硫酸锌中性浸出液净化除钴

以模拟脱除铜镉后的中性浸出液为原料液,在50~90 ℃的温度范围内研究了温度、时间、Cu2+、Sb3+对锌粉置换除钴的影响,并采用锌片电极在上述溶液中进行了开路电位的测试和阻抗研究。结果表明,金属锌置换除钴离子因其析出过电位较高而受到抑制,加入Cu2+和Sb3+对Co2+的置换都具有催化作用。Cu2+催化速度快,但是除钴效果不稳定;Sb3+催化时除钴速度仍然较慢,但是置换出来的钴能够稳定存在;当使用Cu2+、Sb3+联合催化时,钴的脱除速度更快、脱除效果更加稳定。电化学测试结果显示,Cu2+能催化H+在金属锌上的析出,Sb3+会延缓催化H+在金属锌上的析出。电化学阻抗研究发现,50 ℃时,Sb3+对锌置换除Co2+的阻抗具有轻微的降低作用,而Cu2+对锌置换除Co2+的阻抗具有显著的降低作用,当联合使用Cu2++Sb3+时,锌置换除Co2+的阻抗大幅度下降。     

离子交换树脂和交换纤维处理含氰废水

采用离子交换树脂、离子交换纤维处理含氰废水。研究了两种不同材料对含氰废水中游离CN-、铜氰配合物、锌氰配合物的吸附性能。结果表明,和离子交换树脂相比,强碱性离子交换纤维对含氰废水中的主要成分铜氰配合物、锌氰配合物具有快的吸附速度和大的吸附容量,是一种有发展潜力的含氰废水处理材料。     

A newly synthesized single crystal zinc complex as molecular electrocatalyst for efficient hydrogen generation from neutral aqueous solutions

A new chlorobis(2-aminomethylbenzimidazole)zinc(II) perchlorate complex [Zn(AMB)₂Cl](ClO₄) 1 has been synthesized and characterized. Spectral and X-ray structural features led to the conclusion that the zinc(II) complex has a square-pyramidal environment around zinc(II) center with coordination chromophore ZnN₄Cl. Different amounts of complex 1 were supported on glassy carbon (GC) electrode yielding three GC-supported complex 1 electrodes with different loading densities (0.2, 0.4, and 0.8 mg cm^?2). These electrodes were tested as molecular electrocatalysts for the hydrogen evolution reaction (HER) in phosphate buffer aqueous solutions (pH 7), employing linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS). Results showed that GC-complex 1 catalysts are highly active for the HER, and this catalytic activity enhances with the loading density. The one with the highest loading density (0.8 mg cm^?2) exhibited high HER catalytic activity with low onset potential of ?140 mV vs. RHE and a high exchange current density of 0.22 mA cm^?2. It required an overpotential of 240 mV to achieve a current density of 10 mA cm^?2. It also recorded a turnover frequency (TOF) of 1722 mol of hydrogen per mole of catalyst per hour at overpotential 500 mV, which is comparable with the most active molecular electrocatalysts reported in the literature for H₂ generation from aqueous neutral solutions. A catalytic cycle is proposed for the generation of hydrogen by complex 1 and the mechanism of the HER is discussed based on the measured Tafel slope (140 mV dec^?1).     

Chelation of chitosan derivatives with zinc ions. I. O,N‐carboxymethyl chitosan

The chelation between O,N‐carboxymethyl chitosan (ONCMCh) and zinc sulfate in aqueous solution was studied by kinetic experiments and characterized by inductively coupled plasma (ICP) and UV spectrophotometry. The experimental data indicated that the chelating processes were greatly controlled by the reaction conditions (i.e., reaction time, temperature, and Zn²⁺ ionic and ligand concentrations). The consequence of chelating Zn²⁺ onto ONCMCh was the formation of complexes with different solubilities. The favorable complexes for ONCMCh‐Zn²⁺ chelate were at the low zinc ionic and ligand concentrations, as well as at the appropriate temperature. The evidence provided by the kinetic parameters and the changes in zinc concentration by ICP analysis further confirmed the plausible complexing mechanisms. While the formation of water‐soluble products was occasioned by the electrostatic attraction mechanism, the water‐insoluble products were predominantly formed by chelation of Zn²⁺ with O,N‐carboxymethyl chitosan. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2246–2253, 2000     

Evidence of ionic components in vulcanization mixtures by means of electric current measurements: Investigations with natural rubber/sulfur/zinc bis(dimethyldithiocarbamate) and comparison mixtures

