氟离子选择电极在有机元素微量分析中的应用

以氟化镧单晶为敏感膜的氟离子选择电极,由于操作简便、干扰离子少,可在许多方面用于氟的定量分析。此法在有机氟元素微量分析中也已被应用。我们采用玻璃燃烧瓶分解样品,以柠檬酸钠为吸收液,用氟离子选择电极测定有机物中氟的含量,用格氏作图法处理数据,得到了较好的结果。实验部分(一)仪器与试剂 1.DD-2型电极电位仪(江苏泰县无线电厂)。 2.氟离子选择电极:CSB-F-1型氟化镧     

氟离子选择电极的试制及其性能

氟离子选择电极于1966年提出,系用氟化镧单晶薄膜制成,此后除同类电极外,又有不均态薄膜电极。LaF_3单晶电极,由于其灵敏度高,操作简便,干扰较少,并能在连续自动分析中使用,颇受分析工作者的重视。有关氟离子选择电极文献介绍很多。我们本着“自力更生”的方针,利用     

用氟离子选择电极测定水泥及其原料中的氟

水泥及其原料中的氟通常采用水蒸气蒸馏-硝酸钍滴定法、锆-茜素红比色法测定,这些方法手续烦杂费时。近年来,操作简便,测定快速的氟离子选择电极在硅酸盐分析方面的应用日趋普遍。为了将这一分析技术应用于水泥分析,我们试验了水泥及原料中氟的测定条件,比较了三种络合缓冲液对铝的掩蔽效果,拟定了定方法。实验与讨论 (一)主要仪器和主要试剂 1.氟离子选择电极:自制,氟化镧     

氟离子电极作指示电极自动电位滴定法测定氟

氟离子电极在各方面的应用日渐增多。利用氟离子电极作指示电极以硝酸镧溶液滴定氟。Lingane和Berns进行了研究,但均未见实际应用的详细报道。本文研究了试样经高温水解分离氟后,用氟离子电极作指示电极,自动电位滴定仪控制滴定终点,在酒精溶液中以La(NO_3)_3溶液滴定氟并计算氟化钙的方     

La-金属有机骨架化合物的制备及其除氟性能研究

采用水热合成法制备La-MOFs吸附剂,通过扫描电镜、红外光谱、X-射线粉末衍射和N2吸附-脱附曲线对La-MOFs吸附剂的结构和形貌进行表征,并研究其对水溶液中氟离子的吸附特性.La-MOFs吸附剂为毛线团状球形结构,最可几孔径为15.84nm,比表面积为16.95m2/g.吸附氟离子后形成了氟化镧晶体.考察了硝酸镧...     

全固态离子选择性电极研究进展

离子选择性电极是电化学传感器中重要的研究方向之一.随着科学的进步和发展,传统液接式离子选择性电极显示出越来越多的弊端,因此,人们尝试研制全固态的离子选择性电极.经过了数10年的研究,其已经初步应用到临床化验、环境监测以及工业分析等领域.本文根据固态转接层材料的离子-电子转移原理的不同,将全固态离子选择性电极分为:双电层电容型全固态离子选择性电极、赝电容型全固态离子选择性电极以及双电层电容和赝电容混合型的全固态离子选择性电极,并综述了上述3种不同类型的全固态离子选择性电极的研究进展,阐述了对应的响应机理,并展望了其未来的发展趋势.     

全固态锂离子选择性电极研究

研究了新型载体HPMBP-TOPO体系几种全固态锂离子选择性电极（涂丝电极、单层全固态电极、聚吡咯修饰层内接触电极）的性能。与传统型电极相比，固态电极响应斜率有所降低，而选择性稍有提高。其中聚吡咯修饰层内接触电极性能为最佳，该电极响应斜率为56.7mV/decade，并具有良好再现性和长期稳定性。     

氟离子选择电极的修复

由于氟离子选择电极测氟较为成熟,各校的仪器分析实验都选此实验作为电位分析法的教学内容。在离子选择电极中,氟电极价格最昂贵,每支近200元,而使用寿命却不长(厂方规定为一年左右)。据了解,各校都有一批报废氟电极。笔者采用了一些简单修复方法,使我系实验室六支废旧氟电极获得再生,经修复的电极在     

