Stainless steel corrosion scale formed in reclaimed water: Characteristics, model for scale growth and metal element release

Stainless steels generally have extremely good corrosion resistance, but are still susceptible to pitting corrosion. As a result, corrosion scales can form on the surface of stainless steel after extended exposure to aggressive aqueous environments. Corrosion scales play an important role in affecting water quality. These research results showed that interior regions of stainless steel corrosion scales have a high percentage of chromium phases. We reveal the morphology, micro-structure and physicochemical characteristics of stainless steel corrosion scales. Stainless steel corrosion scale is identified as a podiform chromite deposit according to these characteristics, which is unlike deposit formed during iron corrosion. A conceptual model to explain the formation and growth of stainless steel corrosion scale is proposed based on its composition and structure. The scale growth process involves pitting corrosion on the stainless steel surface and the consecutive generation and homogeneous deposition of corrosion products, which is governed by a series of chemical and electrochemical reactions. This model shows the role of corrosion scales in the mechanism of iron and chromium release from pitting corroded stainless steel materials. The formation of corrosion scale is strongly related to water quality parameters. The presence of HClO results in higher ferric content inside the scales. Cl⁻ and SO₄^2 − ions in reclaimed water play an important role in corrosion pitting of stainless steel and promote the formation of scales.     

Estimation of ammonia nitrogen load from nonpoint sources in the Xitiao River catchment, China

Ammonia nitrogen (NH4+-N) is one of the three main forms of total nitrogen (TN). Most studies have estimated the load of TN from nonpoint sources instead of one specific form. The relationship between land use and concentrations of NH4+-N in runoff was analyzed using the hydraulic analysis functions of a Geographic Information Systems (GIS), and the annual loads of NH4+-N in the Xitiao River catchment were estimated according to model results. The results suggested that the calculated annual loads of NH4+-N...     

Algal-bloom control by allelopathy of aquatic macrophytes——A review

Algal-bloom control is an important issue for water environment protection as it induces several negative impacts on the lives of aquatic organisms, aquaculture, landscaping, and human health. The development of an environment-friendly, cost-effective, and convenient alternative for controlling algal bloom has gained much concern. Using the allelopathy of aquatic macrophytes as a novel and safe method for algal-bloom control is a promising alternative. This paper reviews the development and potential application about allelopathy of aquatic plants on algae, including the allelopathic research history, the potential research problems, the research methodology, and the reported aquatic macrophytes and their inhibitory allelochemicals. Potential modes of inhibition action of allelochemicals on algae, possible ways for application, and future development directions of research on algal-bloom control by aquatic macrophytes were also presented.     

5·12震灾中《人民日报》抗震救灾报道实证分析

2008年5·12汶川地震灾难造成了重大的人员伤亡,本文将以<人民日报>作为研究样本,选取5月12日到6月12日共32天的报道,通过对抗震救灾报道进行归类、分析、思考,笔者认为<人民日报>在抗震救灾报道中呈现出议程设置进程化,议题选择多样化、报道公开透明有力等新的特点,充分体现了媒体的社会责任和社会功能,因此本次报道是中国媒体在突发事件报道中新的里程碑.     

In vitro effects of metal ions on lipid peroxidation induced by alcohol in mice liver homogenate

The study is aimed to estimate the effect of different heavy metals such as Hg2+, Cd2+, Mn2+, Cr3+, Ni2+, Se2O3(2-), As2O3 water solution and combined effects of Hg2+, Mn2+, Cr3+ on lipid peroxidation in mice liver homogenate in vitro. Lipid peroxidation was determined as thiobarbituric acid-reacting materials (TBA). We select five different concentrations of selected ions for experiments. Correlations used to identify the concentration of ions associated with lipid peroxidation. The rate of lipid peroxide formation in mice liver homogenate increased with the gradual addition of alcohol. When alcohol dose was up to 0.5 ml, the rate of lipid peroxide formation was greatest. At tested concentrations, the effects of metal ions on lipid peroxidation induced by alcohol were classified into three groups, and are as follows: (1) simulative, Hg2+. (2) inhibitory, Mn2+, Cr3+, Ni2+, Se2O3(2-). (3) ambiguous, Cd2+, As2O3 water solution. When Hg2+, Mn2+ and Cr3+ were added to the mice liver homogenate with alcohol at the same time, Hg2+, Mn2+ were the main agents for the rate of alcohol induced lipid peroxidation. The simulative effect of Hg2+ on lipid peroxidation induced by alcohol indicate that alcohol-drinkers will have further health risk when they are exposed in polluted regions than others, and Mn2+, Cr3+, Ni2+, Se2O3(2-) may act as free radical scavengers and preventive remedy for alcoholism in part. Furthermore, analysis of combined effect of Hg2+Mn2+ and Cr3+ provide us a new way to estimate the combined effect of multi-materials.     

