Mn、Fe取代六铝酸盐的结构和甲烷催化燃烧性能

采用化学可控共沉淀法制备了系列取代六铝酸盐LaMe_xAl_12-xO_19-δ（Me＝Fe、Mn）催化剂,研究了焙烧温度和Fe、Mn的离子取代量对催化剂比表面、结构及甲烷催化燃烧活性的影响.结果表明,催化剂前驱物经1000℃焙烧,催化剂中开始有六铝酸盐晶相生成; 当焙烧温度提高到1200℃时,样品主要以六铝酸盐晶相存在.增加Fe、Mn离子取代量可以提高六铝酸盐晶相的结晶度,但同时导致晶粒增大,引起比表面下降.由XPS和TPR分析表明,Mn在六铝酸盐结构中以+2价和+3价混合价态存在,而Fe以+3价形式存在.用Fe和Mn离子取代晶格中的Al³⁺大大提高了六铝酸盐对甲烷催化燃烧活性,当Mn离子的取代数为1,Fe离子的取代数为2时催化剂的活性最高.     

海藻酸凝胶性质对蛋白质扩散的影响

通过观察冷冻干燥海藻酸凝胶的断面扫描电镜(SEM)照片与卵清蛋白从海藻酸凝胶中的释放试验,分析了海藻酸凝胶性质对蛋白质在凝胶中扩散的影响。凝胶的SEM照片可见,海藻酸钙的冷冻干燥颗粒内为较大的圆孔,海藻酸锌凝胶内为较小的长孔,表明海藻酸锌高分子链在凝胶颗粒中的体积分率相对较大同时刚性较强;卵清蛋白从海藻酸凝胶颗粒中释放的试验结果表明,由于上述海藻酸锌凝胶的特性,导致海藻酸锌对卵清蛋白扩散阻滞作用相对较强;根据试验数据计算得卵清蛋白在海藻酸钙、海藻酸锌凝胶颗粒中的扩散系数分别为1.19×10-7、0.07×10-7cm2/s,利用阻滞模型计算得海藻酸锌高分子链在凝胶颗粒中体积分率约为海藻酸钙高分子链在凝胶颗粒中体积分率的1.7倍。     

基于双分子亲核取代反应海藻酸苄酯衍生物的制备与性能

以溴化苄(BnBr)为疏水改性剂,采用双分子亲核取代反应(SN2)制备了海藻酸苄酯衍生物(BAD)。通过FTIR、1HNMR、TGA、UV-Vis、GPC、DLS和Zeta电位分析表征了BAD的结构和性能。结果表明:所得产物取代度接近于溴化苄与糖醛酸的投料比,说明SN2反应活性高、取代度大。改性后,BAD相对分子质量(Mw)由91544降低至79819。在水热驱动作用下BAD形成的胶束聚集体水动力学粒径(dH)为423.4 nm,Zeta电位值为-36.4 mV。并且随pH的增大,其Zeta电位有不断降低的趋势,而dH先升高后降低。随离子强度的增大,dH和Zeta电位都出现先升高后降低的趋势,因此,BAD有一定的胶体界面活性。     

离子取代与六角铁氧体RAM的结构及微波吸收性能

综述了离子取代与六角铁氧体结构、静磁特性、微波吸收性能的关系.表明离子取代可以有效地控制六角铁氧体的Ms,HA等静磁性能,改善其微波电磁性能,使其在亚毫米及毫米波段具有较好的微波吸收特性.对铁氧体在RAM材料中的发展进行展望.     

