3,5-diBr-DMPAP选择性光度法测定乳粉中微量铁

建立了一种在表面活性剂TritonX -1 0 0存在下 ,用 2 -(3 ,5 -二溴 -2 -吡啶偶氮 ) -5 -二甲氨基酚 (简称 3 ,5 -diBr-DMPAP)作显色剂选择性测定乳粉中微量铁的新方法。结果表明 ,在pH 4 0的乙酸 -乙酸钠缓冲液中 ,以 746nm为测定波长 ,可选择性测定乳粉中微量铁 ,本法线性范围为 0～ 1 2 5 μg· (1 0mL) - 1,表观摩尔吸光系数为 2 83× 1 0 4 L·mol- 1·cm- 1,回收率为 98 1 %～ 1 0 2 4% ,批内和批间变异系数 (CV)分别为 2 5 %与 3 1 %。该法具有操作快速、简便、结果灵敏可靠等优点。     

新显色剂2-[2,3,5-三氮唑偶氮]-5-二甲氨基苯甲酸与铜的显色反应研究及应用

合成了 2 [2 ,3,5 三氮唑偶氮 ] 5 二甲氨基苯甲酸 (TZAMB) ,并研究了试剂与铜的显色反应。结果表明 ,在 0 .1mol·L- 1H3PO4 介质中 ,试剂与铜形成紫红色配合物 ,配合物至少稳定2 4h ,最大吸收波长位于 5 75nm处 ,表观摩尔吸收系数为 4 .2 3× 10 4 L·mol- 1·cm- 1,配合物的组成为 ηCu∶ηTZAMB=1∶2 ,铜浓度在 0～ 1.2mg·L- 1范围内服从比耳定律 ,所拟方法已用于镁合金和铝合金中微量铜的测定 ,试验结果与标准值相符 ,RSD为 0 .0 75 %～ 0 .5 1%。     

2-(5-溴-2-吡啶偶氮)-5-二乙氨基苯酚与二氯化双(丁氧羰乙基)锡的显色反应及其应用

在pH 2 .7的HAc NaAc缓冲溶液中和有TritonX 1 0 0存在下 ,二氯化双 (丁氧羰乙基 )锡 (简写为R2 SnCl2 )与 2 (5 溴 2 吡啶偶氮 ) 5 二乙氨基苯酚 (5 Br PADAP)形成 1∶1紫红色络合物 ,络合物的最大吸收波长为 5 0 5nm ;表观摩尔吸光系数 1 0 5× 1 0 5L·mol- 1 ·cm- 1 。R2 SnCl2 中的Sn浓度在 0 .0 6～ 1 .3 0mg L范围内符合比尔定律。方法用于PVC中间产品及污水中R2 SnCl2 的测定 ,结果满意。相对标准偏差分别为 2 4%和 4 5 % ;回收率在 95 4%～ 98 2 %之间。     

7-碘-8-羟基喹啉-5-磺酸与钒显色反应的研究及应用

在 0 .2 0mol·L- 1硫酸介质中 ,用过氧化氢作增敏剂 ,7 碘 8 羟基喹啉 5 磺酸 (Ferron)与钒 (Ⅴ )形成 1∶1的有色配合物 ,在 4 10nm处有最大吸收 ,其表观稳定常数为 4 .5× 10 3 ,摩尔吸光系数ε4 10 为 1.91× 10 3 L·mol- 1·cm- 1,钒浓度在 0 .10～ 2 0 .0 μg·ml- 1范围内符合比耳定律。该方法用于矿样中钒的测定 ,结果满意     

新试剂1-(2,6-二氯-4-硝基苯)-3-(4-硝基苯)-三氮烯与镉的显色反应及应用研究

研究了新试剂 1 -( 2 ,6 -二氯 -4 -硝基苯 ) -3 -( 4-硝基苯 ) -三氮烯与镉的显色反应。在 Triton X-1 0 0存在下 ,于 p H=9.8～ 1 1 .0的 Na2 B4 O7-Na OH缓冲溶液中 ,镉与试剂有高灵敏的显色反应 ,生成 1∶ 3型黄色配合物 ,最大吸收波长为 44 5nm。用双峰双波长法测定 ,其表观摩尔吸光系数为 2 .85× 1 0 5L·mol- 1·cm- 1。用拟定的方法测定了人发和废水中的镉含量 ,标准加入回收率分别为 1 0 4.5%和 1 0 5.8% ,相对标准偏差分别为 3 .2 %和 4.1 %。     

