Energy-saving drying technology for porous media using liquefied DME gas

Process design and energy requirement for a practical plant are investigated for an energy-saving drying (dewatering) process invented by the authors in 2002 for high-moisture porous materials. The basic concept of the process involves the extraction of water from a high-moisture porous material by bringing it in physical contact with liquefied dimethyl ether (DME) at room temperature. Water content of DME asymptotically increases to the saturation value and the high-moisture porous material is dried almost perfectly. DME from the DME-water mixture is vaporized by decompression. DME and water are separated by flash distillation. DME vapor is compressed and cooled in a heat exchanger, and the latent heat of condensation is reused to vaporize the DME in the heat exchanger. Multistage compression and multistage flash distillation are employed. After compression, the temperature of DME is less than 50?°C. Because specific heat ratio of DME is only 1.11, the energy consumption of the compressor is reduced. Considering the adiabatic efficiency of the compressor and the net thermal efficiency, the total energy for dewatering is about 1100 kJ per 1-kg-water-content of the material being dewatered This process has significant potential and is compact than the existing dewatering processes.     

三维MXene多孔结构的构建与应用研究进展

MXene作为一种新型二维（2D）纳米材料以其独特的高导电性、高电化学表面活性等特性在多个领域引起了广泛关注。然而,MXene纳米片在自组装过程中出现的紧密堆叠现象导致比表面积急剧下降,降低了活性表面积,从而严重阻碍了它们在能源储存、电磁屏蔽、吸附等领域的潜在应用。构建三维多孔结构是解决MXene组装过程中自堆叠问题的一种有效途径,而且通过不同的组装方法可以实现对多孔宏观结构组成成分、孔径分布以及孔径大小的调控,使得MXene多孔材料在机械性能、电学性能以及光热转换性能等方面得到更好的调整,从而满足不同应用领域的需求。本综述以Ti₃C₂T_x MXene为主要研究材料总结了各种多孔MXene宏观结构的制备方法,讨论了其在电池/超级电容器、电磁屏蔽与吸收、海水淡化、光催化以及传感和环境修复等方面的应用,阐述了MXene多孔结构在各种应用中的贡献与意义,并针对MXene多孔结构的制备、结构调控和应用等方面的机遇和挑战作了论述。     

钇掺杂有序大孔TiO_2微球的制备与光催化性能研究

采用溶胶-凝胶法、胶体晶体模板法制备了钇掺杂有序多孔TiO2微球,利用FTIR,SEM,XRD,XPS,UV-V is分析对其进行表征,并研究钇掺杂前后材料的光催化性能。结果表明:钇掺杂有序多孔TiO2微球规整致密,但局部有孔洞的塌陷。钇掺杂前后有序多孔TiO2微球的晶型没有改变,仍为锐钛矿型。XPS分析发现钇掺杂有序多孔TiO2微球是可行的,材料中含有钇元素含量约为1.0%。UV-V is分析表明钇掺杂使得TiO2吸收光红移至可见光区,甲基橙降解实验显示掺钇有序多孔TiO2微球的光催化性能好于未掺钇TiO2的光催化性能。     

Preparation of PCM microcapsules by complex coacervation of silk fibroin and chitosan

Phase change material microcapsules were prepared by complex coacervation of silk fibroin (SF) and chitosan (CHI). n-Eicosane was used as the core material. The effects of SF/CHI ratio, and percentage of cross-linking agent and n-Eicosane content on the properties of microcapsules were studied. The size distribution and the surface morphology of microcapsules were characterized by optical and scanning electron microscopy. The encapsulation of core material was determined by energy dispersive spectrometer analysis. The results indicated that SF/CHI microcapsules were prepared successfully. Microcapsules had smooth outer surface when the ratio of SF to CHI was close to 5. On the other hand, at high SF/CHI ratios (≥14), microcapsules showed a two-layer structure, an inner compact layer, and an outer, more porous, sponge-like layer. The highest microencapsulation efficiency was obtained at a SF/CHI ratio of 20 in the presence of 0.9% cross-linking agent and of 1.5% n-Eicosane content.     

Preparation of Ni–YSZ thin and thick films on metallic interconnects as cell supports. Applications as anode for SOFC

In this work, we propose the preparation of a duplex anodic layer composed of both a thin (100 nm) and a thick film (10 μm) with Ni–YSZ material. The support of this anode is a metallic substrate, which is the interconnect of the SOFC unit cell. The metallic support limits the temperature of thermal treatment at 800 °C to keep a good interconnect mechanical behaviour and to reduce corrosion. We have chosen to elaborate anodic coatings by sol–gel route coupled with dip-coating process, which are low cost techniques and allow working with moderate temperatures. Thin films are obtained by dipping interconnect substrate into a sol, and thick films into an optimized slurry. After thermal treatment at only 800 °C, anodic coatings are adherent and homogeneous. Thin films have compact microstructures that confer ceramic protective barrier on metal surface. Further coatings of 10 μm thick are porous and constitute the active anodic material.     

