Kinetic and equilibrium sorption experiments were conducted on removal of divalent heavy metals (Pb(II), Cu(II), Zn(II), Cd(II)) and trivalent arsenic (As(III)) from aqueous solutions by scoria (a vesicular pyroclastic rock with basaltic composition) from Jeju Island, Korea, in order to examine its potential use as an efficient sorbent. The removal efficiencies of Pb, Cu, Zn, Cd, and As by the scoria (size = 0.1-0.2 mm, dose = 60 g L-1) were 94, 70, 63, 59, and 14%, respectively, after a reaction time of 24 h under a sorbate concentration of 1 mM and the solution pH of 5.0. A careful examination on ionic concentrations in sorption batches suggested that sorption behaviors of heavy metals onto scoria are mainly controlled by cation exchange. On the other hand, arsenic appeared to be sensitive to specific sorption onto hematite (a minor constituent of scoria). Equilibrium sorption tests indicated that the removal efficiency for heavy metals increases with increasing pH of aqueous solutions, which is resulted from precipitation as hydroxides. Similarly, multi-component systems containing heavy metals and arsenic showed that the arsenic removal increases with increasing pH of aqueous solutions, which can be attributed to coprecipitation with metal hydroxides. The empirically determined sorption kinetics were well fitted to a pseudo-second order model, while equilibrium sorption data for heavy metals and arsenic onto scoria were consistent with the Langmuir and Freundlich isotherms, respectively. Natural scoria studied in this work is an efficient sorbent for concurrent removal of divalent heavy metals and arsenic.
Bibliographical noteFunding Information:
This work was supported by a grant (05CCTRD09-High Performance Construction Material Research Center) from the Construction Core Technology Program, funded by the Korean Ministry of Construction & Transportation. We acknowledge H.M. Yang of the Jeju Scoria Co. for supplying scoria samples used in this study. Comments by Drs. Rodney H. Grapes and Young-Jae Lee (Korea University) on a draft version of this manuscript helped to improve this paper. Detailed comments and suggestions by three anonymous reviewers also helped to clarify and improve the final version of this manuscript.
- Heavy metals
- Sorption mechanisms
ASJC Scopus subject areas
- Environmental Engineering
- Environmental Chemistry
- Waste Management and Disposal
- Health, Toxicology and Mutagenesis