Magnetic nanoparticles of TiO₂-NiFe₂O₄-Chitosan for photocatalytic degradation: synthesis, characterization, methyl blue dye - VOCs wastewater treatment, kinetic experimental, and theoretical studies

Photocatalytic oxidation technology is an efficient treatment method for wastewater containing organic pollutants. In this study, we developed a visible-light-driven- ternary catalyst TiO₂-NiFe₂O₄-Chitosan composite particles (TNF-P). The catalyst was synthesized using organic plant extract (Telia) to create nanoparticles through a simple, reliable, direct co-precipitation route. XRD, FT-IR, SEM, and thermal analysis techniques were used to understand the characteristics of the prepared nanomaterials. The photocatalytic ability of the nanoparticles to remove carcinogens and volatile organic compounds (VOCs) such as xylene, toluene, and methyl blue dye from aqueous environments. By irradiating the prepared catalyst with LED visible light for 120 min, we removed 95% of xylene, 99% of toluene, 90% of 1-methyl naphthalene, and 99% of methyl blue dye. The photocatalytic activities of pure NiFe₂O₄, TiO₂-NiFe₂O₄, and TiO₂-NiFe₂O₄-Chitosan composite particles (TNF-P) were investigated by monitoring the degradation of methylene blue (MB) under LED light and TNF-P was superior compared to the other prepared NP. The addition of H₂O₂ has enhanced the degradation of MB drastically up to 99% (58 g.L⁻¹) using TNF-P after 120 min. The kinetic studies revealed that the MB degradation followed the pseudo-first-order model with a rate constant (k_obs) of 6.05 × 10⁻² min⁻¹. The effect of several active species scavengers on the photocatalytic degradation process was investigated and the data shows that hydroxyl radicals are the key active species during the degradation process. The theoretical studies of TNF-P show that the diffusivity of MB within the catalyst surface decreases with increasing its initial concentration; thus, the diffusion resistance increases accordingly. While the mass transfer resistance should decrease with decreasing the initial MB concentration, it shows a slight decrease in the mass transfer coefficient. The average reaction constant value is estimated to 6.53 × 10^–2. The reaction order over the catalyst's surface illustrated a decrease with increasing initial concentration, which reduced the photocatalytic reaction rate of MB. The stability and reusability of the magnetic TNF-P can be used as a cost-effective and highly efficient treatment for various VOC wastewater pollutants using photocatalytic technology.