Dissolution of a surfactant-containing active porous material

We have studied the imbibition and dissolution of a porous material in two separate scenarios: (1) when the porous material contains a surfactant powder and (2) when the porous material is dissolved in a surfactant solution. We show that the dissolution kinetics in both scenarios is significantly affected by the presence of the surfactant and results in an increase in the characteristic imbibition time of the porous material, which can be well understood in the framework of the classical law of capillarity. Slowing of the imbibition kinetics was found to be affected by a modification of the liquid wetting properties, but is also affected by a variation in the solubility of the porous material in the presence of the surfactant. Furthermore, there is a depletion effect of the surfactant inside the rising liquid, which is in good agreement with previous work and theoretical predictions.     

三维结构和氧化度对C6位氧化再生纤维素止血材料性能影响

C6位氧化再生纤维素作为可吸收止血材料,其止血性能受材料理化性质的影响。通过比较氧化再生纤维素的吸水率、凝胶化速率、溶解速率、降解速率、抗老化性能和止血效果,研究三维结构和氧化度对氧化再生纤维素性能影响。结果发现,氧化度增高,氧化再生纤维素吸水率增强,凝胶化速率加快,溶解速率和降解速率变快,抗老化性能变差,产品有效期变短。纤丝松散网状多孔结构比纱布致密结构更有利于提高吸水率,加快凝胶化速率和溶解速率;同时降低氧化剂用量,提高抗老化性能。同一氧化度条件下,纤丝止血速率优于纱布,止血效果更好。     

Li/LiClO4-碳酸丙烯酯体系的交流阻抗研究

结合扫描电子显微镜, 用交流阻抗法对Li/LiClO_4-碳酸丙烯酯锂电极体系的研究表明, 锂电极表面膜层的生长分三个阶段,相当于两个紧密层和一个疏松层。里紧密层由Li_2CO_3组成, 厚度约10 nm, 是Li~+导体和电子绝缘体, 电阻率为1.4×10~8 Ωcm, 对锂电极的充放电无不利影响。外紧密层由Li_2CO_3和有机物组成。疏松层是在外紧密层表面不断破裂和修复中形成的。它们都不利于锂电极的充放电。     

Capillary condensation in porous materials. Hysteresis and interaction mechanism without pore blocking/percolation process

We have performed measurements of boundary hysteresis loops, reversal curves, and subloops in p+-type porous silicon, a porous material composed of straight non-interconnected pores. These data show that a strong interaction mechanism exists between the pores. The pores of porous silicon are non-independent, whereas they are not interconnected. This hysteretic behavior is very similar to that observed in porous glass, which consists of cavities connected to each other by constrictions. This questions the so-called pore blocking/percolation model developed to explain the behavior of fluid in porous glass. More generally, if we disregard the shape of the boundary hysteresis loops which depends on the porous material (H1 for MCM-41 and SBA-15, H2 for porous glass and p+-type porous silicon), the hysteretic features inside the main loop are qualitatively the same for all these porous systems. This shows that none of these systems are composed of independent pores. A coupling between the pores is always present whether they are interconnected or not and whatever the shape of the main loop is.     

Controlled growth for synthesizing a compact mordenite membrane

Controlling the growth of zeolite crystals on a porous alumina support is essential for preparing a compact zeolite membarne. First, mordenite seed crystals applied on a nonporous -alumina disk were grown and morphological change of mordenite crystals were observed in the course of growth. Then, mordenite membranes were synthesized on a porous -alumina tube under the same conditions employed in the study using the alumina disks. We found that seed crystal growth was widely controllable by changing water content in reaction solution, which resulted in better control of the morphology of mordenite crystals for synthesizing a thin compact mordenite membrane. Separation properties for mordenite membranes were studied in water–hydrogen binary system at 473 K with 10 kPa of water partial pressure, where no capillary condensation was expected in non-zeolitic pores. Separation factor for a mordenite membrane with a few defects was poor; however, a defect-free mordenite membrane prepared under a suitable condition highly separated steam from hydrogen.     

