纳米孔材料与形貌控制

纳米孔材料可做以下简单分类,即微孔材料(孔径小于2.0nm)、介孔材料(孔径介于2.0~50.0nm)     

不同模板剂制备介孔纳米γ-氧化铝及表征

分别以十二烷基苯磺酸钠(DBS)、溴化十六烷基三甲铵(CTAB)和吐温-80(TW-80)为模板剂,以硝酸铝为铝源,采用溶胶-凝胶法制备介孔纳米γ-氧化铝。用X射线衍射(XRD)、氮气吸附-脱附、透射电镜(TEM)对样品进行表征;考察了模板剂的种类及用量对产品性能的影响。实验结果表明:采用3种不同模板剂合成的前驱体经550℃煅烧所得产物均为具有孔道结构的介孔纳米γ-氧化铝,其中采用CTAB为模板剂合成的样品其比表面积为551.8 m2/g,平均孔径为6.68 nm,孔径分布较窄(2~16 nm),孔容为0.922 cm3/g,比采用另外两种模板剂合成的样品其孔道分布更均匀,排列更规则致密,孔径分布明显变窄,比表面积有一定程度的增大。     

碳材料吸附脱除二氧化硫性能的影响因素

选用了7种不同物理化学特性的碳材料,分别为活性炭-1（比表面积1779m²/g）、活性炭-2（比表面积970m²/g）、多孔纳米炭-1（平均孔径14nm）、多孔纳米炭-2（平均孔径85nm）、多孔纳米炭-3（平均孔径4.7nm,掺氮）、多孔纳米炭-4（平均孔径4.1nm,不掺氮）和纳米碳纤维。在对比这7种不同的碳材料的物理化学特性与其脱硫性能的基础上,研究材料的物理化学特性、脱硫温度、反应空速等因素对碳材料吸附脱除SO₂性能的影响。结果表明,碳材料吸附脱除SO₂的性能受材料的比表面积、孔隙结构、表面官能团、脱硫温度和反应空速的综合影响。不同的碳材料中,材料的孔隙结构和表面官能团对材料的脱硫性能影响很大,以微孔结构为主的碳材料SO₂去除率较高,以介孔结构为主的碳材料脱硫容量较高;随着脱硫温度升高,碳材料的吸附脱硫性能降低;随着反应空速降低,碳材料的吸附脱硫性能升高。本研究中,多孔纳米炭NCP-10的吸附脱除SO₂性能最好,能在室温下保持100%的SO₂去除率持续1h,且在室温下1h内累积的脱硫容量最高可达108mg(SO₂)/g(材料)。     

不同孔径活性炭吸附挥发性有机物的分子模拟

借助Materials Studio软件建立了0.902nm、1.997nm、3.000nm、4.000nm孔径的活性炭狭缝孔模型,采用巨正则蒙特卡洛模拟（Grand Canonical Monte Carlo）的模拟方法计算了其对挥发性有机物（VOCs,如异己烷、苯、甲苯、丙酮和甲醇）的吸附数据,考察了活性炭孔径的变化对VOCs吸附性能的影响,并对实际应用进行指导。模拟结果显示：活性炭对VOCs的吸附受孔径和吸附能的共同影响,在293.15K、各物质饱和蒸气压p₀下,随着孔径的增大,吸附质吸附剂之间的亲和力呈下降趋势。活性炭孔径由0.902nm增加到4.000nm对异己烷、苯、甲苯的饱和吸附量逐渐增大,而4.000nm孔径活性炭对丙酮饱和吸附量小于3.000nm孔径活性炭,3.000nm、4.000nm孔径活性炭对甲醇饱和吸附量小于1.997nm孔径活性炭。在工业废气VOCs吸附回收中选择0.902～1.997nm孔径活性炭能够达到最佳效果。     

纳米介孔氧化铝制备及表征

以氯化铝和氨水为原料,并在反应体系中加入一定量的非离子表面活性剂聚乙二醇(PEG),通过沉淀-共沸蒸馏-煅烧的方法制备出纳米介孔氧化铝粉体(γ-Al2O3).借助透射电镜、粉末X射线衍射、N:吸附-脱附等先进仪器对所制备的氧化铝进行表征.实验结果表明所得氧化铝在800℃煅烧2 h后可以转变成孔径分布比较集中、结构较为稳定的纳米介孔γ-Al2O3,其平均孔径为13.77 nm,比表面积为199.37 m2/g.该方法原料便宜,实现了纳米介孔氧化铝的低成本制备.     

