Solar driven membrane pervaporation for desalination processes

We describe details of a solar driven pervaporation process for the production of desalinated water from highly contaminated waters. The membrane material is a polyetheramide-based polymer film of 40 μm thickness. This Solar Dew^® membrane is used in a tubular configuration in a direct solar membrane pervaporation process. The feed waters used in this study are untreated seawater and waste water that is simultaneously produced with the mineral oil extraction. In all cases retention of typical ions as sodium, chloride and calcium as well as specific problematic ions (arsenic, boron and fluoride) was higher than data reported for pressure driven membrane processes like NF and RO. The condensate quality was well within WHO limits for drinking water. A reduction of almost five orders of magnitude in conductivity between brine and condensate could be realized, producing condensate with conductivities of 5 μS/cm or lower. Laboratory experiments show that the measured fluxes are independent of severe fouling and virtually independent of concentration up to 100 g/l total solids.     

CHARACTERISTICS-FINITE ELEMENT METHODS FOR SEAWATER INTRUSION NUMERICAL SIMULATION AND THEORETICAL ANALYSIS

0.IntroductionSeawaterintrusionisaproblemwhichhasmuchtodowithnaturalresourcesandenvironmentinmodernsociety,andisgettingmoreandmoreseriousinmanyajreasofourcountryandmailyothercountriesintheworldsuchasUSA,NetherlandsandIsrael.Theharmbroughtaboutbyseawaterintrusionisimmeasurable.Theareasintrudedbyseawaterareusuallycoastalalluvialplainswherethesoilusedtobefertile,groundwaterreservesarerichandagricultureiswell-developed.Becauseofseawaterintrusion,groundwaterbecomessaltedandunfitforpeopleandanimal…     

5083铝合金在海水中的腐蚀电化学行为及活性氯影响研究

采用动电位极化、循环极化和全浸腐蚀试验方法,研究了5083铝合金在静止海水中的腐蚀电化学性能以及活性氯的影响.结果表明,在本文设置的防污活性氯浓度范围(0.2～0.5mg/L)内,活性氯对铝合金的阴极和阳极电化学极化以及腐蚀行为没有明显影响,并可提高铝合金的耐点蚀能力,海水的pH值对铝合金的腐蚀具有显著的影响.该研究为海水中5083铝合金的防腐防污提供了依据.     

福建海岸带地质环境背景与海水入侵的形成条件探讨

提出一种新的网格自适应方法：在需要加密的网格单元中心加入新结点,并对加密后的相邻 三角形网格单元进行公共边变换, 构成新的网格单元. 与传统的在网格边界中点加入新节点的自 适应方法相比,新方法可以更加灵活地控制网格密度,加密后的网格继承原先的网格质量不 发生畸变,并且算法编程简便,容易实现. 将自适应网格生成方法和基于特征线方程的分离 算法相结合,对空腔内不可压缩黏性流动进行了计算. 在特征线方向上进行时间步离散,动 量方程求解过程中采用非增量型分离算法. 计算中,把求解变量梯度值作为判定准则,在 变化剧烈的区域进行网格局部加密. 计算结果表明该组合算法有很好的计算精度,并有效减 少了计算时间和存储量.     

阴极保护和缓蚀剂技术联合保护成膜的阻抗谱研究

本文应用电化学阻抗谱 (EIS)研究了 90 7A钢在海水中受到阴极保护的同时 ,添加多元醇磷酸酯类缓蚀剂 ,其表面膜层变化的情况和缓蚀机理 ,对膜层在海水中浸泡的破损过程也进行了分析 .结果表明缓蚀剂和阳极保护相互促进成膜 ,与成膜过程相对应的EIS变化清楚地显示膜层的变化 ,这种膜层是多层膜结构 ,有良好的持久性和耐蚀能力 .     

Preparation of Pt deposited nanotubular TiO2 as cathodes for enhanced photoelectrochemical hydrogen production using seawater electrolytes

The purpose of this study was to develop effective cathodes to increase the production of hydrogen and use the seawater, an abundant resource in the earth as the electrolyte in photoelectrochemical systems. In order to fabricate the Pt/TiO₂ cathodes, various contents of the Pt precursor (0–0.4 wt%) deposited by the electrodeposition method were used. On the basis of the hydrogen evolution rate, 0.2 wt% Pt/TiO₂ was observed to exhibit the best performance among the various Pt/TiO₂ cathodes with the natural seawater and two concentrated seawater electrolytes obtained from single (nanofiltration) and combined membrane (nanofiltration and reverse osmosis) processes.The surface characterizations exhibited that crystal structures and morphological properties of Pt and TiO₂ found the results of XRD pattern and SEM/TEM images, respectively.     

