Synthesis of iron-based nanoparticles and comparison of their catalytic activity for degradation of phenolic waste water in a small-scale batch reactor

In the present work, iron-based nanoparticles were synthesized by sol-gel method (iron oxide I), modified co-precipitation method (iron oxide II), reduction of FeSO4 by NaBH4 (nano zero-valent iron I, nZVI I), and reduction of FeSO4 by NaBH4 in presence of chelating ligand EDTA (nZVI II) for use as a catalyst for degradation of phenol. Particle characterization was performed for each set of samples by UV-vis spectra, X-ray diffraction, Fourier transformed infrared spectroscopy(FTIR), dynamic light scattering (DLS), and field emission scanning electron microscopy (FESEM). FESEM was performed with iron oxide II and particle size was found to be 36.5nm. The average particle diameter obtained for nZVI was in the range of 141-150nm. nZVI(II) has been found to be most efficient with respect to high percentage degradation of phenol in an hour under optimum operating condition at room temperature which were as follows: catalyst concentration=0.05g/l, pH 3, phenol:hydrogen peroxide (50%) concentration=1:14 (stoichiometric ratio), temperature=ambient. Brunauer-Emmett-Teller (BET) surface area measurement also showed higher surface area for nano zero-valent iron (nZVI) particles than compared to other iron oxides. The initial phenol concentration was varied in the range of 50-400mg/l. Degradation efficiency was found decreasing with increasing initial concentration of phenol. Iron oxide I and II can be successfully recovered and reused.