1. College of Environmental Science and Engineering; Beijing Forestry University; 35 Qinghua East Road, Haidian District Beijing 100083 P. R. China
2. Institut de Chimie et Procedes pour l'Energie, l'Environnement et la Sante, Energy and Fuels for a Sustainable Environment Team; UMR 7515 CNRS - Universite de Strasbourg - ECPM; 25 rue Becquerel 67087 Strasbourg Cedex 2 France