用标准加入光度法同时测定镀液中的Co2+与Ni2+

为寻找合金镀液中Ni2 ,Co2 快速、准确的测定方法,进行了用标准加入光度法同时测定镀液中的钴和镍的研究.用钴的等吸收点波长490 nm和530 nm作为测定波长,以镍为标准加入组分,用4-(2-吡啶偶氮)间苯二酚(PAR)作显色剂,溶液pH值为9～10.在镀液样品中进行加标回收试验,平均回收率钴为100.4%,镍为101.5%,最大相对标准偏差钴为6.1%,镍为4.6%;还探讨了测定条件对结果的影响.结果表明,该方法操作简单,可行性强,准确度较高.     

The formation of disilicides from bilayers of Ni/Co and Co/Ni on silicon: Phase separation and solid solution

Bilayers of Ni/Co and Co/Ni were deposited onto silicon by means of electron beam evaporation. The annealing behavior was investigated as a function of time in the temperature range 475–550 °C by Rutherford backscattering spectrometry, Auger electron spectroscopy, scanning electron microscopy and X-ray analysis. In this temperature range it is observed that the disilicide (solid solution) nucleates and grows from a film containing both the monosilicide of cobalt and that of nickel. These nearly insoluble monosilicides are separated into layers; the disilicide grows from the interface between the NiSi and the CoSi phase. If there are equal amounts of the two metals this interface is located approximately midway between the upper surface and the silicon substrate. The disilicide grows simultaneously both toward the free surface and toward the silicon substrate. The growth kinetics of the disilicide have been analyzed and are found to be complex. The general behavior of the disilicide formation is found to be similar to that found for Co-Ni alloy films and as for the latter case indicates the primacy of nucleation over diffusion as the controlling mechanism in the disilicide formation. The site of nucleation of the disilicide at the NiSi-CoSi interface is explained by a model based on (a) the phase separation of the two monosilicides and (b) the high entropy of mixing of the mixed disilicide. In agreement with this model the nucleation of the mixed disilicides is shown to occur at temperatures much lower than those for either CoSi₂ or NiSi₂. Given the common crystal structure and the almost identical lattice parameters, the mutual solubilities of CoSi₂ and NiSi₂ follow from elementary concepts of alloy phase theory. However, the behavior of the monosilicides is more unexpected. The limited solubilities of the monosilicides, CoSi and NiSi, in each other are shown to result from specific features of the electronic band structure of these two compounds, features which are not found for example in the isomorphous disilicides CoSi₂ and NiSi₂.     

Ni、Co、Mn、Cu掺杂对K4 Nb6 O17光催化活性的影响

通过高温固相反应合成了铌酸盐K4Nb6O17及Ni2 、Co3 、Mn4 、Cu2 (5.0%mol)掺杂的K4Nb6O17并采用X射线衍射、紫外可见漫反射光谱、扫描电镜、比表面积分析等对其进行了结构和形貌表征.在甲醇为电子给体、Pt为助催化剂的情况下,研究了K4Nb6O17及Ni2 、Co3 、Mn4 、Cu2 掺杂的K4Nb6O17作为催化剂在约400nm紫外辐射下分解水产氢的光催化活性,并讨论了引起催化剂活性差异的原因.     

On the formation of M2+ -Sb3+ -alkoxide precursors and sol-gel processing of M-Sb oxides with M = Cr,Mn, Fe,Co, Ni,Cu and Zn

Binary alkoxide complexes of compositions close to MSb(OEt)₅, with M = Mn, Fe, Co and Ni, have been prepared and characterized by their i.r. and u.v.-VIS spectra, while Cr, Cu and Zn do not form similar ethoxide complexes with Sb(OEt)₃. The Mn and Fe complexes must be prepared in inert atmosphere as they are very easily oxidized. The Fe complex is metastable and decomposes within a few hours. The Co complex can only be prepared in the presence of acetonitrile. X-ray amorphous gels were formed upon hydrolysis of solutions containing M to Sb species in the ratio 12 for M = Mn, Fe, Co and Ni. The gels consisted of agglomerated particles of sizes from 75 to 300 nm. The decomposition of the gels in air and in nitrogen has been monitored by means of thermogravimetric measurements. Samples of heated gels were quenched from various temperatures in the region 50–950°C, and the formed oxides were characterized by their X-ray powder patterns and by their infrared spectra. At 950 °C MSb₂O₆ was formed in air, while in nitrogen MSb₂O₄ (M = Mn, Co and Ni) was formed at intermediate temperatures. At higher temperatures the latter compound decomposed and Sb₂O₃ sublimated.     