Application of in-vial membrane assisted solvent extraction to the determination of polycyclic aromatic hydrocarbons in seawater by gas chromatography-mass spectrometry

A device for membrane assisted solvent extraction from an aqueous sample to an organic solvent within a micro-vial compatible with a chromatography auto-sampler was used to extract trace amounts of seven polycyclic aromatic hydrocarbons from seawater. The device consisted in an assembly of a volumetric flask containing the sample and a micro-vial containing the organic solvent by means of a screw stopper in which the septum was replaced by a sized piece of a membrane. Extraction conditions (nature of the organic solvent, extraction time, presence of ethanol in the donor phase, ionic content of the donor phase, characteristics of the membrane and volumes of donor and acceptor phases) were studied in order to find the conditions for maximum extraction. Analytical performance characteristics have also been established. The extraction efficiency was between 12.5 and 23%, which implies an enrichment factor value above 40. The repeatability and reproducibility were in the range of 8.6–10.0% and 13–19%, respectively. Detection limits were in the range of 24–39 ng L⁻¹. Nine seawater samples have been studied. Most of the concentrations were under the limits of detection. Naphthalene and phenanthrene contents have been determined in a sample using the method of standard additions, and concentrations 100 and 91 ng L⁻¹, respectively.     

Determination of picomolar beryllium levels in seawater with inductively coupled plasma mass spectrometry following silica-gel preconcentration

A robust and rapid method for the determination of natural levels of beryllium (Be) in seawater was developed to facilitate mapping Be concentrations in the ocean. A solid-phase extraction method using a silica gel column was applied for preconcentration and purification of Be in seawater prior to determination of Be concentrations with inductively coupled plasma mass spectrometry (ICP-MS). Be was quantitatively adsorbed onto silica gel from solutions with pH values ranging from 6.3 to 9, including natural seawater. The chelating agent ethylenediamine tetraacetic acid was used to remove other ions in the seawater matrix (Na, Mg, and Ca) that interfere with the ICP-MS analysis. The reproducibility of the method was 3% based on triplicate analyses of natural seawater samples, and the detection limit was 0.4 pmol kg⁻¹ for 250 mL of seawater, which is sufficient for the analysis of seawater in the open ocean. The method was then used to determine the vertical profile of Be in the eastern North Pacific Ocean, which was found to be a recycled-type profile in which the Be concentration increased with depth from the surface (7.2 pmol kg⁻¹ at <200 m) to deep water (29.2 pmol kg⁻¹ from 3500 m to the bottom).     

Durability enhancement and degradation of oxygen evolution anodes in seawater electrolysis for hydrogen production

For the anode composed of electrocatalyst oxide, intermediate layer and titanium substrate, the substitution of a certain amount of iridium with tin in the IrO₂ intermediate layer was remarkably effective in elongating the life of the anode in preventing oxidation of the substrate titanium during oxygen evolution. The longest life was realized by preparation of intermediate layer with uniform thickness by brush-coating of H₂IrCl₆-SnCl₄ butanol solution and subsequent calcination. The anode with the intermediate layer prepared from 0.04 M H₂IrCl₆-0.06 M SnCl₄ butanol solution showed the best performance, that is, the oxygen evolution efficiency higher than 99.8% for more than 4300 h in the electrolysis of 0.5 M NaCl solution of pH 1 at the current density of 1000 Am⁻². An increase in SnCl₄ concentration decreased the viscosity of the coating solution with a consequent enhancement of uniformity of the intermediate layer but decreased the thickness of the intermediate layer acting as a barrier to prevent oxidation of titanium. Thus, the best performance was attained at an intermediate SnCl₄ concentration. The growth of an oxide layer on titanium during electrolysis occurred and was found by the potential increase.     

A solvent extraction technique for the isotopic measurement of dissolved copper in seawater

Stable copper (Cu) isotope geochemistry provides a new perspective for investigating and understanding Cu speciation and biogeochemical Cu cycling in seawater. In this work, sample preparation for isotopic analysis employed solvent-extraction with amino pyrollidine dithiocarbamate/diethyl dithiocarbamate (APDC/DDC), coupled with a nitric acid back-extraction, to concentrate Cu from seawater. This was followed by Cu-purification using anion-exchange. This straightforward technique is high yielding and fractionation free for Cu and allows precise measurement of the seawater Cu isotopic composition using multi-collector inductively coupled plasma mass-spectrometry. A deep-sea profile measured in the oligotrophic north Tasman Sea shows fractionation in the Cu isotopic signature in the photic zone but is relatively homogenised at depth. A minima in the Cu isotopic profile correlates with the chlorophyll a maximum at the site. These results indicate that a range of processes are likely to fractionate stable Cu isotopes in seawater.