Chromium VI adsorption on cerium oxide nanoparticles and morphology changes during the process

Area of Science:

• Environmental Science
• Materials Science
• Nanotechnology

Background:

• Hexavalent chromium (Cr VI) is a highly toxic heavy metal pollutant.
• Effective and sustainable methods for Cr VI removal from water are crucial.

Purpose of the Study:

• To investigate the use of cerium oxide nanoparticles for Cr VI removal.
• To evaluate the adsorption efficiency, kinetics, and reusability of the nanoparticles.
• To assess the toxicity of the treated water.

Main Methods:

• Suspended cerium oxide nanoparticles stabilized with hexamethylenetetramine were used as adsorbents.
• Adsorption experiments were conducted with varying concentrations of adsorbent and adsorbate.
• Adsorption equilibrium and kinetics were modeled using Freundlich isotherm and pseudo-second-order expressions, respectively.
• Transmission Electron Microscopy (TEM) was used to observe nanoparticle morphology.
• Microtox® assay was employed to measure water toxicity.

Main Results:

• Freundlich isotherm and pseudo-second-order kinetics accurately described the adsorption process.
• Efficient separation and desorption of chromium were achieved using sodium hydroxide, with no loss of cerium.
• TEM revealed nanoparticle agglomeration and morphological changes post-treatment.
• Treated water exhibited low toxicity, as indicated by the Microtox® assay.

Conclusions:

• Cerium oxide nanoparticles offer a promising solution for Cr VI removal from contaminated water.
• The developed method is efficient, reusable, and environmentally safe.
• This technology can be applied to drinking water purification and wastewater reuse.