Adsorption and photodegrading of Methylene Blue by using of BaLaxGdxFe12-2xO19 (x=0.2, 0.4, 0.6 and 0.8)/PANI nanocomposites

Abstract

In this paper, a series of BaLa­_xGd_xFe_12-2xO₁₉ (x=0.2, 0.4, 0.6 and 0.8)/PANI (polyaniline) nanocomposites synthesized for investigating the photocatalytic properties. Barium hexaferrite doped with La³⁺ and Gd³⁺ prepared via a sol-gel auto-combustion method and then the binary nanocomposites fabricated by the in situ polymerization method. (Fourier transform infrared) FTIR, (x-ray diffraction) XRD, (field emission electron microscopy) FESEM and (vibrating sample magnetometer) VSM confirmed the formation of binary nanocomposites. In FTIR analysis, the peaks at 431 and 580 cm^-1 wavenumbers supported the formation of barium doped hexaferrite. At 1463 and 1554cm^-1 wavenumbers, the formations of quinoid and benzenoid rings were observable. The XRD patterns of nanocomposites proved the formation of PANI by appearing the amorphous peak at 2θ=23.05 and 26.05 degrees beside the hexaferrite phase. In FESEM pictures, the sphere shape of PANI masked the whole nanoparticles of hexaferrite. In VSM hysteresis loops, by doping La³⁺, the saturation magnetization increased to 74 emu. Then, by adding non-magnetic part (PANI) to the magnetic hexaferrite, the saturation magnetization decreased to 11 emu. The photocatalytic properties of samples performed under the irradiation of UV-Vis light. All samples presented the photocatalytic properties. Hexaferrites as a semiconductor generated the electron-hole pairs under irradiation. PANI prevented the accumulation of electron-hole pairs on the valance band and consequently accelerated the photo-degradation of methylene blue. Kinetic studies and calculation of the correlation coefficient (R²) value which was about 0.98, proved that the photocatalytic reactions followed the Pseudo-first order kinetic.