ZnCr-LDHs with dual adsorption and photocatalysis capability for the removal of acid orange 7 dye in aqueous solution

Abstract

This study aims to explore the potential of layered double hydroxides (LDHs) materials for the treatment of contaminated waters by organic pollutants, using a combined dual process, namely adsorption-photocatalysis. A series of LDHs of ZnCr-X where (X = Cl, SO4 and CO3) were synthesized and characterized by several techniques such as DRX, FTIR, BET, TEM, and UV-Visible spectrophotometry. The pollutant acid orange 7 (AO7) is efficiently adsorbed on the surface of the three LDHs. The adsorption depends on the nature of the intercalated anion. The adsorption percentage of AO7 achieved for the intercalated anions SO42-, CO32- and Cl−, was 25, 32 and 49.5% respectively. We find that ZnCr–SO4 LHD is the most effective photocatalyst for AO7 dye decomposition in the UV and visible range and its photocatalytic activity is preserved during three cycles of photocatalytic tests. Such remarkable properties allow considering ZnCrSO4-LDH as a promising photocatalyst with high activity, long-term durability and excellent applicability.

Keywords

• Layered double hydroxides
• Anions exchange
• Adsorption
• Photocatalysis
• Acid orange 7 dye