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

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

NEW JOURNAL OF CHEMISTRY

ROYAL SOC CHEMISTRY

Año: 2018

1144-0546

In this work, a mesoporous nanocast carbon prepared using SBA-15 as template was modified by surface oxidation to produce unique catalysts for sulfide oxidation/elimination from the aqueous medium. Different characterization techniques (BET, SEM, Raman, FTIR, potentiometric titration, elemental analyses, cyclic voltammetry) showed that treatment with concentrated HNO3 at 80 oC 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 small effect on surface area (1080-1148 m2g-1) and pore volumes (micropore 0.17-0.20 cm3g-1 and mesopores 0.36-0.50 cm3g-1). These materials showed high activities for the oxidation of sulfide in aqueous medium forming polysulfides, e.g., S22-, S32- and S42-, 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.