In the present study, phosphotungstic acid decorated on magnetic amine-grafted graphene oxide (GO-Amine/Fe3O4/H3PW12O40; GOA/Fe3O4/HPW) was prepared and evaluated as a new adsorbent for removal and separation of organic dyes from water. The obtained nanocomposite was fully characterized by means of XRD, FT-IR, Raman, VSM, SEM, EDX, AFM and BET surface area analysis. The results demonstrated the successful loading of HPW (similar to 34 wt.%) on the surface of magnetic aminosilanized graphene oxide. The adsorption ability of the nanocomposite was tested towards cationic methylene blue (MB) and anionic methyl orange (MO) dyes. The nanocomposite exhibited very good adsorption performance for cationic organic pollutants; it could absorb approximately 100% of methylene blue (MB) from an aqueous solution within only 5 min. The removal rate of GOA/Fe3O4/HPW nanocomposite was greater than that of pure GOA, Fe3O4 and HPW. Further study revealed that the GOA/Fe3O4/HPW exhibited a fast adsorption rate and selective adsorption ability towards the cationic dyes from dyes mixtures. The effect of adsorbent dosage, initial concentration of dye and pH were studied in detail. Due to the existence of the Fe3O4, the GOA/Fe3O4/HPW nanocomposite could be magnetically separated from the reaction mixture and reused without any change in structure. This research could provide a new easy platform for wastewater purification.
