چكيده به لاتين
In recent years, the waterways polluted with azo dyes caused serious environmental problems, so they must be removed. Recently, combination of photocatalysis with magnetic separation technology has been widely used for dyes removal from wastewaters. Removal of dyes by ferrites is a good choice because of their easy separation under external magnetic fields and the high surface area of ferrites.
In this thesis, four types of ferrite nanoparticles were synthesized by sol gel auto combustion method. The first group is CuFe2O4 and NiFe2O4 nanoparticles as the main group in this study. In second group, new ferrites were prepared by two cationic surfactants: sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB) and the influence of adding surfactants on the structural and catalytic properties of the nanoferrites were studied. In the third, new compounds of copper and nickel ferrites nanoparticles doped with Co and Zn cations have been prepared. The last group is related to mixture ferrites of copper and nickel. In this group, NixCu1–xFe2O4 nanoparticles (x= 0.2, 0.4, 0.5, 0.6 & 0.8) were prepared.
Powder XRD analysis and FT-IR spectroscopy confirmed the formation of ferrite spinel phase. The average crystallite size of samples was calculated using Scherrer’s equation that was in a good agreement with the experimental results. The morphology and size of the synthesized nanoparticles have been observed by scanning electron microscopy. The energy band gaps were calculated from DRS data. The magnetic property of nanoparticles was measured by AGFM. The spectral reflectance of pigment powder was determined using a NIR spectrophotometer.
Photocatalytic degradation of Direct Red 264 azo pollutants by synthesized nanoferrites in batch system were investigated under UV and visible light. Initial and final dye concentration measurements were carried out by UV-Visible spectrophotometer.
The effect of parameters such as the mass of catalyst, presence and absence of auxiliary oxidant, pollutant concentrations, radiation types and types of catalysts were investigated, in a batch system. Copper ferrite nanoparticles have better effect than nickel ferrite in photocatalytic degradation of the polutant. The synthesized catalysts have higher degradation percent in visible irradiation compared to UV irradiation.
The kinetic studies of dye degradation of DR264 were surveyed using Langmuir–Hinshelwood model and constants and correlation coefficient were calculated. Also, the isothermic studies of photocatalytic degradation of pollutants were analyzied using two parameters, three parameters and four parameters isotherms. The correlation coefficient and isotherm parameters have been achieved using isotherm equations and curve expert software. Finally, average percentage errors were calculated using ARE, HYBRID and MPSD functions and experimental data by MATLAB software.
