Microstructure of NiSO4 Solution:A Combined DFT and EXAFS Study
The microhydration structure of nickel sulfate aqueous solution has been determined via density functional theory(DFT)calculation and extended X-ray absorption fine structure(EXAFS)spectroscopy.The geometric optimization and energy calculation of nickel sulfate hydrated clusters of the molecular formula NiSO4(H2O)n0(n =1-12)were determined via DFT using the B3LYP method.Several possible initial structures were considered for clusters of each size to locate the equilibrium geometry.Based on the DFT calculation,the favorable structure of Ni2+ includes the six-coordinated form of NiSO4(H2O)n0 clusters.The results of hydration energy calculation suggest that the six-coordinated contact ion pair(CIP)is the stable configuration for small hydration clusters(n≤5),while the solventshared ion pair(SSIP)represents the favorable structure for medium hydration clusters(6≤n≤10).The solvent is separated by x water molecules(xSIP,x≥2 is the number of water molecule between Ni2+ and SO42-)in larger hydration clusters(n≥11).The EXAFS analysis of the NiSO4 aqueous solutions and NiSO4·6H2O solid established that Ni2+ was surrounded by six water molecules tightly forming an octahedral structure in the first hydration shell,and no CIP was found from 0.70 mol/L to 2.22 mol/L(near saturation).The Ni-O distance and coordinated number were 2.040 ±0.020(A)and 6.0 ±1.0,respectively.These results are consistent with the DFT calculations for NiSO4(H2O)n0 clusters.DFT and EXAFS are powerful techniques that can be used to enhance the resolution of NiSO4 solution microstructure.
NiSO4(H2O)n0 clusters Ion pairs Structure Energy Hydration
LIU Hong-yan ZHU Fa-yan ZHOU Yong-quan WANG Guang-guo FANG Chun-hui FANG Yan ZHANG Wen-qian HAN Li
Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources,Qinghai Inst Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources,Qinghai Inst Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources,Qinghai Inst
国际会议
36th International Conference on Solution Chemistry (36ICSC)(第36届国际溶液化学大会)
西宁
英文
53-68
2019-08-05（万方平台首次上网日期，不代表论文的发表时间）