Sorption of cadmium ions from saline waters onto Fe(III)-zeolite

• Main Authors: Ahribesh Aysha Ali, Lazarević Slavica, Potkonjak Branislav, Bjelajac Anđelika, Janaćković Đorđe, Petrović Rada
• Format: Article
• Language: English
• Published: Association of Chemical Engineers of Serbia 2015-01-01
• Series: Hemijska Industrija
• Subjects: sorption; cadmium ions; Fe(III)-zeolite; seawater; modeling
• Online Access: http://www.doiserbia.nb.rs/img/doi/0367-598X/2015/0367-598X1400038A.pdf

The sorption of Cd2+ from natural seawater, artificial seawater, distilled water and NaCl solution of the same ionic strength as the seawater onto zeolite modified by iron(III) oxide (Fe(III)-zeolite) was investigated. The sorption was found to be time, concentration and pH dependent. The sorption capacity at the initial pH = 7 decreased in the following order: distilled water > NaCl solution > artificial seawater > natural seawater. The isotherm study showed that Langmuir isotherm model could be adequately applied for the sorption in distilled water, indicating the homogeneous monolayer coverage at Fe(III)-zeolite surface, while the Freundlich isotherm model showed a better fit than the Langmuir model of the sorption data in saline waters, indicating multilayer heterogeneous coverage at the sorbent surface. The values of Freundlich parameter n suggested that the sorption was a favorable process and bonds between Cd2+ and Fe(III)-zeolite surface were stronger in NaCl solution than in natural and artificial seawater. Kinetics analyzes showed that the mechanism of Cd2+ sorption from natural seawater differed from the sorption mechanism out of distilled water, NaCl solution and artificial seawater. The intra-particle diffusion kinetic model indicated that both boundary layer diffusion and intra-particle diffusion influenced the rate of sorption. [Projekat Ministarstva nauke Republike Srbije, br. III 45019]