新试剂5-(4-氯苯基偶氮)-8-苯磺酰氨基喹啉光度法测定微量铜

在 p H 8.5的 Na2 B4 O7- HCl介质及有氯化十六烷基吡啶 ( CPC)存在时 ,室温下铜 ( )与 5 - ( 4 -氯苯基偶氮 ) - 8-苯基磺酰氨基喹啉 ( CPBSQ)迅速反应 ,生成络合比为 1∶ 3的有色络合物。研究了反应的最佳条件 ,建立了一个测定 Cu( )的光度分析新方法。Cu( )的浓度在 0～ 1 4.0 μg/2 5 m L 范围内符合比耳定律 ,其摩尔吸光系数为 8.1 2× 1 0 4 L· mol- 1· cm- 1。方法用于面粉、茶叶及奶粉中铜的测定 ,其相对标准偏差为 0 .5 8%～ 1 .2 % ,标准加入回收率为 95 .5 %～ 1 0 4 .5 %。     

用NP-7作增敏剂间接光度法测定微量锰

研究了七种表面活性剂对微量Mn(Ⅱ )测定的增敏效果 ,确定了用NP 7作增敏剂 ,用铋酸钠作氧化剂间接光度法测定微量Mn(Ⅱ )的方法。Mn(Ⅱ )在 0 .0 2 5～ 0 .0 82mmol·L-1遵循比耳定律 ,表观摩尔吸收系数为 1 .68×1 0 4L·mol-1·cm-1(3 63nm) ,用该法测定了邻苯二甲酸原料中锰 ,结果与原子吸收光谱法一致。RSD为 0 .5 0 % ,回收率在 98.0 4%～ 98.5 7%之间     

应用2-(5-硝基-2-吡啶偶氮)-5-二甲氨基苯胺同时测定铑与钯

提出了以 2 - ( 5-硝基 - 2 -吡啶偶氮 ) - 5-二甲氨基苯胺 ( 5- NO2 - PADMA)作为铑、钯同时测定的新光度试剂。钯与试剂可在 0 .3～ 3.9mol/L 的高氨酸介质中形成稳定的配合物 ,其最大吸收位于 62 1 nm处 ;而铑与试剂则在 p H=5.2 5～ 6.75的近中性介质中定量配合 ,配合物一旦形成则很稳定 ,向其中加入强酸酸化该配合物不仅不被分解反而吸收红移、吸光度增大 ,同时二者的吸光度具有良好的加和性。基于二者显色酸度的差异 ,建立了铑、钯同时测定的新方法。方法的灵敏度为 εRh62 0 =1 .39× 1 0 5L·mol-1·cm-1;εPd62 0 =9.4× 1 0 4 L· mol-1·cm-1。铑浓度在 0～ 0 .56、钯浓度在 0～ 1 .4μg·m L-1范围内服从比耳定律。可用于工业样品中微量铑、钯的测定。     

HPLC法测定除草剂二甲戊乐灵中亚硝胺

介绍用高效液相色谱外标法测定除草剂二甲戊乐灵中 N- ( 1 -乙基丙基 ) - N-亚硝基 - 3,4-二甲基 - 2 ,6-二硝基苯胺含量的方法。用 C8反相柱 ,水∶乙腈 =35∶ 65为流动相 ,在 2～ 30 μg·ml-1内线性良好 ,其线性回归方程为 Ai× 1 0 -6=1 .2 354× 1 0 4 Wi+ 0 .0 2 0 9,相关系数为 0 .9988,RSD为 0 .0 2 % ,加标回收率为 99.81 %～ 1 0 0 .2 9% ,最低检出量为 65ng     

