双波长分光光度法测定钴的研究

提出了在高氯酸介质中,以4-(4,5-二甲基噻唑偶氮)-1,3-二氨基苯(DMTADAB)为显色剂,应用双波长叠加分光光度法测定钴(Ⅱ)的新方法.结果表明,在实验条件下,钴与试剂形成稳定的12蓝绿色配合物,该配合物在600nm和435 nm处分别有正负两个吸收峰,且正负峰吸光度绝对值之和与钴浓度线性相关,钴在0～0.4μg/mL浓度范围内服从比耳定律.利用双波长叠加的方法测得其表观摩尔吸光系数为1.56×105L/(mol·cm),灵敏度较单波长测定提高约1.7倍.所拟方法已成功地应用于含钴分子筛和金川矿样中微量钴的测定.     

Synthesis and characterization of carbon-coated cobalt ferrite nanoparticles

Cobalt ferrite nanoparticles (CFNPs) were prepared via a reverse micelle method. The CFNPs were subsequently coated with carbon shells by means of thermal chemical vapor deposition (TCVD). In this process, acetylene gas (C₂H₂) was used as a carbon source and the coating was carried out for 1, 2, or 3 h at 750°C. The Ar/C₂H₂ ratio was 10:1. Heating during the TCVD process resulted in a NP core size that approached 30 nm; the thickness of the shell was less than 10 nm. The composition, structure, and morphology of the fabricated composites were characterized using X-ray diffraction, simultaneous thermal analysis, transmission electron microscopy, high-resolution transmission electron microscopy, and selected-area diffraction. A vibrating sample magnetometer was used to survey the samples’ magnetic properties. The deposited carbon shell substantially affected the growth and magnetic properties of the CFNPs. Micro-Raman spectroscopy was used to study the carbon coating and revealed that the deposited carbon comprised graphite, multiwalled carbon nanotubes, and diamond- like carbon. With an increase in coating time, the intensity ratio between the amorphous and ordered peaks in the Raman spectra decreased, which indicated an increase in crystallite size.     

联氨在金属纳米粉制备中的行为研究

通过ＵＶ、ＸＲＤ和化学分析方法研究了联氨在同Ｆｅ（ＩＩ） 、Ｃｏ（ＩＩ） 、Ｎｉ（ＩＩ） 反应制备金属纳米粉的行为． 认为在乙醇－ 水体系中， 水合肼还原Ｃｏ（ＩＩ） 、Ｎｉ（ＩＩ） 的反应是经过配合催化， 还原Ｆｅ（ＩＩ） 的反应是经过表面催化和高压诱导． 用水合肼对钴、镍纳米粉进行铁的包覆， 以及有钴、镍存在下的岐化分解都是表面催化．     

聚四氨基钴酞菁修饰电极测定水中溶解氧

采用电化学聚合法制备聚四氨基钴酞菁修饰电极,并用循环伏安法研究其对氧的电催化作用.实验表明,修饰电极在pH=5柠檬酸-柠檬酸钠缓冲溶液中,峰电流与氧质量浓度在1.6～8.0mg/L范围内呈线性关系,平行6次测定氧体积分数RSD=1.7%,回收率为98.02%～111.68%.     

2-羟基-4-磺酰氨基苯重氮氨基偶氮苯的合成及与钴的显色反应

研究了2-羟基-4-磺酰氨基苯重氮氨基偶氮苯(HSDAA)的合成及与钴的显色反应.在Triton X-100表面活性剂存在下,pH=9.0～11.0的Na2B4O7-NaOH缓冲溶液中,试剂HSDAA与钴(Ⅱ)生成2:1型深红色配合物,配合物的最大吸收峰位于λ=540 nm处,表观摩尔吸光系数为8.69×104L·mol-1·cm-1,ρ(Co2 )为0～480 μg/L时符合比耳定律.用拟定方法测定维生素B12中的微量钴,结果满意.     

