Copper and zinc adsorption by softwood and hardwood biochars under elevated sulphate-induced salinity and acidic pH conditions

Jiang, Shasha, Huang, Longbin, Nguyen, Tuan A. H., Ok, Yong Sik, Rudolph, Victor, Yang, Hong and Zhang, Dongke (2015) Copper and zinc adsorption by softwood and hardwood biochars under elevated sulphate-induced salinity and acidic pH conditions. Chemosphere, 142 64-71. doi:10.1016/j.chemosphere.2015.06.079


Author Jiang, Shasha
Huang, Longbin
Nguyen, Tuan A. H.
Ok, Yong Sik
Rudolph, Victor
Yang, Hong
Zhang, Dongke
Title Copper and zinc adsorption by softwood and hardwood biochars under elevated sulphate-induced salinity and acidic pH conditions
Journal name Chemosphere   Check publisher's open access policy
ISSN 1879-1298
0045-6535
Publication date 2015-01-01
Year available 2015
Sub-type Article (original research)
DOI 10.1016/j.chemosphere.2015.06.079
Open Access Status Not Open Access
Volume 142
Start page 64
End page 71
Total pages 8
Place of publication Pergamon Press
Publisher Kidlington, Oxford, United Kingdom
Language eng
Subject 2304 Environmental Chemistry
1600 Chemistry
Abstract Biochar adsorption may lower concentrations of soluble metals in pore water of sulphidic Cu/Pb-Zn mine tailings. Unlike soil, high levels of salinity and soluble cations are present in tailing pore water, which may affect biochar adsorption of metals from solution. In the present study, removal of soluble copper (Cu) and zinc (Zn) ions by soft- (pine) and hard-wood (jarrah) biochars pyrolysed at high temperature (about 700°C) was evaluated under typical ranges of pH and salinity conditions resembling those in pore water of sulphidic tailings, prior to their direct application into the tailings. Surface alkalinity, cation exchange capacity, and negative surface charge of biochars affected Cu and Zn adsorption capacities. Quantitative comparisons were provided by fitting the adsorption equilibrium data with either the homogeneous or heterogeneous surface adsorption models (i.e. Langmuir and Freundlich, respectively). Accordingly, the jarrah biochar showed higher Cu and Zn adsorption capacity (Q=4.39 and 2.31mg/g, respectively) than the softwood pine biochar (Q=1.47 and 1.00mg/g). Copper and Zn adsorption by the biochars was favoured by high pH conditions under which they carried more negative charges and Cu and Zn ions were predicted undergoing hydrolysis and polymerization. Within the tested range, salinity had relatively weak effects on the adsorption, which perhaps influenced the surface charge and induced competition for negative charged sites between Na and exchangeable Ca and/or heavy metal ions. Large amounts of waste wood/timber at many mine sites present a cost-effective opportunity to produce biochars for remediation of sulphidic tailings and seepage water.
Formatted abstract
Biochar adsorption may lower concentrations of soluble metals in pore water of sulphidic Cu/Pb–Zn mine tailings. Unlike soil, high levels of salinity and soluble cations are present in tailing pore water, which may affect biochar adsorption of metals from solution. In the present study, removal of soluble copper (Cu) and zinc (Zn) ions by soft- (pine) and hard-wood (jarrah) biochars pyrolysed at high temperature (about 700 °C) was evaluated under typical ranges of pH and salinity conditions resembling those in pore water of sulphidic tailings, prior to their direct application into the tailings. Surface alkalinity, cation exchange capacity, and negative surface charge of biochars affected Cu and Zn adsorption capacities. Quantitative comparisons were provided by fitting the adsorption equilibrium data with either the homogeneous or heterogeneous surface adsorption models (i.e. Langmuir and Freundlich, respectively). Accordingly, the jarrah biochar showed higher Cu and Zn adsorption capacity (Qmax=4.39 and 2.31 mg/g, respectively) than the softwood pine biochar (Qmax=1.47 and 1.00 mg/g). Copper and Zn adsorption by the biochars was favoured by high pH conditions under which they carried more negative charges and Cu and Zn ions were predicted undergoing hydrolysis and polymerization. Within the tested range, salinity had relatively weak effects on the adsorption, which perhaps influenced the surface charge and induced competition for negative charged sites between Na+ and exchangeable Ca2+ and/or heavy metal ions. Large amounts of waste wood/timber at many mine sites present a cost-effective opportunity to produce biochars for remediation of sulphidic tailings and seepage water.
Keyword Biochar
Activated carbon
Jarrah
Pine
Salinity
Copper
Zinc
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Centre for Mined Land Rehabilitation Publications
School of Chemical Engineering Publications
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