A study of the DR23 dye photocatalytic degradation utilizing a magnetic hybrid nanocomposite of MIL-53(Fe)/CoFe2O4: Facile synthesis and kinetic investigations

Abstract

In this research, cobalt ferrite (CoFe2O4) magnetic nanoparticles as well as MIL-53(Fe) structure were synthesized by the hydrothermal and solvothermal methods, respectively. Moreover, magnetic composites of MIL-53(Fe)/CoFe2O4 nanoparticles with different cobalt ferrite loadings (i.e.; 0.05, 0.1 and 0.2 g) were prepared via the solvothermal method. The main novelty of the present research was to synthesize a magnetic composite of MIL-53(Fe)/CoFe2O4 nanoparticles in order to perform rapid photodegradation of Direct Red 23 (DR23) dye under the LED visible light irradiation. Good magnetic properties of the fabricated composite led to easy separation and rapid retrieval of the catalyst from the reaction mixture. Effects of operational variables such as the initial dye concentration, photocatalyst loading and solution pH upon the performance of synthesized materials were understudied. Characterizations of the prepared photocatalysts were performed through the XRD, SEM, TEM, EDX, FTIR, as well as VSM, DRS, BET-BJH and EIS analyses. Results of the XRD, SEM and FTIR analyses confirmed successful synthesis of CoFe2O4, MIL-53(Fe) and their magnetic composites. Moreover, the desired magnetic value of 28.5 emu/g at 8128 Oe was determined for the MIL-53(Fe)/0.1gCoFe2O4 material. Furthermore, the highest light absorption intensity by this composite was obtained through the UV–Visible DRS analysis. In addition, the value of optical bandgap energy (Eg) for the aforementioned composite was determined to be 2.1 eV. Furthermore, the BET surface areas of the MIL-53(Fe), MIL-53(Fe)/0.1gCoFe2O4 and CoFe2O4 species were evaluated to be 13, 34 and 52 m2/g, respectively. Finally, the photocatalytic degradation of the DR23 over the MIL-53(Fe)/0.1gCoFe2O4 was revealed to be 99.35% after 80 min of duration under the LED irradiations. This was higher than the rest of other understudied materials. In addition, results displayed that, the hydroxyl radicals (OH) as well as photo-generated holes (h+) were the main active species in photocatalytic degradation process undertaken. Ultimately, sufficient yet simple rate law models of the aforementioned dye degradation implementing first- and second-order chemical kinetics upon the prepared catalysts were developed.