Synthesis and characterization of a UV absorbent-intercalated Zn-Al layered double hydroxide

Zn-Al-layered double hydroxides (LDHs) containing the organic anion of 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid (HMBA), a highly efficient UV absorber, have been synthesized by reaction in air of HMBA with an LDH-carbonate precursor obtained by a process involving separate nucleation and aging steps. The structural properties, photo- and thermal stability of the resulting Zn-Al-HMBA-LDHs were characterized by PXRD, FT-IR and UV-visible spectroscopy and laser particle-size analysis. The results obtained indicated that Zn-Al-HMBA-LDHs synthesized by this method were relatively highly crystalline and had a narrow distribution of particle size. Intercalation of HMBA in the LDH interlayer galleries resulted in an enhanced photo- and thermal stability without affecting its UV absorption capacity; this shows that the hybrid HMBA-LDH phase has potential applications as a UV absorber.