不同价态无机磷在金属氧化物表面吸附的第一性原理研究  

Adsorption of inorganic phosphorus of different valences on metal oxides:A first-principles study

作　　者：衡忠暄 单超[1,2] 花铭[1,2] 潘丙才[1,2] HENG ZhongXuan;SHAN Chao;HUA Ming;PAN BingCai(State Key Laboratory of Pollution Control and Resource Reuse,School of Environment,Nanjing University,Nanjing 210023,China;Research Center for Environmental Nanotechnology(ReCENT),Nanjing University,Nanjing 210023,China)

机构地区：[1]南京大学环境学院,污染控制与资源化研究国家重点实验室,南京210023 [2]南京大学环境纳米技术研究中心,南京210023

出　　处：《中国科学：技术科学》2021年第5期591-600,共10页Scientia Sinica(Technologica)

基　　金：国家重点研发计划(编号:2017YFE0107200);中央高校基本科研业务费专项(编号:14380145)资助项目。

摘　　要：磷是控制水体富营养化的关键限制因子.目前主流的除磷技术处理正磷酸盐相对成熟,但次/亚磷酸盐的深度去除尚未引起充分关注.金属氧化物是一类常用的去除正磷酸盐的吸附剂,探究不同价态无机磷在金属氧化物表面吸附行为与机理具有重要研究意义.本文构建了晶型和无定形Fe_(2)O_(3),ZrO_(2),La_(2)O_(3)体相与基底模型,基于第一性原理,计算了次磷酸盐、亚磷酸盐、正磷酸盐在上述基底上的吸附构型及吸附能.结果表明,金属氧化物与次磷酸盐、亚磷酸盐、正磷酸盐主要生成M–O–P键(M为金属原子)和氢键(O‒H).根据吸附能比较,正磷酸盐在金属氧化物表面主要为化学吸附,且吸附能普遍大于次/亚磷酸盐在相应基底的吸附能(0.7~6.3倍),表明正磷酸盐易被金属氧化物专属吸附,而次/亚磷酸盐吸附能较小,相对易受到共存离子竞争干扰.无定形金属氧化物对次/亚/正磷酸盐的吸附能力优于晶型金属氧化物(吸附能均值为3.1倍),三种金属氧化物吸附能力由弱到强的顺序为Fe_(2)O_(3)<ZrO_(2)<La_(2)O_(3),次/亚/正磷酸盐在氧化镧基底上的吸附能为氧化铁/锆的2.0~47.5倍,表明了La与POx基团之间强烈的成键作用.本文可为深度除磷技术选择和开发提供参考.Phosphorus is the key factor limiting eutrophication.Although the prevailing decontamination technologies for the removal of orthophosphate are relatively mature,the advanced treatment of hypophosphite and phosphite has not attracted sufficient attention.Metal oxides are commonly employed as adsorbents for phosphate removal and are of great significance to the investigation of the adsorption behaviors and mechanisms of inorganic phosphorus of different valences on metal oxides.In this study,bulk phase and slab models of crystalline and amorphous Fe_(2)O_(3),ZrO_(2),La_(2)O_(3)were constructed,and the adsorption configurations and energies of hypophosphite,phosphite,and orthophosphate on the above substrates were determined using first-principles calculations.Results show that hypophosphite,phosphite,and orthophosphate are adsorbed on the metal oxides mainly via the formation of M–O–P bonds(M=a metal atom)and hydrogen bonds(O–H).Comparison of adsorption energies revealed that orthophosphate is mainly chemisorbed on the surface of metal oxides and its adsorption energies are generally 0.7‒6.3 times greater than those of hypophosphite/phosphite.This finding reflects the specific adsorption of orthophosphate on metal oxides.By contrast,the adsorption energies of hypophosphite and phosphite are relatively low,which implies weak adsorption ability due to the competitive interference induced by coexisting ions.The adsorption energies on amorphous metal oxides are,on average,3.1 times greater than those on their crystalline analogues.The adsorption energies on the investigated metal oxides followed the order Fe_(2)O_(3)<ZrO_(2)<La_(2)O_(3).The adsorption energies on La oxides were 2.0–47.5 times greater than those of iron/zirconium oxides,indicating strong bonding between La and POx groups.This study is helpful for the selection and development of water decontamination technologies for the in-depth removal of phosphorus.

关 键 词：吸附 磷形态 金属氧化物 密度泛函理论 吸附能 

分 类 号：TQ424[化学工程] X52[环境科学与工程—环境工程]