TiO_2太阳能光催化降解有机污染物的研究进展

以太阳能为激发光源的 Ti O2 光催化氧化技术是一项极具运用前景的绿色环保技术。简要介绍了 Ti O2 光催化氧化的原理、催化剂 Ti O2 的制备研究、Ti O2 太阳能反应器的研制以及该项技术在有机污染物降解中的应用     

安徽铜陵鸡冠石银(金)矿床地质地球化学特征

鸡冠石银 (金 )矿床是铜陵地区一个具中型规模的银 (金 )矿床 ,在整个长江中、下游地区都有其代表性。矿床分四个主要成矿阶段 :夕卡岩阶段、氧化物 -硫化物阶段、石英 -硫化物阶段和石英多金属硫化物-碳酸盐阶段。对矿床的微量元素分析结果表明 ,独立的银、金矿物和含Au、Ag低的硫化物、含Ag硫盐矿物 ,主要形成于热液成矿期中晚阶段 ;矿床的轻、重稀土元素总浓度比值与辉石二长闪长岩相近 ,反映出二者的同源特征 ;稳定同位素和流体包裹体成分分析结果 ,反映出该矿床以岩浆热液为主的成因标志 ;成矿热液以岩浆水为主 ,但在成矿晚期有大气降水和地层成分加入 ;成矿流体为NaCl-KCl -H2 O体系 ;矿床成因属夕卡岩 -中低温热液充填 -交代型矿床     

Trophic modification of essential fatty acids by heterotrophic protists and its effects on the fatty acid composition of the copepod Acartia tonsa

To test whether heterotrophic protists modify precursors of long chain n−3 polyunsaturated fatty acids (LCn−3PUFAs) present in the algae they eat, two algae with different fatty acid contents (Rhodomonas salina and Dunaliella tertiolecta) were fed to the heterotrophic protists Oxyrrhis marina Dujardin and Gyrodinium dominans Hulbert. These experiments were conducted in August 2004. Both predators and prey were analyzed for fatty acid composition. To further test the effects of trophic upgrading, the calanoid copepod Acartia tonsa Dana was fed R. salina, D. tertiolecta, or O. marina that had been growing on D. tertiolecta (OM-DT) in March 2005. Our results show that trophic upgrading was species-specific. The presence of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in the heterotrophic protists despite the lack of these fatty acids in the algal prey suggests that protists have the ability to elongate and desaturate 18:3 (n−3), a precursor of LCn−3PUFAs, to EPA and/or DHA. A lower content of these fatty acids was detected in protists that were fed good-quality algae. Feeding experiments with A. tonsa showed that copepods fed D. tertiolecta had a significantly lower content of EPA and DHA than those fed OM-DT. The concentration of EPA was low on both diets, while DHA content was highest in A. tonsa fed R. salina and OM-DT. These results suggest that O. marina was able to trophically upgrade the nutritional quality of the poor-quality alga, and efficiently supplied DHA to the next trophic level. The low amount of EPA in A. tonsa suggests EPA may be catabolized by the copepod.     

利用氧化铝-改性硅胶联柱分离测定水中多氯联苯

本文介绍一种多氯联苯(PCBs)与农药的分离和气相色谱分析PCBs新方法.富集浓缩后的样品首先经浓硫酸酸洗.排除大多数干扰PCBs测定的有机化合物,然后利用氧化铝-硅胶(Ag~+)联柱实现了PCBs和干扰其测定的农药的完全分离,应用毛细管气相色谱分析测试了水样中多氯联苯多种同系物、同分异构体的含量.其方法的回收率在79—88%之间.     

Metabolism of palmitic,linoleic, and linolenic acids in adult oysters,Crassostrea virginica

This study investigated incorporation and metabolism of saturated [(1-¹⁴C) 16:0] and unsaturated [(1-¹⁴C) 18:26 and (1-¹⁴C) 18:33] fatty acids in adult eastern oysters,Crassostrea virginica Gmelin (spawned from parents obtained in 1986 from Mobjack Bay, Virginia, USA), and the influence of temperature on these processes. InC. virginica, incorporation of injected palmitic (16:0) and linolenic (18:33) acids was increased when oysters which had been grown in warm water (22 to 23°C) were transfered to cold water (5 to 7°C) for 8 to 18 d. Incorporation of linoleic acid (18:26) was unchanged under these conditions. The changes in concentration may have been linked to depression of metabolism in these oysters, in particular that of 16:0, which was reduced by 90%. Oxidation of incorporated fatty acids was much higher in warm than in cold water. Cold-temperature conditioning ofC. virginica altered the distribution of fatty acids among the neutral and polar lipid fractions. Long-term exposure to cold water increased the proportion of fatty acids in the polar fraction, which may be related to maintenance of membrane fluidity. Short-term exposure to cold water had the opposite effect, which may be due to increased energy requirements as the oyster adapts to new conditions. Reutilization of¹⁴C-acyl groups demonstrated de novo synthesis of 16:0 and 18:0 fatty acids. Only limited elongation and no desaturation of the administered fatty acids was observed.     

