Radiochemistry Division, Bhabha Atomic Research Centre, Mumbai, 400085, India; Homi Bhabha National Institute, Training School Complex, Anushaktinagar, Mumbai, 400094, India.
Homi Bhabha National Institute, Training School Complex, Anushaktinagar, Mumbai, 400094, India; Radioanalytical Chemistry Division, Bhabha Atomic Research Centre, Mumbai, 400085, India.
Chemosphere. 2021 Apr;269:129327. doi: 10.1016/j.chemosphere.2020.129327. Epub 2020 Dec 24.
The extensive hydrolysis of tetravalent actinides leads to polynuclear formations through oxygen bridging facilitating the formation of colloids as end products. The pH, ionic strength has phenomenal effects on Thorium colloids formation. The quantitative estimation of colloids facilitates the fraction of soluble fraction into ionic, polymeric and colloidal forms of thorium. The colloids accountability and precipitate characterization explains the discrepancies in estimated solubility limits. The supernatants of long equilibrated (∼3 years) saturated thorium solution under various pH (5- 11) and ionic strengths (0-3 M NaClO) were analysed by Inductively Coupled Plasma Mass Spectrometer (ICP-MS) and Ion Chromatography (IC) to determine total and ionic thorium respectively. Laser Induced Breakdown Detection (LIBD) was employed to determine the colloid size and concentrations. The precipitates were characterized by calorimetry and XRD to determine the solubility limiting phase. The results of pH, IC, ICP-MS, and LIBD measurements on the aged thorium samples are discussed with regard to the mechanism of the formation of thorium colloids. The results revealed the formation of colloids having particle size (10-40 nm) at concentrations (10-10 particles/mL). The colloids accountancy resulted in estimated solubility products to 2-4 orders lower than their inclusion as soluble thorium. The soluble thorium was fractionated quantitatively into ionic, polymeric and colloidal forms of thorium. The precipitates formed are found to be semi amorphous.
四价锕系元素的广泛水解会通过氧桥形成多核形成物，从而促进胶体的形成作为最终产物。pH 值和离子强度对钍胶体的形成有显著影响。胶体的定量估算有助于将可溶性部分分为离子、聚合和胶体形式的钍。胶体的可归因性和沉淀物特征解释了估计的溶解度极限之间的差异。通过电感耦合等离子体质谱仪 (ICP-MS) 和离子色谱 (IC) 分析在各种 pH 值（5-11）和离子强度（0-3 M NaClO）下长时间平衡（~3 年）饱和钍溶液的上清液，分别测定总钍和离子钍。激光诱导击穿检测 (LIBD) 用于测定胶体的大小和浓度。通过量热法和 XRD 对沉淀物进行表征，以确定溶解度限制相。讨论了老化钍样品的 pH 值、IC、ICP-MS 和 LIBD 测量结果，以阐明钍胶体形成的机制。结果表明，在浓度（10-10 个粒子/mL）下形成粒径为（10-40nm）的胶体。胶体的定量估算导致估计的溶解度产物比其作为可溶性钍的含量低 2-4 个数量级。可溶性钍被定量地分为离子、聚合和胶体形式的钍。形成的沉淀物被发现为半非晶态。
