Novel kinetic model of the removal of divalent heavy metal ions from aqueous solutions by natural clinoptilolite

• Published in: Journal of hazardous materials 2012-09, Vol.233-234, p.57-64
• Main Authors: Jovanovic, Mina, Rajic, Nevenka, Obradovic, Bojana
• Format: Article
• Language: English
• Subjects: Adsorption; Applied sciences; aqueous solutions; Chemical engineering; copper; Exact sciences and technology; Heavy metals; Ion Exchange; ions; Kinetic model; Kinetics; lead; manganese; metal ions; Metals, Heavy - chemistry; Models, Chemical; Natural zeolite; Pollution; prediction; sodium; Solutions; sorption; Sorption mechanism; temperature; tuff; Water Pollutants, Chemical - chemistry; Water Purification - methods; Water treatment and pollution; zeolites; Zeolites - chemistry; zinc
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2012.06.052

► A novel kinetic model for heavy metal removal by natural clinoptilolite. ► Two-step reaction in zeolite lattice: release of Na+ followed by M2+ bonding. ► Kinetics of Cu(II), Mn(II), Zn(II) and Pb(II) removal from aqueous solutions. ► Kinetic constant of Na+ release is not influenced by different metals. ► Kinetics prediction requires only one experimentally determined parameter. Removal of heavy metal ions from aqueous solutions using zeolites is widely described by pseudo-second order kinetics although this model may not be valid under all conditions. In this work, we have extended approaches used for derivation of this model in order to develop a novel kinetic model that is related to the ion exchange mechanism underlying sorption of metal ions in zeolites. The novel model assumed two reversible steps, i.e. release of sodium ions from the zeolite lattice followed by bonding of the metal ion. The model was applied to experimental results of Cu(II) sorption by natural clinoptilolite-rich zeolitic tuff at different initial concentrations and temperatures and then validated by predictions of ion exchange kinetics of other divalent heavy metal ions (i.e. Mn(II), Zn(II) and Pb(II)). Model predictions were in excellent agreements with experimental data for all investigated systems. In regard to the proposed mechanism, modeling results implied that the sodium ion release rate was constant for all investigated metals while the overall rate was mainly determined by the rate of heavy metal ion bonding to the lattice. In addition, prediction capabilities of the novel model were demonstrated requiring one experimentally determined parameter, only.