原位水解-硝酸镧电位滴定法测定钛合金化铣腐蚀溶液中总氟化物

基于氟钛配合物的原位水解以及硝酸镧电位滴定法建立了测定钛合金化铣腐蚀溶液中总氟化物浓度的新方法。在六次甲基四胺(HMTA)缓冲溶液中,氟钛配合物发生原位水解并释放出游离氟离子,以氟离子选择电极(F-ISE)为指示电极进行测定。对影响测定的各项参数(如p H值、HMTA溶液用量、钛离子浓度等)做了条件实验并予以优化。实验结果表明Ti(Ⅳ)浓度在0~20 g/L范围内对于氟离子测定无干扰,方法的相对标准偏差(RSDs,n=6)在0.27%~0.62%之间,加标回收率在99.5%~101.1%之间。此外,本文对氟钛配合物原位水解反应的机理也进行了探讨,溶液中氟钛配合物的主要存在形式为TiF_6~(2-),适宜的酸度是水解反应进行的必要条件,HMTA作为缓冲溶液为水解反应持续进行提供恒定的p H环境,La(NO_3)_3作为氟清除剂降低游离氟离子浓度促进水解反应的进行,伴随滴定过程氟钛配合物发生完全水解。     

氟化石墨的电化学性能研究

对系列氟化石墨及其作为碱性电池正极添加剂的电化学性能进行了研究,考察了氟化石墨作为电极活性材料及用作添加剂时电池的放电行为以及氟化石墨的氟化程度和电极中氟化石墨的含量对电池的放电性能的影响.研究了MnO₂中添加氟化石墨后对电极循环性能的影响,并用XRD比较了几种不同碳材料与氟化石墨的结构特点及MnO₂电极放电前后的状态变化,初步探讨了氟化石墨改善二氧化锰电化学性能的作用机制.     

室温下快速合成超小Fe3+掺杂BiF3纳米粒子

室温下快速合成了Fe³⁺掺杂的BiF₃超小纳米粒子,只需要反应1 min,较小的Fe³⁺离子即可替代BiF₃晶格中较大的Bi³⁺离子.随着Fe³⁺掺杂量的增加,BiF₃：Fe³⁺纳米粒子的粒径不断减小,当Fe³⁺的掺杂量达到0.119时,可以得到尺寸约为6.9 nm的Fe³⁺掺杂BiF₃超小纳米粒子.此外,Fe³⁺离子的掺杂使BiF₃：Fe³⁺-x样品的能带结构发生了显著变化.制备的Fe³⁺掺杂BiF₃超小纳米粒子在光催化剂和荧光材料方面具有潜在的应用价值.     

Study of the reactions of pyridinium poly(hydrogen fluoride) with some ternary oxides

The products of the reaction of pyridinium poly(hydrogen fluoride), PPHF, with KIO₃, Na₂SnO₃, NaBiO₃, K₂CrO₄, Na₂MoO₄ and Na₂WO₄ were KIO₂F₂; Na₂SnF₆; NaHF₂, BiF₃; K₃CrF₆, KHF₂, (PyH)₃CrF₆; NaHF₂, (PyH)₂MoO₂F₄·2NaHF₂; and (PyH)₂WO₂F₄·2NaHF₂, respectively, while KClO₃, KBrO₃ and KIO₄ react with complete decomposition to form KHF₂ as the fluorinated product. This differential reactivity and mode of reaction has been discussed in terms of the oxidation state of the central atom, the nature and strength of the bonds and the complex behaviour of the formed intermediate or fluorinated products that undergo complexation or solvation with pyridine and/or hydrogen fluoride.     