五种新合成酯基取代的咪唑类离子液体电导率的测定与分析

离子液体的电导率性质反映了离子液体的导电性能,与溶剂中的电离度以及离子的溶剂化能力密切相关。为了研究本实验室合成的5种酯基取代的离子液体的电导率,用DDS307电导率仪测定1-乙酸甲酯基-3-甲基咪唑双三氟甲基磺酰亚胺([MIMCH₂COOCH₃]NTf₂)、1-乙酸乙酯基-3-甲基咪唑双三氟甲基磺酰亚胺([MIMCH₂COOCH₂CH₃]NTf₂)、1-乙酸正丙酯基-3-甲基咪唑双三氟甲基磺酰亚胺([MIMCH₂COOCH₂CH₂CH₃]NTf₂)、1-对甲基苯甲酸甲酯基-3-甲基咪唑双三氟甲基磺酰亚胺([MIMCH₂C₆H₄COOCH₃]NTf₂)和1-对甲基苯甲酸乙酯基-3-甲基咪唑双三氟甲基磺酰亚胺([MIMCH₂C₆H₄COOCH₂CH₃]NTf₂)在二甲基亚砜、甲醇、乙腈和乙酸乙酯中的电导率数据。结果表明,其他条件不变时,在一定浓度范围内,离子液体的电导率随着其浓度的增大而增大;在一定温度范围内,随着温度的升高,离子液体电导率增大;4种溶剂相比电导率从小到大顺序依次为乙酸乙酯、二甲基亚砜、甲醇、乙腈,反映了带酯基的5种离子液体与乙酸乙酯的相互作用。     

海藻酸镁凝胶的制备及其性能研究

在0.05～5 mol/L镁离子浓度范围内制备了一系列具有不同性能的海藻酸镁凝胶，考察了镁离子浓度、镁离子用量、镁盐种类和海藻酸钠M/G比值等因素对海藻酸镁凝胶成胶过程的影响，并测试了不同制备条件下凝胶的力学性能和溶胀性能。结果表明，高离子浓度可将海藻酸镁凝胶的拉伸强度提高到400 kPa以上；采用氯化镁、溴化镁、乙酸镁制备的凝胶力学性能较好。同时海藻酸镁具有成胶慢的特点，不同的制备条件可使凝胶形成时间在1 min～10 h内发生变化，显示了其在可注射水凝胶方面具有良好的应用前景。     

BZN三元系焦绿石陶瓷离子取代改性研究

本文研究了稀土离子Sm3 取代Bi2O3-ZnO-Nb2O5(BZN)基陶瓷Bi(1.5-x)SmxZnNb1.507的A位元素Bi3 后,对其物相结构与介电性能的影响.采用传统电子陶瓷制备工艺制各陶瓷样品.利用XRD、SME等测试手段对样品进行测试,未用Sm2O3取代的纯三元系BZN陶瓷为立方焦绿石单相;当Sm2O3取代量较少时(0相似文献   

金属配合物配体上离子取代基对其部分催化性能影响的研究进展

常规有机取代基在调节催化剂活性方面已经得到广泛的应用与研究。近年来常被用于回收均相催化剂的离子取代基也逐渐被用于调节催化剂的活性。本文着重综述了近十年来离子取代基在调节金属配合物部分催化剂活性方面的研究进展,同时指出了目前离子取代基在调节催化剂催化性能方面存在的问题、挑战及发展方向。     

取代牛磺酸的合成研究进展

牛磺酸和取代牛磺酸既是一类重要的天然氨基酸,也是天然蛋白氨基酸的含硫类似物,具有重要的生理活性.结合作者课题组的研究工作介绍了近年来取代牛磺酸的合成研究进展,特别是作者课题组发展的多种无盐合成法,可以方便地合成高纯度的取代牛磺酸,包括1-和2-单取代牛磺酸,1,1-,1,2-和2,2-二取代牛磺酸.     

阳离子取代石榴石铁氧体纳米材料磁性能研究

通过溶胶凝胶法合成取代的石榴石铁氧体纳米材料单相样品.取代的离子共有7种,分别是Ce3+和Fe3+ 、La3+ 、Nd3+ 、Sm3+ 、Gd3+ 、Dy3+.样品的粒度由Scherrer公式d＝kλ/Bcosθ计算得到,范围在50～60 nm之间.样品的晶体结构通过X-射线衍射仪和X-射线光电子能谱表征.样品的磁性能通过超导量子干涉仪(SQUID)进行表征.本文对影响样品磁性能的因素进行了分析,期望这些新的稀土复合石榴石铁氧体纳米材料能满足磁光材料应用领域对石榴石铁氧体不同饱和磁化强度的要求.     

