An EXAFS Investigation on the Mechanism of Competitive Sorption between Co(Ⅱ)and Ni(Ⅱ)at γ-Alumina/Solution Interface
Co(Ⅱ)and Ni(Ⅱ)are two common toxic heavy metals,and may simultaneously exist in contaminated water,soil,and sediments systems in earths surface environment.Under this circumstance,competitive adsorption between the two metals may pose a threat to influence their migration,toxicity and bioavailability.In this research,the competitive sorption of Co(Ⅱ)and Ni(Ⅱ)on γ-Al2O3 was studied using both macroscopic sorption experiments and Extended X-ray Absorption Fine Structure(EXAFS)spectroscopy.Results showed that Ni(Ⅱ)would reduce the sorption amount of Co(Ⅱ)in binary-solute system at pH 6.0.This is because both Co(Ⅱ)and Ni(Ⅱ)would form inner-sphere surface complexes during sorption on γ-Al2O3 and would compete for the surface reactive sites.However,Co(Ⅱ)exhibits a negligible influence on sorption amount of Ni(Ⅱ)in the binary system at pH 6.0,which suggests Ni(Ⅱ)has a stronger affinity to alumina surface.At pH 7.5,Co(Ⅱ)and Ni(Ⅱ)sorption density are much higher than that of pH 6.0,but there is no mutual competitive effect between each other.EXAFS analysis further reveal that formation of layered double hydrated(LDH)precipitates was the dominant sorption mechanism for both Co(Ⅱ)and Ni(Ⅱ)at pH 7.5.Because this type of sorption does not rely on surface reactive sites,therefore Co(Ⅱ)and Ni(Ⅱ)does not compete at this condition.This finding would shed light on the risk assessment and remediation strategy for Ni/Co pollution.
Co(Ⅱ) Ni(Ⅱ) γ-Al2O3 competitive sorption EXAFS
Wenxian Gou Junfeng Ji Wei Li
Key Laboratory of Surficial Geochemistry,Ministry of Education,School of Earth Sciences and Engineering,Nanjing University,Nanjing 210023,China
国际会议
The 11th International Symposium on Geochemistry of the Earths Surface(GES-11)(第十一届地球表层地球化学国际研讨会)
贵阳
英文
1-3
2017-06-11（万方平台首次上网日期，不代表论文的发表时间）