Iron carbonate nanospheres were synthesized via hydrothermal treatment of aqueous solutions of iron
sulfate, ascorbic acid and ammonium carbonate with a molar ratio of 1 : 1 : 3, respectively, at 140
C for
1.5 h. Pure a-Fe2O3 nanoparticles with an average crystallite size of 10.5–32 nm were produced by
thermal decomposition of FeCO3 at 400–600
C for 2 h. The compositions of the products were
identified by means of XRD, FE-SEM, HR-TEM, FT-IR, BET, zeta potential and thermal analysis. The
adsorption properties of a-Fe2O3 were evaluated using reactive red 195 (RR195) dye. Various parameters
influencing the adsorption process were investigated, using a batch technique. The results show that a-
Fe2O3 nanoparticles show good adsorption capacity and the dye removal percentage reaches about
98.77% in 10 min. Plus, increasing the surface area of the a-Fe2O3 nanoparticles from 107.7 to 165.6 m2
g1 increases the adsorption capacity from 4.7 to 20.5 mg g1. Moreover, the adsorption data fit the
Langmuir isotherm model well and the thermodynamic parameters exhibited an endothermic and
spontaneous nature for the adsorption of RR195 dye on the hematite adsorbent.