夹心结构杂多化合物N(CH3)4Na6[Na3{Co(H2O)}2WOH2O(AsW9O33)2]·35H2O的晶体结构及表征

在 p H≈ 6.5及稀土盐 Gd Cl3 · 6H2 O或 Ce( NO3 ) 3 · 6H2 O的存在下 ,Na2 WO4· 2 H2 O与Na As O2 及 Co( NO3 ) 2 · 6H2 O反应 ,得到了夹层型杂多钨酸盐 N( CH3 ) 4 Na6[Na3 {Co( H2 O) }2 WO( H2 O) ( As W9O3 3 ) 2 ]· 35 H2 O单晶 ,用 X射线单晶衍射法及元素分析确定了其结构 ,晶胞参数为 :a=1 .395 ( 1 8) nm,b=1 .90 ( 2 ) nm,c=2 .2 9( 3) nm,α=1 0 2 .3( 4 )°,β=94.7( 3)°,γ=1 0 5 .3( 3)°,V=5 .65 6( 1 2 5 ) nm3 ,Z=2 ,空间群 Pī,R1=0 .0 60 0 ,w R2 =0 .1 2 0 7( I>2σ)。[Na3 {Co( H2 O) }2 WO( H2 O) ( As W9O3 3 ) 2 ]7-具有 C2 v对称性 ,Co2 +的配位数均为 5 .对题示化合物进行了 IR,UV- Vis表征 ,讨论了其形成条件     

2－（5－硝基－2－吡啶偶氮）－5－二甲氨基苯胺与钴高灵敏显色反应的研究

报道了新试剂２－（５－硝基－２－吡啶偶氮）－５－二甲氨基苯胺（记作５－ＮＯ２－ＰＡＤ－ＭＡ）与钴（Ⅱ）的高灵敏显色反应．实验表明，在ｐＨ４．０～６．２ＨＡｃ－ＮａＡｃ缓冲介质中，试剂可与钴（Ⅱ）形成紫红色配合物，当用高氯酸酸化后配合物转换成一种蓝色稳定的双质子化型体，最大吸收峰位于６１３ｎｍ，摩尔吸光系数为１．１３×１０５Ｌ·ｍｏｌ－１·ｃｍ－１，钴（Ⅱ）浓度在０～３．６μｇ／１０ｍＬ范围内遵守比耳定律．所拟方法已成功地应用于ＶＢ１２针剂、分子筛样品中钴（Ⅱ）含量的测定     

Voltammetric response and electrocatalysis of glassy carbon electrode modified with monolayer nickel hydroxide

The glassy carbon (GC) electrode modified with a monolayer nickel hydroxide (GC/Ni(OH)₂) was prepared by immersion of GC substrate in 1.0×10⁻³ mol/L NiSO₄ solution, and then cyclic voltammetric scanning in 0.20 mol/L KOH. Similarly, GC/Co (OH)₂ electrode was prepared too. The experiments showed that the voltammetric behavior of GC/Ni (OH)₂ electrode in 0.20 mol/L KOH is more stable than that of GC/Co(OH)₂. It was found that the GC/Ni(OH)₂ electrode acts as an effective electrocatalysis for the oxidation of hydrazine. Supported by the Trans-Century Training Program Foundation for the Talents from the State Commission of Education of China and the National Natural Science Foundation of China Liu Shouqing: born in Dec. 1962. Postgraduate     

放电等离子烧结制备超细WC-Co硬质合金

采用放电等离子烧结(SPS)技术制备了超细WC-10Co硬质合金.研究了烧结温度及烧结气氛对WC-Co硬质合金组织及性能的影响.研究发现:烧结体密度随烧结温度的升高而增大,但由于钴的蒸发,合金的成分偏离了原粉末的成分,且随着烧结温度的升高及炉内气压的降低,钴的蒸发速率加大.因此,通过提高炉内气压,可以使合金的成分基本接近原粉末成分,降低了合金的成分偏离.结果表明:炉内气压升高到200 Pa,烧结压力为30 MPa时,在1250℃烧结WC-10.07Co粉末5 min,烧结体中钴的质量分数可以控制在10.02%,密度和硬度分别达到了14.62 g.cm-3和HRA 92.4.     

原子吸收分光光度计测定分子光谱的研究——催化动力学光度法测定微量钴

本文试验了采用原子吸收分光光度计的光路系统测量分子光谱的可行性．在ＰＨ＝３．５的ＨＡＣ－ＮａＡｃ介质中，在避光条件下，钴对无色的Ｆｅ（Ⅲ）－联吡啶配合物还原成红色的Ｆｅ（Ⅱ）－联吡啶配合物有较强的催化作用．在λ＝５２２９ｎｍ处，在原子吸收分光光度计上测定钴的含量，对钴测定的线性范围为３～１５０μｇ／２５ｍｌ，检测限力０．０３８μｇ／２５ｍｌ．本法选择性较好，多数离子允许大量存在，将此法用于维生素Ｂ１２针剂中钴的测定，并与分光光度法及原子吸收分光光度法对照．结果令人满意