聚乳酸接枝丙烯酸纳米孔纤维膜制备及其细胞相容性研究

以V(二氯甲烷)/V(N,N-二甲基甲酰胺)=4∶1为溶剂,通过电纺制备直径为(650±60)nm,孔径为96 nm×72 nm聚乳酸(PLLA)纳米孔纤维膜。利用氧等离子体处理将亲水性单体丙烯酸(AA)接枝到纤维表面制备聚乳酸接枝丙烯酸(PLLAg-PAA)纳米孔纤维膜。与PLLA纳米孔纤维膜相比,PLLA-g-PAA纳米孔纤维膜的水接触角从(119.4±1.2)°降低到(42.3±0.6)°,拉伸强度、杨氏模量和断裂伸长率略有降低。将牙髓干细胞(DPSCs)在纤维膜支架上培养,细胞生长密度顺序为PLLA-g-PAA纳米孔纤维膜PLLA纳米孔纤维膜PLLA纤维膜。由于PLLA-g-PAA纳米孔纤维膜表面粗糙,比表面积大,孔隙率高和表面亲水性好,更有利于细胞的粘附、迁移、分化和繁殖。PLLA-g-PAA纳米孔纤维膜有望成为优良的组织工程支架材料。     

极性单体改性St-DVB吸附树脂的合成及性能研究

采用悬浮聚合方法制备了经极性单体丙烯腈AN(或甲基丙烯酸甲酯MMA)改性的聚丙烯腈AN(或MMA)-苯乙烯(St)-二乙烯基苯(DVB)共聚树脂ASD(或MSD).对ASD、MSD树脂做了红外吸收光谱分析,说明普通St-DVB大孔吸附树脂可被丙烯腈等成功改性;测定了ASD、MSD树脂的孔结构参数,总结了极性单体对树脂孔结构的影响;采用动态吸附法测定了合成树脂对水溶液中苯酚的吸附性能,归纳了极性单体的加入量、极性和树脂的交联度对ASD、MSD树脂吸酚能力的影响.     

不同活化剂对石油焦基活性炭孔结构的影响

以石油焦为原料 ,Na OH,KOH和 Na2 CO3 为活化剂制备活性炭 ,采用氮气吸附考察了不同活化剂对活性炭的比表面积、中孔和微孔孔径分布、孔容积及平均孔径等孔结构的影响 .结果表明 :KOH活化制备的活性炭包含 1 nm的微孔和 4nm的中孔 ,总孔容 0 .648cm3 /g,比表面积大 ;Na OH制备的活性炭以 1 nm的微孔为主 ,占总孔容 ( 0 .1 65 cm3 /g)的 98% ,平均孔径 1 .83nm;Na2 CO3 制备的活性炭以 4nm的中孔为主 ,占总孔容 ( 0 .1 43cm3 /g)的 68.5 % ,平均孔径 3.42 nm,比表面积小 .3种样品的孔径都呈现出多峰分布特征 .KOH和 Na2 CO3 活化制备的活性炭的 N2 吸附脱附曲线属于 型 ,Na OH活化制备的活性炭吸附脱附曲线属于 型 .     

活性炭孔结构对甲苯及丙酮吸附性能的影响

采制3种活性炭样品进行甲苯、丙酮吸附实验,以重量法计算活性炭对甲苯、丙酮气体的饱和吸附率,并将活性炭物性参数与其关联。结果表明,活性炭物性与其对有机物的吸附性能密切相关,活性炭碘吸附值、总比表面积与甲苯吸附率成明显的负相关,较高中孔与总孔比(V_(mes)/V_t)会促进对甲苯的有效吸附;微孔比表面积和孔容积越大,活性炭对丙酮的吸附效果越好。此外,线性回归分析的结果表明,活性炭中孔径小于1.4 nm的微孔及合理的孔径分布对甲苯的吸附起主要作用,孔径1.67～2.22 nm是吸附丙酮的有效孔径。     

树枝状介孔氧化硅及其复合颗粒的制备和压缩弹性模量

以正己烷、三乙醇胺、正硅酸乙酯和十六烷基三甲基溴化铵等为主要原料,采用改进的油水两相反应体系制备树枝状介孔氧化硅(DMS)颗粒;再以硝酸亚铈为铈源、六亚甲基四胺为缓释沉淀剂,在DMS表面均匀包覆Ce O_2纳米粒子,得到核壳结构DMS/Ce O_2复合颗粒。利用扫描电子显微镜、透射电子显微镜、小角度X射线衍射仪、选区电子衍射和氮气吸附–脱附等手段对样品进行结构表征。借助原子力显微镜力曲线技术,评价单个颗粒与探针之间的弹性接触,结合DMT模型拟合计算被测样品的压缩弹性模量。结果表明:DMS颗粒(约92 nm)内部存在中心三维树枝状介孔孔道,平均孔径约6.9 nm;复合颗粒的平均粒径约106 nm,Ce O_2纳米粒子(5～8 nm)在内核表面均匀包覆形成薄层。DMS颗粒的弹性模量为(3.7±1.2)GPa,对比发现增大孔径有助于介孔氧化硅弹性响应的提高。复合颗粒的模量(6.6±1.9)GPa显著低于Ce O_2块体材料,更接近于DMS内核,表明其弹性行为由内核所提供,壳层粒子可提高颗粒的整体表面硬度。     

