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101.
Iron detection at the ultratrace level in seawater is at the forefront in chemical oceanography research and analytical methodologies for its determination are actively sought. Voltammetric methods and specifically cathodic stripping voltammetry (CSV) with catalytic enhancement, are particularly fit for this purpose as they avoid any separation and pretreatment step, showing high sensitivity and robustness towards the saline matrix. Here we introduce a simplification in the instrumentation for iron detection by CSV using 2,3‐dihydroxynaphthalene (DHN) as the ligand, atmospheric oxygen as the catalytic enhancer and a small 0.5 mL cell. The simplification involves the use of a standard, non‐specialized voltammetric cup as a holder for the small cell and the introduction of a simple silver wire as a pseudoreference electrode. The latter reduces the risk of sample contamination and is perfectly suited for employment with the small, 0.5 mL volume cell. Extensive optimization was performed in both ultrapure and seawater: a square wave frequency of 10 Hz was adopted, whereas the ligand concentration did not significantly influence the limit of detection (around 10 and 40 pM for ultrapure and seawater, respectively). The latter difference in signal to noise ratio was explained by the kinetics of iron complex reduction. The method was successfully validated by the analysis of a seawater sample with consensus value. 相似文献
102.
通过引入聚乙烯亚胺(PEI)链与对叠氮苯甲酸(ABA)分子对薄层芳香聚酰胺复合反渗透膜(TFC)进行接枝改性, 采用傅里叶衰减全反射红外光谱(ATR-FTIR)和X射线光电子能谱(XPS)分析了反渗透膜活性分离层的化学组成和结构, 用静态水接触角仪与Zeta电位仪测试了反渗透膜表面的亲疏水性和电荷性质, 并利用扫描电子显微镜(SEM)及原子力显微镜(AFM)观察其表面形貌, 测试了反渗透膜在苦咸水与海水条件下的分离性能. 实验结果表明, 使用PEI与ABA对反渗透膜改性后, 提升了其分离层的致密度, 使硼渗透通过反渗透膜时的传质阻力变大, 从而将改性反渗透膜(TFC-PEI-ABA)对硼的截留率提升至90.45%, 达到了世界卫生组织对水质的要求. 相似文献
103.
研究了以乙二醇为电子给体在Pt/TiO2上光催化分解海水制氢的反应。研究了反应时间、乙二醇起始浓度、溶液pH值、乙二醇中共存物甘油和葡萄糖对光催化放氢的影响。结果表明乙二醇能显著地提高光催化分解海水制氢效率,并且其自身的降解活性也很好。 相似文献
104.
Experiments were performed in the laboratory on synthetic seawater spiked with different selenium species at trace levels to study the formation of volatile selenium compounds under dark or controlled simulated sunlight conditions. Spiking the reaction media with inorganic and organic selenium compounds demonstrated that several volatile selenium species could be formed under these simulated conditions. Selenoamino acids react to produce significant amounts of volatile selenium species in both light and dark conditions. Products formed include dimethyl selenide (DMSe), dimethyl selenyl sulphide (DMSeS) and dimethyl diselenide (DMDSe). Inorganic selenium oxyanions added to the synthetic reaction media did not form volatile species via abiotic reactions despite the presence of strong methylating agents. These results suggest that the formation of stable volatile species from bio‐organic selenium compounds can occur via abiotic reactions in the marine photic zone. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献
105.
106.
The unsteady process of the acidification of seawater by using an electrochemical acidification cell (EAC) is studied in this paper. The model of the concentration of hydrogen ions () in the effluent seawater and the cell voltage of EAC varying with time and working current are built by applying the theory of finite-time thermodynamics, respectively. The semi-empirical formulas of the concentration of in the effluent seawater and the cell voltage under the constant current of the Ionpure EAC are obtained, respectively, by fitting the experimental data of the Ionpure EAC. Then, the simulated data are compared with the experimental data. The total work consumption and average power consumption of the Ionpure EAC are obtained from the semi-empirical formulas. The results show that the semi-empirical formulas can simulate the operation process of the Ionpure EAC well. The validity of the models is verified. The increase of the working current will increase the total work consumption and average power consumption of the Ionpure EAC. The proper current can be selected in engineering practice to achieve different goals, such as high efficiency or low energy consumption. The obtained results can provide some guidelines for the optimal design and optimization of EAC. 相似文献
107.
Imran Ali Gunel Imanova Teymur Agayev Anar Aliyev Sakin Jabarov Hassan M. Albishri Wael Hamad Alshitari Ahmed M. Hameed Ahmed Alharbi 《Molecules (Basel, Switzerland)》2022,27(19)
Hydrogen production is produced for future green energy. The radiation–chemical yield for seawater without a catalyst, with Zr, and with Zr1%Nb (Zr = 99% Nb = 1%) were (G(H2) = 0.81, 307.1, and 437.4 molecules/100 eV, respectively. The radiation–thermal water decomposition increased in γ-radiation of the Zr1%Nb + SW system with increasing temperature. At T = 1273 K, it prevails over radiation processes. During the radiation and heat radiation heterogeneous procedures in the Zr1% Nb + SW system, the production of surface energetic sites and secondary electrons accelerated the accumulation of molecular hydrogen and Zr1%Nb oxidation. Thermal radiation and thermal processes caused the metal phase to collect thermal surface energetic sites for water breakdown and Zr 1%Nb oxidation starting at T = 573 K. 相似文献
108.
Water-soluble 3H-labeled arsenic compounds were phenol-extracted from mussels (Mytilus edulis) and seawater after exposure to [3H]monomethylarsonate (MMAA) and [3H]dimethylarsinate (DMAA). Varying amounts of [3H] arsenobetaine were found in mussels and seawater, depending upon the experimental conditions. The results indicate that arsenobetaine is principally biosynthesized by microscopic organisms in the seawater and that it is bioaccumulated by mussels. Total arsenic concentrations in mussel flesh, byssal threads and shells were also determined, showing concentration increases in all three compartments. 相似文献
109.
The use of a closed-loop on-line enrichment procedure in combination with an ICP plasma emission spectrometer has been developed for the analysis of trace metal ions, such as Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn. The procedure utilizes a preconcentration column filled with an anion exchange resin and 8-hydroxy-7-iodoquinoline-5-sulphonic acid is added to the sample prior to preconcentration. Details on the optimization of pretreatment and instrumental conditions are described. Results obtained for the analysis of river water and antarctic seawater are reported.Presented in part at the 1989 European Winter Conference on Plasma Spectrochemistry, Reutte, Austria 相似文献
110.
Gabriele Capodaglio Carlo Barbante Clara Turetta Giuseppe Scarponi Paolo Cescon 《Mikrochimica acta》1996,123(1-4):129-136
The problem of contamination during the collection of samples of environmental interest to detect trace metal is discussed. Attention is focused on the leaching of metals from sampling devices used to collect surface and deep seawater. A procedure to test metal release is applied to emphasize the importance of conditioning samplers before use. The procedure for checking the contamination extent and decontamination of firn and ice cores to detect ultratrace elements (particularly Cd and Pb) is presented and applied to some firn cores collected in Antarctica during the 1990–1991 Italian expedition. 相似文献