1. College of Environmental Science and Engineering, Hunan University, Changsha 410082, China
2. Key Laboratory of Environmental Biology and Pollution Control, Ministry of Education, Hunan University, Changsha 410082, China
3. School of Design, Hunan University, Changsha 410082, China
4. College of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu 610500, Sichuan Province, P. R. China