1. School of Environmental Science and Engineering, Yangzhou University, Yangzhou 225000, P. R. China
2. School of Science, Yanshan University, Qinhuangdao 066004, P. R. China
3. College of Physics Science and Technology, Yangzhou University, Yangzhou 225002, China
4. School of Chemistry and Materials Science, Hubei Engineering University, Xiaogan 432000, China