摘要
日本福岛核事故发生以后,对海洋环境中关键放射性核素的快速检测技术提出了更高的要求。人工放射性核素~(131)I在核反应裂变产物中活度相对较高且半衰期短,是用来快速评价核污染的关键性核素之一。本工作从亚铁氰化钾、硝酸铜及硝酸银为原料出发,制备出亚铁氰化铜和亚铁氰化银混合(CuFC/AgFC)吸附材料并分散于聚丙烯纤维富集柱上,来实现水环境中~(131)I现场快速富集。通过室内模拟实验发现:在流速为6.25L/min,~(131)I在海水中I~-初始浓度为24μmol/L时,单次吸附效率即可达到50%以上;而当海水中I~-初始浓度为4μmol/L时,一定体积的海水在连续循环8次后(CuFC/AgFC)聚丙烯纤维富集柱吸附效率达到100%。本方法制源时间约40min,测样时间约12~24h,故最快可在30h内完成海水中~(131)I的分析。本方法的检测限与分析周期均低于目前GB/T 13272-1991水中~(131)I的分析标准,极大地提高了~(131)I的分析时间。除此之外,该法可以同时分析海水中的~(137) Cs(~(134) Cs),有望作为淡水和近岸环境中常规监测和应急时对关键核素~(131)I和~(137) Cs(~(134) Cs)进行快速测定的备选方法之一。
After the Fukushima nuclear accident,the rapid detection of critical radionuclides in the marine environment has been required.~(131)I,an artificial radionuclide released from nuclear reaction with high activity but very short half-life,is one of the critical nuclides for rapid assessment of nuclear contamination.In the present study,the compound of CuFC/AgFC were embedded on the polypropylene fiber column to study the enrichment of ~(131)I.The CuFC/AgFC enrichment column can adsorb iodine isotopes efficiently.These results show that within the flow rate of 6.25L/min,the sorption efficiency of ~(131)I by one cycle time of seawater can reach 50%when the initial concentration of I(as I~-form)is 24μmol/L.However,the sorption efficiency by eight cycles times of seawater can reach 100%even when the initial concentration of I(as I~-form)is 4μmol/L.It usually takes 40minutes to prepare the targets after the enrichment experient,and then 12-24hours for the ~(131)I analysis by HPGegamma spectrometry.Therefore,the method of ~(131)I in seawater in the present work can be completed in 30h,which significantly improves the analysis for ~(131)I.Both the detection limit and analysis time of this method in the present work are much lower than the current GB/T 13272-1991standard.Moreover,this method can detect ~(137)Cs(~(134)Cs)in seawater simultaneously,which is expected to be one of the alternative methods to rapidly detect ~(131)I and~(137)Cs(~(134)Cs)in freshwater/seawater nearshores for routine monitoring and also emergency cases.
引文
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