在二甲亚砜中La—Fe合金膜电化学制备的研究

研究了二甲亚砜 (DMSO)中La3 和Fe2 在Pt ,Cu和Ni电极上的电化学行为。Fe2 在Pt电极上一步不可逆还原为Fe ,La3 在Pt电极上表现为准可逆电极过程。在 2 98K时 ,利用循环伏安法测定了 0 0 1mol·L- 1 FeCl2 0 1mol·L- 1 LiCl DMSO溶液中Fe2 的扩散系数、传递系数分别为 2 5 4× 10 - 6 cm2 ·s- 1 和 0 2 4;利用计时电流法测定了 0 0 1mol·L- 1 LaCl3 0 1mol·L- 1 LiCl DMSO溶液中La3 的扩散系数为 3 10×10 - 6 cm2 ·s- 1 。在铜电极上于 -1 75 0～ -2 45 0V (vs .SCE)下恒电位电解 ,可获得La含量达 2 2 7%～ 3 7 1%的La Fe合金膜 ;应用脉冲电解技术于 2～ 6mA·cm- 2 也可获得La Fe合金膜。这些合金膜是均匀的 ,粘附性好并有金属光泽     

WO3纳米颗粒修饰ZnO纳米管的光催化性能

二甲四氯钠(MCPA-Na)是一种广泛用于牧场和果园的除草剂,但由于其生物降解性极低,已成为地下水和浅水中的主要污染物.研究发现,半导体可以有效地辅助降解转化危险化学品.ZnO纳米管因其中空结构和较大的比表面积,而在光催化降解有机物方面备受关注.但是,ZnO只能吸收紫外光,如果将其与窄带隙半导体进行复合,可以有效降低带隙,增强其在可见光区域的光吸收,表现出更好的光催化性能.WO3是一种具有稳定物理化学性质及耐光腐蚀窄带隙半导体.采用WO3修饰ZnO纳米管,能扩展ZnO吸收光的范围以及提高ZnO纳米管的耐光腐蚀性能.本文首先通过电化学合成的方法制备了ZnO纳米管,然后按照不同的W/Zn摩尔比将(NH4)6H2W12O40·XH2O滴加在纳米管表面,并在450 ℃下退火2 h制得ZnO-WO3纳米管阵列.研究了不同WO3含量的ZnO-WO3纳米管光催化降解MCPA-Na性能,并且通过X射线光电子能谱(XPS)、傅里叶红外光谱仪(FTIR)、紫外可见光谱(UV-Vis)和光致发光光谱(PL)等手段研究了复合WO3纳米颗粒后ZnO纳米管半导体光催化性能提高的原因.XPS结果表明,W元素在ZnO-WO3纳米管阵列中以W6+的形式存在.FTIR结果表明,复合WO3后的ZnO-WO3复合半导体上比纯ZnO纳米管表面具有更多的OH-基团.由于OH-可以捕获光生空穴,并转化为具有反应活性的●OH自由基,因此复合WO3能在一定程度上提高ZnO纳米管的光催化活性.UV-Vis结果表明,WO3的复合使得光谱发生明显红移,但随着WO3含量的增加,ZnO-WO3的吸光度明显增加.另外,PL结果表明,适当的复合WO3可以抑制光生电子-空穴的复合.这是因为W6+和晶格氧的相互作用产生了较高不饱和键和表面缺陷,而表面缺陷可以作为光生载流子的陷阱,促进了光生电子和空穴的分离,因而光催化性能提高.在模拟太阳光下研究了不同WO3含量的ZnO纳米管对光催化降解MCPA-Na溶液的性能.发现W/Zn摩尔比为3%的ZnO-WO3样品表现出最好的光催化活性,200 min内其降解率为98.5%.与纯ZnO纳米管相比,其光催化循环性能也有所提高.利用Mott-Schottky测试方法并结合UV-vis结果,我们计算得到不同WO3含量的ZnO-WO3复合半导体导带价带位置.由于WO3导带位置和价带位置都比ZnO的更高,WO3上产生的光生电子会向ZnO的导带移动,而ZnO光生空穴向WO3的价带移动,从而促使光生电子和空穴的分离,提高了光催化性能.但是如果WO3复合的量太大,则在ZnO纳米管上分散性不好,反而成为光生空穴和电子复合中心,导致其光催化活性降低.     

