Abstracts Book - IMRC 2018

• SF5-P104
EFFECT OF pH AND SACRIFICIAL AGENTS IN THE
PHOTOREDUCTION OF Cr 6+ USING VISIBLE LIGHT AND CdS
Luz Amparo Hernández Carabalí 1 , Luis Lartundo Rojas 2 , María de Los Ángeles Mantilla
Ramírez 1 , Jose Escobar Aguilar 3
1 Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada, Legaría, IPN, Posgrado en
Tecnología Avanzada- Fotocatálisis, Mexico. 2 Centro de Nanociencias y micro y
Nanotecnologías del IPN, Laboratorio de espectroscopia de fotoelectrones emitidos por rayos
X, Mexico. 3 Instituto Mexicano del Petróleo, Instituto Mexicano del Petróleo, Mexico.
Hexavalent chromium is a carcinogenic and toxic heavy metal ion present in
wastewater; is used in many industrial applications, being considered by the
World Health Organization (WHO) as one of the most toxic metals in the nature
[1] . The heterogeneous photocatalysis is an effective, simple, clean and cheap
way to convert Cr +6 to the less toxic trivalent form. In this study, CdS with band
gap value of 2.1 eV was employed for the photoreduction of Cr 6+ , irradiated with
low intensity (30W) visible light. The CdS photocatalyst (0.025 g) was tested in a
first step at room temperature, using a solution of K 2 Cr 2 O 7 (30 ppm of Cr 6+ ) as
chromium source and citric acid as sacrificial agent. The evolution of the
photoreduction of Cr 6+ to Cr 3+ was measured by UV spectrophotometry,
following a known method for water analysis for the measurement of
hexavalent chromium in natural waters, saline waters, wastewaters and treated
wastewaters [2,3] and a calibration curve previously plotted. It was observed that
the pH value of the medium has a significant influence on the efficiency of Cr 6+
photoreduction, reaching the best photoreduction behavior at low pH values:
100, 73.4, 58.6 and 0.0 % at pH=1.34, 1.99, 5.60 and pH 8.40, respectively. This
result was improved when citric acid (CA) was added as sacrificial agent to the
reaction medium.
Acknowledgment:
The Coautors are grateful to CONACyT México and the Institutional Training
Program for Researchers (PIFI) for the scholarships and grants that support this
research.
Keywords: Cr6+ photoreduction, Photocatalyst, CdS
Presenting authors email: luam30_09@hotmail.com