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391.
在海水提铀螯合树脂的研究和制备中,会产生大量高浓度丙烯腈废水,其CODCr高达110 770 mg·L-1。以该废水为研究对象,采用Fe-C微电解法、Fenton-UV氧化法和KMnO4氧化等物理化学方法对其进行处理,发现单一方法的CODCr去除率较低,将上述方法进行串联,对废水进行处理,结果表明串联的方式可以明显提高废水的CODCr去除率。采用Fe-C微电解法、Fenton-UV氧化法和KMnO4氧化法3种方法串联的方式处理高浓度丙烯腈废水时,CODCr的去除率高达99.1%,CODCr降至957 mg·L-1,BOD5为406 mg·L-1,BOD5/CODCr为0.42,显著提高了水样的可生化性,达到了化纤工业废水的三级排放标准(GB8978-1996)。研究结果为海水提铀螯合树脂制备中高浓度丙烯腈废水的处理提供了一条有效的技术途径。 相似文献
392.
Philipp Bielec Lucien Eisenburger H. Lars Deubner Daniel Günther Florian Kraus Oliver Oeckler Wolfgang Schnick 《Angewandte Chemie (International ed. in English)》2019,58(3):840-843
Based on the known linking options of their fundamental building unit, that is the SiN4 tetrahedron, nitridosilicates belong to the inorganic compound classes with the greatest structural variability. Although facilitating the discovery of novel Si–N networks, this variability represents a challenge when targeting non‐stoichometric compounds. Meeting this challenge, a strategy for targeted creation of vacancies in highly condensed nitridosilicates by exchanging divalent M2+ for trivalent M3+ using the ion exchange approach is reported. As proof of concept, the first Sc and U nitridosilicates were prepared from α‐Ca2Si5N8 and Sr2Si5N8. Powder X‐ray diffraction (XRD) and synchrotron single‐crystal XRD showed random vacancy distribution in Sc0.2Ca1.7Si5N8, and partial vacancy ordering in U0.5xSr2?0.75xSi5N8 with x≈1.05. The high chemical stability of U nitridosilicates makes them interesting candidates for immobilization of actinides. 相似文献
393.
Hailong Zhang Wei Liu Ao Li Duo Zhang Xiaoyan Li Fuwan Zhai Lanhua Chen Long Chen Yanlong Wang Shuao Wang 《Angewandte Chemie (International ed. in English)》2019,58(45):16110-16114
The design and synthesis of uranium sorbent materials with high uptake efficiency, capacity and selectivity, as well as excellent hydrolytic stability and radiation resistance remains a challenge. Herein, a polyoxometalate (POM)–organic framework material ( SCU‐19 ) with a rare inclined polycatenation structure was designed, synthesized through a solvothermal method, and tested for uranium separation. Under dark conditions, SCU‐19 can efficiently capture uranium through ligand complexation using its exposed oxo atoms and partial chemical reduction from UVI to UIV by the low‐valent Mo atoms in the POM. An additional UVI photocatalytic reduction mechanism can occur under visible light irradiation, leading to a higher uranium removal without saturation and faster sorption kinetics. SCU‐19 is the only uranium sorbent material with three distinct sorption mechanisms, as further demonstrated by X‐ray photoelectron spectroscopy (XPS) and X‐ray absorption near edge structure (XANES) analysis. 相似文献
394.