Porous Carbon Fibers Containing Pores with Sizes Controlled at the Ångstrom Level by the Cavity Size of Pillar[6]arene

We report a new synthesis method of fibrous carbon material with pores sizes that are precisely controlled at the Ångstrom level, by carbonization of two dimensional (2D) porous sheets of pillar[6]arenes. The 2D porous sheets were prepared by 2D supramolecular polymerization induced by oxidation of hydroquinone units of pillar[6]arenes. Owing to the hexagonal structure of pillar[6]arene, the assembly induced by 2D supramolecular polymerization gave hexagonal 2D porous sheets, and the highly ordered structure of the 2D porous sheets formed regular fibrous structures. Then, carbonization of the 2D porous sheets afforded fibrous carbon materials with micropores. The micropore size of the fibrous porous carbon prepared from pillar[6]arene was the same size as that of the starting material pillar[6]arene assembly.     

Further studies of a zinc-air cell employing a Zn-PCH (PVA chemical hydrogel) anode

The capacity utilization of zinc anode is usually very low in alkaline solution because of extreme dissolution and the passivation of zinc surface. This problem can be substantially overcome by using the composite electrode of Zn-PCH (PVA chemical hydrogel). In this work, PCH hydrogel film coated on the surface of the ZnO particles can reduce the solubility of the zinc and the concentration of the Zn(OH)₄^2?. The cell with the Zn-PCH electrode reached 150 cycles before its capacity fell below 90% of the initial capacity, while the standard cell failed after 150 cycles. Based on the scanning electron microscopy observation of the Zn-PCH electrode, it shows a distribution of big spherical particles to form a loose and porous structure rather than a dense and compact film, which can help zinc electrode to stay in a loose and porous structure. Such texture is definitely in favor of the diffusion of OH^? ions, facilitating the utilization of active material. Therefore, the Zn-PCH electrode can effectively improve the cycle performance of the secondary Zn-air battery.     

Preparation of new dioxygen-active triphenylantimony(V) catecholate-containing porous polymer

Novel porous polymers with 4-ethoxy-3,6-di-tert-butyl-o-benzoquinone grafted to the porous surface have been prepared via the secondary functionalization of porous polymer monoliths obtained by the photopolymerization of oligo(carbonate dimethacrylate) and hydroxyethyl methacrylate in methanol solution. These quinone-functionalized polymers have been applied for the synthesis of triphenylantimony(V) catecholate-containing polymers by the oxidative addition reaction of quinone moieties with SbPh₃. The obtained antimony-containing porous polymeric material is able to reversibly bind molecular oxygen in nearly quantitative yield. The rate of molecular oxygen sorption is 900 times higher for the porous material than that for the same film material and comparable with the process rate in solution. Copyright © 2016 John Wiley & Sons, Ltd.     

酸浸蚀Al-Si合金制备锂离子电池高性能多孔硅负极材料

本文首次提出利用酸浸蚀Si-Al（含Al 80%）合金粉末的方法制备多孔硅材料. 分析表明制得的多孔硅材料为晶体,并具有由纳米颗粒结集成的海绵状多孔结构,其粒径约20 μm,比表面102.7 m²·g^-1. 多孔硅电极按多孔硅:导电碳:粘结剂 = 1:1:1（by mass）涂成. 在添加15%氟化碳酸乙烯酯（FEC）的1 mol·L^-1 LiPF₆/EC + DMC（1:1,by volume）电解液,在100 mA·g^-1电流密度充放电,多孔硅电极的首次放电比容量2072 mAh·g^-1 Si. 经237次充放电循环后,其放电容量仍可保持在1431 mAh·g^-1 Si,显示了相当高的充放电稳定性. 这归因于其海绵状多孔结构有足够的微空间以承受充电过程中硅的急剧膨胀. 硅微粒的纳米尺寸有利于锂在Li-Si合金中的扩散. 纳米硅微粒可牢固地联成一整体,不易因膨胀、收缩而粉化断裂. 这种构筑多孔硅负极材料的新方法操作简便、成本低廉,有着很好的应用前景.     

A capillary gas chromatographic column with a porous layer based on a mesoporous material

A procedure for synthesizing an MSM-41-type mesoporous mesophase material (MMM) layer, that is, a layer of a solid porous material with a regular arrangement of nanoscale calibrated pores and a unified geometry, on the inner wall of a capillary column was developed. Because of the high specific surface area of silica, capillary columns with a porous MMM layer on the basis of silica allow the amount of samples introduced to be increased by an order of magnitude compared with the known capillary porous-layer columns. An example of the separation of light hydrocarbons is described. The properties of columns with MMM porous layers are discussed.     

