A novel adsorbent of Ag-FMWCNTs for the removal of SMX from aqueous solution

Abstract

A novel silver nanoparticle-modified magnetic multi-walled carbon nanotube composite (Ag-FMWCNTs) was synthesized by embedding Fe₃O₄ and assembling Ag nanoparticles in one-step. The properties of the Ag-FMWCNTs composites and magnetic multi-walled carbon nanotubes (FMWCNTs) were studied by scanning electron microscopy, vibrating sample magnetometry (VSM) and Fourier transform infrared spectroscopy. The adsorption isotherms, adsorption kinetics and the effects of solution pH and ionic strength to adsorb emerging contaminant sulfamethoxazole (SMX) from aqueous solution on different multi-walled carbon nanotubes-based adsorbents were determined. The results showed that the adsorption kinetics could be explained well by means of the pseudo-second-order and intraparticle diffusion models. The pH experiments showed that maximum adsorption occurred at pH 4. Additionally, all adsorbents had a strong adsorption ability to SMX and the Langmuir maximum capacity followed the order: 5% Ag-FMWCNTs (118.58 mg g⁻¹) > 3% Ag-FMWCNTs (86.41 mg g⁻¹) > MWCNTs (73.69 mg g⁻¹) > 1% Ag-FMWCNTs (70.26 mg g⁻¹) > FMWCNTs (45.13 mg g⁻¹). The spent adsorbents were regenerated in methanol. It was also found that after regenerating four times, multi-walled carbon composites retained up to 80% of their original adsorption performance. Therefore, the Ag-FMWCNTs composite could be used as a potential adsorbent for removing sulfamethoxazole from water.