H2S气敏电极的研制、性能及其初步应用

本文报告了用全固态Ag₂S电极做指示电极和全固态氟离子电极做参比电极所研制的H₂S气敏电极的结构、性能及其在印染污水分析中的初步应用。电极的线性范围5×10^-8-1×10^-2MS^2-,响应快,重现性较好。除浓度较高的CN^-、I^-和CNS^-有干扰外,其他常见阴离子无干扰。对印染污水用电极悬空测定(加入稀释法),试液不需任何处理,也不沾污电极。方法简便、快速,能满足控制分析要求。     

Synthesis, structural and spectroscopic characterisation of three di-μ-fluoro-bis[dioxouranyl] complexes

Three novel uranyl complexes with organic phosphine oxide ligands and bridging fluorides have been synthesised and structurally characterised. In [ UO₂(μ-F)(TPPO)_{3 2}][BF₄]₂ · ⁿC₆H₁₄, 1, and [ UO₂(-μF)(TBPO)_{3 2}][BF₄]₂ 2, (where TPPO and TBPO are triphenylphosphine oxide and tri-n-butylphosphine oxide, respectively) two UO₂ ²⁺ moieties are bridged by two fluorides with three additional terminal PO donor ligands coordinated to each uranium centre. The dicationic complexes are both charge balanced by two uncoordinated tetrafluoroborate anions. In the related structure, [UO₂(μ-F)(F)(DPPMO₂)]₂ · 2MeOH (3), terminal fluoride is also coordinated to both uranyl centres (where DPPMO₂ = bis(diphenylphosphine oxide)methane). All three complexes were prepared during attempted syntheses of complexes with tetrafluoroborate directly coordinated to uranium. It is clear from these results that the fluorophilicity of UO₂ ²⁺ causes the abstraction of fluoride from [BF₄]⁻, with the weakly coordinating anion only present as a counter cation in 1 and 2, and absent completely in 3.     

Effect of H2 on the electrical transport properties of single Bi2S3 nanowires

Field effect transistors have been fabricated using Bi2S3 nanowires. Whether the contact is ohmic or non-ohmic, the current of Bi2S3 nanowires was found to increase remarkably in H2 compared to that in a vacuum. Carrier density and mobility within the nanowires and the contact barriers between the nanowires and the electrodes have been extracted using field effect and two-probe current-voltage curves. It was found that H2 enhances electronic mobility and carrier density within the nanowires dramatically. The effect of H2 on the contact barriers was observed to be negligible compared to the other two effects.     

Two New Alkaline Metal Borates with Supramolecular Framework Constructed from 1D {B5}/{B6} Helical Chains

Two new alkaline metal borates containing 1D{B5}/{B6}oxoboron helical chains,namely Na0.5[B5O8(OH)2]0.5[B5O6(OH)2]0.5·0.5H3O(1)and NaKCs[B6O9(OH)3](2)were synthesized under solvothermal conditions.Compound 1 contains the interesting alternative left-and right-handed helical{[B5O8(OH)2][B5O6(OH)2]}2-({B5}-1 and{B5}-2)1D chains and compound 2 possesses the similar[B6O11(OH)3]7-({B6})chains.Their 1D chains are further assembled into 2D layers and 3D supramolecular frameworks through O-H…O hydrogen bonds.In addition,the UV cutoff edge of compounds 1 and 2 is both below 190 nm.     

Phase behaviour of thermotropic banana-shaped compounds under pressure

The phase behaviour of two achiral bent core banana-shaped compounds, the hexyloxy (compound I) and decyloxy (compound II) members of the 1,3-phenylene bis[N-(2-hydroxy-4-n-alkoxybenzylidene)-4'-aminobenzoate] series was investigated under hydrostatic pressures up to 300 MPa using high pressure differential thermal analysis and light transmission methods. The reversible transition sequence crystal (Cr₁)-B₁ phase-isotropic liquid (I), observed at room pressure for compound I, remains in the pressure region up to c 70 MPa. At higher pressures a pressure-induced crystalline phase (Cr_i) appears between the Cr₁ and B₁ phases, its temperature region becoming wider with increasing pressure. The temperature vs. pressure phase diagram shows a triple point of 72.9 MPa and 160.3°C for the Cr₁, Cr_i and B₁ phases, indicating the lower limit of pressure for the Cr_i phase. In compound II the reversible transition sequence crystal (Cr₁)-B₂ phase-I is seen over the whole pressure region, and the temperature range of the B₂ phase remains unaltered. It is concluded that both the B₁ and B₂ banana phases are stable over the whole pressure region studied.     

