CETMIC   05378
CENTRO DE TECNOLOGIA DE RECURSOS MINERALES Y CERAMICA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Use of modified montmorillonite for the oxidation of aqueous sulfide
Autor/es:
M. CASTRO; M. FERNANDEZ; R. LAGO; R. M. TORRES SÁNCHEZ
Lugar:
Dresden
Reunión:
Conferencia; MECC14 7th MID-EUROPEAN CLAY CONFERENCE; 2014
Resumen:
Sulphur compounds are originated from industrial activities of man as well as from natural sources such
as volcano eruptions, thermal springs and bogs. Concern for the environment and applicable regulations
preclude the discharge of such sulfide-containing water to rivers, lakes or estuaries. For wastewater
streams containing relatively large amounts of sulfides, it is conventional to contact them with acid and large
amounts of steam to drive off, e.g., H2S gas. This gas is recovered and converted, to elemental sulfur. The
implementation of this procedure is costly and became uneconomical when only small amounts of sulfur
are present in relatively large currents. Consequently, there has been a considerable interest on developing
efficient and low cost systems for the removal of sulfide from gas and aqueous phases. Among low-cost
adsorbents Clay minerals present adsorptive properties and some modifications would improve them.
In this work, montmorillonite (Mt) was chemically modified by the addition of dextrose (Mt-Dex) or sucrose
(Mt-Ac) and further thermal treatment at 180 ºC for 6 hs. For comparison effects, a commercial carbon was
used as reference and Mt-Ac samples were prepared with different amounts of sucrose (from 25 to 90%). The
modified Mt and the raw material were characterized by total surface, XRD and zeta potential determinations.
The doped Mt shown three times higher sulfide oxidation capacity compared with the other materials. It
seems that source of carbon used to dope the Mt, do not affect sulfide oxidation capacity. However the
amount of carbon directly increases the sulfide oxidation capacity of the materials. An interesting feature of
the samples doped with high amount of carbon is that after a few minutes of the start of reaction, the material
becomes green (typical color of long polysulfide) which suggest that samples adsorbs the polysulfide from the
solution with a reduction in the intensity of typical band. Zeta potential determinations of doped Mts showed
less negative surface charge values than MMT. The XRD patterns for both Mt-Ac and Mt-Dex samples shift
the d001 reflection 0.22 nm, respect to that of Mt, indicating the Carbon incorporation in the interlalyer. The
chemical modification of the Mt by carbonization of sugar derivate introduced surface oxygen groups, which
strongly improved the activity for sulfide oxidation