Investigation the effect of magnetite iron oxide nanoparticles on adsorption of nickel and cadmium by Azolla filiculoides from aqueous solution and its growth characteristics

In this study, the role of magnetic iron oxide nanoparticles (Fe3O4 NPs) synthesized using three methods of co-precipitation, conventional heating and microwave heating on the growth rate of Azolla filiculoides in aqueous solution was studied. In addition, effect of different iron oxide NPs on adsorption of Cd2+ and Ni2+ by Azolla was investigated. According to the results compared to control, the least growth rate of Azolla during 10 days was observed in the presence of the NPs synthesized using microwave method which majority of its particles were smaller than 10nm in diameter. Increasing concentration of NPs from 1000 to 2000ppm significantly reduced the Azolla growth. Presence of NPs changed the Azolla growth profile at 10 and 50°C, viz. the least growth of Azolla in presence and absence of NPs were observed at 50°C and 10 °C, respectively. In addition, iron oxide NPs resulted in higher removal of Cd2+ and Ni2+ by Azolla, which was fitted to the first order kinetic model despite of reducing Azolla growth.