The system design of UV-assisted catalytic oxidation process--degradation of 2,4-D

Unlike the conventional first- or second-order model, a novel approach to design for the removal of 2,4-dichlorophenoxy (2,4-D) by the UV-catalytic oxidation process (UVCOP) was investigated. Two distinctive parameters, initial decay rate and maximum oxidative capacity, were characterized. By using these parameters, the performance of the degradation of 2,4-D by UVCOP regarding to the reagent dosages could be successfully predicted. Low concentrations of ferrous ion was found to be a rate-limiting factor for the process while the dosage of hydrogen peroxide was concluded as a dominant species in determining the maximum oxidation capacities. This information can be used to optimize the treatment process and achieve the expected performance target; an "optimal-dose model" was developed accordingly. The model is an intelligent and useful tool to evaluate the optimal doses of hydrogen peroxide with the minimum dose of ferrous ion, which leads to a better design of the treatment process.     

低温厌氧处理低浓度废水研究进展

对低温下厌氧处理低浓度废水的最新进展进行了较全面综述。高效厌氧反应器为这一发展提供了可能。首选反应器是膨胀颗粒污泥床 (EGSB)反应器。若废水中颗粒有机物含量较高 ,采用两级系统 (两个EGSB ,水解上流式污泥床(HUSB)反应器 +EGSB ,上流式厌氧污泥床 (UASB)反应器 +EGSB等 )处理效果较好。新兴的厌氧膜生物反应器也是该领域的一个发展方向。低温 ( 3— 12℃ )、低浓度 (COD <10 0 0mg L)废水中培养的嗜温种泥保持令人满意的产甲烷活性。其最佳代谢温度仍在中温范围 ( 30— 40℃ ) ,表明主要菌群仍是嗜温菌。     

Analysis and structure prediction of chlorinated polycyclic aromatic hydrocarbons released from combustion of polyvinylchloride

Chlorinated polycyclic aromatic hydrocarbons (Cl-PAHs) released from combustion of polyvinylchloride (PVC) at different furnace temperatures were investigated. A laboratory-scale tube-type furnace with electric heating was utilized to control combustion conditions. Glass fabric filters and adsorbents were used to collect the combustion emissions. Following Soxhlet extraction, concentration and column chromatography purification, isomers separation, selective detection and identification of Cl-PAHs were performed on GC/MS system on the basis of retention data and mass spectra. Their quantification was accomplished by using external standard calibration technique. About 18 Cl-PAHs were determined, most of which were monochlorinated derivatives of naphthalene, biphenyl, fluorene, phenanthrene, anthracene, fluoranthene and pyrene. Only two dichlorophenanthrenes or anthracenes were identified. The possible positions of chlorine atoms attached to the aromatic rings are predicted by quantitative structure-property relationship. The levels of these compounds were in the range of 0.30-29.08 microg/g PVC. The relationship between the formation of Cl-PAHs and PAHs was discussed.     

Chlorination of dibenzofuran and dibenzo-p-dioxin vapor by copper (II) chloride

Dibenzofuran (DF) is formed from phenol and benzene in combustion gas exhaust streams prior to particle collection equipment. Subsequent chlorination at lower temperatures on particle surfaces is a potential source of chlorinated dibenzofuran (CDF). Gas streams containing 8% O₂ and approximately 0.1% DF vapor were passed through particle beds containing copper (II) chloride (0.5% Cu, mass) at temperatures ranging from 200 to 400 °C to investigate the potential for CDF formation during particle collection. Experiment duration was sufficient to provide an excess amount of DF (DF/Cu=3). The efficiency of DF chlorination by CuCl₂ and the distribution of CDF products were measured, with effects of temperature, gas velocity, and experiment duration assessed. Results of a more limited investigation of dibenzo-p-dioxin (DD) chlorination by CuCl₂ to form chlorinated DD (CDD) products are also presented.The efficiency of DF/DD chlorination by CuCl₂ was high, both in terms of CuCl₂ utilization and DF/DD conversion. Total yields of Cl on CDF/CDD products of up to 0.5 mole Cl per mole CuCl₂ were observed between 200 and 300 °C; this suggests that nearly 100% CuCl₂ was utilized, assuming a conversion of two moles of CuCl₂ to CuCl per mole Cl added to DD/DF. In a short duration experiment (DF/Cu=0.3), nearly 100% DF adsorption and conversion to CDF was achieved. The degree of CDF chlorination was strongly dependent on gas velocity. At high gas velocity, corresponding to a gas–particle contact time of 0.3 s, mono-CDF (MCDF) yield was largest, with yields decreasing with increasing CDF chlorination. At low gas velocity, corresponding to a gas–particle contact time of 5 s, octa-CDF yield was largest. DF/DD chlorination was strongly favored at lateral sites, with the predominant CDF/CDD isomers within each homologue group those containing Cl substituents at only the 2,3,7,8 positions. At the higher temperatures and lower gas velocities studied, however, broader isomer distributions, particularly of the less CDD/CDF products, were observed, likely due to preferential destruction of the 2,3,7,8 congeners.