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101.
A novel carbon paste electrode containing chitosan microspheres for the determination of Cu(II) in instant coffee by anodic stripping voltammetry was developed. Chitosan was crosslinked with the chelating agent 8-hydroxyquinoline-5-sulphonic acid and glutaraldehyde. The microspheres of the crosslinked chitosan biopolymer were obtained by the spray drying technique and employed in the construction of the sensor. In acetate buffer solution (0.1 mol L−1, pH 6.0), the calibration curve obtained was linear for concentrations of 5.0 × 10−7 to 1.4 × 10−5 mol L−1 (r = 0.9990); the detection limit was 5.5 × 10−8 mol L−1. The relative standard deviation (n = 8) was lower than 3.0% for solutions containing 6.0 × 10−6, 5.0 × 10−5 and 1.5 × 10−4 mol L−1 of Cu(II). The method was successfully employed for determination of Cu(II) in instant coffee and the results obtained showed good agreement when compared with those using electrothermal atomic absorption spectrometry. 相似文献
102.
对超重力场条件下Cu熔体中的氧化夹杂进行受力分析,建立夹杂颗粒沿超重力方向上的运动速度与运动距离方程,并通过理论计算分析重力系数、夹杂物特性(尺寸、种类、含量)以及熔体温度对夹杂物在超重力场中运动行为的影响。计算结果表明,超重力场能强化Cu熔体中氧化夹杂的定向分离过程,其中重力系数、夹杂物尺寸、夹杂与熔体之间密度差(固液密度差)对夹杂颗粒运动行为影响较大。较大的重力系数、夹杂物尺寸以及固液密度差均有利于夹杂物的上浮去除。 相似文献
103.
Richard K. Morgan Roger Bowden 《The International journal of environmental studies》2013,70(2-3):161-167
In recent years there has been a move in New Zealand to convert small, uneconomic orchards to other agricultural uses. Overseas research has demonstrated that copper from fungicide sprays often accumulates in the soils of orchards and can cause certain problems for plant growth and livestock. To date, no assessments appear to have been made of the degree of copper accumulation in such older orchards in New Zealand. This study presents the results of an assessment of two well‐established apricot orchards in the Central Otago region of South Island, New Zealand. Two aspects of the results are surprising. The first is the relatively low levels of copper in the soil when compared with results from another orchard in the region. That orchard is 18 years old and mean soil copper has already reached 100.0 μg/g, indicating a much faster rate of accumulation than in the two orchards in the current study. The second unexpected result is that the younger orchard has a significantly higher level of copper than the older orchard. Reasons for these findings are discussed in relation to apparent differences in soil properties. 相似文献
104.
This study examined impacts of concentrations and properties of natural organic matter (NOM) on copper release from characteristic copper solid model phases such as tenorite CuO and malachite Cu2(OH)2CO3. Unaltered Aldrich humic acid (AHA) and standard Suwannee River fulvic acid (SRFA) strongly increased copper release from the model phases but NOM alteration by chlorination or ozonation gradually suppressed or, at higher oxidant doses, eliminated these effects. The nature of NOM changes induced by chlorination and ozonation was examined using differential absorbance spectroscopy (DAS) and high-performance size-exclusion chromatography (HPSEC). The data of these methods show that NOM molecules with higher apparent molecular weight (AMW), higher aromaticities and contributions of protonation-active phenolic and carboxylic groups play a key role in adsorption and colloidal dispersion of the model solids. The data also show that metal release from model phases was well correlated with a number of spectroscopic parameters characterizing NOM properties, notably SUVA254, spectral slopes of NOM absorbance, and differential absorbance at wavelength of 280 nm and 350 nm that is indicative of the contributions of carboxylic and phenolic functional groups. Changes of ζ-potential of the model solid phases were the strongest predictor of the enhancement of copper release especially in the system controlled by malachite. While effects of NOM on the ζ-potential of tenorite and malachite were prominent for unaltered NOM, its oxidation by chlorine and ozone was accompanied by a gradual decrease and ultimately disappearance of its surface activity. 相似文献
105.
