Improving Fenton-like oxidation of Rhodamin B using a new catalyst based on magnetic/iron-containing waste slag composite

Abstract

Heterogeneous catalytic Fenton of Rhodamine B (RhB) was enhanced by magnetic waste iron slag composite (MIS) as a novel catalyst. The MIS was successfully enriched by an increase in mass rate of Fe element from 26.60% (in iron slag-IS) to 50.68% (in MIS-10). Besides, the textural properties of MIS-10 were remarkably improved in porous structure and BET specific surface area compared with IS. An almost complete degradation of RhB was obtained at the composite ratio between mixture of (Fe2+ and Fe3+) and IS of 10% (w/w), solution pH of 3, H2O2 of 1680 mg/L and catalyst dosage of 4000 mg/L for both IS/H2O2 and MIS-10/H2O2 systems within 120 min reaction time At this optimal operational condition, the decolorization and mineralization of RhB, respectively, reached 71.84% and 59.75% for IS/H2O2 system and 98.48% and 83.33% for MIS-10/H2O2 system. The first-order reaction rate constant (Kd) values of the pseudo-first-order kinetic followed the same sequence as COD removal. The Fe amount enriched in MIS-10’s constituent was proved the improving considerably reaction rate with H2O2 to generate continuously more hydroxyl (.OH) radicals which led to higher oxidation of RhB by MIS-10/H2O2 compared with IS/H2O2. The mechanisms of RhB enhanced degradation included adsorption, leaching iron through homogeneous Fenton reactions and heterogeneous Fenton reaction. The main mechanism of RhB oxidation by MIS-10/H2O2 system was through .OH which was produced by heterogeneous Fenton reaction due to the contribution of Fe elements enriched on the catalyst’s surface. The MIS-10 exhibited a high stability with very low iron leaching and maintained a high catalytic activity after 5 successive cycles, indicating MIS-10 is fully promising catalyst for Fenton oxidation of persistent organic compound from wastewater.