Modified Magnetite Nanoparticles for Hexavalent Chromium Removal from Water

Abstract

Water treatment is an important concern of human societies. Using magnetic nanoparticles as adsorbents for metal removal has been greatly considered due to their particular characteristics such as small sizes, high surface area to volume ratios, and good magnetic properties. In the present study, a modification was implemented in magnetite particles by functionalized carbon nanotubes and carboxylic groups to enhance the performance of magnetite particles in removing hexavalent chromium from water using the adsorption method. The applicability of the nanoadsorbent and magnetic nanoparticles was compared based on adsorption factors affecting the chromium removal including pH, contact time, pollutant concentration, and the adsorbent amount. Properties of the nanocomposites were analyzed by transmission electron microscopy (TEM) and X-ray diffraction (XRD). The results show that the highest percentage of Cr (VI) removal for both adsorbents was under acidic ambient conditions and lasted less than 45 minutes. The study of Langmuir, Freundlich, and Temkin isotherms in the prediction of adsorption behavior revealed that the Langmuir model better fitted the adsorption equilibrium data. The kinetic analysis of pseudo-first and second-order equations showed that the pseudo-second-order equation was more suitable for describing the kinetic behavior of data. Moreover, the obtained nanocomposite had a better performance in Cr (VI) removal from water in comparison to magnetite nanoparticles.

GRAPHICAL ABSTRACT

Keywords:

• Adsorption
• carbon nanotubes
• hexavalent chromium
• magnetite nanoparticles