Mesoporous iron oxide nano spheres for capturing organic dyes from water sources

Abstract

Over the last few years mesoporous iron oxide nanosphere and related products have received disproportionate interest. Nano sphere with highly ordered mesoporous iron oxide (α-Fe2O3) was successfully synthesized. The chemical composition and crystal structure of the mesopoures iron oxide nano spheres (MINs) were confirmed by X–ray diffraction and Fourier transform infrared measurements. The surface morphology and spherical mesostructures of MINs were characterized by scanning electron microscope (SEM) and transmission electron microscopy (TEM). The morphology of the MINs in spherical form is very uniform, the average particle size of which is 23–27 nm in diameter range. The content MINs has a quite high BET surface area of 188.25 m2g−1 and a total pore volume of 0.14 cm3g−1. BJH average pore size is 3.5 nm which is beneficial for adsorption application. In order to find the optimal adsorption conditions for extracting Acid Red 57 (AR57) and Remazol Red (RR) from aqueous solutions, parameter factors like initial pH, dosage of adsorbent, contact period, and temperature were examined. For AR57 and RR respectively, the optimum pH for extracting the investigated anionic dyes from water solutions was found to be 3 and 4. The maximum predicted adsorption capacities for AR57 and RR dyes were obtained as 930.16 and 896.87 mgg−1, respectively. The adsorption equilibrium also showed that for both AR57 and RR, the Langmuir equation provided the best fit of the experimental data compared with the other models. The mean values of adsorption energy (Ea) are 18.23 and 22.95 kJmol−1 for AR57 and RR, respectively, suggesting a chemisorption process. The adsorption kinetics was found to obey the kinetic model of the pseudo-second order. The adsorption process was verified to be endothermic and spontaneous by thermodynamic studies. The method of desorption of the adsorbed anionic dyes was also studied using ethanol as the solvent.