1. Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources, Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, P. R. China
2. University of Chinese Academy of Sciences, Beijing 100049, P. R. China
3. Qinghai Engineering and Technology Research Center of Comprehensive Utilization of Salt Lake Resources, Xining 810008, P. R. China
4. College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, P. R. China