Chemical Solution Deposition of (Pb1−xCax)TiO3 Thin Films with x∼0.5 as New Dielectrics for Tunable Components and Dynamic Random Access Memories

Calcium lead titanate ((Pb,Ca)TiO₃) thin films, with calcium contents of ∼50 at.%, have been prepared by chemical solution deposition (CSD). Different synthetic sol–gel methods have been used for the preparation of the precursor solutions. 1,3-propanediol, OH(CH₂)₃OH, and water, H₂O, were used as solvents. Lead (II) acetate trihydrate, Pb(OCOCH₃)₂·3H₂O, and titanium di-isopropoxide bis(acetylacetonate), Ti(OC₃H₇)₂(CH₃COCHCOCH₃)₂, were used as reagents of lead and titanium, respectively. Calcium was incorporated into the solutions as calcium acetate hydrate, Ca(OCOCH₃)₂· x H₂O, or as calcium acetylacetonate hydrate, Ca(CH₃COCHCOCH₃)₂· x H₂O. Only the use of calcium acetate led to precipitate-free solutions. Pb(II)–Ti(IV)–Ca(II) sols were obtained when calcium acetate was refluxed with the lead and titanium reagents in a diol–water solvent. These sols led to films with a homogeneous compositional profile. Solutions obtained by mixing a water solution of calcium acetate with a Pb(II)–Ti(IV) sol led to films with a heterogeneous compositional profile in which an interface between the film and the Pt bottom electrode is formed. The films derived from the Pb(II)–Ti(IV)–Ca(II) sols have values of dielectric constant at room temperature of ∼500, which, together with their low leakage currents, low dielectric losses, and tunability, make these films promising for dynamic random access memories and tunable devices.     

Bionanocomposites based on alginate and chitosan/layered double hydroxide with ciprofloxacin drug: Investigation of structure and controlled release properties

In this research work, the antibiotic drug Ciprofloxacin (CFX) was intercalated into interlayer space of Zn/Al layered double hydroxides (LDH) by coprecipitation method and CFX‐LDH nanohybride was obtained. Then, the Alginate/LDH and Chitosan/LDH bionanocomposites were prepared by coating of CFX‐LDH nanohybride with Alginate and Chitosan. The LDH‐CFX nanohybride and the bionanocomposites were characterized using the powder X‐ray diffraction, the scanning electron microscope, the thermogravimetric analyses, and the Fourier transform infrared spectroscopy. In vitro release behavior of the CFX from LDH and bionanocomposites is observed in buffer solution under pH conditions (pH = 1.2, 6.8, 7.4) which have been chosen from a model of the passage materials through the gastrointestinal tract. POLYM. COMPOS., 36:1819–1825, 2015. © 2014 Society of Plastics Engineers.     

壳聚糖对金属离子的吸附选择性

壳聚糖是一种天然高分子化合物,高分子链段中含有-NH2,-OH活性基团,与重金属离子形成配位化合物,可制成高分子吸附剂吸附重金属离子。以Cu^2＋、Zn^2＋和Pb^2＋为研究对象,通过等温吸附的分析,讨论壳聚糖吸附重金属离子的选择性。     

Immobilization of Cr, Cd, Zn and Pb in alkali-activated slag binders

Granulated blast furnace slag is the main component of alkali-activated slag cementitious materials (AASCs). Calcium silicate hydrates with a low Ca/Si ratio, hydrotalcite-type phase, some amounts of hydrogarnets and sodium zeolites form as main AASC hydration products. The microstructure of alkali-activated slag pastes shows a higher amount of gel pore content compared to OPC pastes and, simultaneously, significantly lower amount of capillary pores. The microstructure and phase composition of hydrated slag indicate that they can play an essential role in the immobilization of heavy metals. The properties of alkali-activated slag pastes in the presence of Zn, Cd, Cr and Pb ions were studied. The leaching TANK test was used to evaluate the level of immobilization of particular elements in mortars made containing these elements. It was found that the degree of Cd, Zn and Pb ion immobilization was very high (exceeding 99.9%). The values for Cr⁶⁺ were lower (ca. 99.0%). The strength development as well as microstructure observations are presented in the paper.     

