Simultaneous Adsorptive/photocatalytic Removal of Organic Dyes and Hexavalent Chromium in Single and Binary Component Systems by Manganese Ferrite Nanoparticles

Background: As a major source of pollutant, the effluents of dye based industries are mostly associated with several toxic heavy metals. Limited efforts have been made on simultaneous removal of both dyes and heavy metals from these effluents through adsorption/ photocatalysis processes. Spinel ferrites with narrow band gap and high stability are suitable for further exploitation in this regard. Objective: Synthesis and characterisation of manganese ferrite nanoparticle and to assess its efficiency towards removal of organic dyes and hexavalent chromium in single and binary component systems are the objectives of this study. Methods: Manganese ferrite nanoparticle (MF NPs), prepared by coprecipitation, was characterised systematically by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, UV-Visible diffuse reflectance and magnetic measurement. Adsorptive and photocatalytic performances of the material under visible light were evaluated using aqueous solutions of different dyes and Cr(VI). Results: Characterisation by various techniques revealed the formation of cubic MF nanoparticles with narrow band gap (1.78 eV) and moderate saturation magnetization (38.5 emu/g). In comparison, the anionic dyes and Cr(VI) were better adsorbed on MF, while photoactivity was more pronounced in the case of cationic dye. Conclusion: MF NPs displayed potential for photo-degradation/reduction of different dyes and Cr(VI) individually or simultaneously under visible light. The catalyst can be recovered magnetically from the reaction mixture for recycling and further use.