1. Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong
2. National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
3. School of Energy and Environment, City University of Hong Kong, Kowloon, Hong Kong
4. Department of Physics, City University of Hong Kong, Kowloon, Hong Kong