Aiming at the thermal stability of technetium, the present work focuses on the influences of the main parameters (temperature and time) on the stability of technetium during ash.The pretreatment procedure of solid sample is optimized.At the same time, the thermal stability of technetium during sample solution evaporation in different solution systems is also discussed.The results show that the effective removal of organic matter is achieved under the conditions of wetting soil samples with concentrated ammonia and ash at 550 ℃ for three hours.There is no loss of technetium during the ash process.It can be found that the loss of technetium will generate if the sample solution is evaporated to dryness in hydrochloric acid, and loss ratio increases with the increasing of concentration of hydrochloric acid.However, if a small amount of NaCl contained in the solution, the loss of technetium will be weakened.The stability of technetium in nitric acid media is well, which can't result in loss of technetium even to dryness.%针对锝的化学特性,研究了样品灰化过程中的主要参数(温度和时间)对锝热稳定性的影响,优化了预处理流程.同时,对不同溶液体系蒸发过程中锝的热稳定性也进行了探讨.结果表明,浓氨水浸润后的土壤样品可在550 ℃下灰化3 h以实现有机物的有效去除,灰化过程中不发生锝的损失.盐酸介质中蒸干溶液会引起锝的损失,且随盐酸浓度增加损失变大,但当溶液中有少量NaCl存在时锝的损失会减弱;锝在硝酸介质中热稳定性较好,即使溶液蒸干也不会带来损失.
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