Catalytic activities of the vaterite and the calcite based solid supported catalysts for spontaneous Fenton-like dye degradation: A comparative study

Abstract

Advanced oxidation processes (AOPs) have been adopted to address the increasing threat of wastewater discharge from industries. In this work, we have tried to improve the performance of magnetite (Fe3O4) nanoparticles as catalysts in Fenton-like processes for dye-degradation. In vitro biomineralized vaterite was used as solid support for Fe3O4 nanoparticles, and the resulting composite was utilized as a heterogeneous catalyst for the degradation of toxic organic dyes, Methylene Blue (MB) and Rhodamine B (RhB). Vaterite supported Fe3O4 enhance ~ 36% and ~30% degradation of MB and RhB in comparison to bare Fe3O4. As a comparison, the calcite phase of CaCO3, was also used as a support for Fe3O4 and the composite when used as a catalyst resulted in 81% and 73% degradation of MB and RhB. The comparative studies revealed that the use of solid supports had improved the catalytic activity of the material. The biomineralized vaterite microspheres behaved as a better support and therefore, high rate constants of 3.15 × 10−2 min−1 and 1.82 × 10−2 min−1, were observed for the degradation of MB and RhB, respectively. Further, the magnetic nature of the catalyst makes it a great prospect towards reusability and catalytic efficiency was retained even after five consecutive cycles. Also, the versatility of the catalyst was proven by its ability to perform in natural water sources; lake water and river water.