1. School of Resources and Safety Engineering, Central South University, Changsha 410083, China
2. School of Metallurgy and Environment, Central South University, Changsha 410083, China
3. School of Molecular Sciences, The University of Western Australia, Perth 4009, Australia
4. Korea Biochar Research Center, APRU Sustainable Waste Management Program and Division of Environmental Science and Ecological Engineering, Korea University, Seoul 142-820, Republic of Korea