从电锌和电镉生产的含钴废料产物中提取钴

介绍了一种从钴净化渣中回收钴的新方法，既可在工艺过程中生产出具有商业价值的富钴精矿，又能使大部分锌和镉返回流程。采用化学方法处理钴精矿可产出许多有用的钴基产品。这样做还避免了钴、镍和铜对电解工艺的危害。钴精矿还可以加工成其他的钴化合物和颜料。

Process and anodic reaction mechanism of cadmium electrically enhanced cementation on zinc plate under an ultrasonic field in ammoniacal system

Cadmium was replaced by zinc in ammoniacal system using an electrically enhanced method under ultrasonic waves.Five main influencing factors were investigated by a single-factor experiment to determine the optimum parameters.Cyclic voltammetry and linear sweep voltammetry were applied to investigating the reaction mechanism of electrically enhanced cementation of cadmium on a zinc plate.The optimum parameters were a temperature of 35℃,a cathode-to-anode area ratio of 1:2,an anode current density of 15 A/m2,an ultrasonic frequency of 40 kHz a reaction time of 6 h and an ultrasonic power of 100 W.The extraction rate was 99.21%,and the production of byproduct“floating sponge cadmium”was inhibited.The analysis of the cyclic voltammetry and linear sweep voltammetry diagrams showed that ultrasonic waves can promote and accelerate the replacement reaction,decrease the voltage requirement of the electrically enhanced replacement reaction,and change the reaction steps.In addition,increasing the temperature and ultrasonic power can promote and accelerate electrically enhanced replacement reactions and decrease the electric potential requirement.

Selective separation of copper and cadmium from zinc solutions by low current density electrolysis

Copper and cadmium ions were selectively separated from zinc sulphate aqueous solution or zinc ammonia/ammonium sulphate aqueous solution by low current density electrolysis.It was shown that the concentration of cadmium ion in zinc sulphate solution decreased from 4.56 g/L to 0.18 g/L in an electrolysis time of 8.5 h,whilst it decreased from 5.16 g/L to lower than 0.005 g/L in zinc ammonia/ammonium sulphate aqueous solution.On the other hand,the deposition rate of copper was so low that it was difficult to separate copper and cadmium ions from the zinc ammonia/ammonium sulphate aqueous solution during electrolysis.But copper ion could be decreased to 0.002 g/L in this solution through solvent extraction by using kerosene diluted LIX984N as extractant.Therefore,it is favorable to recover cadmium ion from the zinc ammonia/ammonium sulphate solution by electrolysis after solvent extraction of copper.

Simultaneous determination of trace Cu^(2+), Cd^(2+), Ni^(2+) and Co^(2+) in zinc electrolytes by oscillopolarographic second derivative waves

Simultaneous determination of impurity metal ions in high concentration zinc solution is very important for zinc hydrometallurgy,and the purpose is to establish a method for determining the trace Cu^2+,Cd^2+,Ni^2+and Co^2+in zinc electrolytes at the same time using the second derivative waves of single sweep oscillopolarography.Factors affecting the derivative waves of the ions were researched in a medium of dimethylglyoxime(DMG)-sodium citrate-sodium tetraborate.The results indicated that the interferences of a high concentration of Zn^2+and most other coexisting ions on the determination can be eliminated;when the Cu^2+,Cd^2+,Ni^2+and Co^2+are in the ranges of1×10^-7-3×10^-4,6×10^-7-2×10^-4,2×10^-8-1×10^-5and1×10^-8-3×10^-5mol/L,respectively,the relationships between the peak currents of the second derivative waves and the concentrations are linear;the detection limits to determine the Cu^2+,Cd^2+,Ni^2+and Co^2+are8×10^-8,2×10^-7,6×10^-9and4×10^-9mol/L,respectively.Without any sample pretreatment,the method was used to directly determine the trace Cu^2+,Cd^2+,Ni^2+and Co^2+in actual zinc electrolytes with satisfactory results.The method is simple,sensitive and rapid.

