水合铀酰离子在三水铝石(001)表面的吸附  

Adsorption of hydrated uranyl on gibbsite(0 0 1) surface

作　　者：辜家芳 许可[2] 黄协锋 陈婷 张书泉 陈文凯[3] 陈建中[3] GU Jiafang;XU Ke;HUANG Xiefeng;CHEN Ting;ZHANG Shuquan;CHEN Wenkai;CHEN Jianzhong(Department of Chemical Engineering,Zhicheng College,Fuzhou University,Fuzhou,350002,China;Minjiang University,Fuzhou,350108,China;Fuzhou University,Fuzhou,350108,China)

机构地区：[1]福州大学至诚学院化学工程系,福州350002 [2]闽江学院,福州350108 [3]福州大学,福州350108

出　　处：《环境化学》2021年第10期3207-3216,共10页Environmental Chemistry

基　　金：国家自然科学基金(61775039);福建省自然科学基金(2018J01431);福建省教育厅科研基金(JT180806);国家创新创业项目(ZJ1935)资助。

摘　　要：本文采用周期性密度泛函理论研究三水铝石(0 0 1)面吸附水合铀酰离子过程中的能量和结构的变化以及质子化对吸附的影响.对三水铝石(0 0 1)表面的吸附位置进行不同程度的去质子化,得到x=0、x=1和x=2吸附面(x表示三水铝石(0 0 1)表面吸附位置上去质子化的个数). x=0吸附面上各吸附位的吸附能最大差值在40 KJ·mol^(-1)左右,Edge-sharing吸附总体比Corner-sharing吸附的更稳定,并且以双齿配位吸附为主.在x=1吸附面的吸附位上,也显现出大部分的Edge-sharing吸附比Corner-sharing吸附得更稳定.该面以单齿配位吸附为主.在x=2吸附面上,各个吸附位均表现出良好的吸附能力.该面以双齿配位吸附为主,但形成铀氧化物吸附的可能性增大.三水铝石(0 0 1)表面与铀酰离子通过配位键的作用形成稳定吸附.发生吸附配位后吸附面的电荷分布发生变化.吸附底物Al(OH)_(6)八面体上氧原子离子化程度增大即带更多的负电荷.吸附通过减弱三水铝石表面H—O和Al—O共价键强度,增强其表面氧与水合铀酰的配位键强度,来形成稳定吸附结构.随着去质子化程度的增加,各个吸附位均表现出良好的吸附能力,吸附能变大.In this paper, periodic density functional theory was used to study the changes of energy and structure during the adsorption of hydrated uranyl ions on gibbsite(0 0 1) surface and the effect of protonation on adsorption. The adsorption surfaces x=0, x=1 and x=2 were obtained by deprotonating the adsorption sites on the gibbsite(0 0 1) surface in different degrees(x represents the number of deprotonations on the adsorption sites of gibbsite(0 0 1) surface). For x=0 adsorption surface, the maximum difference of adsorption energy was about 40 KJ·mol^(-1), and the adsorption of Edge-sharing site was generally more stable than that of Corner-sharing site, moreover the dominant adsorption type was bi-dentate coordination. For x=1 adsorption surface, it still showed that most of the Edge-sharing adsorption was more stable than the Corner-sharing adsorption, but mono-dentate coordination adsorption was dominated on this surface. It could also find that x=2 adsorption surface showed good adsorption capacity. The surface was mainly bidentate coordination adsorption, and the possibility to form uranium oxide adsorption increases. The surface of gibbsite(0 0 1) formed stable adsorption with uranyl ion through coordination bond. After adsorption coordination, the charge distribution on the adsorption surface changed, and the ionization degree of oxygen atoms on the adsorption substrate Al(OH)_(6) octahedron increased, that was, it carried more negative charges. By weakening the covalent bonds strength between H—O and Al—O on the adsorption surface, the coordination bond strength between surface oxygen and hydrated uranyl was enhanced, and finally a stable adsorption structure was formed. With the increase of deprotonation degree, each adsorption site showed good adsorption capacity, and the adsorption energy become larger.

关 键 词：三水铝石 密度泛函理论 铀酰吸附 

分 类 号：X771[环境科学与工程—环境工程]