Two New Borates Built by Different Types of {B9} Cluster Units

Two new belt-like borates Na₄[B₉O₁₄(OH)₃]·0.5H₂O(1) and Na₅[B₉O₁₄(OH)₄](2) have been synthesized under solvothermal conditions. Both compounds contain unprecedented B₉O₁₆(OH)_n^(n+5)-[n=3(1), 4(2)] clusters, which are constructed from four B₃O₃ rings via three BO₄ tetrahedra. Compound 1 exhibits a rare 1D belt with two types of 8-membered ring(MR) windows based on B₉O₁₆(OH)₃^8- clusters. Compound 2 features two different 1D belts built by different B₉O₁₆(OH)₄^9- units, which is first discovered in borate family. UV-Vis diffuse reflectance spectra reveal that compounds 1 and 2 have the cut-off edges below 190 nm, indicating that they may have potential application in deep UV(DUV) region.     

Theoretical studies of third-order nonlinear optical response for B12N12, B24N24 and B36N36 clusters

In this paper, we have calculated the third-order nonlinear optical polarizabilities corresponding to three optical processes: third-harmonic generation (THG), electric-field-induced second-harmonic generation (EFISHG) and degenerate four-wave mixing (DFWM) for B₁₂N₁₂, B₂₄N₂₄ and B₃₆N₃₆ clusters. The calculations have been performed by employing ab initio time-dependent density functional theory combined with sum-over-states method (SOS//TDDFT). We obtained the similar dynamic behavior of third-order NLO polarizabilities for three BN clusters. At input photon energy below 1.25 eV, the resonance enhancements of response haven't occurred. This is due to the fact that the calculated BN clusters have the large transition energy. B₂₄N₂₄ cluster has the larger transition dipole moments and the third-order polarizabilities of B₂₄N₂₄ are much larger than those of B₁₂N₁₂ and B₃₆N₃₆. We also estimate the static third-order optical susceptibility χ⁽³⁾ for BN fullerene materials from the average static third-order polarizability <γ>. The static χ⁽³⁾ of B₂₄N₂₄ fullerene materials are 1.36×10⁻¹⁴ esu for three NLO processes.     

B2O3对Ag/TiO2-Al2O3吸附剂的柴油吸附脱硫性能影响

采用浸渍法制备了不同B₂O₃负载量(e.g. 5%~20% (w))的Ag/TiO₂-B₂O₃-Al₂O₃吸附剂。以含硫量为245.36mg(S)/L 的商业柴油作为考察对象,常温常压下采用静态评价进行吸附脱硫性能研究。结果表明,B₂O₃改性后的Ag/TiO₂-Al₂O₃吸附剂的柴油吸附脱硫活性有了较大提高,当B₂O₃的负载量为15%时,吸附剂的吸附脱硫活性最高,2%Ag/4%TiO₂-15%B₂O₃-Al₂O₃ (w)的饱和吸附硫容达到2.36mg(S)/g 吸附剂。这对于未经预处理的商业柴油而言,吸附脱硫活性已经达到较高水平。采用N₂物理吸附、O₂化学吸附、X射线衍射(XRD)、NH₃程序升温脱附(NH₃-TPD)、傅里叶红外光谱(FT-IR spectra)、¹¹B核磁共振(¹¹B-NMR)等表征手段对不同负载量B₂O₃改性Ag/TiO₂-Al₂O₃吸附剂的织构性质、晶相结构和表面酸性的影响进行研究。关联活性测试和表征结果发现,吸附剂的吸附脱硫活性主要与吸附剂的表面弱酸性有关,而B₂O₃改性在吸附剂表面引入了较多的四配位的BO₄物种,能显著增加吸附剂表面弱酸性位点数量,提高吸附剂的吸附脱硫活性。