Ag2CO3-halloysite nanotubes composite with enhanced removal efficiency for water soluble dyes

Emmanuel Nyankson; Benjamin Agyei-Tuffour; Ebenezer Annan; Abu Yaya; Bismark Mensah; Boateng Onwona-Agyeman; Reuben Amedalor; Benson Kwaku-Frimpong; Johnson Kwame Efavi

doi:10.1016/j.heliyon.2019.e01969

Ag₂CO₃-halloysite nanotubes composite with enhanced removal efficiency for water soluble dyes

Heliyon. 2019 Jun 21;5(6):e01969. doi: 10.1016/j.heliyon.2019.e01969. eCollection 2019 Jun.

Authors

Emmanuel Nyankson¹, Benjamin Agyei-Tuffour¹, Ebenezer Annan¹, Abu Yaya¹, Bismark Mensah¹, Boateng Onwona-Agyeman¹, Reuben Amedalor¹, Benson Kwaku-Frimpong¹, Johnson Kwame Efavi¹

Affiliation

¹ Materials Science and Engineering Department, University of Ghana, P.O. Box LG 77, Accra, Ghana.

Abstract

The release of water soluble dyes into the environment is an utmost concern in many countries. This paper presents the effects of Ag₂CO₃-halloysite composites on the efficient removal of water soluble dyes. In this study, NaHCO₃ solution was added dropwisely to halloysite nanotubes (HNTs) dispersed in aqueous AgNO₃ to form Ag₂CO₃-HNTs composite. The synthesized Ag₂CO₃-HNTs composite was characterized with Diffused Reflectance Spectroscopy (DRS), X-ray Diffraction (XRD), Thermogravimetric analysis (TGA), Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDX) and Fourier Transform Infra-Red (FT-IR) spectroscopy. The photocatalytic activity and the adsorption capacity of Ag₂CO₃-HNTs on methylene blue and rhodamine b dyes were dependent on pH and the amount of HNTs used in the synthesis. The photodegradation efficiency of Ag₂CO₃ was lower when compared with that of the composite material. This observation is due to the reduction in the electron-hole recombination with the HNTs acting as electron trapping site and the enhanced aqueous dispersity of Ag₂CO₃-HNTs. The enhanced adsorption of water soluble dyes by the Ag₂CO₃-HNTs resulted from the electrostatic attraction of cationic dyes to the surface of the HNTs (negatively charged). The Ag₂CO₃-HNTs therefore removed dye pollutants through a combination of photocatalytic and adsorption processes. The results obtained during the study confirmed the potential application of Ag₂CO₃-HNTs composite in water treatment technologies.

Keywords: Adsorption; Ag2CO3; Halloysite nanotubes; Materials science; Photocatalysis; Water soluble dyes.