DNA Damage （Comet Assay） as Biomarker of Cd Exposure in Marine Seed Scallops Mizuhopecten Yessoensis Age 1 Year

Cadmium-induced DNA degradation in gill cells of the scallop Mizuhopectenyessoensis was assessed using the comet assay （single-cell gel electrophoresis）. Accumulation of highly toxic cadmium in the gill cells of bivalve is accompanied by the damage of the cell genome revealed as DNA migration in the comet assay. The main mechanisms of Cd effects on the integrity of the DNA structure are discussed.

PVC Membrane Selective Electrode for Determination of Cadmium(Ⅱ) Ion in Chocolate Samples

Benzil bis(carbohydrazone)(BBC) is prepared and explored as new N N Schiff's base, which plays the role of an excellent ion carrier in the construction of a Cd(II) ion membrane sensor. The tris(2-ethylhexyl) phosphate best performance corresponds to a membrane composition of 30% poly(vinyl chloride), 65%(TEHP), 3.5% BBC and 1.5% tetradodecyl-ammoniumtetrakis(4-chlorophenyl) borate(ETH 500). This sensor shows very good selectivity and sensitivity towards cadmium ion over a wide variety of cations, including alkali, alkaline earth, transition and heavy metal ions. The effect of membrane composition, selectivity, pH and influence of additive on the response properties of electrode were investigated. The response mechanism was discussed in the view of UV-spectroscopy. The electrode exhibits a Nernstian behavior(with slope of 29.7 mV per decade) over a very wide concentration range from 1.0×10?1 to 1.0×10?8 mol·L?1 with a detection limit of 3.2×10?8 mol·L?1. It shows rela-tively fast response time in whole concentration range(<8 s) and can be used for at least 10 weeks in the pH range of 2.0-9.0. The proposed sensor is successfully used for the determination of cadmium in different chocolate sam-ples and as indicator electrode in titration with ethylene diamine tetraacetate(EDTA).

CdTe Films Deposited by Closed-space Sublimation

CdTe films are prepared by closed-space sublimation technology. Dependence of film crystalline on substrate materials and substrate temperature is investigated. It is found that films exhibit higher crystallinity at substrate temperature higher than 400 ℃. And the CdTe films deposited on CdS films with higher crystallinity have bigger crystallite and higher uniformity. Treatment with CdCl 2 methanol solution promotes the crystallite growth of CdTe films during annealing.

Fabrication of ferrocenyl glutathione modified electrode and its application for detection of cadmium ions

l＇-cysteaminecarbonyl-1-glutathionecarbonyl-ferrocene （Fc-GSH） was synthesized from ferrocene dicarboxylic acid and reduced glutathione （GSH） with 4 steps. IR and 1^H-NMR were used to characterize the products. Then Fc-GSH was immobilized on the surface of gold electrode. Cyclic votammetry （CV） was adopted to investigate the electrochemical properties of this Fc-GSH modified electrode in the absence and presence of Cd^2＋ aqueous solutions. The peak oxidation potential （Ea） and reduction potential （Ec） of Fc-GSH modified electrode were observed at Ea= 0.74 V and Ec= 0.64 V （vs Ag/AgCl） before the accumulation of Cd^2＋. This redox process is a monoelectron chemical reaction. The anodic shift is about 80 mV in the presence of 20 nmol/L of Cd^2＋ aqueous solution. Moreover, this shift is in proportion to the concentration of Cd^2＋ when the concentration of Cd^2＋ is lower than 20 nmol/L. So the modified electrode can be used as probes to detect cadmium ions with the limit of 0.1 nmol/L by cyclic voltammetry.

Purification of Starch from Cadmium-Contaminated Rice and Development of Functional Recombinant Rice

In order to provide a new utilization method for cadmium-contaminated rice,a preliminary study of the removal of rice starch cadmium by water,calcium hydroxide,sodium hydroxide and citric acid was conducted,the damage degree of starch was compared by SEM,and then the recombinant rice was obtained by a twin-screw extruder using the starch which met the safety standard.The physical and chemical properties of recombinant rice were analyzed by acid hydrolysis and texture analyzer.The results showed that citric acid was a good rice cadmium removal agent.The quality of recombinant rice prepared from cadmium-removed rice starch was improved;the acid resistance was increased.Heavy metal contaminated rice can be a staple food with better quality and higher value through processing.

