Papers by Keyword: Zn

Abstract: The concentration and distribution of Cr, Pb and Zn in 22 Jurassic coals from northern Shaanxi,and Ningxi, China were studied. The samples were collected from eight coal mines of five different region, including Yuyang Region, Hengshan, Shenmu, Huangling and Lingwu. Comparing with Chinese coals, American coals and coal Clarke value: Pb showed different degree enrichment in the study region except Ningxia ; Cr was enriched in Shenmu coals, Huangling coals and Hengshan coals; whereas the content of Zn in the study region coals was lower than in American coals. Horizontal variation of the three elements in the study region indicated that different elements showed different variation trend. Based on statistical analyses, Pb showed a moderate relationship with ash yield, whereas Cr had a high correlation coefficients with total sulfur.

Abstract: A thermodynamic study (Pourbaix type diagrams, using the software Hydra/Medusa) of acid leaching solutions to obtain the electrochemical recovery of Ni, Cu and Zn present in printed circuit boards is reported. Solutions were characterized by atomic absorption spectroscopy at room temperature. The metals were leached in a 0.9237 M H₂SO₄ solution (pH = 1.56) at temperatures of 313, 323, 333 and 343 K. From this data, the reduction potentials were determined for each metal, finding the values of -0.0024, -1.1274 and-0.5892 V vs calomel for Cu, Ni and Zn, respectively. Displacement in the reduction potential with the increase of the metal concentration in the leaching solution was observed.

Abstract: The primary objective of this research paper is to develop a dynamic nonlinear pH neutralization process model, based on physical and chemical principles that can represent the specific pH neutralization pilot plant. The accuracy of this model should be sufficient to allow development of conventional and advanced control systems through simulation for subsequent implementation and testing on the plant itself. The pH neutralization process is modeled based on the reaction between strong basic solution (NaoH) and strong acidic solution (H2SO4) in Continuous Stirred Tank Reactor (CSTR). From open loop response pH system is considered as First Oder plus Dead time process. Comparison was made between four strategies like ZN, Fruehauf et al, Original IMC and Min ISTSE tuning Methods of PI and PID controllers. From the simulation results Error Indices and Time domain specifications where calculated for different tunings methods of PI and PID controller.

Abstract: The corrosion behavior of typical grounding materials Zn and Cu in Shanbei soil solution was studied by immersion test technique, galvanic corrosion current measurement and simulated stray current test. The results showed that Zn was seriously corroded with the corrosion product of ZnCO₃, while Cu was slightly corroded with the main rust of Cu₂(OH)₂CO₃ and copper oxides. The corrosion of Zn was accelerated and Cu was protected when coupled them together. Stray current can significantly increase the corrosion process of both Zn and Cu.

Abstract: By collecting dust samples from seven different functional areas of Guiyang city, we studied the distribution pattern of the level of Zn in dusts with particle size fractions. The result showed the geometric means of Zn concentration in dusts of Guiyang was 435mg/kg. The Zn in most functional areas was primarily associated with middle particles, while the Zn in industrial area and garbage stations were primarily associated with fine particles.

Abstract: Diffusion couple experiments for Mg-Al and Mg-Zn were carried out with Mg single crystal to determine the anisotropic diffusion coefficients of Al and Zn in hcp Mg at the temperature range between 553 and 693 K. Based on the experimental results, anisotropic diffusion coefficients of Al and Zn were calculated using multiphase diffusion simulations. Al diffusion in hcp Mg is slightly faster than Mg self-diffusion itself, but the diffusion of Zn is slightly slower than Mg self-diffusion. The diffusion coefficients of Al and Zn along the a-axis (basal plane) of hcp Mg is slightly higher (1.1-1.4 times) than those along the c-axis (normal to the basal plane), which is also similar to Mg self-diffusion behaviour.

Abstract: In this work we have studied the effects of Zn and ZnO addition on grain boundaries in the magnetic properties of NdFeB magnets. Zn and ZnO were added at the grain boundaries by double alloy process. Study on Zn and ZnO were effected of sintered NdFeB permanent magnetic materials .Results show that Zn and ZnO powder were added to grain boundary of improves magnets, coercivityHcj, remanenceBr, maxi-mum magnetic energy (BH)max, Zn was added1.2wt%,ZnO was added 1wt% to the maximum value, continue to add drop。Zn powders were added to the intergranular regions of NdFeB magnets, and their effects on the magnetic properties and corrosion resistance were investigated. In the scanning electron microscope, energy spectrum analysis showed that Zn and ZnO did not appear after entering the new metallographicals, Zn or ZnO distributed in where the main enrich at the Nd-rich phase[1]

Abstract: In order to investigate the ability of Pteris vittata restoring Zn polluted soil, water cultured experiment is utilized to study the enriching ability of Pteris vittata to Zn, and the detoxification mechanism of Pteris vittata to Zn. The experimental results show that Pteris vittata has certain enriching ability to Zn,and the translation coefficient of Zn in Pteris vittata reaches 1.0. With the increasing of Zn application amount, chlorophyll and soluble sugar contents of Pteris vittata show ascending first and then descending,O2-• and MDA contents continuously ascend,starch content continuously descends.These results show that soluble sugar, starch,O2-• and MDA have detoxification effect,and can enhance the resistance of plant to heavy metal.

Abstract: Choose Suzhou city’s different functional areas (industrial zone, commercial district, near the station, residential area and urban green space) to collect 55 surface soil samples and determine the zinc content of the soils by XRF and evaluate the zinc pollution level in soils with the methods of geo-accumulation index and zinc pollution index respectively. Result: The fact that the average content of Zn is beyond the soil background value in Anhui province shows soils of Suzhou city have suffered from different degrees of zinc pollution; In industrial zone, commercial district and near the station ,the zinc content of the soils is commonly higher which is mainly related to the transportation and industrial production; the evaluated results of geo-accumulative index and zinc pollution index methods show zinc pollution in soils of Suzhou city belongs to mild pollution and partial moderate pollution and the pollution is particularly serious in industrial zone, commercial district and near the station.

Abstract: The available states of Manganese (Mn) and zinc (Zn) in soil exert important roles in same biochemical reactions. Their deficiency can result in plant micronutrient disorders, but the excess contents may contribute to several environmental issues. Their spatial distribution and influential factors in the middle reaches of Tuojiang River Basin, a typical region with the broken terrain and densely populated hill, were studied with the combination of statistics, geostatistics, global positioning system (GPS) and geographic information system (GIS). According to the data of the contents in topsoil (0~20 cm) from the 296 random sampling points,the contents of soil available Mn and Zn were 5.95 and 1.05 mg kg-1, respectively. The highest value regions (>11 mg kg-1) of Mn contents were mainly distributed in the central parts of study area, and first decreased to the both sides from the central and then increased towards the northwest. The highest value regions (>1.8 mg kg-1) of Zn contents were mainly distributed in the northwest parts, and then reduced gradually towards to the southeast and southwest presenting zonal shapes. Almost 30% of the area had higher than 50% probability to exceed the threshold value (7.00 mg kg-1) of the soil available Mn based on probability kringing, Similarly, more than 70% part of the area with the probability more than 50% exceed the threshold value (0.50 mg kg-1) of soil available Zn. The content and spatial distribution of soil Mn and Zn were affected by parent materials, landform types, slopes, landuse patterns, textures, pH and organic matters (OM). While the above factors except for OM and texture (P>0.05) had significant influence on soil available Mn (P<0.05). On the contrary, only OM was the significant influent factor to soil available Zn (P<0.05).