Removal of arsenic with functionalized multi-walled carbon nanotubes (MWCNTs-COOH) using the magnetic method (Fe3O4) from aqueous solutions

Abstract

Heavy metals such as arsenic are one of the most important water pollutants and cause many environmental problems. One of the mechanisms for removing arsenic from aqueous media is the adsorption process. In this study, we investigated the efficiency of magnetized multi-walled carbon nanotubes with iron oxide (Fe₃O₄) nanoparticles. The precipitation method was used to synthesize Fe₃O₄ on PAC-(Fe₃O₄-f/MWCNTs) functionalized multi-walled carbon nanotubes. The effects of pH, contact time, amount of adsorbent, and contaminant concentration on the adsorption process were examined. Residual arsenic concentration was measured using induction chromatography and inductively coupled plasma mass spectrometry (ICP-MS). The physical and structural characteristics of the adsorbent were analyzed using XRD, TEM, FT-IR, TGA-DTA, BET, FESEM-EDS, Raman spectrum and X-ray. Optimal conditions for arsenic removal were pH = 2, As concentration = 6 mg L⁻¹, and contact time = 30 minutes, using 0.02 g of adsorbent at room temperature. Also, fitting regression curves to the results showed that the Freundlich model (R² > 0.9981) and a pseudo-second-order model (R² = 1) best describe the isothermal and kinetic models of the adsorption process, respectively.