Design and Synthesis of Reusable Nanoparticles for Reversible Chemisorption of Hexavalent Chromium Anions from Aqueous Media and Catalysis

Abstract EN

A magnetically active nanocomposite material has been synthesized from the reaction mixture of magnetite core iron nanoparticles electrostatically coated with SiO2, hydrotalcite nanosheets ([Eu8 (OH)20 (H2O)n]4+), and decatungstophosphate anion ([α-PW10O367−]).

The resulting nanocomposite material, denoted as Fe3O4@SiO2@LEuH@PW10, is demonstrated to effectively adsorb chromate anions from aqueous solutions.

The adsorption isotherms fit the Langmuir model with a capacity of 23 mmol·g−1 after 42 minutes at 25°C.

The reaction is spontaneous at room temperature with 44.22 kJ·mol−1 of activation energy required.

In addition, heating the chromate-adsorbed nanocomposite material at 40°C results in dissociation of the chromate anions from the nanocomposite material.

As such, the recycled adsorbent Fe3O4@SiO2@LEuH@PW10 is reused for chromate removal in aqueous solutions for at least ten times without obvious loss of activity.

This spontaneous reversible chemisorption mechanism for chromate adsorption provides a new pathway for separation and cleaning of industrial wastewater contaminated with chromate ions.

The robust catalytic activity of the nanocomposite is also demonstrated.