The bactericidal characteristics of nano-copper oxide or functionalized zeolite coated concrete pipes against Acidithiobacillus thiooxidans were studied by measuring the temporal variation of bacterial dry cell weight measurement, cellular Adenosine Triphosphate production, as well as oxygen uptake rate of the aforementioned bacterium. Uncorroded (UC), severely corroded (SC), and moderately corroded (MC) concrete pipes were electrochemically coated with a nano-copper oxide, while another uncorroded concrete pipe was used to apply functionalized zeolite coating (Z2). Specimens were characterized by field emission-scanning electron microscopy, and optical microscopy. Oxygen uptake rate of the bacterium was the highest in UC followed by the MC. Oxygen uptake rate and cellular Adenosine Triphosphate decreased progressively in Z2 and SC throughout the duration of the experiment due to decline in live bacterial cell. The maximum bacterial specific growth rate was 1.1 × 10−2 day−1 for both UC and MC, with a decay rates varying from 1.4 × 10−2 to 2.6 × 10−2 day−1. The minimum concentration limits for the inhibition of the bacterium in the nano-copper oxide coated concrete pipes ranged from 2.3 mg to 2.6 mg Cu per mg dry cell weight. 相似文献
106.
107.
本文简要介绍了日立化成高速/高频PCB用基板材料路线图,分析了日立化成最新推出的环境友好的高速/高频PCB用基板材料MCL—LZ-71G的技术特点,从传输损失、树脂体系组成、填料界面控制等方面详细介绍MCL—LZ-71G树脂体系设计,从高频性能、传输损失、耐湿性能、耐热性、可靠性、眼图测试、耐CAF性能、热冲击测试等方面综述了MCL—LZ-71G的性能。 相似文献
108.
用原子吸收光谱法测定高岭土中铜,分别用标准曲线法及标准加入法定量分析铜元素含量,比较了作图法和回归方程法处理标准加入法数据。结果表明,随铜元素变量,标准曲线法及标准加入法均有较好的线性关系,但测定的结果有差异。标准加入法因可消除基体干扰,测得铜结果准确度高。标准加入法适合基体复杂的试样的分析。作图法及回归方程均适用于标准加入法测铜的数据处理,作图法误差大,而回归方程法是快捷,误差小的简便方法。 相似文献
109.
Inhibition of copper corrosion in aerated hydrochloric acid solution by heterocyclic compounds containing a mercapto group 总被引:1,自引:0,他引:1
Inhibition of copper corrosion by benzotriazole (BTA), 2-mercapto benzoxazole (MBO) and 2-mercapto benzimidazole (MBI) in 0.5 mol L−1 HCl was investigated by weight-loss measurements, potentiodynamic polarization curves and electrochemical impedance spectroscopy. MBI was shown to be the most effective inhibitor among those tested. Potentiodynamic polarization results revealed that the three compounds acted as anodic inhibitors, particularly MBI strongly suppressed anodic current densities. Molecular structure parameters of BTA, MBO and MBI were obtained by using an MM2 forcefield program and PPP–SCF quantum chemical calculation. It was found that MBI has higher levels of HOMO and LUMO energy and the larger π-electron density. 相似文献
110.
A series of alkyl esters (methyl, butyl, hexyl, and octyl) synthesised from a mixture of 4- and 5-carboxybenzotriazole (4-CBTAH and 5-CBTAH) inhibited copper corrosion in aerated solution (pH∼0). Inhibition efficiency (IE%) of the protonated esters (CBTAH2+-R) increased with hydrocarbon chain length and this is attributed to chemisorption (through azole ring N) and increased physical adsorption as more methyl groups are introduced. A modelling package employing molecular mechanics and molecular dynamics has been used to simulate the docking of a single protonated species (5-CBTAH2+-R) onto a clean copper (1 1 0) surface. A decrease in potential energy was associated with the flattening of the ester ring system onto the surface and further decreases in energy were associated with the extension of the aliphatic chain onto the surface. The crude binding energy (Ebind) of each ester with the surface was estimated and this energy also increased regularly with carbon chain length. The study suggests that molecular modelling and calculation of Ebind of a single molecule on a specified metallic surface can be used to predict the inhibition performance of compounds whose structures change in a regular way. 相似文献