Ultra-small Ni@NiFe₂O₄/TiO₂ magnetic nanocomposites activated peroxymonosulphate for solar light-driven photocatalytic mineralization of Simazine

In the heterogeneous photocatalytic degradation of environmental contaminants the recovery, reuse of employed nanocatalyst was crucial and it is essentially required for the scale up applications. Besides, designing a magnetic material with heterojunction that can effectively oxidize the toxic organic contaminants to non-toxic substance under different reaction conditions including direct solar light irradiation remains a challenge. Considering the above facts, herein, we tailored heterojunction between the magnetic materials and non-magnetic materials with ultra-small Ni nanoparticles modified NiFe₂O₄/TiO₂ nanostructures (Ni@NiFe₂O₄/TiO₂ magnetic nanocomposites) through a simple sonochemical route. The Raman phonons at ∼ 540 cm⁻¹ consistent to nickel metal nanoparticles and the spinel ferrites crystal structure confirmed the formation of Ni@NiFe₂O₄/TiO₂ magnetic nanocomposites. The reduced optical bandgap of the resulting nanocomposites indicated the effective absorption of direct solar light irradiation when compared to the bare TiO₂. Thus in-turn, enhanced the photocatalytic efficiency of simazine degradation in the presence of Ni@NiFe₂O₄/TiO₂ magnetic nanocomposites (k´= 11.0 × 10^–4 s⁻¹) and augmented the activation of peroxymonosulphate (PMS) in the presence of Ni@NiFe₂O₄/TiO₂ magnetic nanocomposites (k´= 32.5 × 10^–4 s⁻¹). Ni@NiFe₂O₄/TiO₂ +PMS exhibited 3 folds enhanced efficiency in the presence of sunlight. The as-prepared NiFe₂O₄/TiO₂ magnetic nanocatalysts were more stable and the efficiency of simazine oxidation was approximately same for the continuous five cycles at the optimized experimental conditions. The Ni@NiFe₂O₄/TiO₂ magnetic nanocomposites preparation and the activation of PMS may promise the applications in an efficient wastewater treatment.