Effective removal of As (III) from drinking water samples by chitosan-coated magnetic nanoparticles

Abstract

Chitosan-coated Fe3O4 nanoparticles were developed with the purpose of removing arsenic from aqueous solution. Chitosan was first carboxymethylated and then covalently bounded on the surface of Fe3O4 nanoparticles via carbodiimide activation. The grafted chitosan on the Fe3O4 nanoparticles contributed to the enhancement of the adsorption capacity, because of the strong ability of chitosan’s multiple hydroxyl and amino groups to adsorb arsenic. The prepared magnetic adsorbent was characterized by Transmission electron microscopy (TEM), vibrating sample magnetometer, and Fourier transform infrared. The characterization results showed that chitosan is grafted onto Fe3O4 nanoparticles. TEM micrographs showed that the chitosan-coated Fe3O4 nanoparticles were monodispersed and had a mean diameter lower than 10 nm. The chitosan-coated Fe3O4 nanoparticles exhibit superparamagnetic properties at room temperature and saturation magnetization equaled 50 μg−1. To achieve the highest efficiency in absorption experiments, the effect of some influential parameters on the arsenic removal such as pH, dosage of adsorbent, and contact time were evaluated. The adsorption data obeyed the Langmuir equation with a maximum adsorption capacity of 10.5 mg g−1 for arsenic (III) at pH 9 and at room temperature. This material can be used for arsenic adsorption from water and wastewater, and can be easily separated by applied magnetic field. This nanoadsorbent can reduce arsenic concentration to under the allowed limit declared by the World Health Organization.