Determinación de la eficiencia del proceso de adsorción de mercurio utilizando óxido de grafeno reducido para efluentes contaminados.

Abstract

In the present research work, to determine the mercury adsorption efficiency, using the reduced graphene oxide, to present an alternative method for treating mercury-contaminated effluents from the gold extraction process. Through a green synthesis method of oxidation of graphite with sulfuric acid, potassium permanganate, and hydrogen peroxide, the exfoliation of graphene oxide (GO) is carried out and later, through reduction with ascorbic acid, obtain reduced graphene oxide (rOG). The characterization of the adsorbent material performed using Fourier transform infrared spectroscopy (FTIR), energy dispersed X-ray spectroscopy (EDS) and scanning electron microscopy (SEM) scanning. Batch tests performed with variations in pH and at different contact times helped to determine the Hg adsorption efficiency, the concentration of Hg in the samples determined by hydride generator (AAs) atomic absorption spectrometry. The results obtained showed that the rOG with ascorbic acid at a temperature of 85ºC and with a contact time of 30 minutes shows the decrease of oxygenated groups when observing vibration signals of the bonds C-O (1230-1250 cm-1), C=C (1590-1620 cm-1), C=O (1740-1720 cm-1), and vibrations in the 3600-3300 cm-1 region of hydroxyl and carboxyl groups. The maximum adsorption capacity of rOG against Hg was reached after 20 minutes of contact, obtaining an adsorption coefficient of 178.57 mg / g, in solutions with a pH between 6-8 and following pseudo-second-order kinetics. The results obtained encourage the use of rOG as a high capacity alternative adsorbent material for the removal of heavy metals such as Hg in effluents from mining.