The effect of salinity on the sorption of cadmium ions from aqueous medium on Fe(III)-sepiolite
In this study, the sorption of cadmium ions onto sepiolite modified with hydrated iron(III) oxide, Fe(III)-sepiolite, has been investigated in natural seawater, artificial seawater, aqueous solution of NaCl of the same ionic strength as the seawater and distilled water. The sorption experim...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Association of the Chemical Engineers of Serbia
2015-01-01
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| Series: | Chemical Industry and Chemical Engineering Quarterly |
| Subjects: | |
| Online Access: | http://www.doiserbia.nb.rs/img/doi/1451-9372/2015/1451-93721400028H.pdf |
| Summary: | In this study, the sorption of cadmium ions onto sepiolite modified with
hydrated iron(III) oxide, Fe(III)-sepiolite, has been investigated in natural
seawater, artificial seawater, aqueous solution of NaCl of the same ionic
strength as the seawater and distilled water. The sorption experiments were
performed as a function of the initial solution pH value, the initial metal
concentration and the equilibration time, using the batch method. The
equilibrium sorption data were analyzed by the Langmuir, Freundlich and Sips
isotherm models and the kinetics of sorption was analyzed using the
pseudo-first-order and the pseudo-second-order kinetic models. The maximum
sorption capacity and the strength of the sorbate-sorbent bonds at initial pH
= 7 were found to decrease in the following order: distilled water > NaCl
solution > artificial seawater > natural seawater. The values of parameter nS
in the Sips model, which fitted the equilibrium sorption results best, showed
that heterogeneity of the sorbent surface was the highest in distilled water
and the lowest in natural seawater. The sorption kinetic data fitted well
with the pseudo-second-order kinetic model, which suggests that the
rate-limiting step in Cd2+ sorption onto Fe(III)-sepiolite could be
chemisorption. The low desorption percentage in both distilled water and
0.001 M HNO3 indicated that sorption occurred mainly by chemisorption
mechanisms. [Projekat Ministarstva nauke republike srbije, br. III 45019] |
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| ISSN: | 1451-9372 2217-7434 |