1. College of Chemistry and Material Weinan Normal University Weinan 714099 P. R. China
2. Oil & Gas Field Applied Chemistry Key Laboratory of Sichuan Province Chengdu 610500 P. R. China
3. College of Chemistry and Chemical Engineering Shaanxi Province Key Laboratory of Environmental Pollution Control and Reservoir Protection Technology of Oilfields Xi'an Shiyou University Xi'an 710065 P. R. China
4. State Key Laboratory of Petroleum Pollution Control CNPC Research Institute of Safety and Environmental Technology Beijing 102206 P. R. China