* Corresponding authors

^a Beijing Engineering Research Center of Process Pollution Control, National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
E-mail: tyzhu@ipe.ac.cn
Fax: +86 010 82544821
Tel: +86 010 82544821

^b Chemistry and Chemical Engineering, Guizhou University, Guiyang, Guizhou 550025, China

^c Graduate University of Chinese Academy of Sciences, Beijing 100049, China

^d Institute of Chemical Engineering, China University of Petroleum, Beijing, China