Improving thermal stability and light fastness of Acid Red 114 by incorporating its anions in a ZnAl-layered double hydroxides matrix

Incorporation of anions of Acid Red 114 dye (1,3-naphthalenedisulfonic acid, 8-[2-[3,3′-dimethyl-4′-[2-[4-[[(4-methylphenyl)sulfonyl]oxy] phenyl]diazenyl] [1,1′-biphenyl]-4-yl]diazenyl]-7-hydroxy-, disodium salt) (denoted as NPDA) into ZnAl-layered double hydroxides (LDHs) has been carried out by an anion-exchange method in an effort to improve their thermal stability and light fastness. After intercalation of NPDA anions, the interlayer distance of the LDHs increases from 0.87 to 2.18 nm, confirming their incorporation into the interlayer galleries of the LDHs host. Infrared spectroscopy and thermogravimetric analysis revealed the presence of host–guest interactions between LDHs layers and NPDA anions. The thermal stability of NPDA and ZnAl–NPDA–LDHs was compared by thermogravimetric-differential thermal analysis, UV–visible spectroscopy and infrared spectroscopy. It was found that the thermal stability of NPDA anions was markedly improved by incorporation into the ZnAl–LDHs matrix, while the light fastness was also enhanced.

TG–DTG–DTA curves of ZnAl–NPDA–LDHs.Figure optionsDownload as PowerPoint slideHighlights
► Acid Red 114 (NPDA)-incorporated ZnAl-LDHs were prepared by anion-exchange method.
► Intercalation of NPDA into LDHs significantly enhances its thermal stability.
► NPDA-incorporated ZnAl-LDHs has better light fastness than NPDA.