Variations in Laboratory-Scale Actinomycete Communities Exposed to Cadmium as Assessed by Denaturing Gradient Gel Electrophoresis Profiles

The actinomycete populations and functions in cadmium （Cd） contaminated soil were investigated by the cultivation- independent molecular methods. The genomic DNA was extracted and purified from soil adulterated with various con- centrations of Cd in the laboratory. The partial 16S rDNA genes were amplified by polymerase chain reaction （PCR） using specific primers bound to evolutionarily conserved regions within these actinomycete genes. The diversity in PCR- amplified products, as measured by denaturing gradient gel electrophoresis （EGGE）, was used as a genetic fingerprint of the population. Principle component analysis and Shannon-Weaver diversity index （H） analyses were used to analyze the DGGE results. Results showed that the two principal components accounted for only a low level of the total variance. The value H in contaminated soil was lower than that in the control at later stages of cultivation, whereas at earlier stages it was higher. Among the six sampling time points, the first, fifth and sixth weeks had the highest values of H. Significantly negative correlations between bioavallable Cd concentration and H values existed in the samples from weeks 2 （R = 0.929, P 〈 0.05） and 4 （R = 0.909, P 〈 0.05）. These results may shed light on the effect of Cd on the soil environment and the chemical behavior and toxicity of Cd to actinomycetes.

Study of Back Contacts for CdTe Solar Cells

ZnTe/ZnTe∶Cu layer is used as a complex back contact. The parameters of CdTe solar cells with and without the complex back contacts are compared. The effects of un-doped layer thickness, doped concentration and post-deposition annealing temperature of the complex layer on solar cells performance are investigated.The results show that ZnTe/ZnTe∶Cu layer can improve back contacts and largely increase the conversion efficiency of CdTe solar cells. Un-doped layer and post-deposition annealing of high temperature can increase open voltage. Using the complex back contact, a small CdTe cell with fill factor of 73.14% and conversion efficiency of 12.93% is obtained.

Synthesis of Porphyrin-Appended Pyridine as a Fluorescent Chemosensor for Cd（Ⅱ） and Hg（Ⅱ）

In this research, specific molecular sensors are classified according to the type of receptor-cation interaction, that is ligand-metal interactions. Receptors are based on a multidentate protoporphyrin-appended pyridine platform, which leaves at least a vacant coordination site for the incoming metal ions. A protoporphyrin-appended pyridine, 2,5-pyridine dicarboxyamidyl-8,13-bis（vinyl）-3,7,18,17-tetramethyl-21 H, 23 H-porphyrin（P-PTP）, was designed and synthesized. Its application as potential fluoroionophore for recognition of cadmium and mercury ions is reported. P-PTP shows chelation-enhanced fluorescence effect with Cd（Ⅱ） and Hg（Ⅱ） via the interruption of photoinduced electron transfer （PET） process, which has been utilized as the basis of the fabrication of the metal ions-sensitive fluorescent chemosensor. The analytical performance characteristics of the proposed Cd（Ⅱ）- and Hg（Ⅱ）- sensitive chemosensors were investigated. It shows a linear response toward Cd（Ⅱ） and Hg（Ⅱ） in the concentration range of 1.0×10-3 to 1.0×10-7 M with a limit of detection of 1.0×10-7 M and 0.5×10-7M for Cd（Ⅱ） and Hg（Ⅱ）, respectively. The chemosensor shows good selectivity for Cd（Ⅱ） over a large number of other transition metal ions, i.e., Cu（Ⅱ）, Zn（Ⅱ） and mixed metal ions.

Electronic Structure of the Nanodiatomic Compounds CdS

The potential energy curves of the molecule CdS have been calculated for 245 internuclear distances in the range 2.15 A 〈 r ≤6.471 A for 17 states in the representation 2S＋lA（±）via CASSCF method. Multireference CI calculations （single and double excitations with Davidson corrections） were performed by using Gaussian basis sets for the two considered atoms. The potential energy curves, the harmonic frequency ωe, the internuclear distance re, the rotational constant Be, the electronic energy with respect to the ground state Te and the static dipole moment have been calculated. The comparison of these values to the available data in the literature shows a good agreement. To the best of our knowledge, eleven electronic states have been investigated here for the first time.

