Kinetic Studies on the Catalytic Degradation of Rhodamine B by Hydrogen Peroxide: Effect of Surfactant Coated and Non-Coated Iron (III) Oxide Nanoparticles

Iron (III) oxide (Fe(3)O(4)) and sodium dodecyl sulfate (SDS) coated iron (III) oxide (SDS@Fe(3)O(4)) nanoparticles (NPs) were synthesized by the co-precipitation method for application in the catalytic degradation of Rhodamine B (RB) dye. The synthesized NPs were characterized using X-ray diffractometer (XRD), vibrating sample magnetometer (VSM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Fourier transform infra-red (FT-IR) spectroscopy techniques and tested in the removal of RB. A kinetic study on RB degradation by hydrogen peroxide (H(2)O(2)) was carried out and the influence of Fe(3)O(4) and SDS@Fe(3)O(4) magnetic NPs on the degradation rate was assessed. The activity of magnetic NPs, viz. Fe(3)O(4) and SDS@Fe(3)O(4), in the degradation of RB was spectrophotometrically studied and found effective in the removal of RB dye from water. The rate of RB degradation was found linearly dependent upon H(2)O(2) concentration and within 5.0 × 10(−2) to 4.0 × 10(−1) M H(2)O(2), the observed pseudo-first-order kinetic rates (k(obs), s(−1)) for the degradation of RB (10 mg L(−1)) at pH 3 and temperature 25 ± 2 °C were between 0.4 and 1.7 × 10(4) s(−1), while in presence of 0.1% w/v Fe(3)O(4) or SDS@Fe(3)O(4) NPs, k(obs) were between 1.3 and 2.8 × 10(4) s(−1) and between 2.6 and 4.8 × 10(4) s(−1), respectively. Furthermore, in presence of Fe(3)O(4) or SDS@Fe(3)O(4), k(obs) increased with NPs dosage and showed a peaked pH behavior with a maximum at pH 3. The magnitude of thermodynamic parameters E(a) and ΔH for RB degradation in presence of SDS@Fe(3)O(4) were 15.63 kJ mol(−1) and 13.01 kJ mol(−1), respectively, lowest among the used catalysts, confirming its effectiveness during degradation. Furthermore, SDS in the presence of Fe(3)O(4) NPs and H(2)O(2) remarkably enhanced the rate of RB degradation.