Microwave-specific heating of crystalline species in nuclear waste glass

The microwave heating of a crystal-free and a partially trevorite-crystallized nuclear waste glass simulant was evaluated. Our results show that a 500-mg monolith of partially crystallized waste glass can be heated from room temperature to above 1600°C within 2 minutes using a single-mode, highly focused, 2.45-GHz microwave, operating at 300 W. Using X-ray diffraction measurements, we show that trevorite is no longer detectable after irradiation and thermal quenching. When a crystal-free analog of the same waste glass simulant composition was exposed to the same microwave radiation, it could not be heated above 450°C regardless of the heating time. The reduction in crystalline content achieved by selectively heating spinels in the presence of glass suggests that microwave-specific heating should be further explored as a technique for remediating crystal accumulation in a glass melt.     

The influence of iodide on glass transition temperature of high-pressure nuclear waste glasses

The glass transition temperature (T_g) is a key parameter to investigate for application in nuclear waste immobilization in borosilicate glasses. T_g for several glasses containing iodine (I) has been measured in order to determine the I effect on T_g. Two series of glass composition (ISG and NH) containing up to 2.5 mol% I and synthesized under high pressure (0.5 to 1.5 GPa) have been investigated using differential scanning calorimetry (DSC). The I local environment in glasses has been determined using X-ray photoelectron spectroscopy and revealed that I is dissolved under its iodide form (I⁻). Results show that T_g is decreased with the I addition in the glass in agreement with previous results. We also observed that this T_g decrease is a strong function of glass composition. For NH, 2.5 mol% I induces a decrease of 24°C in T_g, whereas for ISG, 1.2 mol% decreases the T_g by 64°C. We interpret this difference as the result of the I dissolution mechanism and its effect on the polymerization of the boron network. The I dissolution in ISG is accompanied by a depolymerization of the boron network, whereas it is the opposite in NH. Although ISG corresponds to a standardized glass, for the particular case of I immobilization it appears less adequate than NH considering that the decrease in T_g for NH is small in comparison to ISG.     

磷灰石中氟的测定

研究了采用1mol／L盐酸低温分解矿样，以二甲酚橙-锆减色法测定矿石中的氟，铝的干扰可在显色后放置一定时间予以消除，该法具有灵敏度高、重现性好、易掌握等特点。     

微波消解容量法快速测定玻璃中二氧化硅含量

利用微波消解技术对玻璃样品进行快速消解,并用氟硅酸钾法测定其SiO2含量.对0.1 g试样,消解剂浓HNO3和浓HF溶液加入量分别为9 mL和2 mL,消解压力分别为1.0 MPa和2.0 MPa,消解时间分别为1 min和4 min,共计5 min,远少于常规高温碱熔法分解的时间.用此法测定了2种玻璃标准物质和3种玻璃样品,测定结果分别与标准值和传统方法一致,可用于玻璃中SiO2含量的快速测定.     

制氟技术及氟的应用

氟是非常独特的元素,它赋予含氟材料和含氟化学品许多优异的性能,在国民经济领域应用广泛,因此研究制氟技术具有重要现实意义。本文主要介绍电解法、化学药剂法和等离子体裂解法制氟技术,并对每种技术的特点和研究现状进行分析,同时对氟气的应用进行概述。     

Preliminary observations on the microstructure of nuclear waste glasses

The microstructures of simulated nuclear waste glasses prepared by the mixing of glass frit and calcined waste oxides at 1000°C are shown to contain well defined boundaries that are depleted of heavy elements. The development of small crystallites and phase separation have also been observed but no evidence of microcracking or interfacial separation at these discontinuities was found. The same glasses prepared at 1350°C were quite uniform at the microstructural level.     

微波消解光度法快速测定无挥发性废水的化学需氧量

介绍了一种微波消化制样、分光光度快速测定无挥发性废水化学需氧量的新方法,确定了微波功率250W,硫酸-硫酸银溶液10 mL,消解时间为10 m in为最佳消解条件,并于351 nm波长处分光光度测定过量Cr(Ⅵ)的浓度,结果表明,吸光度与COD值在0~400 mg/L范围内呈良好的线性关系,能有效排除C l-的干扰,实际水样测定结果的准确度达到99%,精密度小于4%,加标回收率达到98.7%。并与经典重铬酸钾回流法进行了对比,证实了两种方法处于同一种水平。     

微波预处理剩余污泥的研究进展

介绍了微波预处理污泥的作用机理及作用过程,包括污泥絮体破解、污泥细胞破碎及有机物的释放、有机物水解、美拉德反应等,总结了微波预处理污泥的作用效果（物理特性、化学特性、生物特性）、影响微波预处理效果的因素（污泥特性、处理条件）和微波预处理污泥对其后续厌氧消化的影响。指出了目前研究中存在的主要问题是试验规模偏小,预处理方式为间歇处理,在对污泥中有毒有害有机物和病原微生物的去除研究方面还需加强。提出今后应重点开展微波组合工艺对污泥中有毒有害有机物和病原微生物去除的基础研究,同时积极开发相关设备,开展微波预处理污泥的连续和中试研究,推动微波技术在污泥资源化、减量化和无害化处理中的应用。     

氟离子选择电极测定矿石中氟含量

用氟离子选择电极对多种矿石中的氟进行了测定,其测定范围在0.005%～x%.研究表明,用本方法测定多种矿石中氟含量精密度好,回收率在94.0%～103.2%,方法简便.此方法已应用于实际工作中.     

