Adsorption Efficiency and Photocatalytic Activity of Silver Sulfide Nanoparticles Deposited on Carbon Nanotubes

A multimode, dual functional nanomaterial, CNTs-Ag2S, comprised of carbon nanotubes (CNTs) and silver sulfide (Ag2S) nanoparticles, was prepared through the facile hydrothermal process. Before the deposition of Ag2S nanoparticles, hydrophobic CNTs were modified to become hydrophilic through refluxing with a mixture of concentrated nitric and sulfuric acids. The oxidized CNTs were employed to deposit the Ag2S nanoparticles for their efficient immobilization and homogenous distribution. The CNTs-Ag2S could adsorb toxic Cd(II) and completely degrade the hazardous Alizarin yellow R present in water. The adsorption efficiency of CNTs-Ag2S was evaluated by estimating the Cd(II) adsorption at different concentrations and contact times. The CNTs-Ag2S could adsorb Cd(II) entirely within 80 min of the contact time, while CNTs and Ag2S could not pursue it. The Cd(II) adsorption followed the pseudo-second-order, and chemisorption was the rate-determining step in the adsorption process. The Weber-Morris intraparticle pore diffusion model revealed that intraparticle diffusion was not the sole rate-controlling step in the Cd(II) adsorption. Instead, it was contributed by the boundary layer effect. In addition, CNTs-Ag2S could completely degrade alizarin yellow R in water under the illumination of natural sunlight. The Langmuir-Hinshelwood (L-H) model showed that the degradation of alizarin yellow R proceeded with pseudo-first-order kinetics. Overall, CNTs-Ag2S performed as an efficient adsorbent and a competent photocatalyst.

Automated summary

A multimode, dual functional nanomaterial, CNTs-Ag2S, consisting of carbon nanotubes (CNTs) and silver sulfide (Ag2S) nanoparticles, was prepared through a facile hydrothermal process. The modified CNTs were used to efficiently immobilize and uniformly distribute the Ag2S nanoparticles, allowing CNTs-Ag2S to adsorb toxic Cd(II) and completely degrade hazardous Alizarin yellow R in water. The adsorption of Cd(II) by CNTs-Ag2S followed pseudo-second-order kinetics, with chemisorption being the rate-determining step. The degradation of Alizarin yellow R by CNTs-Ag2S proceeded with pseudo-first-order kinetics according to the Langmuir-Hinshelwood (L-H) model.