Luminescence of rare earth 3D hydroxide framework Eu3+-doped and its application in dye adsorption tests

Rare-earth three-dimensional hydroxide frameworks ((Yb1-xLnx)3O(OH)6Cl.2H2O) were synthesized according to a previously published procedure, without modifications. The study of the structural behavior of these compounds against doping with Eu3+ ions showed that the replacement of 20% of Yb3+ by Eu3+ led to the formation of a lamellar structure. The maximum percentage of Eu3+ that can be included in the doping of the three-dimensional structure is 19%. Isophthalate was used as a luminescence sensitizer for the compounds and increased the quantum yield to 107 and 46% for the starting samples, doped with 10 and 20% of Eu3+, respectively. The lifetimes were adjusted to second order exponential decays for all samples, indicating the existence of two emitting centers. Samples were tested as adsorbents for methylene blue and methyl orange dyes in water. None of the samples showed positive results for the adsorption of methylene blue. For methyl orange, the lamellar sample showed promise. In preliminary tests, 10 mg of this sample managed to adsorb 70% of the dye present in 10 mL of a 10 mg L−1 methyl orange solution.