1. Key Laboratory of New Membrane Materials, Ministry of Industry and Information Technology, School of Environmental and Biological Engineering, Nanjing University of Science & Technology, Nanjing 210094, P. R. China
2. School of Chemical Engineering, Nanjing University of Science & Technology, Nanjing 210094, P. R. China
3. Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06520-8286, United States