双组分无机电解质溶液的纳滤膜分离性能

纳滤膜是20世纪90年代问世的新型分离膜,具有两个显著特点：一是其截留分子量介于反渗透膜和超滤膜之间,约为2002000;另一是纳滤膜的表面分离层由聚电解质构成,一般带有负电荷,因此对无机电解质有一定的截留率．     

硝酸钾真空冷却结晶温度与真空度关联式研究

采用数学建模方法研究了硝酸钾溶液真空冷却结晶操作真空度与冷却结晶终点温度及溶液质量分数的关联式,据此可合理选择硝酸钾真空冷却结晶操作条件。实例验证出当硝酸钾溶液质量分数组成为26.85%NO3-、13.35%C l-、7.79%NH4+时,计算出真空冷却结晶终点温度为293.15 K,结晶真空度为0.015 14 Pa,与实测结果几乎一致。     

Sintering Behavior of Cadmium-Doped Pb(Ni1/3Nb2/3)O3–PbZrO3–PbTiO3 Ceramics

Substituting Cd²⁺ ions into the A and B sites in a Pb(Ni_1/3Nb_2/3)O₃PbZrO₃PbTiO₃ (PNNPZPT) ternary perovskite material made it possible to determine the effects of the Cd²⁺ ion substitution site on sintering behavior. The substitution site of the Cd²⁺ ion was identified by using X-ray photoelectron spectroscopy spectra. Although Cd²⁺ ions were substituted into the A and B sites in PNNPZPT, the Cd²⁺ ions preferred the A site over the B site. When Cd²⁺ ions replaced Pb²⁺ ions, a weight gain was observed during sintering. On the other hand, replacing Ni2 ions with Cd²⁺ ions promoted weight loss. Those weight changes indicated that Cd²⁺ ions change the bonding strength between the B-site cations and the oxygen of the octahedron in a perovskite structure. Density was influenced by the Cd²⁺ ion substitution site, and the A-site-doped compositions had higher densities than the B-site-doped compositions.     

热分解法制备负载型固体碱催化剂—K_2O/γ-Al_2O_3

用浸渍法制备 KNO3 /Al2 O3 样品。所得样品于 973 K下焙烧并抽空 2 h便制得负载型固体碱 K2 O/γ- Al2 O3 。拉曼光谱显示 973 K抽空的样品 KNO3 已完全分解成 K2 O。而 γ- Al2 O3 载体的存在可增强 KNO3 的分解 ,表明了 KNO3 与 Al2 O3 间存在着较强相互作用     

Study on the active centers of methane coupling catalysts by means of fluorescence emission of Eu

Eu³⁺ ion was adopted as a probe to detect the probability of entrance of alkali elements into the crystal lattice of MgO, CaO and La₂O₃ by means of its characteristic emission. Based on the experimental data it is concluded that Li⁺ and Na⁺ ions can substitute Mg²⁺ and Ca²⁺ ions and only a small amount of K⁺ ion can enter into the lattice of CaO. Whilst Li⁺ ion can not enter into the lattice of lanthana. The conclusion of this investigation is in good agreement with that obtained by Lunsford by ESR studies.     

金属离子对水热法制备半水硫酸钙晶须的形貌及粒径的影响

以二水硫酸钙为原料,采用水热法制备了半水硫酸钙晶须。通过单因素实验得出制备半水硫酸钙晶须的较优工艺条件为：反应温度120℃、料浆质量分数2%、反应时间2h、搅拌速度200r/min,此时所得晶须产物平均直径2.4μm,长径比103.9,晶须呈长针状、规则统一,分散性好。探讨了K⁺、Mg²⁺、Cu²⁺、Fe³⁺、Al³⁺对较优工艺条件下制备的半水硫酸钙晶须形貌及粒径的影响,结果表明：金属离子对晶须产物形貌及粒径有显著影响。其中低浓度的Mg²⁺、Cu²⁺有助于获得小直径、高长径比的晶须产物;Al³⁺、Fe³⁺对晶须的生长有较强的抑制作用,特别是低浓度的Al³⁺、Fe³⁺使得晶须的形貌发生明显的变化,导致长径比较低;除K⁺外,金属离子浓度越高,所得晶须产物直径越大,长径比越小,并发生团聚现象,晶须由针状变为短棒状,分散性变差。同时探讨了金属离子的作用机理。     