Molecular simulation of CH4 adsorption behavior in slit nanopores: Verification of simulation methods and models

The aim of this study is to select an appropriate method for CH₄ adsorption in organic nanopores for shale-gas development. Molecular dynamics (MD) and grand canonical Monte Carlo (GCMC) simulations were performed. Three comparison studies were included: (i) comparison of the adsorption behavior in kerogen nanopores using different schemes for dispersion correction, (ii) comparison of the adsorption behavior in graphite nanopores using MD and GCMC simulations, and (iii) comparison of the adsorption behavior in kerogen and graphite nanopores using MD simulations. The result was reliable when using a particle-mesh Ewald scheme or a cut-off ≥1.5 nm without dispersion correction. The simulation results were essentially identical for the MD and GCMC simulations. The free-gas CH₄ density inside the nanopores started to deviate from the bulk density at ~2 nm for the graphite model and at ~7–10 nm for the kerogen model, whereas the total CH₄ density deviates from the bulk density at ~20 nm.     

以辛胺为模板剂制备空心SiO2微球

以辛胺为模板剂,正硅酸乙酯为前驱体,在酸性条件下,制备出空心SiO2微球,运用SEM、XRD、N2吸附、IR、TG-DTA等测试手段对所制备的产物进行了表征。结果表明:制备的空心SiO2微球表面光滑、分散性较好;空心SiO2微球具有双模孔结构,其中的介孔孔径为2.1nm,微孔孔径为0.62nm。试样的比表面积和孔容分别是1123m2/g,0.6291mL/g。     

Electrochemical study of the diffusion of cytochrome c within nanoscale pores derived from cylinder-forming polystyrene-poly(methylmethacrylate) diblock copolymers

This paper reports cyclic voltammograms of cytochrome c on recessed nanodisk-array electrodes (RNEs) based on nanoporous films (11, 14 or 24 nm in average pore diameter; 30 nm thick) derived from polystyrene-poly(methylmethacrylate) diblock copolymers. The faradic current of cytochrome c was observed on RNEs, indicating the penetration of cytochrome c (hydrodynamic diameter ≈ 4 nm) through the nanopores to the underlying electrodes. The faradic current on RNEs with 11- and 14-nm nanopores mainly originated from cytochrome c adsorbed on the underlying electrodes, whereas the current on RNEs with 24-nm pores was diffusion-controlled. Interestingly, the diffusion-controlled current of cytochrome c was significantly smaller than that estimated from the faradic current of 1,1′-ferrocenedimethanol on the RNEs. The smaller faradic current suggested more effective decrease in the diffusion coefficient of cytochrome c as compared to that of 1,1′-ferrocenedimethanol, which probably reflected enhanced steric and chemical interactions within the nanopores. Comparison between experimental data and results of finite-element computer simulations made it possible to assess the structure of the nanoporous films and the diffusion coefficients of redox species within the nanopores.     

Evaluation of carbon nanopores using large molecular probes in grand canonical Monte Carlo simulations and experiments

Nanopores (pores between 1 and 5 nm) have been the object of a great deal of attention because they can selectively adsorb relatively large molecules such as macromolecules and polymer molecules. Conventional methods for analyzing porous structures—such as N₂ adsorption measurements at 77 K—can be used to investigate microporous and mesoporous structures, but there is a lack of investigation of nanopores or the boundary between micropores (<2 nm) and mesopores (2–50 nm). Here, we propose the evaluation method of nanopores using a large probe molecule, SF₆. Grand canonical Monte Carlo simulations for N₂ and SF₆ suggested that SF₆ was adsorbed in 1.5–5 nm nanopores, while there was N₂ adsorption for the wide range of pore sizes. The SF₆ adsorption could therefore be used to confirm existence of the nanopores. To test this, we used single-walled carbon nanohorns as porous carbons with widely distributed pore size. SF₆ was well adsorbed only in the nanopores at 195 K, whereas N₂ adsorption was observed in all micropores and mesopores. This structural analysis of nanopores using a large-molecule probing method complements structural analyses using N₂ adsorption, as well as other techniques.     

