Development of zerovalent iron and titania (Fe0/TiO2) composite for oxidative degradation of dichlorophene in aqueous solution: synergistic role of peroxymonosulfate (HSO5−)

Binary composite of zerovalent iron and titanium dioxide (Fe⁰/TiO₂) was synthesized for the catalytic removal of dichlorophene (DCP) in the presence of peroxymonosulfate (PMS). The as-prepared composite (Fe⁰/TiO₂) exhibits synergistic effect and enhanced properties like improved catalytic activity of catalyst and greater magnetic property for facile recycling of catalyst. The results showed that without addition of PMS at reaction time of 50 min, the percent degradation of DCP by TiO₂, Fe⁰, and Fe⁰/TiO₂ was just 5%, 11%, and 12%, respectively. However, with the addition of 0.8 mM PMS, at 10 min of reaction time, the catalytic degradation performance of Fe⁰, TiO₂, and Fe⁰/TiO₂ was significantly improved to 82%, 18%, and 88%, respectively. The as-prepared catalyst was fully characterized to evaluate its structure, chemical states, and morphology. Scanning electron microscopy results showed that in composite TiO₂ causes dispersion of agglomerated iron particles which enhances porosity and surface area of the composites and X-ray diffraction (XRD), energy dispersive X-ray (EDX), and Fourier-transform infrared (FTIR) results revealed successful incorporation of Fe⁰, and oxides of Fe and TiO₂ in the composite. The adsorption–desorption analysis verifies that the surface area of Fe⁰/TiO₂ is significantly larger than bare Fe⁰ and TiO₂. Moreover, the surface area, particle size, and crystal size of Fe⁰/TiO₂ was surface area = 85 m² g⁻¹, particle size = 0.35 μm, and crystal size = 0.16 nm as compared to TiO₂ alone (surface area = 22 m² g⁻¹, particle size = 4.25 μm, and crystal size = 25.4 nm) and Fe⁰ alone (surface area = 65 m² g⁻¹, particle size = 0.9 μm, and crystal size = 7.87 nm). The as-synthesized material showed excellent degradation performance in synthesized wastewater as well. The degradation products and their toxicities were evaluated and the resulted degradation mechanism was proposed accordingly. The toxicity values decreased in order of DP1 > DP5 > DP2 > DP3 > DP4 and the LC₅₀ values toward fish for 96-h duration decreased from 0.531 to 67.2. This suggests that the proposed technology is an excellent option for the treatment of antibiotic containing wastewater.