title: Comparison of the characteristics and mechanisms of Hg(II) sorption by biochars and activated carbon.
abstract: Two biochars were produced from bagasse and hickory chips (referred to as BB and HCB, respectively) and evaluated for their sorption ability of Hg(II) in aqueous solution. A commercial activated carbon (AC) which is commonly used for Hg(II) removal was included for comparison. Both biochars showed higher sorption capacities than AC, following the trend of BB>HCB>AC. The sorption of Hg(II) by BB and AC was mainly attributed to the formation of (COO)2Hg(II) and (O)2Hg(II). As a result, the adsorption capacity of Hg(II) by BB decreased 17.6% and 37.6% after COOH and OH were blocked, respectively and that of Hg(II) by AC decreased 6.63% and 62.2% for COOH and OH hindered, respectively. However, blocking the function groups had little effect on the Hg removal by HCB since sorption of Hg(II) by HCB was mainly resulted from the π electrons of CC and CO induced Hg-π binding. Further X-ray photoelectron spectroscopy analysis indicated the possibility of reduction of the Hg(II) to Hg(I) by phenol groups or π electrons during the removal of Hg(II) by both biochars. In conclusion, biochar is more effective than activated carbon in removing Hg(II) and there exists a high potential that biochar can be a substitute of activated carbon for removal of Hg(II) from wastewater.
authors.affiliation: School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China; Department of Civil, Architectural and Environmental Engineering, University of Texas, Austin, TX 78712, USA.
authors.forename: Xiaoyun
authors.initials: X
authors.lastname: Xu
authors.affiliation: Department of Civil, Architectural and Environmental Engineering, University of Texas, Austin, TX 78712, USA; Department of Civil and Environmental Engineering, Texas Tech University, Lubbock, TX 79409, USA.
authors.forename: Ariette
authors.initials: A
authors.lastname: Schierz
authors.affiliation: School of Chemical Biology and Materials Engineering, Suzhou University of Science and Technology, Suzhou 215000, China.
authors.forename: Nan
authors.initials: N
authors.lastname: Xu
authors.affiliation: School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China. Electronic address: xdcao@sjtu.edu.cn.
authors.forename: Xinde
authors.initials: X
authors.lastname: Cao
mesh_terms: D000327:Adsorption; D002244:Carbon / Q000737:chemistry*; D002606:Charcoal / Q000737:chemistry*; D008628:Mercury / Q000737:chemistry*; D013499:Surface Properties
chemical_list: C540010:biochar; D002606:Charcoal; D002244:Carbon; D008628:Mercury
keywords: Biochar; Functional groups; Mercury; Reduction; Sorption