摘要
^(210)Po是加速器驱动次临界系统(ADS)次临界堆铅铋冷却剂和散裂靶产生的重要放射性核素.本文以同主族元素Te(Ⅳ)代替Po(Ⅳ),首先对氧化石墨烯(GO)吸附Po(Ⅳ)的性能进行了模拟实验研究.结果显示:GO对Te(Ⅳ)的吸附率随时间增加可分为快速增加阶段、缓慢上升阶段和吸附2.5 h后的饱和阶段;GO对Te(Ⅳ)的吸附率随溶液pH值增加呈先上升后下降的趋势,当pH值为4.7时,吸附率最大;随着吸附体系GO量逐渐增加,GO对Te(Ⅳ)的吸附率先线性上升后恒定,吸附量则呈现先不变后下降的趋势.进一步的吸附机理分析结果表明:GO对Te(Ⅳ)的吸附以弱化学作用为主,且随吸附过程进行,吸附限速步骤由内扩散转变为膜扩散,吸附表面由非均质转变为均质;羧基、环氧基和C=C键是GO吸附Te(Ⅳ)的主要结合位点,且结合中Te(Ⅳ)化合价不变.
^210Po is a major radionuclide for accelerator driven critical system（ADS） in which the lead-bismuth eutectic（LBE） is used as the coolant and the spallation target.In the present work,the lighter chalcogen Te（Ⅳ） was used to substitute for the radioactive Po（Ⅳ） to study the performance of Po（Ⅳ） adsorption by graphene oxide（GO）.The results are as follows：（1） the Te（Ⅳ） accumulation on GO could be divided into the rapid increasing,the slow increasing and the saturation stage during 2.5 h;（2） the adsorption efficiency of Te（Ⅳ） on GO varies with pH,ascended at first and then descended with the increase of pH,and it reached the maximum at pH 4.7;（3） when the amount of GO increased gradually,the percentage of accumulated Te（Ⅳ）rose linearly at first and then saturated,and the adsorption capacity kept constant before it decreased.Furthermore,the analysis of adsorption mechanism showed that the Te（Ⅳ） was accumulated on GO mainly through weak chemical reactions.For the adsorption progressing,the rate limiting step was translated from intra-particle diffusion to membrane diffusion and the inhomogeneous surface of GO was converted to homogeneous.The C=C bond,carboxyl group and epoxy group were the main binding sites for Te（Ⅳ） adsorption,and the chemical valence of Te（Ⅳ） was not changed during the binding process.
出处
《环境科学学报》
CAS
CSCD
北大核心
2018年第1期208-216,共9页
Acta Scientiae Circumstantiae
基金
国家自然科学基金(No.21403246)
中国科学院战略先导科技专项(No.XDA03040000)
关键词
氧化石墨烯
钋
碲
吸附率
吸附机理
graphene oxide
polonium
tellurium
adsorption rate
adsorption mechanism
