Application of New Synthesized Materials Based on Anionic Clays for Industrial Effluent Decoloration

This work reports hydrotalcite and zinc-substituted hydrotalcite (MeAlLDHs) anionic clays as novel catalytic formulations for some environmental applications regarding specific industrial coloured effluents. In this context, layered double hydroxides, covered or with tailored compositions, were synthesized, characterized using advanced analytical analysis techniques (XRD, FTIR, SEM) and tested in specific environmental applications. More specifically, LDHs samples were tested as catalysts for different treatments of coloured effluents, especially some advanced oxidation processes (i.e. heterogeneous advanced oxidation processes with H2O2 of Orange 16 dye-containing effluent). The influence of some operating factors such as catalyst type, concentration of hydrogen peroxide, presence of ferrous ions or UV light, contact time was studied, and the adequate operating values were established. Results show that Orange 16 removal is more than 70%, in specific operating conditions, for two of new tested materials (ZnAlLDH 3:1, and MgAlLDH 3:1). Moreover, the action of UV radiation was found efficient in decomposition of Orange 16 dye in the presence of all four tested catalytic materials, improving with more than 40-50% the color removal.