Abstract
Iron oxide nanoparticles were synthesized by co-precipitation using three different iron salt stoichiometric mole ratios. Powder X-ray diffraction patterns revealed the inverse cubic spinel structure of magnetite iron oxide. Transmission electron microscopic images showed Fe(3)O(4) nanoparticles with different shapes and average particle sizes of 5.48 nm for Fe(3)O(4)-1:2, 6.02 nm for Fe(3)O(4)-1.5:2, and 6.98 nm for Fe(3)O(4)-2:3 with an energy bandgap of 3.27 to 3.53 eV. The as-prepared Fe(3)O(4) nanoparticles were used as photocatalysts to degrade brilliant green (BG), rhodamine B (RhB), indigo carmine (IC), and methyl red (MR) under visible light irradiation. The photocatalytic degradation efficiency of 80.4% was obtained from Fe(3)O(4)-1:2 for brilliant green, 61.5% from Fe(3)O(4)-1.5:2 for rhodamine B, and 77.9% and 73.9% from Fe(3)O(4)-2:3 for both indigo carmine and methyl red. This indicates that Fe(3)O(4)-2:3 is more efficient in the degradation of more than one dye. This study shows that brilliant green degrades most effectively at pH 9, rhodamine B degrades best at pH 6.5, and indigo carmine and methyl red degrade most efficiently at pH 3. Recyclability experiments showed that the Fe(3)O(4) photocatalysts can be recycled four times and are photostable.