Continuous low‐level current (CLLC) measurements for detecting ionic species in the course of vulcanization reactions were applied to investigate the vulcanization of a mixture of natural rubber (NR), sulfur (S), and zinc bis(dimethyldithiocarbamate) (ZnDMTC). A dc voltage was applied to the reaction mixture in a special vulcanization mold and the current (e.g., in the range of 10⁻⁹ A) was measured. Temperature‐dependent current maxima were found after reaction times t_max. The simplest explanation is that transitory ionic species occur during vulcanization. An activation energy (E_a ) = 116.4 kJ/mol, similar to that obtained in previous chemical investigations, was determined from the decrease of t_max with increasing temperature. The maxima corresponded to reaction times where a strong increase of polymer crosslinking was observed, as measured using vulcametry. For comparison, dc measurements were carried out with the corresponding mixture without elemental sulfur (NR/ZnDMTC) and mixtures containing zinc stearate (ZnST) instead of zinc bis(dimethyldithiocarbamate) (NR/S/ZnST and NR/ZnST). © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 2206–2212, 2000     

Improving the throwing power of acidic zinc sulfate electroplating baths

The effect of some plating parameters, such as Zn²⁺ ion concentration, pH, current density, temperature and duration on the throwing power, as well as on the throwing index of acidic zinc sulfate baths has been investigated. The addition of p‐anisidine (PA) and/or sodium dodecylbenzenesulfonate (DBS) has been examined as a possible means of improving the uniformity of deposit distribution. The additives cause a substantial increase in the overpotential for the reduction of Zn²⁺ ions and consequently improve the throwing power of the baths. The throwing power increases by a factor of four in the presence of DBS and a factor of one‐and‐a‐half in the presence of PA. The inhibition of zinc reduction was assumed to occur via adsorption of the PA or DBS molecules on the cathode surface and the adsorption followed the Langmuir adsorption isotherm. The surface morphology of the zinc plated with and without the additives was examined by using scanning electron microscopy (SEM). © 2000 Society of Chemical Industry     

Zinc maleate and zinc anthranilate as thermal stabilizers for PVC

The results of the evaluation of zinc maleate and zinc anthranilate as thermal stabilizers for poly(vinyl chloride) (PVC) are reported in this article. Calcium stearate, diphenyl isodecyl phosphite, and epoxidized soya oil were used as costabilizers. Both zinc compounds showed good stabilizing performance in static and dynamic tests, particularly at low concentrations. The best results were obtained with zinc anthranilate. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2603–2605, 2000     

In situ preparation of zinc salts of unsaturated carboxylic acids to reinforce NBR

Through the neutralization reaction of zinc oxide (ZnO) and methacrylic acid (MAA) or acrylic acid (AA), zinc methacrylate (ZMA) or zinc acrylate (ZA) was in situ prepared in nitrile rubber (NBR). The mechanical properties and crosslinking structure of the resulting peroxide‐cured NBR vulcanizates were studied. The results showed that ZnO/MAA (AA) had a great reinforcing effect for NBR, and their amounts and ratio played important roles in influencing the mechanical properties. Such vulcanizate contains both covalent crosslinks and salt crosslinks, and the change in the tensile strength of the vulcanizate was related to the variation of the salt crosslink density. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2740–2748, 2000     

纳米ZnO整理剂的改性分散工艺研究

通过单因素分析了超声时间、pH值、分散剂低聚丙烯酸钠PAAS、硅酸钠、OP-10及偶联剂KH-570的用量对纳米氧化锌的分散,并通过正交实验确定纳米氧化锌改性分散的最佳工艺条件,最终分散结果纳米氧化锌的平均粒径达到53.16nm,且形貌均一稳定。     

Extraction of zinc from ammoniacal/ammonium sulphate solutions by LIX 54

The extraction of zinc from ammoniacal/ammonium sulphate aqueous media using LIX 54 has been studied. The metal extraction rate has been examined and also the effect of temperature on the extraction of zinc (ΔH° = −8·8 kJ mol⁻¹). The effect of the aqueous pH, and therefore zinc ammine complex formation, on the extraction of zinc was studied. Stripping of the metal from loaded organic phases was carried out at various rates, temperatures (ΔH° = 3·2 kJ mol⁻¹) and sulphuric acid concentrations. The results obtained were compared with others obtained from the literature wherein different extractants were used. © 1998 SCI.