描述了硫酸铵溶液中铀矿坑水样品中铀的电沉积层特性。 电沉积液为10 ml 0.8 M的硫酸铵溶液, 电流密度0.6 A/cm2, pH值为2.5, 电镀1 h。 电沉积经化学分离后的水样品和电沉积的纯硝酸铀酰样品进行了比较, 并对二者分别做了红外(IR)光谱、 扫描电镜(SEM)、 元素分析以及α能谱测量。 IR谱上铀酰离子的反对称伸缩振动峰在887 cm-1附近, 使电沉积在不锈钢片上的铀主要以铀酰离子水合物的形式存在, 有一部分NH+4以NH3的形式替代水合物中的水, 使电沉积层中铀的化合物形式为UO2(OH)2·xNH3·yH2O或者UO2(OH)2-x·(ONH4)x·yH2O, 铀酰离子通过链的形式形成聚合结构。 SEM照片显示电沉积层均匀, 没堆积成团现象出现。 α谱表明电沉积层中铀的同位素主要是238U和234U, 相应的α能量峰4198和4773 keV很显著, 没其它峰的干扰。 Characteristics of electrodeposited uranium films of uranium ore water sample in ammonium sulphate was investigated in this work. The optimized electrodeposited conditions were as follows: electrolyte was ammonium sulphate of 0.8 M, and current density at the cathode was 0.6 A/cm2, electrolyte pH value was 2.5, the time of plating on the electrodeposition was 1 h. In this situation, the uniform, thin and adheresive films were produced by electrodeposition method. Two samples were made, one electrodeposition of pure uranyl nitrate, and another electrodeposition of uranium ore water sample after chemical separation. Characteristics of electrodeposited uranium films of uranium ore water sample after chemical separation was studied, making comparisons with electrodeposited films of uranyl nitrate. The analysis of film characteristics was done through infrared (IR) spectrum, scanning electron microscopy(SEM), element analysis and α spectrum measurment. According to Fourier transform infrared spectra, the asymmetric stretching vibration band of uranyl group is around 887 cm-1. In addition, according to IR spectrum, we know that uranium exists mainly as the form of hydrated polymeric compound in the film. Electrodeposited uranium films also included many NH+4. Polymeric structures of variable composition were present in the electrodeposited samples, with the unit monomeric formula UO2(OH)2·xNH3·yH2O or UO2(OH)2-x·(ONH4)x·yH2O. Scanning electron microscopy shows that the two samples have similar surface characteristics and no cluster is observed. The samples were also measured by spectrometer equipped with Passivated Implanted Planar Silicon(PIPS) detector. From the α spectrum, we know that isotopes of uranium in the film are 238U and 234U. 235U is not found in the α spectrum. It also shows that the chemical separation process can isolate uranium from other interfering elements effectively, the result of chemical separation is very satisfactory and electrodeposited process is rather efficient. Source electrodeposited in ammonium sulphate through optimized conditions satisfies the need of high resolution α spectrum. 相似文献
395.
针对尾矿堆存和塌陷区占用土地资源的问题,研究尾砂干排至活动地表塌陷区的可行性.设计了放矿条件下尾砂穿流特性实验,以矿岩散体高度和尾砂高度作为影响因素,采用高速摄影技术,实现尾砂移动过程的可视化.实验结果表明:松动体高度小于尾砂和矿岩散体的交界面时,尾砂不能到达放矿口;松动体高度高于交界面时,尾砂受到放矿扰动的影响且与尾砂接触的岩石发生松散,随即颗粒大量到达放矿口,对井下回采造成影响.随着尾砂高度的不断增加,尾砂在初始阶段渗入量增大,但松动体高度小于尾砂和矿岩散体的交界面时,尾矿未能到达放矿口,因此持续向塌陷区内干排尾砂对矿石的贫化影响较小. 相似文献
396.
针对铀矿冶废水中存在过量硝酸根的问题,通过以轻质黏土陶粒为载体的上流式固定床生物反应器对模拟的铀矿山废水进行了NO-3的去除试验研究。考察了载体种类、挂膜次数、NO-3质量浓度、pH、n(C)/n(N)和水力停留时间(hydraulic retention time ,HRT)等因素对反硝化效果的影响,结果表明生物反应器对硝酸根去除效果良好。以NO-3质量浓度为500 mg/L模拟废水进行流动实验,tHRT由6 h下降至2 h的过程中,反应体系稳定后NO-3去除率均为100%,达到了预期的去除效果。 相似文献
397.