高效WO3掺杂MCF催化剂的合成及其在环戊烯选择氧化制戊二醛反应中的应用

以钨酸钠和正硅酸乙酯为前驱体直接合成高含量WO₃掺杂介孔氧化硅泡沫(MCF)催化剂. 在773 K焙烧后显示出更高的热稳定性. 小角X射线散射, N₂-物理吸附和透射电子显微镜结果表明钨物种嵌入后, 材料仍保持MCF特征的三维织构介孔特征. 紫外拉曼和紫外可见漫反射光谱结果表明钨物种主要以孤立的或者低聚态的氧化钨形式存在, 所以在氧化钨质量分数(w)低于20%时氧化钨物种能够高度分散在载体上. 在环戊烯选择氧化制戊二醛反应中, 反应16 h 后环戊烯的转化率达到100%, 戊二醛的产率达到83.5%. 催化剂重复利用实验表明催化剂的稳定性较好, 没有钨物种的脱落. 这种优异的催化性能归结于合适的氧化钨含量和高分散的钨物种.     

Fluorescence quenching method for determination of trace tungsten in environmental samples with dibromohydroxyphenylfluorone

A highly sensitive and selective fluorescence quenching method has been developed for the determination of trace tungsten in environmental samples using dibromohydroxyphenylfluorone (DBHPF) as an emission reagent. In the presence of 0.04?mol/L of sulphuric acid and acetyltrimethylammonium bromide, tungsten(VI) reacts with DBHPF to form a 1?:?3 red complex within 5.0?min. In order for the DBHPF–tungsten(VI) complex to form, the fluorescence intensity of the reagent solution was quenched linearly by adding 0.1 to 1.0?µg of tungsten(VI) in 25?mL of solution. This was measured at 528?nm with excitation at 495?nm. In this work, a standard addition method was investigated and used for sample analysis. The decrease in fluorescence intensity of the reagent solution (ΔF) was linear for 0?～?0.9?µg of tungsten(VI) in 25?mL of solution, and the detection limit (3?s) of the standard addition method was found to be 0.012?ng/mL of tungsten(VI). The effects of various metal and nonmetal ions were studied in detail. The experiments clearly showed that most foreign ions can be tolerated in considerable amounts; in particular, 50-fold Mo(VI), V(V), Zr(VI) and Ti(IV) do not interfere, and the selectivity of the proposed method is better than other previously described methods. Moreover, the method proposed here is very stable and simple, the fluorescence intensity of the solution can remain almost unchanged for 2.0?h at room temperature, and the method has been used successfully to determine tungsten in environmental samples.     

W掺杂SiO2介孔材料的制备与表征

以非离子表面活性剂三嵌段共聚物P123为模板剂、正硅酸乙酯(TEOS)为硅源、钨酸钠(Na2WO4·2H2O)为钨源, 通过水热法一步合成了W掺杂的二氧化硅介孔材料W-SiO2, 并通过XRD、HRTEM、EDX、FT-IR、N2吸附-脱附等表征手段, 考察了随着W含量增加, W-SiO2介孔材料结构的变化规律以及钨物种在材料中的存在状态. 结果表明, 当WO3含量w(WO3)约为10%时, W-SiO2中的钨物种是高度分散进入介孔骨架,形成W-O-Si 键; 当w(WO3)=20%时, 样品中开始有未掺入到SiO2骨架中WO3的结晶出现; 当w(WO3)约60%时, W-SiO2 样品能保持很好的介孔孔道结构, 更高含量WO3掺入将破坏二氧化硅介孔结构.     

Catalytic method for the determination of traces of tungsten by linear scan voltammetry

A novel, sensitive and selective catalytic method for the determination of tungsten is described, based on the W(VI-catalysed redox reaction between methyl red and Ti(III) in a hydrochloric acid medium; methyl red exhibits a sensitive oscillopolarographic wave at −0.68 V vs. SCE in NaOH solution. A calibration graph from 3.2 to 72 ng ml⁻¹ W (detection limit 1.1 ng ml⁻¹) is obtained by the fixed-reaction time procedure. The influence of 29 foreign ions on the catalytic determination of W was examined; none interfered at < 100-fold excess. The method is used to determine W in steel and ore samples, with satisfactory results.     

