Sonocatalytic dye degradation using CaF2 nanoparticles produced from eggshells

This study investigates the sonocatalytic activity of calcium fluoride nanoparticles for methylene blue dye degradation. CaF₂ NPs were prepared by first calcining calcium carbonate extracted from eggshells to produce calcium oxide, afterwards reacted with hydrofluoric acid at room temperature. The average crystallite size of the nanoparticles synthesized via co-precipitation method found to be ∼ 32 nm. The sonocatalytic process achieved a degradation of 76 % over 180 min, having rate constant (k) of 8.2 × 10^-3 min⁻¹.Parametric study was conducted to study the effect of dye concentration, catalyst dosage and solution volume. It was found that varying catalytic dosage had a significant impact on dye degradation, with efficiency increasing from 61 % to 92 % with increase in the rate constant from 5.1 × 10^-3 min⁻¹ and 14.7 × 10^-3 min⁻¹. To further evaluate the catalytic performance of CaF₂ NPs, photocatalysis and sono-photocatalysis experiments were conducted, revealing degradation efficiencies of 38 % and 95 %, respectively.