Iron oxide nanoparticles obtained from steel waste recycling as a green alternative for Congo red dye fast adsorption

Iron oxides can be applied as adsorbents to remove harmful substances from the water used in the textile process. If these oxides can be synthetized through acid digestion of ferrous metal compounds, they can create a cycle of pollutants control from pollutant materials. In this study, two iron oxides were synthetized from steel waste, through razor blades (RB) and bottle caps (BC) acid digestion followed by coprecipitation, for application as Congo red dye adsorbent. Studies about the structure, composition and materials' properties were obtained through x-ray fluorescence, x-ray diffractometry, x-ray absorption, Fourier transform infrared spectroscopy, Raman spectroscopy, thermogravimetric analysis, UV-Vis electronic spectroscopy, nanoparticle tracking analysis, zeta potential and Brunauer, Emmett, Teller method. The structural and composition analysis showed a mixture of iron oxide phases and nanometric average particle sizes. The oxides presented maximum adsorption capacity (q(max)) of 418.41 mg.g(-1) for IO-RB, and 104.17 mg.g(-1) to IO-BC, at mom temperature. Furthermore, the particles present magnetic properties from the produced iron oxide that facilitates their removal from the system, after application. The adsorbents were characterized after adsorption through the same initial techniques; thus, the produced compounds and the adsorption capacity of each oxide were correlated.