Trace Metal Contamination of Water in Naviundu River Basin, Luano and Ruashi Rivers and Luwowoshi Spring in Lubumbashi City, Democratic Republic of Congo

Aluminum （AI）, Vanadium （V）, Chromium （Cr）, Manganese （Mn）, Iron （Fe）, Strontium （Sr）, Molybdenum （Mo）, Silver （Ag）, Cadmium （Cd）, Tin （Sn）, Caesium （Cs）, Barium （Ba）, Lead （Pb）, Bismuth （Bi） and Uranium （U） concentrations were investigated in water samples from fifteen sampling locations in Naviundu river basin, Luano and Ruashi rivers and Luwowoshi spring in Lubumbashi city during February, March and April 2016. Chemical analyses of the samples were carried out using Inductively Coupled Plasma-Mass Spectrometer. Water pH was determined using a pH-meter and mean pH values ranged from 4.2 to 5.8. The highest mean levels of Al （5,961.954 μg·L^-1）, Pb （472.287 μg·L^-1）, V （21.014 μg·L^-1）, Cr （8.185μg·L^-1）, U （4.163μg·L^-1） and Bi （0.012 μg·L^-1） were recorded in Chemaf （Chemicals of Africa） hydrometallurgical plant effluent, those of Mn （29,714.593 μg·L^-1）, Sr （374.377μg·L^-1）, Cd （11.358μg·L^-1） and Cs （0.107μg·L^-1） in Naviundu river at Cimenkat （Katanga＇s Cement Factory） exit, those of Fe （14,258.9 μg·L^-1） and Ba （307.641μg·L^-1） in Luano river and those of Ag （2.669 μg·L^-1）, Mo （0.559 μg·L^-1） and Sn （0.325 μg·L^-1） were respectively noted in Foire channel, Naviundu river under bridge on Kasenga road and Kalulako river. The concentrations of Cd in Naviundu river at Cimenkat exit （11.358 μg·L^-1）, Chemaf bydrometallurgical plant effluent （9.697μg·L^-1）, Naviundu river under bridge on De Plaines Avenue （6.95 μg·L^-1） and Kalulako river （3.229 μg·L^-1）, Pb concentrations in Chemaf hydrometallurgical plant effluent （472.287 μg·L^-1） as well as the AI, Fe and Mn concentrations recorded in most waters in this study exceeded the WHO （World Health Organization） maximum permissible limits for drinking water. The metal contamination of waters of the studied rivers, channel and spring might be partially attributed to natural processes, unplanned urbanization and poor waste management, and mostly to abandoned and ongoing mining and ore processing activities in Lubumbashi city.

Trace Metal Contamination of Water in the Lubumbashi River Basin, Kafubu, Kimilolo and Kinkalabwamba Rivers in Lubumbashi City, Democratic Republic of Congo

