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

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 (K-d) 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)-O-center dot) 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. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

The study demonstrates that the use of magnetic waste iron slag composite as a catalyst enhances the heterogeneous catalytic Fenton of Rhodamine B. The enriched Fe content in MIS-10 significantly improves the catalytic efficiency of RhB degradation and oxidation under optimal conditions. MIS-10 exhibits high stability and promising catalytic activity for the oxidation of persistent organic compounds in wastewater.