title: Characteristics and mechanisms of nickel adsorption on biochars produced from wheat straw pellets and rice husk.
abstract: The adsorption characteristics and mechanisms of Ni2+on four-standard biochars produced from wheat straw pellets (WSP550, WSP700) and rice husk (RH550, RH700) at 550 and 700 °C, respectively, were investigated. The kinetic results show that the adsorption of Ni2+on the biochars reached an equilibrium within 5 min. The increase of the solid to liquid ratio resulted in an increase of Ni2+removal percentage but a decrease of the adsorbed amount of Ni2+per weight unit of biochar. The Ni2+removal percentage increased with the increasing of initial solution pH values at the range of 2-4, was relatively constant at the pH range of 4-8, and significantly increased to ≥98% at pH 9 and stayed constantly at the pH range of 9-10. The calculated maximum adsorption capacities of Ni2+for the biochars follow the order of WSP700 > WSP550 > RH700 > RH550. Both cation exchange capacity and pH of biochar can be a good indicator of the maximum adsorption capacity for Ni2+showing a positively linear and exponential relationship, respectively. This study also suggests that a carefully controlled standardised production procedure can make it reliable to compare the adsorption capacities between different biochars and investigate the mechanisms involved.
authors.affiliation: Geotechnical and Environmental Research Group, Department of Engineering, University of Cambridge, Cambridge, CB2 1PZ, UK. ztshennju@gmail.com.
authors.forename: Zhengtao
authors.identifier: http://orcid.org/0000-0002-4841-710X
authors.initials: Z
authors.lastname: Shen
authors.affiliation: Geotechnical and Environmental Research Group, Department of Engineering, University of Cambridge, Cambridge, CB2 1PZ, UK.
authors.forename: Yunhui
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Geotechnical and Environmental Research Group, Department of Engineering, University of Cambridge, Cambridge, CB2 1PZ, UK.
authors.forename: Oliver
authors.initials: O
authors.lastname: McMillan
authors.affiliation: Geotechnical and Environmental Research Group, Department of Engineering, University of Cambridge, Cambridge, CB2 1PZ, UK.
authors.forename: Fei
authors.initials: F
authors.lastname: Jin
authors.affiliation: Geotechnical and Environmental Research Group, Department of Engineering, University of Cambridge, Cambridge, CB2 1PZ, UK.
authors.forename: Abir
authors.initials: A
authors.lastname: Al-Tabbaa
mesh_terms: D000327:Adsorption; D002606:Charcoal; D009532:Nickel; D012275:Oryza; D014908:Triticum
chemical_list: C540010:biochar; D002606:Charcoal; D009532:Nickel
keywords: Adsorption capacity; Adsorption mechanisms; Adsorption studies; Biochar; Nickel; Standardised production