Removal of phosphate ions with a chemically modified chitosan/metal‐ion complex

The adsorption of metal ions (Mo⁶⁺, Cu²⁺, Fe²⁺, and Fe³⁺) was examined on chemically modified chitosans with a higher fatty acid glycidyl (CGCs), and the adsorption of Cu²⁺ was examined on ethylenediamine tetraacetic acid dianhydride modified CGCs (EDTA‐CGCs) synthesized by the reaction of the CGCs with ethylenediamine tetraacetic acid dianhydride. The adsorption of phosphate ions onto the resulting substrate/metal‐ion complex was measured. Mo⁶⁺ depicted remarkable adsorption toward the CGCs, although all the Mo⁶⁺ was desorbed under the adsorption conditions of the phosphate ions. The other metal ions were adsorbed to some extent on CGCs by chelating to the amino group in the substrate, except for CGC‐1, which had the highest degree of substitution (83.9%). Considerable amounts of Fe²⁺ were adsorbed onto CGCs; however, only a limited number of phosphate ions was adsorbed onto the substrate/metal‐ion complex. As a result, the following adsorbent/metal‐ion complexes gave higher adsorption ability toward phosphate ions: CGC‐4/Cu²⁺, CGC‐4/Fe³⁺, and EDTA‐CGC‐3/Fe³⁺. Where, CGC‐3 is a chemically modified chitosan with the degree of substitution of 26.5 percentage, and CGC‐4 is one with the degree of substitution of 16.0 percentage. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

黄腐酸基Cd2+离子印迹聚合物的吸附性能测试

以改性黄腐酸为功能单体,反相悬浮聚合法制备了Cd²⁺离子印迹聚合物,并研究其吸附性能。动力学模型表明,黄腐酸基Cd²⁺离子印迹聚合物对Cd²⁺的吸附符合准二级动力学吸附模型,相关系数达到0.9977;热力学研究发现,黄腐酸基Cd²⁺离子印迹聚合物吸附重金属离子的形式为单分子层表面吸附,与Langmuir等温吸附模型相符;竞争吸附实验显示,竞争离子Pb²⁺、Cr³⁺存在时,Cd²⁺/Pb²⁺、Cd²⁺/Cr³⁺的相对选择性系数分别为4.32、13.47,说明MFA-IIP对模板离子拥有较强的选择识别性能,竞争离子化合价不同,选择识别性更加显著。     

Reverse osmosis of ionic aqueous solutions on aMFI zeolite membrane

separation of ions from aqueous solutions was performed by reverse osmosis (RO) on an -alumina-supported MFI:-type zeolite membrane synthesized by in-situ crystallization. For the 0.1 M chloride single-salt solutions, the separation efficiency in terms of ion rejection was found to increase with the ion valence in the order r_Al³⁺ > r_Mg²⁺ > r_Na⁺, while the ion and water fluxes changed in the reverse order. The charge density, size, and apparent dynamic hydration number of the ion as well as the mobility of the hydrated ion were found to have critical influences on ion diffusion and water permeation through the polycrystalline zeolite membrane.     

Electrical resistivity of transition metal ion doped Mullite

The electrical resistivity of pure mullite (3Al₂O₃.2SiO₂) varies from 10¹³ ohm-cm at room temperature (r.t.) to 10⁴ ohm-cm at 1400 °C. It was observed that by doping mullite with the 3d-type transition metal ions, e.g. Mn, Fe, Cr and Ti, the resistivity of mullite could be reduced to 10¹¹ ohm-cm, i.e. 1/100 that at r.t. and 1/5 that at 1400 °C. The resistivity of doped and undoped mullite decreased by 6–5 orders at about 500–600 °C but 4–3 orders between this temperature and 1400 °C. The 3d orbital electrons, the oxidation states and the concentration of the transition metal ions as well as the sites of mullite lattice occupied by the ions were found responsible for lowering of resistivity of mullite. Evidence of the presence of Mn²⁺, Mn³⁺, Fe³⁺, Cr³⁺ and Ti⁴⁺ ions in mullite had been obtained which entered the octahedral site. The Ti⁴⁺ ion which substituted Al³⁺ ion in the octahedral site of mullite structure appeared to be the most efficient one to reduce the resistivity. This has been confirmed by the results of activation energy of resistivity/band gap energy, Eg which was the lowest for mullite doped with 1·0 wt% Ti⁴⁺ ion. At 1·0 wt% concentration level, these ions lowered the resistivity of mullite to minimum.