Effect of the conditions of activated carbon synthesis from wood on its porous structure and the specific characteristics of double layer supercapacitors with a sulfuric acid-based electrolyte

For supercapacitors with sulfuric acid electrolyte, a promising carbon material was suggested, namely, activated carbon from waste wood. It was shown how the synthesis conditions of activated carbon affect its porous structure and electrochemical characteristics of supercapacitors on its basis. The changes in the porous material under different synthesis conditions were controlled using the highly informative limited evaporation method, which allows us to obtain complete information about the porous structure of the micro- and mesopores of the material within a relatively short period of time. The negative effect of the excess volume of macropores in the electrode on the capacity and energy based on the dry mass of electrodes was shown experimentally and analyzed. The properties of the synthesized material were compared with those of other carbon materials. The best samples of the developed material possess a specific electric capacity of over 390 F/g.     

百香果皮基原位氮掺杂多孔碳/硫复合正极的制备及储锂性能

以生物质百香果皮为碳源,KHCO3为活化剂,采用同步活化碳化方法制备原位氮掺杂的分级多孔碳材料,将其与单质硫复合制得多孔碳/硫正极材料。通过X射线衍射(XRD)、X射线光电子能谱(XPS)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)等表征技术对制备材料的物相组成、微观形貌、比表面积及孔结构进行研究分析。同时,利用紫外可见吸收光谱研究了多孔碳对多硫化物的吸附作用,用恒电流充放电测试了不同硫含量(60%～80%)的多孔碳/硫复合正极材料的电化学性能。结果表明,制得的多孔碳材料为无定型,具有1 093 m²·g^-1的高比表面积和0.63 cm³·g^-1的孔容;丰富的多孔结构和原位氮掺杂对多硫化物的物理化学协同吸附作用,有效降低了锂硫电池的“穿梭效应”,提高了电池的放电比容量和循环性能。硫含量为60%的多孔碳/硫复合材料,在0.05C和0.2C倍率下可释放1 057.7和763.4 mAh·g^-1的高初始放电比容量,在1C的高倍率下循环300次后的保持率为75%。     

Novel Synthesis of Cu-Schiff Base Complex@Metal-Organic Framework MIL-101 via a Mild Method: A Comparative Study for Rapid Catalytic Effects

The use of metal complex immobilized/decorated porous materials as catalysts has found various applications. As such, finding a new and mild method for synthesis of metal complex immobilized over porous material is of great interest. Immobilized porous materials for styrene oxidation were reported in this work. Immobilized porous material of Cu-Schiff base complex @MIL-101 were described, in which immobilized Cu-Schiff base complex within super cage of a metal-organic framework (MOF)-based porous material, chromium (III) terephthalate MIL-101. They were systematically characterized by using elemental analysis, powder X-ray diffraction, fourier transform infrared spectroscopy, N₂ absorption-desorption, and so on, also used as catalyst for the selective oxidation of styrene to benzaldehyde. Comparatively, the immobilized heterogeneous catalyst of Cu-Schiff base complex@MIL-101 acted as an efficient heterostructure catalyst in the oxidation of styrene to benzaldehyde up to six cycles, and showed superior activity for styrene oxidation over MIL-101.     

In situ fabrication of macroporous polymer networks within microfluidic devices by living radical photopolymerization and leaching

Novel fabrication techniques and polymer systems are being explored to enable mass production of low cost microfluidic devices. In this contribution we discuss a new fabrication scheme for making microfluidic devices containing porous polymer components in situ. Contact lithography, a living radical photopolymer (LRPP) system and salt leaching were used to fabricate multilayer microfluidic devices rapidly with various channel geometries and covalently attached porous polymer plugs made of various photopolymerizable substrates. LRPP systems offer the advantages of covalent attachment of microfluidic device layers and facile surface modification via grafting. Several applications of the porous plugs are also explored, including a static mixer, a high surface area-to-volume reactor and a rapidly responding hydrogel valve. Quantitative and qualitative data show an increase in mixing of a fluorescein and a water stream for channels containing porous plugs relative to channels with no porous plugs. Confocal laser scanning microscopy images demonstrate the ability to graft a functional material onto porous plug surfaces. A reaction was carried out on the grafted pore surfaces, which resulted in fluorescent labelling of the grafted material throughout the pores of the plug. Homogenous fluorescence throughout the depth of the porous plug and along pore surfaces indicated that the porous plugs were surface modified by grafting and that reactions can be carried out on the pore surfaces. Finally, porous hydrogel valves were fabricated which swelled in response to contact with various pH solutions. Results indicate that a porous hydrogel valve will swell and close more rapidly than other valve geometries made with the same polymer formulation. The LRPP-salt leaching method provides a means for rapidly incorporating porous polymer components into microfluidic devices, which can be utilized for a variety of pertinent applications upon appropriate selection of porous plug materials and surface treatments.