二(叔丁基苯)二硫代次膦酸从硝酸-硝酸钠介质中萃取Th(Ⅳ)  

Extraction of Th(Ⅳ)From Nitric Acid-Sodium Nitrate MediaWith Bis(p-Tert-Butylphenyl)Dithiophosphinic Acid

作　　者：邓琴 曹亚娟 柳倩 杨雅婷 杨素亮[1] 田国新[1,2] 张生栋 DENG Qin;CAO Ya-juan;LIU Qian;YANG Ya-ting;YANG Su-iang;TIAN Guo-xin;ZHANG Sheng-dong(Department of Radiochemistry,China Institute of Atomic Energy,Beijing 102413,China;Research Institute of Harbin Engineering University,Yantai 264006,China)

机构地区：[1]中国原子能科学研究院放射化学研究所,北京102413 [2]哈尔滨工程大学烟台研究院,山东烟台264006

出　　处：《核化学与放射化学》2025年第2期118-125,I0001,共9页Journal of Nuclear and Radiochemistry

摘　　要：研究了二(叔丁基苯)二硫代次膦酸(bis(p-tert-butylphenyl)dithiophosphinic acid,HL)从硝酸-硝酸钠介质中萃取Th(Ⅳ)的行为和机制。以其二甲苯溶液作为有机相,考察了萃取时间、萃取剂浓度、水相NaNO_(3)浓度、平衡水相pH值及温度等因素对萃取的影响。结果表明,该萃取剂萃取Th(Ⅳ)的分配比随萃取剂浓度、平衡水相pH值以及温度的增大而增大,随水相NaNO_(3)浓度的增大而减小。斜率法分析结果表明,该萃取剂萃取Th(Ⅳ)符合阳离子交换机制,萃合物组成为ThL_(4),萃取反应式为Th^(4+)+4HL_((o))■ThL4_((o))+4H^(+),25℃时的萃取平衡常数(K_(ex))为10^(-7.84),ΔH~Θ为25.8 kJ/mol,ΔS^(Θ)为-66.4 J/(mol·K)。实验平衡水相pH值范围内,Th(Ⅳ)、U(Ⅵ)和Ln(Ⅲ)(以Eu(Ⅲ)和Nd(Ⅲ)为代表)的相互分离因子(SF)随pH值增大而增大。当平衡水相pH值为3.11时,SF_(Th(Ⅳ)/Eu(Ⅲ))、SF_(Th(Ⅳ)/Nd(Ⅲ))和SF_(U(Ⅵ)/Th(Ⅳ))分别为4.2×10^(4)、1.1×10^(4)和1.0×10^(2)。Thorium,a crucial and prospective nuclear material,whether enriched and extracted from ores or recovered from the complex composition of nuclear waste,is imperative for alleviating pressure on energy resources and sustaining ecological balance.A variety of methods are currently applied within the domain of thorium isolation and purification,among which solvent extraction has the distinction of being the most commonly used and recognized extraction method in the nuclear field.Nevertheless,identifying a suitable extractant continues to pose a significant challenge.Dithiophosphinic acid has been the subject of considerable research interest due to its exceptional ability to selectively separate trivalent actinide ions,An(Ⅲ),from lanthanide ions,Ln(Ⅲ).However,the extraction of tetravalent actinide ions has received comparatively less attention.In order to further evaluate the potential application of those extractants,the extraction behavior of Th(Ⅵ)from nitric acid-sodium nitrate media was investigated using bis(p-tertbutylphenyl)dithiophosphinic acid(HL)in xylene as the organic phase.The effects of HL concentration in the organic phase on the extraction of Th(Ⅳ)were studied,as well as the NaNO_3 concentration in the aqueous phase,the pH of the equilibrated aqueous phase,and the temperature,to determine the composition of the extracted complex and further to reveal the extraction mechanism.In addition,the selectivity for Th(Ⅳ)in coexistence with U(Ⅵ)and Ln(Ⅲ)was analyzed to evaluate its potential application in the advanced nuclear fuel cycle.The extraction is governed by the cation exchange mechanism,described by the equation of Th^(4+)+4HL_((o))■ThL_(4(o))+4H^(+),with the extracted complex species of ThL4.At 25℃,the extraction equilibrium constant(K_(ex))is measured as 10^(-7.84),whileΔH^(Θ)is25.8 kJ/mol andΔS^(Θ)is-66.4 J/(mol·K).Moreover,the determined mutual separation factors of Th(Ⅳ),U(Ⅵ)and Ln(Ⅲ)increase with the increasing pH within the experimental pH range.When the pH of the e

关 键 词：二(叔丁基苯)二硫代次膦酸 Th(Ⅳ) 萃取 萃取平衡常数 

分 类 号：TL245[核科学技术—核燃料循环与材料]