Submixture model to predict nepheline precipitation in waste glasses

High-alumina high-level waste (HLW) glasses are prone to nepheline precipitation during canister-centerline cooling (CCC). If sufficient nepheline forms, the chemical durability of the glass will be significantly impacted. Overly conservative constraints have been developed and used to avoid the deleterious effects of nepheline formation in U.S. HLW glasses. The constraints used have been shown to significantly limit the loading of waste in glass at Hanford and therefore the cost and schedule of cleanup. A 90-glass study was performed to develop an improved understanding of the impacts of glass composition on the formation of nepheline during CCC. The CCC crystallinity data from these glasses were combined with 657 glasses found in the literature. The trends showed significant effects of Na₂O, Al₂O₃, SiO₂, B₂O₃, CaO, Li₂O, and potentially K₂O on the propensity for nepheline formation. A pseudo-ternary submixture model was proposed to identify the glass composition region prone to nepheline precipitation. This pseudo-ternary with axes of SiO₂ + 1.98B₂O₃, Na₂O + 0.653Li₂O + 0.158CaO, and Al₂O₃ was found to divide glasses that precipitate nepheline during CCC from those that do not. Application of this constraint is anticipated to increase the loading of Hanford high-alumina HLWs in glass by roughly one-third.     

Fractographic analysis of silicate glasses by computer vision

ASTM C1678 describes the state-of-the-art's fractographic techniques to estimate the fracture strength of glasses and ceramics through empirical, strength vs. fracture mirror length relationships. However, the methodology is subjective and only applicable to a few loading scenarios and relatively pristine fracture surfaces. This work presents a semi-automated, alternative approach to objectively estimate the strength of silicate glasses for ampler loading and geometric scenarios. The proposed method relies on a baseline set of fracture surface profilometry-scans gathered on samples of known strengths. A computer vision-based algorithm compares relevant, topological features extracted from the baseline set to the features on the fracture surfaces investigated. An empirical relationship based on over 2,100 fractured silicate specimens is used to compute the strength of the trial sample. The proposed scheme could accurately estimate the strength of specimens beyond the capacity of ASTM C1678, such as in chemically strengthened glasses and fracture surfaces displaying significant damage.     

玻璃固化体抗浸蚀性能实验研究进展

玻璃固化是高放废物固化中较成熟、应用较广的一种技术。本文综述了玻璃固化体的浸出机理、浸出模型及浸蚀实验方法的研究进展。针对目前对温度和pH这两种因素在静态条件下的影响情况研究较多,对气体环境、压强和辐射等因素对玻璃固化体浸出行为的影响研究较少的现状,建议今后应重点进行玻璃固化体受浸泡剂-温度-辐射-压力-气流等多种因素耦合作用影响的抗侵蚀实验研究。     

全球含氟农药品种概况及新开发的含氟农药

氟化学品是人们开发的热点,含氟农药也是人们开发的关注点。阐述了全球含氟农药的概况,并介绍了近年新开发的含氟农药。     

掺氟二氧化锡/二氧化钛复合薄膜的光催化和低辐射性能

采用溶胶-凝胶法在Sn02：F（FTO）低辐射镀膜玻璃衬底上旋涂制备Ti02,获得FTO／TiOz复合薄膜。采用扫描电镜、X射线衍射、紫外-可见透射光谱、Fourier变换红外反射光谱等手段分析了复合薄膜的结构和形貌。结果表明：FTO／TiO2复合薄膜的光催化性随着Ti02薄膜厚度的变化而变化,当Ti02薄膜的厚度为190nm时具有最佳的光催化活性,并从能带角度解释了光催化性能提高的原因;Ti02薄膜能防止FTO在热处理时发生氧化,热处理后的复合薄膜仍具有较好的低辐射性能。     

氟气在直接氟化反应中的应用

介绍了氟气的性质及其应用,同时介绍了氟气在无机氟化反应和有机氟化反应中的应用。     

浅析提高氟橡胶耐寒性的途径

从分子结构和配合体系两方面介绍了提高氟橡胶耐寒性的主要途径.对分子结构进行改性,引入能够破坏分子链规整性的侧基,或在主链上引入能够提高分子链柔顺性的基团,是提高氟橡胶耐寒性最有效的途径.另外,通过橡胶并用或添加合适的增塑剂,既可提高氟橡胶耐寒性,还能降低材料的成本.     

环境样品消解问题浅析

本文综述了环境样品消解方法的分类、各自的优缺点以及各种方法在不同样品消解方面的应用情况,为环境分析工作者在消解方法选择上提供依据。     

粘土制砖过程中氟化物逸出和固定的研究

The firing tests with clay blocks were undertaken to study the fluorine expulsion and retention characteristics of calcium-based materials during the firing of brick clays.The results indicate that fluorine expulsion begins at approx.600-700℃,and the main portion occurs in 800-1000℃. The mode of firing has some effects on fluorine expulsion.Additives of calcium-based material can reduce fluorine expulsion,which is mainly attributed to the increased formation of CaF2 during clay firing.In addition,the optimum addition tests of 6 calcium-based materials with higher efficiency were carried out in a brick kiln.More than 75% fluorine is retained in the brick body and there is no adverse effect on brick product.This makes it possible for brickyard to achieve non-polluting production.