Quantum dot based photocatalytic decolorization as an efficient and green strategy for the removal of anionic dye

In this study, zinc sulfide (ZnS) quantum dots (QDs), as a pure and iron doped were synthesized using a chemical precipitation method in aqueous solution, in the presence of 2-hydroxyethanthiol as a capping agent. Optical and structural properties of the pure and Fe3+ ion doped (i.e. Zn(1−x)FexS) QDs were investigated by various techniques including X-ray diffraction (XRD), transmission electron microscopy (TEM), and UV–vis absorption spectroscopy. In addition, the prepared ZnS QDs, as pure and doped with various mole fractions of Fe3+ ion were used for photodecolorization of thymol blue (TB) as an anionic and pollutant dye, under UV light irradiation. In photodecolorization studies, the effect of main experimental parameters on the decolorization efficiency (DE) of QDs as green nano-semiconductors were studied and optimized. The results indicated that DE is affected by some parameters such as dopant mole fraction; the pH of initial dye solution, nanophotocatalyst amount, irradiation time, and initial dye concentration. The maximum decolorization efficiency of 100% and 99.88% was obtained at pH 9.5 of dye solution for 10 ppm of TB dye, in the presence of 10 mg of undoped and doped (for 5% of Fe3+) ZnS QDs, respectively.