SYNTHÈSES, CARACTÉRISATIONS ET APPLICATIONS D’ARGILES ANIONIQUES DU TYPE HYDROTALCITE A LA DÉPOLLUTION DES EAUX

Abstract

In the present work, three materials type layered double hydroxides «LDH» (ZAF3-HT, ZA3-HT and ZA4-HT) were synthesized and followed by heat treatment at 500°C (CZAF3, CZA3 and CZA4). The materials were characterized by several technics. The prepared materials were used to remove organic pollutants (industrial dyes) from water via two different processes: adsorption and heterogeneous photocatalysis. The investigations were related to the influence of the parameters governing the adsorption of the anionic dyes of textile industry indigo carmine and green Bezanyl-F2B from aqueous solutions in particular the kinetic, concentration of the solution, pH effect, sorption isotherms and temperature. The removal of the dyes by adsorption process showed that the adsorbed quantities by the calcined materials are much higher than those obtained by LDHs phases. Furthermore, the regeneration of CZAF3, CZA3 and CZA4 showed their stability for at least two thermal cycles. The second type of treatment is the heterogeneous photocatalysis. The CZA4 material was used as photo-catalyst to enhance the degradation of the following cationic dyes: Rhodamine B (Rh-B) and crystal violet (CV). In the presence of CZA4, the dyes were completely discolored and degraded after 90 min of exposition to ultraviolet (365nm) and solar radiations. The discoloration rate by direct photolysis was less than 28% under the same conditions. The reusability study of CZA4 showed a good stable efficiency after four uses under ultraviolet and sunlight radiation.