Cu²⁺ sequestration by amine-functionalized silica nanotubes

다국어 초록 (Multilingual Abstract)

A novel method for Cu<SUP>2+</SUP> sequestration in Cu<SUP>2+</SUP> aqueous solution has been demonstrated using amine-functionalized double-walled silica nanotubes (DWSNTs). Herein, the precipitation method and the adsorption method are combined to remove Cu<SUP>2+</SUP> in the Cu<SUP>2+</SUP> aqueous solution. Primary (1<SUP>o</SUP>), secondary (2<SUP>o</SUP>), tertiary (3<SUP>o</SUP>), di-, tri-amines are immobilized on the surface of DWSNT as the adsorption site. The results show that the Cu<SUP>2+</SUP> adsorption amount on the amine-functionalized DWSNTs is in the following order: tri-amine>di-amine>1<SUP>o</SUP> amine>2<SUP>o</SUP> amine>3<SUP>o</SUP> amine. The complexed Cu<SUP>2+</SUP>s with the amine-functionalized DWSNTs become Cu(OH)<SUB>2</SUB> crystals due to the reaction with OH<SUP>-</SUP>s dissociated from water. Thus, the amine-functionalized DWSNTs show the superior sequestration capacity of Cu<SUP>2+</SUP> in the Cu<SUP>2+</SUP> aqueous solution owing to the Cu(OH)<SUB>2</SUB> crystals growth on them. FT-IR, FEG-SEM, HR-TEM, and XRD studies demonstrate the mechanism of the Cu<SUP>2+</SUP> adsorption and the Cu(OH)<SUB>2</SUB> 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.