Preferential and Enhanced Adsorption of Different Dyes on Iron Oxide Nanoparticles: A Comparative Study

The iron oxide nanoparticles, having an average size of 20−40 nm with a surface area of ∼70 m 2 g −1, have been synthesized and used for selective adsorption of various dyes (selectively containing hydroxyl groups) from aqueous solution. The nanoparticles are ferromagnetic in nature at both room and low temperature and can be separated by an external magnetic field. Herein, we report a preferable and enhanced adsorption phenomena of the dyes containing hydroxyl (−OH) groups on iron oxide nanoparticles. The group of erichrome black-T, bromophenol blue, bromocresol green, and fluorescein was adsorbed more on the iron oxide surface as compared to methyl red, methylene blue, and methyl orange, which does not have any hydroxyl (−OH) groups. The association−OH of the dye in preferential adsorption phenomena has also been supported with FT-IR analysis. The adsorption process was studied by varying different regulating parameters like solution pH, initial dye, and iron oxide concentration and analyzed in terms of kinetic and isotherm models. Moreover, the adsorbed dyes could be desorbed completely from nanoparticle surfaces at higher pH and efficient for multicyclic use.