Síntesis y caracterización de hematita, para aplicación en la remoción de mercurio

Abstract

In this titration work, the synthesis and characterization of hematite nanoparticles (NPs- Fe2O3) for the application in Hg removal was carried out. It was identified that the controlled precipitation method is optimal for the synthesis of these NPs; it consists of three stages which are: precursor precipitation, washing and calcination. Cl3Fe*6H2O 1M was used as precursor and NaOH 6M as precipitant, 300 mL of Cl3Fe*6H2O solution was drop titrated with NaOH solution up to reaching pH 6, the reaction time was 8 hours at the boiling temperature. Subsequently, the elimination of by-products is given through several washes by centrifugation. Finally, the obtained wet solid was dried in an oven at 60 °C for 48 hours, then it was crushed in a mortar and calcined in a muffle at 500 °C for 2 hours. For the characterization, FT/IR spectroscopy was used to determine the bands from 570 to 474 cm- 1 verifying the presence of Fe2O3. UV spectroscopy determined that the NPs absorb light approximately in the band from 300 to 550 nm, with relevant peaks from 370 to 550 nm. On the other hand, Scanning Electron Microscopy allowed to observe their sizes between 30 and 45 nm. For the removal of Hg we worked with atomic absorption equipment, a stock sample of Hg at 90 ppm was prepared, then 30, 20 and 15 ppm dissolutions of 50mL were made, which were put in contact with 1g NPs in two times, 10 and 30 minutes. It is concluded that the analyzed samples achieved an adsorption of more than 80% of Hg in the samples, which allowed to evidence the feasibility of the NPs as Hg remover. It is recommended to decrease the pH to obtain smaller size NPs.