钠基膨润土对废水中Ni2+,Cu2+的吸附效果

为了提高膨润土吸附废水中Ni2+,Cu2+的效果,对其改性制备了钠基膨润土,考察了吸附时间、废水pH值以及Ni2+和Cu2+初始浓度对自制钠基膨润土吸附Ni2+,Cu2+效果的影响,分析了吸附等温线,并探讨了吸附机理。结果表明:钠基膨润土对Ni2+,Cu2+都有较好的吸附性能;初始阶段(前10 min)吸附很快,之后随时间延长吸附量提高甚微;pH值为6.2时,处理后的水质即可达国家排放标准;随着Ni2+,Cu2+初始浓度增加,去除率先增加后降低,而吸附量迅速增加,Ni2+和Cu2+初始浓度分别为25 mg/L和40 mg/L时,钠基膨润土对Ni2+,Cu2+的去除率均可达98.6%;钠基膨润土对Ni2+,Cu2+的吸附等温线符合Freundlich吸附等温式。     

Isosteric heats of n-hexane sorption in ion-exchanged NaX containing Co2+, Ni2+, Zn2+, and Cd2+

Sorption—desorption isotherms of n-hexane have been measured at 288 and 298 K in zeolites M_xNa_87-2xX (M = Co, Ni, Zn, Cd) and the corresponding isosteric heats have been obtained. The effect of cations on isosteric heats is highly pronounced at low cowerage, being different for each particular cation. An attempt is made to explain the large differences in those heats in terms of cationic size, charge, electronic configuration, and location in the lattice.     

Effect of Co and Ni nanoparticles formation on carbon nanotubes growth via PECVD

The effect of cobalt (Co) and nickel (Ni) nanoparticle catalysts on the growth of carbon nanotubes (CNTs) were studied, where the CNTs were vertically grown by plasma enhanced chemical vapour deposition (PECVD) method. The growth conditions were fixed at a temperature of 700 °C with a pressure of 1000 mTorr for 40 minutes with various thicknesses of sputtered metal catalysts. Only multi-walled carbon nanotubes are present from the growth as large average diameter of outer tube (～10–30 nm) were measured for both of the catalysts used. Experimental results show that high density of CNTs was observed especially towards thicker catalysts layers where larger and thicker nanotubes were formed. The nucleation of the catalyst with various thicknesses was also studied as the absorption of the carbon feedstock is dependent on the initial size of the catalyst island. The average diameter of particle size increases from 4 to 10 nm for Co and Ni catalysts. A linear relationship is shown between the nanoparticle size and the diameter of tubes with catalyst thicknesses for both catalysts. The average growth rate of Co catalyst is about 1.5 times higher than Ni catalyst, which indicates that Co catalyst has a better role in growing CNTs with thinner catalyst layer. It is found that Co yields higher growth rate, bigger diameter of nanotube and thicker wall as compared to Ni catalyst. However, variation in Co and Ni catalysts thicknesses did not influence the quality of CNTs grown, as only minor variation in I_G/I_D ratio from Raman spectra analysis. The study reveals that the catalysts thickness strongly affects not only nanotube diameter and growth rate but also morphology of the nanoparticles formed during the process without influencing the quality of CNTs.     

羧酸盐/玉米芯接枝共聚物的制备及其对Cd2+和Ni2+的吸附

利用原子转移自由基聚合技术在玉米芯表面引发丙烯酸甲酯发生聚合反应,再分别通过NaOH和t-BuOK进行水解,制备出两种羧酸盐/玉米芯接枝共聚物(MC-g-PAA-Na和MC-g-PAA-K).结果 表明:两种羧酸盐/玉米芯接枝共聚物吸附Cd2+和Ni2+是自发、吸热且伴随焓增加的过程,该过程更符合Langmuir模型,...     

锰矿尾渣对Cu2+和Ni2+的吸附性能研究

研究了锰矿尾渣对重金属离子Cu2 和Ni2 的吸附性能,分析了锰矿尾渣的吸附动力学,就吸附时间、Cu2 和Ni2 浓度及pH值等因素对锰矿尾渣吸附性能的影响作了系统考察,并对锰矿尾渣的吸附机理进行了初步探讨.结果表明,在温度为25°℃、pH值为7.5的条件下,锰矿尾渣对Cu2 和Ni2 的吸附容量可达到1.6 mg/g以上,去除率均可达到97.5%以上,适宜于处理含低浓度Cu2 或Ni2 的废水.锰矿尾渣的吸附机理为离子交换吸附和表面配位吸附.     

酸改性膨润土吸附去除镍镉离子的研究

在静态条件下,研究了改性膨润土对重金属离子的吸附性能和吸附机理,着重探讨了改性膨润土去除模拟水样中重金属离子Ni2 ,Cd2 的适宜条件及改性膨润土的再生方法.结果表明,改性膨润土对Ni2 ,Cd2 具有较好的吸附性能;pH值是影响改性膨润土对重金属离子吸附的重要因素,不同的金属离子都有其适宜的pH值范围.吸附的最佳条件是pH值5.0～7.0,废水中Ni2 ,Cd2 含量不大于45 mg/L,搅拌时间约60 min.利用改性膨润土吸附处理Ni2 ,Cd2 含量小于45 mg/L的模拟水样,效果很好,Ni2 ,Cd2 的去除率均可分别达到98.5%以上,出水可达到国家排放标准.     

