1. State Key Laboratory of Advanced Processing and Recycling of Non-Ferrous Metals, School of Materials Science and Engineering, Lanzhou University of Technology, Lanzhou 730050, P. R. China
2. College of Geography and Environmental Engineering, Lanzhou City University, Lanzhou 730070, P. R. China
3. College of Chemistry and Chemical Engineering, Hexi University, Zhangye 734000, P. R. China