Surface modified mesoporous nanocast carbon as a catalyst for aqueous sulfide oxidation and adsorption of the produced polysulfides

BARRERA, DEICY; DE MENDONÇA, FERNANDA GOMES; DE CASTRO, ARTHUR HENRIQUE; DE MESQUITA, JOÃO PAULO; LAGO, ROCHEL MONTERO; SAPAG, KARIM

NEW JOURNAL OF CHEMISTRY

ROYAL SOC CHEMISTRY

Lugar: CAMBRIDGE; Año: 2018

1144-0546

In this work, a mesoporous nanocast carbon prepared using SBA-15 as a template was modified by surface oxidation to produce unique catalysts for sulfide oxidation/elimination from an aqueous medium. Different characterization techniques (BET, SEM, Raman, FTIR, potentiometric titration, elemental analyses, cyclic voltammetry) showed that treatment with concentrated HNO3 at 80 1C for 5, 15 and 30 min attacks the carbon structure creating different oxygen surface functionalities in concentrations varying from 0.4?1.1 mmol g_1 with a small effect on the surface area (1080?1148 m2 g-1) and pore volumes (micropore 0.17?0.20 cm3 g_1 and mesopores 0.36?0.50 cm3 g-1). These materials showed high activities for the oxidation of sulfide in an aqueous medium forming polysulfides, e.g.,S2-2, S3-2 and S4-2, which are rapidly eliminated from the aqueous medium. These results are discussed regarding efficient sulfide oxidation at redox surface oxygen sites leading to the formation of higher polysulfides followed by adsorption of these relatively large and more hydrophobic molecules into the mesopores.