title: Adsorption behavior comparison of trivalent and hexavalent chromium on biochar derived from municipal sludge.
abstract: In this work, static equilibrium experiments were conducted to distinguish the adsorption performance between the two valence states of chromium on biochar derived from municipal sludge. The removal capacity of Cr(VI) is lower than 7mg/g at the initial chromium concentration range of 50-200mg/L, whereas that of Cr(III) higher than 20mg/g. It indicates that Cr(III) is much easier to be stabilized than Cr(VI). No significant changes in the biochar surface functional groups are observed before and after the adsorption equilibrium, demonstrating the poor contribution of organic matter in chromium adsorption. The main mechanism of heavy metal adsorption by biochar involves (1) surface precipitation through pH increase caused by biochar buffer ability, and (2) exchange between cations in solution (Cd(2+)) and in biochar matrix (e.g. Ca(2+) and Mg(2+)). The reduction of Cr(VI) to Cr(III) is necessary to improve removal efficiency of chromium.
authors.affiliation: School of Environment, Tsinghua University, Beijing 100084, China.
authors.forename: Tan
authors.initials: T
authors.lastname: Chen
authors.affiliation: School of Environment, Tsinghua University, Beijing 100084, China.
authors.forename: Zeyu
authors.initials: Z
authors.lastname: Zhou
authors.affiliation: School of Environment, Tsinghua University, Beijing 100084, China.
authors.forename: Sai
authors.initials: S
authors.lastname: Xu
authors.affiliation: School of Environment, Tsinghua University, Beijing 100084, China. Electronic address: htwang@tsinghua.edu.cn.
authors.forename: Hongtao
authors.initials: H
authors.lastname: Wang
authors.affiliation: School of Environment, Tsinghua University, Beijing 100084, China.
authors.forename: Wenjing
authors.initials: W
authors.lastname: Lu
mesh_terms: D000327:Adsorption; D002606:Charcoal / Q000737:chemistry*; D002857:Chromium / Q000737:chemistry* / Q000302:isolation & purification*; D002947:Cities; D004785:Environmental Pollutants / Q000737:chemistry* / Q000302:isolation & purification*; D008422:Materials Testing; D012037:Refuse Disposal / Q000379:methods; D012722:Sewage / Q000737:chemistry*
chemical_list: D004785:Environmental Pollutants; D012722:Sewage; C540010:biochar; D002857:Chromium; D002606:Charcoal; C074702:chromium hexavalent ion
keywords: Adsorption; Biochar; Heavy metal; Hexavalent chromium; Trivalent chromium