1. College of Environment and Safety Engineering, Qingdao University of Science and Technology, Qingdao 266042, P. R. China
2. College of Chemical Engineering, Qingdao University of Science and Technology, Qingdao 266042, P. R. China
3. State Key Laboratory of High-Efficiency Utilization of Coal and Green Chemical Engineering, Ningxia University, Yinchuan 750021, P. R. China