NUNES, R. A.; http://lattes.cnpq.br/9171908740383059; NUNES, Raquel Araújo.
Résumé:
Among the electrochemical processes used in the electrolytic production of chlorine
(Cl2) and caustic soda (NaOH), diaphragm technology is the most widely used in the
world. For a long time, asbestos was the main material used in the manufacture of
diaphragms, but its use was gradually banned due to its toxicological effect on the
human body. Polymeric diaphragms have been developed to replace it. Although there
are commercially available polymer diaphragms, their applications are limited because
they present high market costs. In addition to polymeric materials, it is necessary to
use clays and oxides in their preparation in order to reduce the permeability of the
diaphragms. This work aimed to develop polymeric diaphragms and compare them
with the Tephram® commercial diaphragm. Eleven diaphragms doped with three
types of attapulgite clays and zirconium oxide were developed. The clays were
submitted to the following characterizations: X-ray diffraction (XRD), X-ray
fluorescence by dispersive energy (XRF) and particle size analysis by laser diffraction
(GA). Doped polymeric diaphragms were characterized by thickness, permeability and
resistivity measurements. The results showed that the Basf and Brazil Minas
atapulgites had the smallest diameters and a wide distribution of the particle size, the
Basf atapulgite showed the highest concentration of MgO and CaO, and higher purity
being present only the crystalline phases of the atapulgite and the quartz in its
composition, and the diaphragms studied in this work with 75% of atapulgite clay
presented the best results. The obtained results showed that the diaphragms studied
in this work with 75% of atapulgite clay presented the best results. Among these, the
D4 diaphragm with 75% attapulgite Basf presented results closer to Tephram®
obtaining a soda concentration of 15,36 g/L and the lowest content of sodium chlorate
in the cell liquor (0,33 g/L).