Removal of tannic acid from aqueous solution by magnetic carbohydrate natural polymer

Adsorptive removal of tannic acid (TA) form aqueous solution by synthesized magnetic lignocellulosic adsorbent was investigated. SEM, EDAX, and FTIR analysis were performed to characterize the magnetic saw dust (MSD). The effect of various operational parameters such as contact time, concentration and solution pH etc were studied. The optimum adsorption of TA was observed at pH 4. Results revealed that the Temkin isotherm model fitted well to the adsorption equilibrium data and obeyed the pseudo-second order kinetics model. The values of free energy change and activation energy suggested that physical forces were involved in the adsorption of TA onto MSD.     

甲苯法生产己内酰胺水溶液的吸附精制工艺试验研究

以活性炭、活性炭纤维及离子交换树脂作为吸附剂，在甲苯法己内酰胺水溶液中试验了不同吸附剂对己内酰胺水溶液中杂质的吸附能力。结果表明，当光密度均降低30％时，采用活性炭吸附，对己内酰胺中有机杂质的动态吸附容量为26．7mL／g；活性炭纤维杂乱填充时的动态吸附容量为67．48mL／g；强碱性离子交换树脂IAR900的动态吸附容量为46．66mL／mL。提出了活性炭纤维与离子交换树脂组合吸附工艺，当光密度均降低50％时，动态吸附容量为36．67mL／g，该组合工艺能有效去除己内酰胺水溶液中的杂质，提高了产品的质量。     

酚类化合物在矿化垃圾中的吸附机理研究

研究了苯酚、2-氯酚、4-氯酚、2,4-二氯酚在矿化垃圾中的吸附性能,并从动力学和热力学角度探讨了有机酚在矿化垃圾中的吸附机理。等温吸附曲线研究表明,在试验的浓度范围内,有机酚在矿化垃圾中的吸附符合Freundlich等温吸附方程。有机酚在矿化垃圾中的吸附动力学符合二级反应动力学方程,反应受孔扩散和内部扩散共同控制。在试验的温度范围内,有机酚在矿化垃圾中的吸附是一个自发过程,温度对吸附反应的自发性有着显著的影响,自由能随着温度的升高而降低,自发性增强。     

Adsorption behavior modeling of confined hydrocarbons in shale heterogeneous nanopores by the potential theory

In this article, a new method is proposed to quantificationally evaluate the effect of pore heterogeneity on the adsorption behavior of fluids in nanopores. First, the assumptions of furrowed, sinusoidal, and ravine pore surfaces are proposed to represent the heterogeneous nanopores in shale. Under the assumptions, a multicomponent potential theory of adsorption (MPTA) is coupled with Peng–Robinson equation of state (PR EOS) to model the adsorption behavior of hydrocarbons in nanopores. And, the geometrical and chemical heterogeneities in shale nanopores are, respectively, simulated by a spatial alteration and an amplitude deformation on potential energy. The fluid–fluid interaction is modeled by PR EOS, and the fluid-pore wall surface interaction is simulated by a Steel 10-4-3 model for slit-like nanopores and by a modified Lennard–Jones (LJ) 12-6 model for cylindrical ones. Thereafter, the results of our theory are compared against the experimental data of shale rocks to validate its accuracy.     

Light-controlled ion transport through spiropyran-modified nanoporous silica colloidal films

The transport of positively charged redox active species through spiropyran-modified nanopores in silica colloidal films was controlled using light. The silica colloidal films were comprised of 18 layers of face centered cubic (fcc)-packed 170 nm silica spheres. The surface of the films was first modified with amines, which were then used to attach the spiropyran moiety to the surface. The limiting current of a positively charged redox active species through the spiropyran-modified nanopore decreased after irradiation with UV light at pH 6.6. When the silica colloidal film was subsequently irradiated with visible light the initial limiting current was restored.     

二氧化硅自有机溶剂中吸附丁酸十二铵的研究

测定了２９８２Ｋ时二氧化硅ＣＡＢ Ｏ ＳＩＬ自环己烷、苯、甲苯、氯苯和邻二氯苯五种有机溶剂中吸附丁酸十二铵（ＤＡＢ）的等温线。ＣＡＢ Ｏ ＳＩＬ自不同溶剂中吸附ＤＡＢ的多少依次是：环己烷＞邻二氯苯＞甲苯≈苯＞氯苯。吸附等温线都可用Ｌａｎｇｍｕｉｒ公式代表，由此求得的各体系的ＤＡＢ单分子层饱和吸附量很接近，平均相当于每个ＤＡＢ分子约占据０７０４ｎｍ２。实验表明吸附了ＤＡＢ后的ＣＡＢ Ｏ ＳＩＬ微粒可大大提高其在有机溶液中的分散稳定性。讨论了吸附层的结构、性质以及对二氧化硅微粒分散稳定性的影响。