Keggin-type heteropoly acid H۳PW۱۲O۴۰ supported on magnetic amine-grafted Graphene oxide: A new magnetically separable adsorbent for rapid and selective removal of cationic organic pollutants in aqueous solutions

In the present study, phosphotungstic acid decorated on magnetic amine-grafted graphene oxide (GO-Amine/Fe۳O۴/H۳PW۱۲O۴۰; GOA/Fe۳O۴/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 (~۳۴ 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 ۱۰۰% of methylene blue (MB) from an aqueous solution within only ۵ min. The removal rate of GOA/Fe۳O۴/HPW nanocomposite was greater than that of pure GOA, Fe۳O۴ and HPW. Further study revealed that the GOA/Fe۳O۴/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 Fe۳O۴, the GOA/Fe۳O۴/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.   

Keywords:

Aminated Graphene Oxide , Keggin-Type H۳PW۱۲O۴۰ , Magnetic Adsorbent , nanocomposite , Organic dyes , Polyoxometalate