针对铀矿山放射性污染物治理需要,根据物联网技术的优良性能,结合铀矿山通风降氡机理,提出了一种基于物联网架构的铀矿山通风降氡监测控制系统,并构建了氡析出自适应神经模糊推理系统模型。通过实时监控及预警,对风机发布远程调控指令,改变井下风量、风压、风流以达到降氡目的。试验分析结果表明,该系统能较好实现铀矿山氡安全监测及控制。 相似文献
398.
针对低浓度铀废水的修复,实验以合果芋与内生细菌Pseudomonas sp. XNN8和放线菌XNG3构建共生体系,研究植物-微生物联合修复铀污染废水。研究结果表明:共生体系修复效果优于未定殖的合果芋,在0. 5 mg/L铀废水中达到最高铀富集率98. 34%。在0. 5 mg/L、1 mg/L、2 mg/L铀废水中,溶液中的浓度分别降至16. 615μg/L、17. 903μg/L、26. 067μg/L,均在排放标准0. 05 mg/L以下,因此该共生体系可用于低浓度铀废水修复。红外表征显示,内生菌可能增加了—OH含量或强化了—OH对铀的结合作用。 相似文献
399.
应用基于量子力学的密度泛函计算和过渡态搜寻的CI-NEB方法,研究了锆掺杂前后二氧化铀晶格中氧空位和氧间隙本征缺陷的扩散机理,计算了扩散路径和扩散能垒。计算结果表明,锆掺杂使得氧空位缺陷<100>方向的扩散能垒降低了0.40 eV,氧间隙交换机制的扩散能垒降低了0.07 eV。锆掺杂后,氧空位远低于氧间隙缺陷的扩散能垒。最后分析了扩散过程中氧原子和金属原子之间的键长,说明锆掺杂导致点缺陷扩散能垒降低与晶格畸变密切相关。Oxygen vacancy and interstitial diffusion mechanisms in uranium dioxide doped with zirconium are investigated by the density functional theory calculations. The migration pathways and barriers are identified using the climbing-image nudge elastic band (CI-NEB) method. It is found that the vacancy migration barrier along the <100> direction decreases by about 0.40 eV, while the indirect interstitial migration barrier decreases by about 0.07 eV in the zirconium doped uranium dioxide. The oxygen vacancy migration barrier is far lower than the oxygen interstitial migration barrier in the uranium dioxide doped with zirconium. Based on the analysis of bond length of local structures during the migration of oxygen atoms, it is concluded that the lattice distortion may be responsible for the reduction of oxygen migration barrier. 相似文献
400.
Amanjeet Panghal Suneel Kumar Joga Singh Sumit Sharma Parminder Singh 《辐射效应与固体损伤》2017,172(5-6):441-455
Uranium gets into drinking water when the minerals containing uranium are dissolved in groundwater. Uranium and radon concentrations have been measured in drinking water samples from different water sources such as hand pumps, tube wells and bore wells at different depths from various locations of four districts (Jind, Rohtak, Panipat and Sonipat) of Haryana, India, using the LED flourimetry technique and RAD7, electronic silicon solid state detector. The uranium (238U) and radon (222Rn) concentrations in water samples have been found to vary from 1.07 to 40.25?µg?L?1 with an average of 17.91?µg?L?1 and 16.06?±?0.97 to 57.35?±?1.28?Bq?L?1 with an average of 32.98?±?2.45?Bq?L?1, respectively. The observed value of radon concentration in 43 samples exceeded the recommended limits of 11?Bq?L?1 (USEPA) and all the values are within the European Commission recommended limit of 100?Bq?L?1. The average value of uranium concentration is observed to be within the safe limit recommended by World Health Organization (WHO) and Atomic Energy Regulatory Board. The annual effective dose has also been measured in all the water samples and is found to be below the prescribed dose limit of 100?µSv?y?1 recommended by WHO. Risk assessment of uranium in water is also calculated using life time cancer risk, life time average daily dose and hazard quotient. The high uranium concentration observed in certain areas is due to interaction of ground water with the soil formation of this region and the local subsurface geology of the region. 相似文献