Optimization of synthesis parameters of iron oxide nanoparticles prepared by reverse microemulsion method

Iron oxide-hydroxide nanoparticles have been prepared by a microemulsion route using n-heptane as oil phase, di-n-dodecyldimethylammonium bromide (DDAB) as double-tailed cationic surfactant, polyoxyethylene(23)lauryl ether (Brij 35) as nonionic surfactant and ammonia (NH3) solution as precipitant. Inside micelles, the chemical reaction of Fe precursor (ferric nitrate) and NH3 resulted in formation of precipitate (Fe(OH)3) which was centrifuged, washed with acetone and highly pure water, dried and calcined. Properties such as specific surface area (SBET) and average pore size (ap) were determined [1]. In this research, in order to evaluation of the influence of parameters, determination of the effective parameter and finally, optimization of synthesis conditions, response surface methodology (RSM) was applied. It was found that the surfactant concentration was the most influencing parameter on the surface area and pore size. The best conditions in terms of higher surface area and smaller pore size was obtained when the water to surfactant ratio of 21.49 and surfactant concentration of 0.19 M were employed. In these conditions, the smallest droplets and the highest number and concentration of droplet were obtained. This explanation was proved by small-angle neutron scattering (SANS) [2].