Concentrations of fifteen trace metals including Aluminum （Al）, Vanadium （V）, Chromium （Cr）, Manganese （Mn）, Iron （Fe）, Strontium （Sr）, Molybdenum （Mo）, Silver （Ag）, Cadmium （Cd）, Tin （Sn）, Caesium （Cs）, Barium （Ba）, Lead （Pb）, Bismuth （Bi） and Uranium （U） were investigated in water samples collected from sixteen sampling locations in the Lubumbashi river basin and five locations in Kafubu, Kimilolo and Kinkalabwamba rivers during February, March and April 2016. Chemical analyses of the samples were carried out using ICP-MS （Inductively Coupled Plasma-Mass Spectrometer）. Water pH was determined using a pH-meter and pH values ranged from 4.2 to 7.8. The highest mean trace metal levels of water were 5,515.816 ）μg·L^-1, 166.925μg·L^-1, 3.898μg·L^-1 and 1.879μg·L^-1 for Al, Ba, Cr and U, respectively in Kashobwe river, 2,419.522 μg·L^-1 and 17.994 μg·L^-1 for Fe and Cd, respectively in Kafubu river at its confluence with Lubumbashi rivers, 1,408.136μg·L^-1 for Mn in Kafubu river 1.36 kilometer downward its confluence with Naviundu river, 222.406 μg·L^-1 and 0.092 μg·L^-1 for Sr and Cs, respectively in Kamalondo river 60 meters from the GCM-Lubumbashi （General of Quarries and Mines-Lubumbashi） smelter, 140.294μg·L^-1, 12.063 μg·L^-1 and 0.008μg·L^-1 for Pb, V and Bi, respectively in Munua river, 3.544 μg·L^-1 for Ag in Kabulameshi river, 1.49 μg·L^-1 for Mo in Kafubu river and 0.081μg·L^-1 for Sn in Tshondo river. The mean concentrations of Al, Cd, Fe, Mn and Pb in water of many rivers and the channel exceeded the maximum admissible limits of the WHO （World Health Organization）, USEPA （United States Environmental Protection Agency） and EU （European Union） drinking-water standards. Trace metal contamination of water of the studied rivers, channel and springs might be partially attributed to natural processes, unplanned urbanization, poor waste management and mostly to abandoned and ongoing mining and ore processing activities in Lubumbashi city.

Comparative analysis on homogeneity of Pb and Cd in epoxy molding compounds

Reference materials for quantitative determination of regulated heavy metals, such as Pb and Cd in electronic components, were designed and investigated in terms of stability and homogeneity. Reference materials with two concentration levels of heavy metals were prepared by spiking Pb and Cd compounds to epoxy molding compounds made by mixing silica powders and epoxy resin. The concentration changes of the reference materials during stability test for 1 a were not observed. In the homogeneity assessment, the as-prepared reference materials were studied by using three different analytical tools, inductively coupled plasma atomic emission spectrometry (ICP-AES), X-ray fluoroescence spectrometry (XRF) and laser ablation ICP mass. The results show different homogeneities by the characteristics of analytical tools and the materials.

Characterization of cellulose-based electrospun nanofiber membrane and its adsorptive behaviours using Cu(Ⅱ),Cd(Ⅱ),Pb(Ⅱ)as models

Nanofiber membranes from the composite of cellulose acetate/polyvinylpyrrolidone were prepared using electrospinning technique. After treated with water and alcoholic KOH to remove partially polyvinylpyrrolidone and deacetylate the cellulose acetate, the membranes were further functionalized with thiol groups using thioglycolic acid. Related materials were characterized using infrared and thermogravimetric analysis. And the results showed that the membranes were success of functionalisation. Then the nanofiber membranes were used in the sorption-desorption process. The effects of pH, contacting time and adsorption capacity of nanofiber membranes were studied against Cu（II）, Cd（II） and Pb（II） ions. And the maximum adsorption capacities of Pb （II）, Cu （II）, and Cd （II） ions were estimated at 30.96, 19.63, 34.70 mg g-1. Our results suggested that the adsorption be- haviour of metal ions could be described using Langmuir model. Their adsorption kinetics was in agreement with the model of pseudo-second order, suggesting chemical adsorption as the rate-limiting step of the adsorption mechanism. The durability of the thiol-functionalized cellulose nanofiber membranes was also evaluated by repetitive adsorption-desorption.

The analysis of X-ray response of CdZnTe detectors

CdZnTe is an excellent material candidate for high efficiency,high-resolution room-temperature nuclear radiation detectors,and the CdZnTe detectors are being widely used in medicine,industry,safeguard and scientific X-ray and γ-ray imaging and spectroscopic applications.In this work,three CdZnTe planar detectors with different grades,named CZT-1,CZT-2 and CZT-3,respectively,were fabricated.And the effects of mobility,lifetime and de-trapping time on the performance of CdZnTe planar detector,such as the energy resolution,charge collection efficiency and peak to valley ratio,were analyzed.The charge collection efficiency depends on the product of carrier mobility and lifetime,which has a great effect on the energy resolution of detector when the efficiency is less than 90%.The de-trapping time of carriers in deep levels should be responsible for the peak to valley ratio and "polarization".