Removal and degradation of sunset yellow by Fe (ӀӀ)-modified vermiculite

This study investigates the degradation and removal of sunset yellow from simulated wastewater using oxidation and adsorption methods. A composite of vermiculite/iron oxide was synthesized via the co-precipitation method and utilized to activate peroxymonosulfate (PMO) for the degradation and removal of sunset yellow. The response surface method (RSM), based on the central composite design (CCD), was employed to optimize the effects of independent factors and their interactions on sunset yellow color removal. The maximum removal efficiency, exceeding 78.69 %, was achieved at a pH of 4, sunset yellow concentration of 30 mg/L, persulfate oxidant dose of 75 mM, vermiculite/iron oxide composite dose of 3 g/L, and a reaction time of 20 min. The removal process of sunset yellow was enhanced with increasing temperature. The presence of chloride, nitrate, and carbonate reduced the degradation efficiency of sunset yellow by reacting with the main radicals. The proposed PMO activation mechanism indicated that SO₄^•- plays a pivotal role in the degradation removal. Toxicity tests conducted with Daphnia pulex revealed that the treated effluent necessitated further catalytic treatment and improved stabilization due to the presence of Fe ions and intermediates.