Enhanced simulated sunlight-driven magnetic MgAl2O4-AC nanophotocatalyst for efficient degradation of organic dyes

Abstract

In this paper, with the aim of using the solar light as an unlimited and clean source of energy, novel magnetic MgAl2O4-AC nanophotocatalysts with different mass percentages of activated carbon were synthesized for water purification applications. In order to synthesize the magnetic MgAl2O4-AC nanophotocatalysts, three different methods of combustion, sono-impregnation, and sono-solvothermal were used at different stages. Different analyses such as XRD, FESEM, TEM, EDX, BET-BJH, FTIR, DRS, PL, pHpzc, and VSM were performed to evaluate the structural, chemical and optical properties of the prepared samples. For example, BET-BJH analysis results showed that bare MgAl2O4 had low specific surface area, pore volume and pore diameter that they would impede the entry and absorption of dye molecules. While MgAl2O4(90)-AC(10)(Mag) sample, due to the presence of carbon active had high specific surface area, large pore volume and pore diameter. Also, DRS analysis represented that MgAl2O4(90)-AC(10)(Mag) had narrower band gap energy compared to bare MgAl2O4. PL analysis results also revealed the decreased recombination rate of the excited electron-hole pairs in MgAl2O4(90)-AC(10)(Mag), due to the presence of activated carbon. Moreover, the prepared samples were examined in the solar-light-driven degradation of organic dyes. The tremendous enhanced photocatalytic activity under the simulated solar light with 96% removal of MB was observed over MgAl2O4(90)-AC(10)(Mag). It also degraded 80 and 70% of EY and AO7, respectively, indicating its ability to the removal of a wide range of organic dyes. Then, the effect of initial solution pH as one of the important factors on photocatalytic activity, the reusability of the best sample and its reaction kinetic were investigated. At last, MB degradation mechanism over MgAl2O4(90)-AC(10)(Mag) was proposed.