低压离子色谱法测定水和酸雨样品中F~-,Cl~-,NO_3~-,SO_4~(2-)离子

本文介绍了低压离于色谱法测定水样(井水、湖水、矿泉水、自来水)和酸雨中氟、氯、硝酸根、硫酸根离子的方法.欲测阴离子在阴离子交换柱上被分离,同时用1.2mol·l~(-1)N_2CO_3溶液作流动相,流速为 1.6ml·min~(-1).各离子的流分用电导检测.进样量为50μl时F~-,Cl~-,NO_3~-,SO_4~(2-)的最低检出限(2倍噪音比)分别为10,20,250,500ng·ml~(-1).     

高铁酸钠电化学合成条件的研究

利用含铁材料为阳极，铜为阴极，NaOH溶液为电解液，于隔膜电解槽中电解制备高铁酸钠。探索了该工艺所必需的各种参数和反应条件，确定了隔膜材料，并对Na2FeO4浓度和电流效率的非一致性变化作出了解释。研究结果表明：在阳极距离为1．3cm（极距2．3cm）、阳极电解液浓度为14mol／L，阴极电解液浓度为4mol／L、温度为35℃、电压为8～9V时，电解2h后得到的Na2FeO4浓度为18．7g／L，电流效率为20％。     

悬浮颗粒物在河道滞留塘系统中的沉降与沉积特性

河道滞留塘系统是以颗粒物沉降为污染物主要净化机理的污染河流净化技术。通过1年的现场试验研究，考察了悬浮颗粒物SS在滞留塘中的沉降和沉积特性。在本试验条件下，随水力停留时间（HRT）延长（HRT为1．5-7h），SS平均去除率逐渐增加，介于20％-40％之间，而SS去除速率则快速降低，SS去除速率与进水SS浓度成正比关系；不同季节河水中SS的沉降性能有较大差异，冬季河水中有机物含量较低的易沉降颗粒物比例较春秋季河水的为高，滞留塘HRT的选择应以去除易沉降颗粒物为标准，本研究条件下5h以内是适宜的HRT选择范围。在滞留塘动态运行中，SS的沿程沉积量呈指数规律下降。     

脲硫酸分解磷矿过程氟逸出规律的研究

对脲硫酸分解磷矿过程中酸解剂配比(即尿素加入量)、反应温度、磷矿粉细度、搅拌强度等对磷矿转化率和气相氟逸出率的影响进行了．探讨。实验结果表明．酸解剂配比是影响氟逸出率的最主要因素，由于尿素的加入．可使氟逸出率降低75％以上。     

介质特性对DBD降解苯的影响

为了提高介质阻挡放电（dielectric barrier discharge，DBD）等离子体的处理效率，研究了内外介质组成分别为：（1）石英＋石英；（2）陶瓷＋石英；（3）陶瓷＋陶瓷这3种情况下苯的降解情况。试验结果表明，在处理低浓度含苯废气时，陶瓷＋陶瓷效果最好；陶瓷（内管）＋石英（外管）在处理高浓度含苯废气时显示出优势。通过对气相产物和固相结焦产物的分析验证了DBD能有效降解苯，降解产物不会带来新的污染。进一步分析了实验条件和介质材料的变化对DBD降解苯的影响机理。