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用王水分解含金矿物的机理探讨 总被引：2，自引：0，他引：2
本文从理论上对王水分解含金矿物的机理进行了探讨。在非标准状态下,温度、压力不变,改变体系中物质的浓度、酸度条件,用能斯特公式求解体系中HNO_3和Au的电极电位值,而后用EMF(电池电动势)根据规则判断反应是否可以进行。经理论计算,结论是可行的。另外由于Au~(3 )和Cl~-大量存在时,生成稳定的[AuCl_4]~-,经过络合作用,促使了HNO_3和Au的氧化还原反应,最终使含金矿物溶解完全。作者认为王水同含金矿物反应的机理是:氧化和络合的双重作用。 相似文献
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M. Amme 《Aquatic Geochemistry》2002,8(3):177-198
The behaviour of many radiotoxic elements, which are contained within spent nuclear fuel planned for direct disposal, is strongly dependent on the redox chemistry of the aqueous media present in the deep geological systems, where such disposal options are investigated. Especially actinide elements are known to be sensitive. The knowledge of the speciation of actinides in the case of a possible mobilisation by intruding groundwater is therefore crucial and part of the source term calculation of many countries' performance assessment procedures. In this study, the influence of redox conditions and complexant concentration in two selected groundwaters upon the species distribution of U and Pu is assessed by using the thermodynamic modeling code PHREEQC version 2.3. The modeled systems were derived from laboratory leaching experiments testing nuclear fuel dissolution. For the calculations, critically reviewed data for U and Pu complexation were used. The results show that under the conditions calculated, U and Pu are present mainly as U(VI) and Pu(IV). The presence of solid UO2 substrate is supposed to change this distribution. The calculational use of different groundwaters as aqueous phase, implying a slightly different solution composition, affects U and Pu speciation: U species distribution is affected mainly by complexant concentration, Pu species are influenced by pH changes. A sensitivity study on Pu speciation is performed; constants changed within their confidence intervals were applied. The results are compared with experimental observations, and differences and possible expected effects during the dissolution of real, complex materials are discussed. 相似文献
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用于深海极端环境下的pH电极制备方法改进 总被引：2，自引：2，他引：0
pH值是表征深海热液环境以及扩散流区域溶液化学性能的基本参数,因此原位精确获取溶液pH值是很多海洋科学研究者关注的问题。以前试制的电化学原位传感器IrOx电极,在实际海试中虽然对海底异常信号有响应,但由于信号漂移问题,电极只能用于定性地发现异常。基于熔融碳酸锂氧化金属原理,提出了改进传统熔融碳酸锂法,并设计了强制空气对流和碳酸锂添加过氧化钠两种制备方法。通过实验室的性能测试以及相应的表面扫描电镜测试表明,用改进的方法制得的电极,校正曲线均符合能斯特定律。用强制空气对流和混合碳酸锂/过氧化钠法制得的电极,其性能均明显优于传统熔融碳酸锂法。可推断,在熔融碳酸锂氧化贵金属铱的过程中,氧含量的充分与否是影响IrOx电极的性能和表面形态的重要因素,其中性能最优的是混合碳酸锂/过氧化钠法制得的电极。该类电极具有如下优点:重复性好;在大跨度pH溶液之间的响应快速稳定,长时间连续监测的漂移小于5 mV;同一批次所制备电极性能几乎相同;使用寿命长等。因此,该pH电极可用于深海的原位探测。该工作为进一步制备高性能的IrOx电极奠定了坚实的基础。 相似文献
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