Photocatalytic degradation of Acid blue 113 dye by montmorillonite/copper ferrite nanocomposite: Characterization, optimization, and toxicity assessment

The MMT/CuFe₂O₄ nanocomposite, prepared based on loading spinel ferrite copper (CuFe₂O₄) nanoparticles onto montmorillonite (MMT), was selected as a catalyst for removing acid blue 113 dye (AB113) in the system operated in the presence of UV and visible light. Response Surface Methodology (RSM) served as the tool for optimizing the considered parameters, and maximum efficiency of 99.2 % was obtained. Generating superoxide (^•O₂^-) radical, hydroxyls (^•OH), holes (h⁺), and electrons (e^-) during the studied process was confirmed based on trapping experiments. The dye degradation efficiency, after the five consecutive reaction cycles, had only a low decrease (<6 %). In the MMT-CuFe₂O₄/Visible system, the degradation of AB113 was significantly impeded by anions like Cl^-, NO₃^-, HCO₃^-, and SO₄^2-. The primary species in the catalytic system, as revealed by trapping experiments, is ^•OH. By conducting the experiments in the presence of Daphnia Magna for assessing the toxicity of the treated solution, a detectable reduction in the toxicity was achieved. Our results were also representative of approximately similar results for degrading dye in the presence of both UV and visible lights. The results illustrated that the BOD₅/COD (biological oxygen demand over 5 days/chemical oxygen demand) and BOD₅/TOC (Total Organic Carbon) ratios were enhanced from 0.191 to 0.764 and 0.641 to 1.47, respectively, as the irradiation period was prolonged from 10 to 120 min. The synergistic effect of CuFe₂O₄ and MMT in the nanocomposite enhances the photocatalytic degradation of Acid Blue 113 dye by generating reactive oxygen species, leading to effective dye breakdown and mineralization under light irradiation.