title: A comparative study for the sorption of Cd(II) by K-feldspar and sepiolite as soil components, and the recovery of Cd(II) using rhamnolipid biosurfactant.
abstract: This study investigated the sorption characteristics and recovery of selected heavy metal Cd(II) from K-feldspar and sepiolite, representative soil components, using rhamnolipid biosurfactant. Although the proposed technique was classified as a soil bioremediation process, it can also be applied to treatment of waste waters containing Cd(II) ions with minor modifications. The effect of initial Cd(II) concentration on sorption capacity was characterized by determining the sorption isotherms. Of the four models examined, the Freundlich model showed the best fit for the sorption of Cd(II) on K-feldspar, whereas the Langmuir-model was used successfully to characterize the sorption of Cd(II) on sepiolite. Although a high Cd(II) uptake of 7.49 mmol/kg by K-feldspar was obtained, sepiolite was a superior Cd(II) accumulater, with a maximum Cd(II) uptake of 24.66 mmol Cd(II)/kg. The presence of Cd(II) in the sepiolite or K-feldspar prior to addition of the rhamnolipid generally resulted in less rhamnolipid sorption to sepiolite or K-feldspar. The maximum Cd(II) desorption efficiency by rhamnolipid from K-feldspar was substantially higher than that of sepiolite and determined to be 96% of the sorbed Cd(II), whereas only 10.1% of the sorbed Cd(II) from sepiolite was recovered by rhamnolipid solution.
authors.affiliation: Department of Chemical Engineering, Eskişehir Osmangazi University, 26480 Bati Meşelik, Eskişehir, Turkey.
authors.forename: Y
authors.initials: Y
authors.lastname: Aşçi
authors.forename: M
authors.initials: M
authors.lastname: Nurbaş
authors.forename: Y Sağ
authors.initials: YS
authors.lastname: Açikel
mesh_terms: D000327:Adsorption; D000538:Aluminum Silicates / Q000737:chemistry*; D002104:Cadmium / Q000737:chemistry*; D006017:Glycolipids / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D017633:Magnesium Silicates / Q000737:chemistry*; D017680:Potassium Compounds / Q000737:chemistry*; D012989:Soil Pollutants / Q000737:chemistry*; D013501:Surface-Active Agents / Q000737:chemistry; D013816:Thermodynamics
chemical_list: D000538:Aluminum Silicates; D006017:Glycolipids; D017633:Magnesium Silicates; D017680:Potassium Compounds; D012989:Soil Pollutants; D013501:Surface-Active Agents; C418382:rhamnolipid; D002104:Cadmium; C016447:feldspar; C001671:magnesium trisilicate