title: Pb(II), Cr(VI) and atrazine sorption behavior on sludge-derived biochar: role of humic acids.
abstract: Pyrolyzing municipal wastewater treatment sludge into biochar can be a promising sludge disposal approach, especially as the produced sludge-derived biochar (SDBC) is found to be an excellent sorbent for heavy metals and atrazine. The aim of this study was to investigate how and why the coexisting humic acids influence the sorption capacity, kinetic, and binding of these contaminants on SDBC surface. Results showed humic acids enhanced Pb(II)/Cr(VI) sorption binding, and increased the corresponding Pb(II) Langmuir sorption capacity at pH 5.0 from 197 to 233 μmol g(-1), and from 688 to 738 μmol g(-1) for Cr(VI) at pH 2.0. It can be mainly attributed to the sorbed humic acids, whose active functional groups can offer the additional sites to form stronger inner-sphere complexes with Pb(2+), and supply more reducing agent to facilitate the transformation of Cr(VI) to Cr(III). However, humic acids reduced the atrazine adsorption Freundlich constant from 1.085 to 0.616 μmol g(-1). The pore blockage, confirmed by the decreased BET-specific surface area, as well as the more hydrophilic surface with more sorbed water molecules may be the main reasons for that suppression. Therefore, the coexisting humic acids may affect heavy metal stabilization or pesticide immobilization during SDBC application to contaminated water or soils, and its role thus should be considered especially when organic residues are also added significantly to increase the humic acid content there.
authors.affiliation: School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou, 510275, China.
authors.forename: Fengsa
authors.initials: F
authors.lastname: Zhou
authors.affiliation: China Energy Conservation DADI Environmental Remediation Co. Ltd, Beijing, 100082, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Wang
authors.affiliation: School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou, 510275, China.
authors.forename: Sheng'en
authors.initials: S
authors.lastname: Fang
authors.affiliation: School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou, 510275, China. zhangwh5@mail.sysu.edu.cn.|Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Guangzhou, 510275, China. zhangwh5@mail.sysu.edu.cn.
authors.forename: Weihua
authors.initials: W
authors.lastname: Zhang
authors.affiliation: School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou, 510275, China.|Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Guangzhou, 510275, China.
authors.forename: Rongliang
authors.initials: R
authors.lastname: Qiu
mesh_terms: D000327:Adsorption; D001280:Atrazine / Q000737:chemistry*; D002606:Charcoal / Q000737:chemistry*; D002857:Chromium / Q000737:chemistry*; D052918:Environmental Restoration and Remediation / Q000295:instrumentation / Q000379:methods*; D006812:Humic Substances / Q000032:analysis*; D007700:Kinetics; D007854:Lead / Q000737:chemistry*; D010575:Pesticides / Q000737:chemistry; D012722:Sewage / Q000737:chemistry*; D062065:Wastewater / Q000737:chemistry
chemical_list: D001280:Atrazine; D002606:Charcoal; D002857:Chromium; D006812:Humic Substances; D007854:Lead; D010575:Pesticides; D012722:Sewage; D062065:Wastewater; C540010:biochar; C074702:chromium hexavalent ion
keywords: Atrazine; Cr(VI); Humic acids; Pb(II); Sludge-derived biochar; Sorption