标题：Insight into the Segregation Phenomenon in Metal-Cation-Doped Aluminum Sol during the Drying Process with NO3- as Counterions
作者：Zhang, Jian;Xia, Yuguo;Zhang, Li;Jiao, Xiuling;Chen, Dairong
作者机构：[Zhang, J] School of Chemistry and Chemical Engineering, Shandong University, Jinan, 250100, China;[ Xia, Y] National Engineering Research Center for 更多
通讯作者地址：[Jiao, XL]Shandong Univ, Sch Chem & Chem Engn, Jinan 250100, Peoples R China.
来源：The journal of physical chemistry, C. Nanomaterials and interfaces
摘要：The segregation mechanism of metal ions (Na+, K+, Mg2+, Ca2+, Co2+, Ni2+, La2+, La3+, Y3+) in gamma-AlOOH was investigated during the sol-gel process by a combination of experiments and density functional theory (DFT) calculations. The DFT calculations showed that all of the adsorption energies of metal ions were smaller than the hydrogen ion in neutral conditions, and the metal ions even could not be adsorbed on the protonated gamma-AlOOH surface due to electrostatic repulsion. The segregation of metal ions in gamma-AlOOH sol during the drying process was caused by weak adsorption of metal ions on the gamma-AlOOH surface in acidic conditions and mainly occurred at the late period of drying with the removal of adsorbed water. The computational segregation sequence of metal ions was consistent with experimental results, which was La3+ approximate to Y3+ > Ni2+ approximate to Co2+ > Mg2+ approximate to Ca2+ > K+ approximate to Na+. According to the segregation mechanism during sol-xerogel transition, it is speculated that an additive which could strengthen the combination between metal ions and the protonated gamma-AlOOH surface could diminish the segregation. On the basis of this speculation, citric acid was added into the gamma-AlOOH sol, and the segregation percentage of La3+ decreased to 3.54% from 16.4%.