement-water system during rewetting. Measurements of solid volume and density demonstrate irreversible changes to the structure. Measurement of changes in volume of interlayer space are made and are shown to be due to new alignment of layers and to the moving apart of layers as a result of water penetration. The density of the interlayer water is found by these techniques to be 1.20 ± 0.08 gm/m?. Calculation of the parameter Total Volume/Monolayer Volume for the interlayer space yields a value of 1.32. This shows that the space approximates that bounded between two parallel plates.     

Thermal degradation of organic matter in the interlayer clay–organic complex: A TG-FTIR study on a montmorillonite/12-aminolauric acid system

The storage of natural organic matter within the interlayer space of layered silicate is an important type of clay–organic association in sediment. However, the role of the interlayer space of clay minerals in the thermal degradation of organics and the generation of hydrocarbons has not been well understood. In this study, an interlayer clay–organic complex was synthesized using montmorillonite (Mt) and 12-aminolauric acid (ALA). An Mt–ALA complex in which Mt and ALA were simply mixed was also prepared for comparison. Thermogravimetry coupled with Fourier transform infrared spectroscopy (TG-FTIR) was applied to monitor the thermal events and the corresponding products during the thermal degradation of the Mt–ALA complexes. In the absence of Mt, ALA decomposed at 467 °C via the cleavage of CC bonds, producing aliphatic hydrocarbon, N-containing compounds, and carboxylic acid. The decomposition temperatures of organic matter in the mixed Mt–ALA complex and the interlayer Mt–ALA complex decreased to 402 and 342 °C, respectively. The most characteristic products of the interlayer Mt–ALA complex were NH₃ and saturated hydrocarbons. The Brønsted acid sites in the interlayer space of Mt, arising from the dissociated interlayer water, initiated the deamination of ALA via the Hoffmann elimination pathway and significantly promoted the cracking of hydrocarbons via a carbonation mechanism. Lewis acid sites had little effect on the thermal degradation of ALA. This work indicated that the interlayer space of clay minerals provided the storage space for organic matter. Moreover, the active sites within the interlayer space strongly promoted the thermal degradation of organics.     

Deconstructing water sorption isotherms in cement pastes by lattice density functional theory simulations

The moisture content in cement pastes influences their mechanical properties and durability. However, the complex, multiscale nature of cement pastes makes it challenging to isolate the contributions of each scale to their macroscopic water sorption isotherms. In particular, the contribution of the calcium–silicate–hydrate gel (the binding phase of cement pastes) remains only partially understood. Here, we introduce a density functional theory lattice model describing water sorption in calcium–silicate–hydrate, which properly reproduces experimental water sorption isotherms in cement pastes. Based on this model, we deconstruct the contribution of each pore scale (interlayer spacing, gel pores, and capillary pores) to the total sorption isotherm. We show that, when the relative humidity is below 80%, the calcium–silicate–hydrate gel accounts for more than 90% of the moisture content adsorbed in cement pastes. In turn, we find that the contribution of the interlayer space within the calcium–silicate–hydrate grains is governed by the competition between the rate of interlayer space opening and the increasing propensity for water to fill larger pores upon increasing relative humidity. Overall, our results highlight the key role played by the calcium–silicate–hydrate in governing the sorption isotherms of cement pastes.     

Introduction of amino groups into the interlayer space of graphite oxide using 3-aminopropylethoxysilanes

