Development of magnetic carriers for metal ion removal

Broomberg, Joachim.; Broomberg, Joachim.

Thesis

Development of magnetic carriers for metal ion removal

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Creator

Broomberg, Joachim.

Contributors

Finch, Jim (advisor)

Abstract

English

A novel method has been developed to prepare magnetic carriers for metal ion removal from dilute solutions. In this work, magnetic carriers were prepared by coating an organic surfactant on magnetic particles. The coating was deposited by molecular self-assembly. Two coatings were tested, using two similar bolaamphiphiles* of different chain lengths, HS-(CH2)11-COOH and HS-(CH 2)15-COOH. The magnetic particles were nanosized maghemite (gamma-Fe2O3). The surfactants were synthesized and characterized. Magnetic carriers were prepared, characterized, and tested for metal ion loading. Molecular orientation, density, and stability of the surfactant coatings were characterized by diffuse reflectance infrared Fourier-transform spectroscopy (DRIFTS), x-ray photoelectron spectroscopy (XPS), wetting tests, and leaching tests. The coatings, resulting from the chemisorption of the surfactants on maghemite through carboxylate bonding, were found to be dense, well-packed, and resistant to acid and base attack. The potential use of coated particles for metal ion removal was assessed with Cu and Ag solutions. The metal ion uptake by the carriers was characterized by atomic adsorption and MRS. The influence of pH and metal concentration on adsorption was studied. Metal ion uptake was found to be dependent on pH, and was not significantly different for both types of coated carriers and for bare maghemite. The maximum loading capacity was low, at approximately 6 mg Cu/g particles for Cu. The similarity in loading for coated and bare particles needs further clarification. *Bolaamphiphiles are surfactants with a functional group at each end.

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