High-performance pure and Fe3+-ion doped ZnS quantum dots as green nanophotocatalysts for the removal of malachite green under UV-light irradiation

Highlights: ► Synthesis of ultra-small ZnS and ZnS:Fe QDs in aqueous media. ► Characterization of QDs by TEM, XRD, FAAS and UV–vis absorption techniques. ► The new report on the photocatalytic behavior of QDs on removal of MG. ► Effective degrade of dye by novel modified QDs up to 98%. -- Abstract: The heterogeneous photocatalysis using UV-radiation and quantum dots (QDs) is an interesting method for the treatment of water polluted with the organic substances. In this study, ZnS QDs, as a pure and doped with Fe3+, were prepared for photodecolorization of malachite green (MG) as a model dye. The synthesis of QDs was carried out using a chemical precipitation method in aqueous solution, in the presence of 2-mercaptoethanol as a capping agent. The XRD patterns indicated that the doped nanoparticles are crystalline, with cubic zinc blend structure. The effects of dopant content, pH, nanophotocatalyst amount, irradiation time, and initial dye concentration on the removal efficiency of MG were studied. Results showed that the QDs presented high MG decolorization efficiency, and doping with Fe3+ promoted the dye removal. The maximum removal of dyes was obtained at 80 mg/L of photocatalyst as an optimum value for the dosage of photocatalyst in pH of 8.0