Magnetic nanoparticles decorated with synthetic zeolite derived from coal fly ash: Application to removal of heavy metals and organic dyes

Abstract:

Fly ash, a coal combustion by-product, can be converted into zeolites with enhanced adsorption capacity for removing toxic pollutants. This study modified fly ash-derived zeolites with amino propyl imidazole, creating imidazolium-based zeolites for loading Fe₃O₄ NPs. The resulting magnetic film (Fe₃O₄ NPs@zeolite) showed an excellent adsorption of heavy metals and dyes, making it effective for detoxifying industrial wastewater.

Introduction:

Chromium and selenium contamination from industrial and geological sources causes severe health and ecological problems. Chromium, found in wastewater, and selenium, emitted from geothermal and volcanic activities, pose risks such as hair loss and kidney damage. Synthetic zeolites, modified with imidazolium-based ionic liquids and magnetic nanoparticles, offer a promising solution for removing these contaminants from water, providing effective and sustainable water treatment options.

Methods:

NaX-UP zeolites were synthesized from fly ash by mixing with NaOH and heating, followed by sodium aluminate addition and stirring. The product was washed, dried, and modified with 1-(3-aminopropyl) imidazole to form IL-NaX-UP zeolites. Fe₃O₄ NPs were then synthesized on these zeolites, resulting in a magnetic thin film.

Results:

The as-fabricated magnetic films exhibited excellent functionality and durability in the adsorption of Cr(VI), Se(IV), Congo Red, and RhB [1]. The magnetic films are very suitable for practical applications as they can achieve maximum removal performance over a wide pH range. According to the pseudo-second-order kinetic model, the magnetic films have fast adsorption kinetics compared to earlier evidence from the literature.

Conclusion:

The resulting magnetic films, incorporating PSS, PVA, and chitosan, demonstrated an excellent adsorption of Cr(VI), Se(IV), Congo Red, and RhB, and were effective in treating water, creating drinkable water by meeting WHO and EPA standards.