Synthesis Of Iron Oxides Nanoparticles And Nanocomposites For Water Treatment

With the development of industry, water pollution has been becoming a seriousbut still challenging problem. Iron oxides nanoparticles and nanocomposites havebeen playing an important role in water treatment though many methods, such asadsorption, chemical degradation, photodegradation and electrochemical technologies,etc. Furthermore, iron oxide nanomaterials have been widely used for the treatment ofmetal ions wastewater and dyes wastewater, because they are inexpensive, stable,eco-friendly and possibly magnetic separable. Here, several kinds of iron oxidenanomaterials including nanoparticles and nanocomposites have been prepared foradsorptive and photocatalytic applications in water treatment.Firstly, the iron oxide nanoparticles had been successfully synthesized via anadditive-free hydrolysis process at75oC for12h. The product was characterized byX-ray diffraction (XRD), transmission electron microscopy (TEM), and N2adsorption-desorption. The results of XRD and N2adsorption-desorptiondemonstrated that the as-prepared product was mainly α-Fe2O3with a large surfacearea of164.1m2g-1. The TEM images illustrated that the as-prepared product wasfound to consist of a mixture of irregular spherical nanoparticles (a diameter of~50nm) and nanowhiskers (a diameter of~50nm and uneven length). The as-preparedproduct was used to investigate its promising adsorptive applications in watertreatment. Due to its small size and large surface area, the maximum adsorptioncapacities of Congo red and Cr(VI) have been determined using the Langmuirequation and found to reach up to253.8and17.0mg g-1, respectively. The facilesynthesis method and the superior adsorption performance derived from the ironoxide nanoparticles display the potential applications for the removal of Congo redand Cr(VI) from aqueous solution.Secondly, mall-sized α-Fe2O3nanoparticles deposited Ca-bentonite(α-Fe2O3/bentonite) had been successfully synthesized though an additive-free adsorption-hydrolysis-calcination method from the Fe3+model wastewater. Theproducts were characterized by X-ray diffraction (XRD) and transmission electronmicroscopy (TEM). The results of XRD and TEM illustrated that the as-preparednanocomposites were found to be rod-like or irregular spherical α-Fe2O3nanoparticles evenly dispersed on the surfaces of bentonite. The as-prepared productswere used to investigate their promising adsorptive and photocatalytic applications inwater treatment. According to the Langmuir equation, the maximum adsorptioncapacity of the α-Fe2O3/bentonite nanocomposite for CR has been calculated to be96.9mg g-1. Further more, the α-Fe2O3/bentonite nanocomposite also showed anexcellent photocatalytic property in the photocatalytic degradation of methyl orange(MO). This facile and novel synthesis method has the potential to be applied toprepare the low-cost α-Fe2O3/bentonite nanocomposite from the Fe3+ionscontaminated water for the removal of CR and MO.Lastly, the magnetic separable iron oxide/C nanocomposites have been preparedwith the two-phase hydrothermal-calcination method. The products werecharacterized by X-ray diffraction (XRD) and transmission electron microscopy(TEM). The results of XRD and TEM illustrated that the as-prepared nanocompositeswere quasi-spherical Fe3O4or γ-Fe2O3nanoparticles (~20nm) evenly dispersed on thesurfaces of carbon membranes. The as-prepared products were used to investigatetheir promising adsorptive applications in CR removal. According to the Langmuirequation, the maximum adsorption capacities of the Fe3O4/C nanocomposite and theγ-Fe2O3/C nanocomposite for CR were calculated to be48.1and105.3mg g-1,respectively. This novel synthesis method has the potential to prepare magneticseparable iron oxide/C nanocomposites for the removal of CR from aqueous solution.