Cu2+ sequestration by amine-functionalized silica nanotubes

Abstract

A novel method for Cu2+ sequestration in Cu2+ aqueous solution has been demonstrated using aminefunctionalized double-walled silica nanotubes (DWSNTs). Herein, the precipitation method and the adsorption method are combined to remove Cu2+ in the Cu2+ aqueous solution. Primary (1 degrees), secondary (2 degrees), tertiary (3 degrees), di-, tri-amines are immobilized on the surface of DWSNT as the adsorption site. The results show that the Cu2+ adsorption amount on the amine-functionalized DWSNTs is in the following order: tri-amine>di-amine>1 degrees amine>2 degrees amine>3 degrees amine. The complexed Cu(2+)s with the amine-functionalized DWSNTs become Cu(OH)(2) crystals due to the reaction with OH-s dissociated from water. Thus, the amine-functionalized DWSNTs show the superior sequestration capacity of Cu2+ in the Cu2+ aqueous solution owing to the Cu(OH)(2) crystals growth on them. FT-IR, FEG-SEM, HR-TEM, and XRD studies demonstrate the mechanism of the Cu2+ adsorption and the Cu(OH)(2) crystals growth. The crystallization-technique of the heavy metal ion on the amine-functionalized DWSNTs is also expected to have potential applications such as the facile synthesis of nano- and microparticles, and the metal catalyst supporter. (C) 2013 Elsevier B.V. All rights reserved.