PREDICTION OF BREAKTHROUGH CURVE OF METAL ION ON EXTRACTION CHROMATOGRAPHIC COLUMN

ABSTRACT

A mathematical model to predict the breakthrough curve of metal ion on an extraction chromatographic column was proposed. This model, which is the extension of that proposed in the previous paper (12), consists of the mass transfer equation of metal ion into a polymer gel impregnated with an extractant and the mass balance equation of chromatographic column. SDB (styrene-divinylbenzene copolymer) gels impregnated with CMP (dihexyl-N,N'-diethylcarbamoylmethylphosphonate), CMPO (octyl(phenyl)N,N'-diisobutylcarbamoylmethylphosphine oxide) and the equimolar mixture of CMP and CMPO were prepared. The column experiments for the extraction of Ce(III) from an aqueous solution containing nitrate ion were carried out. The predicted breakthrough curves of Ce(III) for the gels impregnated with CMP and the mixture of CMP and CMPO were in good agreement with the experimental ones. That for the gel impregnated with CMPO, however, overestimated the experimental data. This is due to adhesion among gel particles which is caused by the deliquescence of CMPO and not attributable to the mathematical model. These results suggest that the proposed model is applicable to the prediction of breakthrough curve and available as a design tool of extraction chromatographic column.     

Reaction kinetics of metal deposition via surface limited red-ox replacement of underpotentially deposited metal monolayers

The study of the kinetics of metal deposition via surface limited red-ox replacement of underpotentially deposited metal monolayers is presented. The model system was Pt submonolayer deposition on Au(1 1 1) via red-ox replacement of Pb and Cu UPD monolayers on Au(1 1 1). The kinetics of a single replacement reaction was studied using the formalism of the comprehensive analytical model developed to fit the open circuit potential transients from deposition experiments. The practical reaction kinetics parameters like reaction half life, reaction order and reaction rate constant are determined and discussed with their relevance to design and control of deposition experiments. The effects of transport limitation and the role of the anions/electrolyte on deposition kinetics are investigated and their significance to design of effective deposition process is discussed.     

龙门架在废热锅炉更换吊装中的应用

在合成氨装置二段炉废热锅炉设备整体更换中，应用龙门架吊装方法，汽包挂在龙门架的吊梁下固定原位不动，汽包平台以及与汽包相连的工艺管道也不动，设备更换工期短、方便、快捷、安全性高，对施工现场以及汽包的影响小。     

典型金属材料在模拟海水微生物环境中的腐蚀行为(Ⅰ)模拟生物膜对钢在海水中腐蚀性能影响

根据生物膜的结构特征 ,以含羧酸官能团的 β -D -甘露糖醛酸单元等构成的天然高分子多糖凝胶沉积于电极表面 ,形成模拟生物膜 ,初步建立起模拟微生物腐蚀环境的实验方法 .采用极化曲线及电化学阻抗谱等电化学方法研究了A3钢、 10CrMoAl和E2低合金钢及 1Cr18Ni9不锈钢等材料的腐蚀电化学行为 ,并首次用环境扫描电镜 (E -SEM )表征了附着生物膜金属材料表面 .模拟微生物环境的方法可为揭示复杂的海水环境早期腐蚀过程中微生物因素的作用提供信息     

溶解和离子交换反应中K+的快速测定

离子溶液中快速传递及反应动力学过程的跟踪研究在实验上较为困难 ,为此基于离子选择性电极建立溶液中离子活度即时采集系统 ,并结合活度系数模型准确计算离子浓度 .该方法测定速度快 ,最小间隔为 1s,且所得离子浓度最大偏差小于 2 % .用此方法测定了硫酸钾溶解过程以及钛酸钾离子交换反应过程中钾离子浓度的变化 ,获得传统方法难以测定的数分钟内相关动态过程受溶剂、pH值的影响结果 .该方法可推广应用于研究其他各种动态过程 (如溶解、结晶、沉淀、离子交换、吸附和扩散等过程 )     

铅离子敏化学传感器在陶瓷工业中的应用

以硫化银—硫化铅陶瓷膜为离子载体的铅离子化学传感器对Ｐｂ２＋ 具有很高的灵敏度和选择性,Ｐｂ２＋ 的浓度低到１０－６ｍｏｌ／Ｌ时也呈现Ｎｅｒｎｓｔ 响应;通过标准添加或电势滴定操作,该传感器可应用于陶瓷工业的环保检测和陶瓷材料中的铅、钛、铝及硫酸根的测定。