Graphite oxide was silylated by 3-aminopropylethoxysilanes under various reaction conditions. Two types of layered materials were obtained when 3-aminopropyltriethoxysilane was reacted with graphite oxide. One obtained at lower temperatures was 3-aminopropyltriethoxysilane-intercalated graphite oxide with an interlayer spacing of 1.27 nm, in which amino groups of 3-aminopropyltriethoxysilane were bonded to hydroxyl groups of graphite oxide. At higher temperatures, silylation of graphite oxide occurred, giving a phase with larger interlayer spacing of 1.37 nm. Chemical reduction of graphite oxide to disordered carbon by amino groups occurred at the same time. Similar reactions occurred when 3-aminopropyldiethoxymethylsilane and 3-aminopropylethoxydimethylsilane were reacted and they were introduced into the interlayer space of graphite oxide. Large amounts of silicon, and accordingly amino groups, were introduced in graphite oxide when it was silylated by 3-aminopropyldiethoxymethylsilane because its reactivity for chemical reduction of graphite oxide was relatively lower than that of 3-aminopropyltriethoxysilane and additional silylation was possible. The amount of amino groups available for chemical adsorption of formaldehyde reached a very high value of 3.8 mmol/g for graphite oxide silylated by 3-aminopropyldiethoxymethylsilane.     

不同结构聚苯乙烯/蒙脱土复合材料的熔体流动行为研究

分别将聚苯乙烯树脂(PS)与钠基蒙脱土(Na-MMT)和有机化蒙脱土(OMMT)通过熔融复合制备纳米黏土改性的复合材料。通过X射线衍射(XRD)对复合材料的微观结构进行了分析,采用HAAKE流变仪和熔体流动速率仪研究了复合材料的熔体流动行为。结果表明,Na-MMT在与PS熔融复合前后,其片层间距没有发生变化,PS分子链没有插入蒙脱土片层之间,所形成的是一种填充型复合材料。OMMT在熔融复合后,片层间距显著增大,与PS分子链形成了插层复合结构。蒙脱土含量相同时,PS/Na-MMT复合体系的熔体流动性能比PS/OMMT体系更好。研究认为,熔融复合过程中PS分子链的断链和2种复合材料结构上的差异是影响2种材料流动性能的主要因素。     

Intercalation behavior of hydroxylated dendritic polyesters in polymer clay nanocomposites prepared from aqueous solution

Second and fourth generations of hydroxylated dendritic polyesters based on 2,2-bis-methylopropionic acid (bis-MPA) with an ethoxylated pentaerytriol (PP50) core were combined with unmodified sodium montmorillonite clay (Na⁺MMT) in water to generate a broad range of polymer clay nanocomposite films from 0 to 100% wt/wt. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to investigate intercalation states of the clay galleries. Intercalation was the dominant state in these nanocomposites. Significant exfoliation was only observed within 0–5% wt/wt of mineral composition range. It was shown that interlayer spacing changed within the composition range 5–95% wt/wt from 0.5 nm to up to 3.5 nm in a step-like fashion with 0.5 nm increments which corresponded to a flattened conformation of confined hyperbranched polymers (HBP). Second and fourth generations exhibited the same layer-by-layer intercalation of completely flattened HBPs. No dependence of interlayer spacings on generation number was found. XRD and TEM revealed the presence of mixed intercalated populations with interlayer spacings at multiples of 0.5 nm.     

Electrochemical, textural and microstructural effects of mechanical grinding on graphitized petroleum coke for lithium and sodium batteries

A graphitized coke material obtained from petroleum residua was mechanically ground at different milling times between 0 and 100 h. Electrochemical reactions with both lithium and sodium are significantly altered as a function of grinding time. Short-time ball milling of graphite (1 and 5 h) induces a limited decrease in particle size and an increase in microstrain content. Simultaneously, alkali metal intercalation and electrolyte decomposition are hindered, and thus the irreversible and reversible capacities decrease. For longer milling time (up to 100 h), average crystallite size decreases and particles adopt a lamellar shape. Simultaneously, the irreversible capacity increases and correlates with an increase of the resistance, as obtained by impedance spectroscopy. Ex-situ XRD shows that extensively ground graphite samples need a higher discharge specific capacity to reach the formation of n-stages as compared to non-ground graphite, this being indicative of lithium incorporation in energetically different sites to the interlayer space. Sodium storage capacity increases with prolonged grinding time. This effect is shown here for the first time for graphitized cokes.