Metal ions biosorption

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Biosorption of Cd(II), Cr(III), and Cr(VI) by Saltbush (Atriplex Canescens) Biomass: Thermodynamic and Isotherm Studies

Journal Title, Volume, Page: 
Journal of Colloid and Interface Science Volume 300, Issue 1, Pages 100–104
Year of Publication: 
2006
Authors: 
Maather F. Sawalha
Environmental Science and Engineering Ph.D. Program, University of Texas at El Paso, El Paso, TX 79968, USA
Current Affiliation: 
Department of Chemistry, Faculty of Science, An-Najah National University, Nablus, Palestine
Jose R. Peralta-Videa
Chemistry Department, University of Texas at El Paso, El Paso, TX 79968, USA
Jaime Romero-González
University of Guanajuato, Guanajuato, Gto. 36000, Mexico
Jorge L. Gardea-Torresdey
Chemistry Department, University of Texas at El Paso, El Paso, TX 79968, USA
Preferred Abstract (Original): 

The biosorption data of Cd(II), Cr(III), and Cr(VI) by saltbush leaves biomass were fit on the Freundlich and Langmuir adsorption isotherms at 297 K. The Cd(II) and Cr(III) solutions were adjusted to pH 5.0 and the Cr(VI) solution was adjusted to pH 2.0. The correlation coefficient values indicated that the data fit better the Freundlich model. The maximal capacities (KF) were found to be 5.79×10−2, 3.25×10−2, and1.14×10−2 mol/g for Cr(III), Cd(II), and Cr(VI), respectively. Similar results were obtained using the Langmuir and the Dubinin–Radushkevick equations. Thermodynamic parameters calculated from the Khan and Singh equation and from the qe vs Ce plot show that the equilibrium constants for the biosorption of the metals follow the same order of the maximal capacities. The negative Gibbs free energy values obtained for Cd(II) and Cr(III) indicated that these ions were biosorbed spontaneously. The mean free energy values calculated from the Dubinin–Radushkevick equation (10.78, 9.45, and 9.05 for Cr(III), Cr(VI), and Cd(II), respectively) suggest that the binding of Cd(II), Cr(III), and Cr(VI) by saltbush leaves biomass occurs through an ionic exchange mechanism.

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Thermodynamic and Isotherm Studies of the Biosorption of Cu(II), Pb(II), And Zn(II) by Leaves of Saltbush (Atriplex Canescens)‎

Journal Title, Volume, Page: 
The Journal of Chemical Thermodynamics Volume 39, Issue 3, Pages 488–492
Year of Publication: 
2007
Authors: 
Maather F. Sawalha
Environmental Science and Engineering, University of Texas at El Paso, El Paso, TX 79968, United States
Current Affiliation: 
Department of Chemistry, Faculty of Science, An-Najah National University, Nablus, Palestine
Jose R. Peralta-Videa
Chemistry Department, 4 Health Science Program, College of Health Science, University of Texas at El Paso, El Paso, TX 79968, United States
Jaime Romero-González
University of Guanajuato, Guanajuato, Gto. 36000, Mexico
Jorge L. Gardea-Torresdey
Environmental Science and Engineering, University of Texas at El Paso, El Paso, TX 79968, United States
Maria Duarte-Gardea
Department of Health Promotion, College of Health Science, University of Texas at El Paso, El Paso, TX 79968, United States
Preferred Abstract (Original): 

The Freundlich and Langmuir isotherms were used to describe the biosorption of Cu(II), Pb(II), and Zn(II) onto the saltbush leaves biomass at 297 K and pH 5.0. The correlation coefficients (R2) obtained from the Freundlich model were 0.9798, 0.9575, and 0.9963 for Cu, Pb, and Zn, respectively, while for the Langmuir model the R2 values for the same metals were 0.0001, 0.1380, and 0.0088, respectively. This suggests that saltbush leaves biomass sorbed the three metals following the Freundlich model (R2 > 0.9575). The KFvalues obtained from the Freundlich model (175.5 · 10−2, 10.5 · 10−2, and 6.32 · 10−2 mol · g−1 for Pb, Zn, and Cu, respectively), suggest that the metal binding affinity was in the order Pb > Zn > Cu. The experimental values of the maximal adsorption capacities of saltbush leaves biomass were 0.13 · 10−2, 0.05 · 10−2, and 0.107 · 10−2 mol · g−1 for Pb, Zn, and Cu, respectively. The negative ΔG values for Pb and the positive values for Cu and Zn indicate that the Pb biosorption by saltbush biomass was a spontaneous process.

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