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Metal desorption from copper(II)/nickel(II)-spiked kaolin as a soil component using plant-derived saponin biosurfactant

Paper ID Volume ID Publish Year Pages File Format Full-Text
35630 45099 2008 11 PDF Available
Title
Metal desorption from copper(II)/nickel(II)-spiked kaolin as a soil component using plant-derived saponin biosurfactant
Abstract

This study reports experimental measurements on the washing ability of quillaja saponin biosurfactant in kaolin suspensions, which were presorbed with the binary heavy metals of Cu(II) and Ni(II). A synthetic surfactant (SDS) and chelating agent (EDTA) were also evaluated for comparison studies. The sorption capacity for Cu(II) and Ni(II) onto kaolin were measured through the variation in pH and initial metal ion concentration. Much attention has been paid to understanding the micelle-forming properties of biosurfactant solution and its interaction with metals at the clay–water interface so washing strategies can then seek to achieve the ideal capacities of saponin biosurfactant for desorbing heavy metals from kaolin clays. The desorption of Cu(II) and Ni(II) from kaolin were examined as a function of pH, saponin concentration, temperature, time and mass/volume ratio of kaolin suspension. Because the saponin successfully competes with the kaolin clay for complexing with the metal ions by the Lewis acid–base interaction induced by pH, structure size, or charge of surfactant solution, the highest desorption improvements by 2000 mg/l of saponin were gained at 20 g/l kaolin suspension and pH 5–8, in which a single washing at room temperature could remove ∼83% of the copper and ∼85% of the nickel from kaolin containing 0.45 mg copper/g kaolin and 0.14 mg nickel/g kaolin. These results were interpreted as showing the action of a three-step micellar washing mechanism on the desorption efficiencies for Cu(II) and Ni(II). It is then pointed out quillaja saponin may be applied as a useful biosurfactant for the removal of heavy metals in contaminated clays or soils.

Keywords
Heavy metal removal; Kaolin clay; Biosurfactant; Quillaja saponin; Sorption; Desorption
First Page Preview
Metal desorption from copper(II)/nickel(II)-spiked kaolin as a soil component using plant-derived saponin biosurfactant
Publisher
Database: Elsevier - ScienceDirect
Journal: Process Biochemistry - Volume 43, Issue 5, May 2008, Pages 488–498
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering