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.

Keywords:

• Arsenic removal
• Drinking water treatment
• Magnetic nanoparticle
• Chitosan

Acknowledgment

We acknowledge the nanotechnology research Institute of Shiraz University and the ministry of science and technology as providers of financial sum, facilities, contributors, etc.