Abstracts Book - IMRC 2018

• SF2-P017
COMPARATIVE STUDY OF THE PHOTOCATALYTIC RESPONSE OF
METHYLENE BLUE BY DIFFERENT SEMICONDUCTOR OXIDES
A. C. Gómez Monsiváis 1 , M. de la L. Olvera 1 , A. Maldonado 1
1 Centro de Investigación y de Estudios Avanzados del IPN - CINVESTAV, Electric Engineering,
Mexico.
Water pollution is a problem that has been increasing over time without better
treatment techniques. They require innovative processes that ensure a higher
percentage of elimination or degradation of contaminants, such as dyes (like
methylene blue, MB), which may contain very stable species that are difficult to
treat with conventional methods. The most implemented techniques are
filtration, electroflocculation, inverse osmosis, etc., however, they are not
efficient enough. Advanced oxidation processes (AOP) are a set of techniques
that allow the elimination and degradation of water pollutants through the
generation of reactive species (OH and O 2 - ) that by acting with the pollutant, they
can generate species that are less harmful to humans (mostly CO 2 and H 2 O).
Heterogeneous photocatalysis belongs to the AOPs, allows the use of different
photocatalytic materials such as TiO 2 , ZnO, SnO 2 , WO 3 and others, to improve
the degradation activity of the contaminant. It is possible to carry out the
deposition of these materials in the form of a film by different techniques such
as sol-gel, PVD evaporation, pyrolysis spraying, among others. The sol-gel
technique is less expensive compared to physical techniques, it can be applied
to large areas, in addition, similar and even better ones properties can be
obtained for the photodegradation process. In this work we present the
deposition of TiO 2 , SnO 2 and ZnO films by means of the sol-gel dip-coating
technique and its photocatalytic activity through the degradation of methylene
blue (MB), analyzing the effect of the thickness (100, 200 and 300 nm). Using
profilometry and scanning electron microscopy (SEM) the thicknesses was
confirmed. The degradation measurements were realized every 30 minutes
(0.5h - 2.5h) with UV irradiation. By the XRD diffractograms and the Scherrer
equation were calculated the crystal sizes (below 25 nm for all materials) and
the crystallographic phase. Complete degradation of MB was accomplished
after 150 minutes for ZnO samples.