A modified acid digestion procedure for extraction of tungsten from soil

Interest in tungsten occurrence and geochemistry is increasing due to increased use of tungsten compounds and its unknown biochemical effects. Tungsten has a complex geochemistry, existing in most environmental matrices as the soluble and mobile tungstate anion, as well as poly- and heteropolytungstates. Because the geochemistry of tungsten is substantially different than most trace metals, including the formation of insoluble species under acidic conditions, it is not extracted from soil matrices using standard acid digestion procedures. Therefore, the current work describes a modification to a commonly used acid digestion procedure to facilitate quantification of tungsten in soil matrices. Traditional soil digestion procedures, using nitric and hydrochloric acids with hydrogen peroxide yield <1 up to 50% recovery on soil matrix spike samples, whereas the modified method reported here, which includes the addition of phosphoric acid, yields spike recoveries in the 76-98% range. Comparison of the standard and modified digestion procedures on National Institute of Standards and Technology Standard Reference Materials yielded significantly improved tungsten recoveries for the phosphoric acid modified method. The modified method also produces comparable results for other acid extractable metals as the standard methods, and therefore can be used simultaneously for tungsten and other metals of interest.     

Determination of tungsten by acidimetric titration

A new method is described for the acidimetrie titration of tungstate, based on the reaction (x)WO(4)(2-) + xH(+) + mannitol = complex. Quantities of tungsten greater than 2.5 mmole may be determined with a relative standard deviation of not more than 0.1 %. The method is subject to interference by any species in the tungstate solution which absorbs protons in the pH range 5.5-8.5.     

A simple hydrothermal method for the large-scale synthesis of single-crystal potassium tungsten bronze nanowires

The large-scale synthesis of single-crystal K(x)WO(3) tungsten bronze nanowires has been successfully realized by a hydrothermal method under mild conditions. Uniform K(0.33)WO(3) nanowires with diameters of 5-25 nm and lengths of up to several micrometers are obtained. It is found that the morphology and crystallographic forms of the final products are strongly dependent on the sulfate and citric acid, which may act as structure-directing and soft-reducing agent, respectively. Some other influential factors on the growth of tungsten bronze nanowires, such as temperature and reaction time, are also discussed. It is worth noting that other alkali metal tungsten bronzes such as (NH(4))(x)WO(3), Rb(x)WO(3), and Cs(x)WO(3) could also be selectively synthesized by a similar route. Thus, this novel and efficient method could provide a potential mild route to selectively synthesize various tungsten bronze on-dimensional nanomaterials.     

一种新的WO3纳米管的制备方法

一维纳米材料因可用来构造高性能纳米器件的结构单元而成为纳米材料研究的热点．目前的研究重点集中在材料的制备和结构性能表征方面,已发展了多种制备方法,主要有模板法、V-L-S法、L-L-S法和V-S法等,其中阳极氧化铝(AAO)模板法是制备一维材料的好方法．AAO模板的制备工艺已相当成熟,     

Synthesis and characterisation of tungsten(VI) oxo-salicylate complexes for use in the chemical vapour deposition of self-cleaning films

Tungsten(VI) oxo-salicylate complexes were prepared in moderate yield (47 to 63%) by the reactions of WOCl4 and two equivalents of either 3-methylsalicylic acid (MesaliH2) or 3,5-di-isopropylsalicylic acid (di-i-PrsaliH2). Performing the reaction in refluxing toluene afforded the two analogous ditungsten complexes 1, [{WO(Mesali)(MesaliH)}2(mu-O)], and 2, [{WO(di-i-Prsali)(di-i-PrsaliH)}2(mu-O)], however in refluxing hexane the mononuclear tungsten complex , [WO(di-i-Prsali)(di-i-PrsaliH)Cl], was isolated. The single crystal X-ray study of revealed a pseudo-octahedral geometry around the tungsten centres. Aerosol assisted chemical vapour deposition of or afforded brown tungsten trioxide thin films. These films were converted to yellow fully oxidised WO3 on annealing in air at 550 degrees C for 30 minutes. The yellow WO3 films demonstrate preferred orientation on the substrate and show interesting functional properties-photo induced hydrophilicity and photocatalytic activity.