1. Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, P. R. China
2. Key Lab of Comprehensive and Highly Efficient Utilization of Salt Lake Resources, Chinese Academy of Sciences, Xining 810008, P. R. China
3. College of Science, Central South University of Forestry and Technology, Changsha 410004, P. R. China
4. College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, P.R. China