改性膨润土对溶液中Co2+、Mn2+的吸附研究

以膨润土为原材料,盐酸为改性剂,制备改性膨润土。研究了改性膨润土的制备条件,其对重金属Co2+、Mn2+的吸附性能及对苯二甲酸(PTA)工业中的副产品对甲苯甲酸对吸附的影响。实验结果表明,盐酸的最佳改性浓度为1.5mol/L,改性膨润土在40℃的吸附能力最好,可达到12～14mg/g,经过热力学分析得出,改性膨润土对钴离子、锰离子的吸附方式均符合Langmuir吸附模型,PTA工业中的副产品对甲苯甲酸对吸附没有影响。     

纳米羟基磷灰石对Ni^2＋的吸附性能及机理研究

以硝酸钙和磷酸氢二铵为原料用化学共沉淀法制备纳米羟基磷灰石(n-HA),用XRD、TEM 和BET表征样品的相组成、结晶形貌和比表面积.结果表明:制备的针状羟基磷灰石长轴约为31.9nm,短轴约为21.3nm,粒径均匀且表面活性高,具有较低结晶度,比表面积高达135m2/g.选用Ni2+作为吸附目标离子,通过Zeta电位、XRD和XPS分析n-HA吸附前后的表面电位、晶体物相和表面原子结合能的变化可知:Langmuir等温吸附模型仅适用于Ni2+初始浓度低于0.1mol/L的范围;当Ni2+初始浓度高于0.1mol/L时,Ni2+取代Ca2+与表面的O成键,吸附过程包括离子交换、静电吸附和溶解沉淀作用.     

Spatial evolutions of Co and Ni atoms during single-walled carbon nanotubes formation: measurements and modeling

Spatial investigations of nickel and cobalt atoms and of C2 and C3 radicals are performed by laser induced fluorescence (LIF) in a continuous CO2 laser-vaporization reactor during the synthesis of single-walled carbon nanotubes. The chemical composition of the gas vaporized from bimetallic Ni/Co catalysts-carbon targets is determined using a chemical kinetic model. In this model, the evolution of Ni and Co atoms is driven by kinetics of condensation/evaporation process of pure metal clusters. Metal-carbon clusters are assumed to form from soot particles (C80) and 128-atom metal clusters. Spatial profiles of Ni and Co atoms obtained by LIF are compared with the calculations to validate the modeling and to adjust the input data. The value of the initial molar fraction of carbon-metal mixture diluted in helium is determined through a parametric study. Good agreement is found between the measured and the calculated evolution of Ni for a molar fraction of the helium diluent ranging from 10 to 15%. To fit the spatial profile of Co, the activation energy is adjusted in the evaporation rate, changing the cobalt dimer bond energy. The latter is found to be largely uncertain; and three values are tested: 167, 208, and 230 kJ x mol(-1). From comparison, the activation energy is found to be 208 kJ x mol(-1). However, the C2 LIF profiles show that the depletion of C2 is accelerated when cobalt is present. The observed Co evolutions suggest that small Co-C clusters are easier and/or faster to form compared to Ni-C clusters.     

Electronic and spin configurations of Co3+ and Ni3+ ions in oxides of K2NiF4 structure: A magnetic susceptibility study

In La₄LiCoO₈, Li⁺ and Co³⁺ ions are ordered in two dimensions and Co³⁺ ions undergo transitions from the low-spin to the intermediate as well as the high-spin states. Both Sr₄TaCoO₈ and Sr₄NbCoO₈ exhibit low to intermediate-spin state transitions of Co³⁺ ions. In the system LaSr_1?xBa_xNiO₄, the e_g electrons are essentially in extended states forming a band. With increase in x, the band width decreases accompanying an increase in unit cell volume; high-spin Ni³⁺ ions are formed to a small extent with increasing x, but there is no spin-state transition. In LaSrAl_1?xNi_xO₄, at small x, there is a small proportion of high-spin Ni³⁺; when x ≈ 0.6, there is an abrupt decrease in the $\text{c}$/$\text{a}$ ratio, signalling the formation of the band. In LnSrNiO₄, the $\text{c}$/$\text{a}$ ratio decreases sharply between Ln = La and Nd; this is likely to be accompanied by a broadening of the band.     

Facile synthesis Mn/Co dual-doped Ni3S2 nanosheets for supercapacitor

Journal of Materials Science: Materials in Electronics - Ni3S2 nanosheets dual-doped with manganese, cobalt elements on conductive nickel foam (MC-Ni3S2) had been synthesized by two steps...     

Synthesis and complex permeability of Co/SiO2 nanocomposites

In this paper, a simple sol–gel combined hydrogen reduction synthesis of Co/SiO₂ nanocomposites was reported. The specific magnetization of the sample can be as high as 146.34 emu/g even including silica, which is a non-magnetic material. The real part μ′ of the permeability for Co/SiO₂ nanocomposites is almost independent of frequency up to at least 10 MHz, at the same time, the loss of μ″ is very small. Our method provides a promising route to achieve soft magnetic material with good magnetic properties, especially in the high-frequency range.