Resorcinol-formaldehyde coated XAD resin beads for removal of cesium ions from radioactive waste: synthesis, sorption and kinetic studies
Resorcinol-formaldehyde coated XAD resin beads for removal of cesium ions from radioactive waste: synthesis, sorption and kinetic studies
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DOI：
10.1039/c2ra20054f
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发表时间：
2012-01-01
期刊：
影响因子：
3.9
通讯作者：
Bajaj, Parma Nand
中科院分区：
文献类型：
--
作者：
Dwivedi, Charu;Kumar, Amar;Bajaj, Parma Nand
以XAD-4为模板剂，采用一种新的合成方法，合成了具有所需粒径的球形间苯二酚-甲醛（RF）树脂。使用不同的技术表征合成的RF涂覆的XAD（RF-XAD）珠。合适的尺寸和机械稳定性，沿着它们的球形形状，使得这些珠粒最适合柱操作。这些珠的效率进行了评价，从碱性介质中除去铯，在分批条件下，使用放射性分析技术。研究了钠离子浓度、铯离子初始浓度和接触时间对反应的影响。据观察，随着Na+离子浓度的增加，Cs+离子的Kd值降低。平衡数据拟合到不同的等温模型，并被认为是很好地代表了Langmuir等温方程，与单层吸附容量为287毫克g（-1）。使用伪一阶、伪二阶和颗粒内扩散方程进行动力学建模分析表明，伪二阶方程是描述铯离子在RF-XAD珠上吸附的最合适模型。在不同的初始浓度下测定了速率常数。研究发现，该过程的机理是复杂的，包括表面吸附和孔扩散。
A novel synthetic method was developed to synthesize resorcinol-formaldehyde (RF) resin in spherical form, of required mesh size, using XAD-4 as template beads. The synthesized RF-coated XAD (RF-XAD) beads were characterized, using different techniques. Suitable size and mechanical stability, along with their spherical shape, make these beads most appropriate for column operation. The efficiency of these beads was evaluated for removal of cesium from alkaline medium, in batch conditions, using a radioanalytical technique. The effect of sodium ion concentration, the initial cesium ion concentration and the contact time were also investigated. It was observed that the Kd value for Cs+ ions decreases with increase in Na+ ion concentration. The equilibrium data were fitted into different isotherm models, and were found to be represented well by the Langmuir isotherm equation, with a monolayer sorption capacity of 287 mg g(-1). Kinetic modeling analysis, using pseudo first-order, pseudo second-order and intraparticle diffusion equations, shows that the pseudo second-order equation is the most appropriate model for the description of the sorption of cesium ions onto the RF-XAD beads. The rate constants were determined at different initial concentrations. The process mechanism was found to be complex, consisting of both surface sorption and pore diffusion.